ABS TRACT AN EXPERIMENTAL MEASUREMENT OF COSMIC-RAY MUON SCATTERING BY ALUMINUM, IN THE MOMENTUM REGION OF 1.60 Bev/c by Ronald Wilbur Beery An account is presented of an investigation into the scattering behavior of (1.60 + 0.05, - 0.04) Bev/c p+ mesons from cosmic rays. The muons were allowed to traverse a spark chamber triggered by a counter telescope. The alums inum plates of the spark chamber provided the scattering material for the incoming muons. A description of circuits and equipment developed for this experiment is presented. ‘Momentum selection was made by using a lead absorber to slow muons having the above momentum, stopping them in a scintillation counter. Final selection of events required observation of a proper‘p-e decay signature in oscilloscope photographs made of the signal from the stopping scintil- lation counter. The oscilloscope display was also arranged to distinguish between protons, pions, and the desired muons. This served as a method of eliminating the former two types of events from the muon data. As a further verification of the particle selection, the apparent muon lifetime was measured and was in excellent agreement with the accepted value. The narrow limits of momentum obtained and the posi- tive particle-identification procedure represent an im— provement over previous cosmic-ray experiments of this kind. The track photographs obtained were measured on semi-automatic scanning equipment, the output of which was analyzed by a computer program developed for this experiment to determine the scattering angle of the particle in the chamber. Details of this analysis program are presented. The results of the scattering measurements, in the form of an integral distribution of projected angles, are compared with the distributions predicted by the theories of Moliere, of Cooper and Rainwater, and of Drell and Schwartz. Details of the computer calculations required for the theoretical predictions are also presented. The results of the present experiment demonstrate agreement with both the theory of Cooper and Rainwater and of Drell and Schwartz throughout the range of scattering angles observed: 0 - 4.5 degrees. This range corresponds to momentum transfers up to 190 Mev/c. Good agreement with Cooper-Rainwater and somewhat better agreement with Drell- Schwartz rather than with Moliere is clear. This experiment does not display the excessive appearance of high—angle scattering reported in early cloud chamber experiments with cosmic-ray muons. This experiment, using cosmic-ray muons, corroborates the results of the recent experiment performed by Masek et al., with 2 Bev/c muons obtained from the Bevatron. AN EXPERIMENTAL MEASUREMENT OF COSMIC RAY MUON SCATTERING BY ALUMINUM, IN THE M MENTUM REGION OF 1.60 Ecv/c By Ronald Wilbur Bcery A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Physics and Astronomy 1966 ACKNOWLEDGMENT I wish to acknowledge my appreciation to Professor Joseph Ballam for his suggestion of the problem and direction in the early stages of the work. I am grateful also for his interest and willingness to continue the responsibility of seeing the work completed even after his transfer to Stanford University. The valuable suggestions and advice of Dr. John Scandrett during the construction of the spark chamber equipment are acknowledged. I am also grateful to the many professors and staff of the Department of Physics who have given encouragement during the long—term construc- tion and operation schedule of a cosmic—ray experiment such as this. With regard to construction assistance I am indebted to the late Mr. Charles Kingston and to Mr. Richard B. Hoskins as well as the entire staff of the machine shop for their counsel and assistance in the design and mechan- ical construction of the experimental apparatus. I am also indebted to Mr. Ernest F. Brandt and the staff of the elec- tronics shop for their assistance in constructing the electronic equipment necessary to the experiment. My thanks go to Mr. William M. Patmos and to Professor David Marker for their assistance in the early stages of the computer programming for the data analysis and the theory calculations respectively. 'My thanks also go to Mr. Michael Yarnold who, as an undergraduate, headed up my film-scanning staff, and to the other students on the scanning staff for their interest and help in the work. ii I wish to express finally my appreciation to my wife Alice for her patience and encouragement throughout the work and for her efforts in typing the manuscript and final copies of this work. The construction and operation of the apparatus for this experiment were made possible by a grant supported by the National Science Foundation. iii TABLE OF CONTENTS ACKNOWLEDGMENT TABLE OF FIGURES I. INTRODUCTION A. Background of muon investigations B. Motivation for the present experiment 0. Approach of this experiment II. EXPERIMENTAL.APPARATUS A. General description B. Spark-chamber system C. Counter—telescope system D. Automatic photographic system E. Stopping-pulse display system F..Analysis system III. ANALYSIS PROCEDURE A. Analysis of oscilloscope photographs 1. Types of events identified 2. Lifetime study B. Analysis of track photographs C. Data reduction IV. THEORETICAL PREDICTIONS A. The Cooper-Rainwater calculation B. The Moliere calculation C. The Drell-Schwartz calculation V. RESULTS AND CONCLUSIONS A. Discussion of experimental uncertainties B. Comparison of observed scattering with predicted values C. Summary and conclusions APPENDICES A. Spark—chamber system B. Counter—telescope system C. Modification of Tektronix 517 oscilloscope for 1ij-e display iv Page ii vi oo O\O\l—' I—‘ 78 84 89 Page D. The automatic-camera system 95 E. Momentum determination 101 F. Program "Spark" 105 G. Calculation of theoretical multiple- scattering distributions 126 REFERENCES 155 TABLE OF FIGURES Figure 11-1 II-la 11-2 11-3 II-n II-5 III-l V-l V-2 A-l B-l B—la D-l Block diagram of experimental arrangement Detail of scattering apparatus Overall view of apparatus Close-up of spark chamber Close-up of coincidence circuit Characteristic Oscilloscope trace, showing‘p-e decay signature Normalized plot of lifetimes for 1280 events Results from 100 "doubles" events Normalized integral scattering distributions Spark-chamber circuit diagram Coincidence-circuit diagrams Page 10 ll 12 16 20 26 #1 71 75 83 87 Coincidence-circuit diagrams (cont'd) 88 Circuit diagram of primary modifications to 517 oscilloscope Camera-circuit diagram and diagram of optical geometry of experiment vi 9h 98 I. INTRODUCTION A. Background of muon investigations The characteristic properties of muons have in recent years been the subject of considerable interest among those working in particle physics. The following characteristics measured in these muon investigations are of interest here: 1) Muon mass found to be 206.767 1- 0.00321 times that of the electron. 2) Muon mean lifetime found to be 2.2001 1 0.008 usecondszz. 3) Yb - 7e distinction. In an experiment by Danby, et al.,23 it was demonstrated that the muon has its own neutrino, quite apart from that assoc- iated with the electron. This was concluded from the fact that neutrinos, produced by"nfip decays and allowed to interact subsequently with protons, caused the appearance of numerous muons but no observed electrons. This provided an answer to the problem of the forbiddenness of the decay mode .P+‘—I e+ +I', Of particular interest are other characteristics in which the muon displays a high degree of similarity to the elec- tron. The following are of interest here: 1) Muon charge found to be 1.00002 1 0.0000412292l times that of the electron. 2) Muon-electron similarity in weak interactions. 1 2 A value for the P- + p capture rate has been calculated24 using the observed rate of neutron decay (an electron-producing process) to evaluate the required constants. This calculated rate is in good agreement with the capture rates measured with both bubble chamberszsa26 and counters27928. 3) Muon-electron similarity in electromagnetic interactions. a) Measured value of gP = 2(1.001162 i b) 0.00005)192:29. This measured value gives a comparison ratio gP/ge = 1.000001 1 0.000005. Thus the muon is a spin % particle, obeying Fermi-Dirac statistics as does the electron. Comparison of e-p ande-p scattering. Extensive work on electron scattering by protons as well as by various nuclei has been carried out by R. Hofstadter30, D. G. Ravenshall3l, L. N. Hand et al.,32 and J. R. Dunning, Jr. et al.,33 among others. Work witth-p scattering is more recent, having been carried out notably by H. F. Davis et al.,3h and R. Cool et al.35 The latter work presents a detailed comparison between e-p and‘p-p scattering, with the conclusion that there is no observable difference throughout momentum transfers ranging from 450-1100 Mev/c. 3 It has seemed on the basis of these results that the muon may be described by essentially the same theo- retical formulations as have been developed for the electron. Results of scattering experiments of muons upon atomic nuclei, however, have not always been in agreement with the above results, particularly when compared with the e-p,‘p-p similarity cited above. Discrepancies were first noted in the behavior of muons obtained from cosmic rays, which, of course, were the original sources for these particles. For higher energies, where the momentum exceeds 600 Mev/c, excessive scattering contributions-—particu1arly at higher angles-—have been reported by a number of cosmic— ray researchers, beginning with the first systematic search for this effect by Amaldi and Fidecaro in 19503. Outstanding among the experiments since 1950 is the work of Whittemore and ShuttL’ in 1952 with 0.3—3 Bev/c muons, McDiarmid5 in 1954 with 0.2-4 Bev/c muons, Lloyd and‘Wolfendale6 in 1955 with 0.6-10 Bev/c muons, and Lloyd, Rossle and‘Wolfendale7 in 1957 with 5—.50 Bev/c muons. Without exception their results show high-angle scattering in excess of that pre- dicted by theories based on a nuclear-charge distribution of finite extent. The fact that the muon-scattering results between 1950-58 seemed to agree more nearly with the Molierelo "point-charge nucleus" theory than with the "finite-nucleus" theories advanced during that time was not taken to imply that the nucleus was acting in fact as a POint charge, but rather as suggesting either a deficiency 4 in the theory or that the muon has some mode of interaction not covered by the "finite-nucleus" theories. An increasing anomaly for greater momenta was not found to occur in an experiment by Lloyd and'Wolfendale7. Also a short-range interaction with nucleons was not indicated, since the amount of large-angle scattering in light elements is much less than would be expected from the cross section per nucleon obtained from muon-scattering results for leadz. "Finite-nucleus" theories with which the experimental results have been compared include primarily those of Olbert8, of Cooper and Rainwaterg, and of Drell and Schwartzl7. Olbert's theory is a modified version of the Molierelo theory, where the finite extent of the nucleus is accounted for by forcing the single-scattering law to be 55 0 for scattering angles greater than a cutoff angle 0,. The Olbert theory provides an underestimation of large-angle scattering whereas the Moliere theory provides, of course, an overestimation of scattering in this region. The Cooper-Rainwater theory using the same general approach represents a more accurate treatment of the effects on the scattering to all angles due to a nucleus of finite extent. The Drell-Schwartz theory, however, approaches the problem by developing a sum rule which yields the scattering dis- tribution resulting from both inelastic and elastic scat- tering. This sum rule is particularly useful since it does not require knowledge of the complicated final-state wave functions associated with the final excited states in which the scattering nucleus may be found. A knowledge of the 5 ground-state wave function is sufficient. The experiments conducted previous to 1959 were plagued by several serious limitations, typical of cosmic- ray work during that period, which included: 1) poor statistics at large angles, caused by the slow data-gathering capability of cloud chambers 2) measurement errors in determining particle momentum and/or deflection angles 3) contamination of results by events involving particles other than muons, pions being the major concern. An experiment by Fukui, Kitamura, and Watasell in 1959 with 1 Bev/c muons gave results consistent with the Cooper-Rainwater theory. This experiment though showing a degree of improvement in some of the above areas was shown to be inconclusive by Lloyd and Wolfendale12 in 1960, primarily because of uncertainties in momentum determination and in particle identification. To fill the need for a conclusive experiment on this subject Masek, Heggie, Kim and‘Williams13 performed an experiment with the Bevatron at Berkeley using 2 Bev/c muons obtained from decay of the pion beam. Scattering was done both in lead with momentum transfers up to 265 Mev/c, and in carbon with momentum transfers up to #00 Mev/c. .A total muon flux of 2.5 x 107 particles was obtained in the experiment. Mbmentum spread was not more than i 3.5 6 percent, and the fractional contamination by pions was of the order of h.9 x 10‘5. The scattering in lead was com- pared with the predictions of the Cooper-Rainwater theory and excellent agreement was found. The scattering in carbon was compared with the predictions of the Drell- Schwartz theory and again excellent agreement was found. Thus the question appeared settled, for machine—made muons at least, that no anomalous scattering exists. B. Mbtivation for the present experiment There remained a need, however, for a cosmic-ray experiment to demonstrate conclusively whether the anom— alous scattering observed by so many cosmic-ray workers was indeed due solely to the inaccuracies encountered in the three categories listed above. Such an experiment should provide significant improvements in each of these three difficult areas. The present experiment was designed to fill this need by applying the capabilities of a number of recently—developed research tools to a cosmic—ray scattering investigation. C. Approach of this experiment The approach of this experiment was first of all to utilize a spark chamber to replace the cloud chambers used almost exclusively for cosmic-ray work in the past. This allowed a greater rate of data collection and greater accuracy of angle measurEment. Plastic scintillation cubunters were used in place of the trays of Geiger— Phleller tubes common to cosmic-ray work. These provided 7 a significant improvement in the momentum determination and made possible the type of particle identification technique developed for this experiment. This technique provided for, among other things, direct observation and removal from the data of pion events seen. Also computer- programmed scattering-angle calculations developed in this experiment replaced the hand deflection-angle measurement methods previously employed. Thus significant improvements have resulted in areas (2) and (3) above. Some improvements were made in (l), with further improvement available in this area upon continued pursuit of the method of this experiment. II. EXPERIMENTAL.APPARATUS A. General description The apparatus for this experiment consisted of an aluminum-plate spark chamber located in a cosmic-ray counter telescope, which was composed of three scintil- lation counters: an aperture counter, a stopping counter, and an anticoincidence counter. The three-channel coin- cidence system provided a mode of event selection which required double coincidence between the first two counters and anticoincidence with the third. The output of the coincidence circuit then triggered the spark chamber. The visible track formed in the spark chamber was recorded on 35mm film by a motor-driven camera which automatically advanced to the next frame after each spark~chamber event. In addition, the pulse from the stopping counter was displayed on a fast oscilloscope and photographed by a second automatic camera, synchronized to the first. This provided a simultaneous photograph of the stopping pulse corresponding to each chamber event selected by the coincidence system. In view of the low rate of data collection inherent iJI this experiment, the apparatus was designed to be fully au1tomatic in its operation. Use of lOO—foot rolls of film III each camera allowed eight-hour periods of operation before film changes were required. 8 9 The data was analyzed with the help of the follow- ing basic items of equipment: 1) A Gilliland motorized film-projection machine on which the oscilloscope film was scanned for event selection, 2) A Hydel digitized film scanner tied to an IBM 526 3) summary card punch by which the coordinates of each spark in the chamber photograph of a given event were digitized and punched on IBM cards for processing, The Michigan State University Control Data Corporation--3600 computer by which all calculations upon the raw data were performed. OH szzmwz53 32332.8 1 A. m l we... 23 N- :5 31:5 ‘ “a .p - 295.4% . .3 uu53 93,. .8 H35 3 _ >33 . - “coon “.55 r585 ~32 Em .. 3225 $2.5 .‘!x .1- ->- \ >< Id “a 6 gal—'8 kW“ 5‘ In! ‘ \ 9...; “5.5; W“ 3.53 .2. 7 .. .. 2. a 3 1 >2 «3.35 .5; new? biz. 5.... a 52% uz: .zurE 33:2. (52.3 :2: _|||©||w‘ 403.200 (335 <3u2 z = (0.301 psechm)d TNT-{3) t/T 2.20 JJSEC 2.302 log (No/N(t)) = (l.403/cm)d Choosing d = 20 cm for convenience, a ratio of No/N(t) = 16.60 satisfies this equation. The solid line in Fig. III—1 is drawn with this slope. Slight departure from a straight line at each extreme of the plot is due to nonlinearities in the oscilloscope sweep rate at the extremes of the trace. This came about in connection with the response time of the circuit causing the automatic change in sweep speed after the first fast trace. A best fit to the data in Fig. III-l yields a muon mean life 0.6 percent less than the accepted value of 2.201Psec21 used above in forming the theoretical curve. This is well within the estimated 1 percent sweep calibration tolerance that it was found possible to main- tain over the long term duration of the experiment. In view of the good agreement of the measured mean life with the accepted value for muons, the particle selection procedure used in this experiment is established as a satisfactory criterion for muon selection. __10-1 L'7 5 l l Figure III-1. ’C‘ =2.20pseo/' 41 (conversion to time is 0.310psec/cm.) 10 15 20 25cm. l l I l 1 l J l j Normalized lifetime plot of 1280 events selected at random from 8000 two-pulse events. B. Analysis of track photographs The muon track photographs taken in the spark chamber were measured on a Hydel scanning machine and the digitized output was punched out on IBM cards by the IBM 526 Summary punch attached to the Hydel. With this scanning-punching chain the x-y coordinate position of any point on the film frame may be recorded on IBM cards in b-digit numbers having an arbitrary scale factor but nearing a relationship to position on the film which is linear to rive significant figures. Each data card contains a ten-column heading which records the film frame number being measured, the view number ("1” for direct, "2" for stereo), card number within a given view measurement (1—5 to complete the measurements in each View), and the operator number. The remaining seventy columns are available for punching data. Since both the x-y coordinates require 5 columns on the card, totalling ten columns per point on the film, each card carries the coordinate data of seven points along the track. The position of the center of the spark in each gap along the track was recorded in this manner; there are 30 such points to be recorded in each view. In addition to these 30 points the upper and lower front corners of the main chamber, which are visible in both views, were chosen as tiducial marks. These riducial marks were used as a means of establishing both the 42 43 vertical Z axis reference direction and the scale factor pertaining to real distances in each view. This makes a total of 32 points in each view, requiring five cards per View or ten cards in all, per event. From these recorded points the complete track can be reconstructed and the desired quantities calculated using a computer program ‘written for this experiment. C. Data reduction The computer program, for which a listing is given in Appendix F, performed the following tasks upon the raw track data obtained on the Hydel scanner. 1. Sorting and geometric reconstruction a. The cards are processed ten at a time and are checked for identical frame number and sequential View and card numbers. If cards are missing or out of order, the program will cause an appropriate diagnostic to be printed, scrap that particular event and move on to the next. b. The position data of the 32 points is first converted to centimeters measured in real space. Then the coordinate points are corrected for camera parallax, using the known optical geometry of the experimental set-up. c. These data are then written on tape for permament storage. This phase of the calculations will thus never have to be repeated for subsequent runs with the same data. Nor will the original data cards again be needed, as future calculations can be made directly from the tape. 2. Performing the necessary calculations upon the data tape a. First the appropriate track points are taken from memory, from which line fits are formed 44 45 to the incoming and outgoing directions in both chamber views. There are often gaps in the chamber which do not fire in a given photograph, leaving points missing from the track data. A minimum of two points in the four gaps or the thin plate chamber and two in the first tour gaps of the main chamber is set as the criteria for acceptance of a given event for processing. A maximum of six points would be available for the line fit if all gaps in the thin plate chambers fired properly. b. Having met this criteria, a least squares line fit is made to each of the projected track segments. This line fit process yields values for the slope with reapect to the u a: is and the intercept in the x-y plane at Z = 0. c. A statistical parameter called R2 is calculated for each of the four line fits done above. This q aantity defined as _e a «t- a (m- OVEN... ,ZXL-Mr)” 2, Z. ‘MGUD #1-'1 where lg . M —.—= 2* X-‘fiélxk ‘Rd 2 mks! has values between 0 - 1.0 and is a measure of how nearly the observed points fall exactly on the least squares line. A cutoff value of R2 = 0.960 was estab- lished by correlating the values obtained for R2 with 46 the appearance of the track as viewed on the scanning screen. The event was rejected if any one of the four line fits yielded a value of R2 less than 0.960. Causes of this could be either operator error or individual spark displacements. The former was effectively eliminated by remeasuring all events rejected for too low a value of R2. A portion of the rejected events were recovered in this way. The latter are assumed to be caused by delta rays formed in a given gap. These events which pass the R2 test have their line fit parameters made available to the space angle and projected angle calculation procedUre that follows. d. Another subroutine uses the values obtained in step b. above for the slope and intercept of each track segment, to determine the azimuth angle O of both the incoming and outgoing tracks projected on the x-y plane. From the signs of the slopes, the quadrant in which each track segment lies around the Z axis in the upper hemisphere is determined. These quadrant values are in turn used in assigning the correct value of 4) to the arctan¢ , yielding values ranging from 0 degrees to 360 degrees measured counterclockwise from the positive X axis. e. The value of the apparent total deflection angle 9 present in the track is calculated in a function subroutine, by a process derived upon direction cosines. 47 f. Next the projected angle with respect to the + Z axis of each track segment is calculated from the corresponding slope parameter. A modified value of the two projected angles in the direct view is formed by correcting for the inclination angle in the y-z plane made by the top track. This is done in order than when the projected deflection angle in the direct view is calculated from the value of the projected incoming and outgoing directions, it will be indeed the deflection angle projected in every case on a plane containing the incoming direction of the particle. This formality is dictated by the nature of the statistical scattering theories with which the experimental results are to be compared. In principle this is quite different from the deflection angle projected upon an arbitrary plane, i.e., that of the front face of the chamber, which does not necessarily contain the direction of the incoming par- ticles coming in from random directions within the vertical acceptance cone of the counter telescope system. Yet since this cone has a maximum opening angle of 15 degrees or less, the correction to the calculated deflection angle required for track in~ clination amounts to only a few percent. The values of incoming and outgoing projected angles for both views are printed out on the Projected Angle Data page. Along with this are printed the calculated values of projected deflection angle in the direct 48 and stereo views and the projected deflection angle in the direct view, corrected as described above. g. A calculation of the zenith angle (with respect to the +Z axis) of the incoming track was per- formed at this point from the values found for the slope of the incoming track in each view. Vector addition of the tangents in each view was used to find the tangent of the. zenith angle. 3. Summary functions performed by the computer program a. A partitioning operation was performed upon the resulting values of ¢in, ¢out, the total deflection angle 6, the zenith angle gin, the incoming direction in the direct view (projected) Gin, and the corrected projected deflection angle in direct View 9 dir. This operation consists of having the computer take successive small increments of the quantity in question, counting and storing for each interval the total number of cases, out of each group of fifty events, that yielded a value of that quantity within each such interval. This is a valuable aid to subsequent plotting of the results in the form of distribution functions for each of the above quantities. Each interval is defined to be single-ended so as to avoid ambiguity for any resulting value of the angle. In the case of ¢ in, 49 for example, the first interval is formed by the relation 02 ¢ C 10°; the second is 10 Q ¢< 20’, et cetera, up to 360 degrees. The interval size chosen for the above quantities is 10 degrees, 10 degrees, 0.25 degrees, 0.20 degrees, 0.20 degrees, and 0.25 degrees respectively. The number of events occurring in each interval is cum~ ulative for each successive group of fifty events through- out the entire run. b. There is assembled at the end of each group of fifty events a list of frame numbers for all events rejected for having an insufficient number of spark points from which to form a line fit. c. There is also assembled at this point a list of those events rejected for R2 less than 0.960. Recovery of these events was attempted by remeasuring each such rejected event. Some 15-20 percent of such remeasured events then passed the R2 test. 4. Print-out of results The following information was printed out by the program in this order. a. Information printed out at beginning of run (1). List of events stored on tape. After storage of the data on tape, a complete list of frame numbers of all such events is printed out in groups of fifty. (2). List of frame numbers for events not placed on tape due to cards out of order 50 Within event, wrong event number on a card, et cetera. Along with each frame number will be an appropriate diagnostic statement describing the reason for deletion. b. Information printed after processing of each group of fifty events throughout the run (1). Line data page. The slopes, intercepts, correlation factors, and number of points used are listed for each of the four line fits asso- ciated with each event number. Two pages are required to list this information for fifty events. (2). Space angle data page. On this page the computed values of azimuth angle ¢ and corre- sponding quadrant are printed out for both the incoming and outgoing track. Along with this the calculated value of the projected incoming direction a‘in and of the total deflection angle 9is listed. A final column relists all values of 9 which were 1.000 degrees or more, with zeros listed for all events having Bless than 1.000 degrees. The events whose value of 9 is listed in this column have their spark position data duplicated on another tape for separate storage of all events giving high deflection angles. (3). Projected angle data page. On this page are printed the calculated values of the in- coming and outgoing projected angles for both views, the values of the projected deflection angle in each view, and the projected deflection angle in the direct view, 51 corrected for track slant as described previously. (4). First list of rejected events. A list of event numbers for events having less than the minimum number of spark points present is printed on the page following the projected angle data. (5). Second list of rejected events. A list of event numbers for events not passing the 2 0.960 test on R2 is printed on the next page. Events appearing in this list were remeasured and rerun as a group. c. Information printed at the end of an entire run (1). The last page number used in the run. (2). The total number of events processed to date. (3). The total number of events "saved" (i.e., having 9 2. 1.000 degree) to date. This information is printed out so that a total count of these quantities may be accumulated over any number of runs. This is accomplished by reading these numbers back in on a data card for the next run. (4). Also the number of events saved during this run is listed. (5). List of the frame numbers of every event having a calculated track deflection angle 9 of 1.000 degree or greater. 52 (6). Results of the partitioning subroutine upon P in, ¢ out, 9 , 9 dir. (cor- rected),akf,, 0:16 in as defined above are printed out last, using a separate page for each. A complete listing of Program Spark is presented in Appendix F. IV. THEORETICAL PREDICTIONS The data of this experiment are to be compared with the scattering theories set forth by L. Cooper and J. Rain- water9 and by s. D. Drell and c. L. Schwartzl7 for multiple scattering of fast particles by extended nuclei. These methods deal directly with the case where the scattering centers are nuclei of a known charge distribution of finite extent. This is in contrast to previous treatments of the problem, notably the Molierelo theory which assumes the nucleus to be a point charge and the Olbert8 theory which, as a first approximation to treating the extended nucleus case, assumes that the single scattering law becomes iden- tically zero for angles greater than a certain maximum angle Cg calculated from the properties of the scattering material in question. As can be inferred from the above listed assumptions, the former theory overestimates the multiple scattering at higher angles, while the latter underestimates predicted scattering in this region. A. The Cooper-Rainwater calculation The Cooper-Rainwater theory begins as does that of Moliere and of Olbert with a single scattering law which is the Rutherford scattering law, modified to account for shielding by atomic electrons. This law has the following form: tumor“) = 0/2(c92 +CPm2)‘3/2 where C? is the projected angle (Fm is the equivalent screening angle 53 54 and Q = 477 (Nt/A)[(Z/p )(eZ/mecz)(0.51l/pc‘)7a eZ/mec2 = re = 2.82 x 10'13 cm N = Avagadro's number Z = proton number of the scattering material A = atomic number of the scattering material (1’ ll thickness of the scattering material 9 = v/c :5l.for'the relativistic particles dealt with in this experiment pc = momentum in Mev. This basic single scattering law is taken as is, in the Moliere theory. In the Olbert treatment f1(4’,4’m) is taken as above for angles CPsuch than OéIU/flq’al but is set E 0 for ICPI>C,9,. The cutoff angle CPO is deter- mined from 69m by the relationship (1.67 x lQE)rg§:}{i a/rn = roAIIJ (fb/CPm _ (1.67 x 10“)(2.81a;x 10-13) ' 1.1 x lO-I3IAZL/3 _ 1 3 2 where CPm.- lslfleiflacz) Z / 1.13 + 3.76(z/137.€)2 l/ 137pc z x/a = ’hc/pca and £90 =‘fic/pcrn ='hc/pc(l.l x 10"13)A1/3 The Cooper-Rainwater theory, however, employs the above single scattering law for all angles, modified by the appearance of a form factor which also is a function of angle, thus: fIC'RM) = 0/22 + CPm2)'3/2 fiNW/aa where 5FN(CP/ZPO) = 5FN(y) is defined by 5fn = FNC + FNI 1 In the present theory §N(y)becomes Z":L instead of zero for large values of y and the functional form is known by which it reaches this value from its value of l for y = 0. The Fourier representation of the single scattering law can be written thus act-3(4) = iii/ECUeV‘? «N I’ . and g0) =-/‘fiC‘R(CP)e“]-7Q (14? From this a value for the probability of a final projected angle after any number of scatterings is given by 11(0)ch = da/27[21w e g<7>"g(°)df The quantity g(T) - g(0) = Q/2 (e170,?"1) 31K d'flflfldfl' _.. (0'2 +4m2)3/2 For the sake of convenience, the variables are transformed, following Moliere, as follows: x = (200)-249, n = (zcofif and G = -g- 1n[( XZ/e)CPm2/2GQ] 2, 24/3 A"1 t ._ 5.66 + 1.2L» log 10 [1.139 + 3.76CZ/137)Z Thus gm - em) = g<7(/<260>%> - gm E 300 Whence 8(n) = l/2E//’ a M(x) then becomes ' e/einx esc’oan After suitable integration and expansion by powers of l/2G as described in the Cooper-Rainwater paper, the following form of MCX) is obtained. 57 MC'RCX) = e'xz/W/‘f [1 + q(1,x)/t+0] + l/4GVTN(L,X) q(L,x) = 2(2x2-1) [1n(L/1.26) + {2%osth)‘1/t)dt] + 6x2 -(i/L%)\-3 T(x’,)\)d)~ L T(x,A) = exp [;(x +ql)%7 + exp [;(x-A)E]-2 expC-xz) B. The Moliere calculation The Moliere multiple scattering distribution which assumes a point nucleus,is latent in the expression: ‘ MC-R(x) = 1/21r/ei7tx e301) c171 -’ an - jI‘JCX'/X )(cosQLx')-l)dx' where 3(a) - l/2G 0 (x'3+ Xm2)3/§— The single scattering law used by Moliere was far) = 0/2 (4’2 + 42112er This differs from the one used by COOpernflainwater only by the omission of the factor 5f3(dth). Thus the Moliere scattering distribution may be obtained from the Cooper-Rainwater calculation by merely setting fNCy) = 1 —‘ 58 in the above expression for M(x). The machinery set up to calculate M(x) from the final form shown in part A above can thus be used to also calculate MM01'(X). The results of this Moliere calculation are used for com- parison purposes in discussing the results of the present experiment. C. The Drell-Schwartz calculation The data of this experiment are further to be compared with the scattering distribution predicted by the method set forth by Drell and Schwartzl7. In this method the total differential scattering cross section (elastic plus inelastic) is constructed from a knowledge of the nuclear ground state wave functions. This method considers the specific case of high energy electrons scattering from light nuclei so that the interaction may be treated in the first Born approximation. Only values of the momentum transfer [if] 5. 200 Mev/C are considered so that the nucleon recoil velocities Vrec are kept well in the nonrelativistic range ( Free ,6 1/5). In this region of momentum transfer values the dominant factors in the scattering are the Coulomb forces and the magnetic forces, viz., single-particle magnetic moment interactions. The form for the low resolution (all final energies accepted at each specified angle) differential cross section df/dn, given as equation 19 in the Drell- Schwartz paper, is dU-__ a Z 1 2 9/ —1 o __. 2%”)fi‘flfjfii’ +59%, + (25c: ( a) ) d.m [GAME/M4 T> " 7%" (2%,” W * +13 gig 4 53' '7'} MA; "I" ("i ’ 14499.7}, ,3 me (05 (94) i The term d (To/€111 = Aka slh’fl/a) ko 59 60 2.818 x 10'l3cm (classical electron radius) re me 0.511 Mev (mass of electron in Mev units) K = PC (in Mev) where P is the final momentum of the particle after scattering K0 = P00 (in Mev) where po is the initial momentum of the particle before scattering fl = total Spatial scattering angle (in radians) Note here that only through the factor reme do the properties of the electron, which was taken to be the incident particle in the Drell-Schwartz development, appear. Since, however, the classical electron radius re is defined as re = ez/meC2 = 2.818 x 10‘13cm the product reme = e2/C2 is actually independent of electron characteristics. Thus for scattering of muons no change is required in d Vo/dn. since rpmp = (eZ/mPCZ)mP = e2/C2 = reme. From the kinematics of the problem the relationship between K and K0 is l K/KO = _ 1 + 2Ko/AM sin2 0/2 This ratio is essentially unity for the present experiment since the quantity (2Ko sin2 5/2)/AM is 2.69 x 10"3 even for 9 = 17 degrees, the largest value encountered any 61 place in the calculation. The term f2(q), the proton form factor given by Hofstadter18 as 2 = - 2 The momentum transfer q, from the kinematics has the form . i q = 2Ko 310(9/2)[l + 2Ko/AM sin2(9/23‘2 = 2Ko sin( 6/2) V K/Ko Since K/Ko was shown to be essentially unity above, q is replaced by qo, the momentum transfer as a function of 6 for purely elastic scattering qO = 2K0 SID 9/2 This value of qo was used in the present calculation wherever q appears in the expression for da'/d;¢ above. For use in calculating the proton form factor above, qo must be in units of f‘l. This requirement is satisfied by using .K0 in units of PC/‘FtC where PC is in Mev and 11C is in Mev—f. The term lglq) is related to the form factor for two body correlations and is given by Drell-Schwartz as * o4 A ‘5) j(q)=Z+Z(Z-1)/¢po elq'h‘l-rzqgo’r where FCQ) is the form factor for two body correlations. In an electron scattering experiment by Chollet, Bounin 62 and Bishop19 performed at the Linear Accelerator Labor- atory of the University of Paris at Orsay, the form of F(q) for aluminum in the momentum transfer region of this experiment was found (in terms of x) to be Feed [1 -(16/39)x +(5/1559x2] e-(x/2) where x = (aq)2/2 with the quantity a, the nuclear size parameter, = 1.86 x 10'13cm according to their results. For the present experiment q may be replaced by qo in the above expressions. The terms following fan) in the above expression for the cross section represent scattering contributions due to magnetic forces and are denoted herein by finagmo). The terms infinagmo) were evaluated for the present experiment using Z = 13, A = 27, M = l3(938.256) + 14(939.552) = 938.8 Mev, q -_-’: qo 27 s (the average ground state kinetic energy per nucleon) = 30 Mev, ,pp = 2.793 nm, andlpn = -l.9l nm. The final term in the 5Fhag(qo), however, was taken as negligible since it is not expected to make any larger relative contribution than was the case in the work of Masek, et 31.? for carbon. The differential cross section obtained as above was converted to a differential scattering distribution by the following defining relationship.20 40' __ 111’.) Iii-(ma New 63 where N0 = total number of incident particles ()n = density of nuclei (nuclei per unit volume) t = thickness of target in cm. Also dn. is defined 27 sin 9d? , whence d 9/ d1; l/2T/sin 0 Using this in the above relationship yields d T/dn(NofJnt) = (dN/daxda/dm) = (dN/da)(1/2p'sin9) Thus (on/d6), = 277‘ sin9€nt(d0’/d}t.)g Now En can be written as P“ - ‘“°‘/m%;:;:“;:.:ia°m "wast: - M A where NA is Avagadro's number, (niis the mass density, and A is the atomic weight. The quantity No, the total number of incident particles, was set equal to 1.0, with the result that the quantity (dN/d 9), d9 gives the probability for a given particle to be scattered to the element of angle d9 at 9 . This facilitates the normalization of all distributions to unity, which has been the practice in this work. ‘ The above expression for (dN/da )9 is written in terms of total spatial scattering angle rather than projected angles. Since, however, both the Cooper- Rainwater and Moliere multiple scattering theories, 64 described in parts A. and B. of this section, are written in terms of projected angles, a method was developed for converting the Drell-Schwartz single scattering distribution to projected angles. This method is based on taking a conical view of the path of an incoming particle. The point of scattering defines the apex of the cone formed by a figure of revolution done upon the deflected track about an axis along the incoming direction. Azimuthal symme:ry about the incoming direction is assumed throughout. Taking such a conical view of the scattering geometry, a plane may be imagined at an arbitrary distance R0 from the scattering site along the incoming direction and perpen- dicular to it. On this plane may be imagined concentric circles about the point where the incoming direction vector pierces the plane. These concentric circles are constructed such that each i-th one has an equal incremental radius increase dri over the previous one of Rod 6? . The relative number of projected angle events occurring within d (.7 at C? were found by establishing a plane of projection containing the incoming direction vector. The contributions to the projected angle scattering distribution from the various spatial deflection angles were found by calculating the fractional area of each successive concentric ring which lies between the parallel lines in the plane of the circles, perpendicular to the plane of projection, that bound the element of projected angle d6? . For each element d6? at projected angle 47the fractional area contributions for all 97 (P weighted by the 65 scattering distribution dN/d9 evaluated ate , are summed to form the total value of (IN/d6? evaluated at (P . The resulting conversion relationship is as follows .0 (dN/dqlhy = g}, exam/<19 )9, where the sum- mation is incremented by an amount A 9 . At a given value of 9 the beginning point of the summation is at 9io = 4+ A9. Thereafter the successive terms in the sum are evaluated at 01 = C? +(i - i0 + 1)49 , where using 459 is taken to be numerically equivalent to using the quantity 4 47. The Ci coefficients represent the fraction of each concentric ring which falls within the parallel lines bounding the zone of width RodC? at angle 6? . The first coefficient C10 arises from an area which is a segment of a circle and is bounded at 91=CP tnra chord of the circle as it bounds the element A4) and at I9 = C? +467 by the arc segment which is tangential to the remaining boundary of dfl. The area of such a segment is found from geometry to be given by 310 = %r210 (2 Yb" sinZ [10) where {10 is the angle in the plane of the rings measured in either direction from the projection plane around to the intersection of the lower boundary of 44’ with the outside of the io-th ring. From the above definition Yio is given by I (up _ )9, may _ 10.0 3 -arcos r4; - arcos Fraud: - arcos true, ‘64»? ‘t«(&P+A€P) 3‘ BFCDS 66 There are two identical area contributions such as that above, symmetrically placed about the incoming direction vector. Thus the fractional area coefficient Cio = 34;, (ii/F WCJQ‘SMJX‘SZJ A..- ”1.0-1 7[’:‘03 _ 6:. '1 a] tan"1 9;, (.1 )2, ~5/n 1);") 7666151494" ‘ t4”’€;.1) .1 To form the remaining terms in the summation Xio 1s generalized to Y1 = arcos 61) = arcosaznni.) = arcosftdhgo/ a I t‘h(294(zage04uéy In all cases of 1) 10 the area contributions di were approximated by a parallelogram whose area is given by a. c[cascP(R¢)AC}_’]L-€r—j—:5: (R6; 49)] where R4: RO/cosd, Roi = Ro/cos 91, and [49’ is taken equal to [4?] . Thus (11 becomes __ MACH: 4" " sin )5; It is apparent that rather than two there are four such area segments in the i-th ring symmetrically placed around the incoming direction vector. The fractional area coefficient Ci then is .1 44, _ 4140/ R3 ’FL- Fla-1 “mange”, tang) 5;? 67 The values of Ci thus calculated, together with the values of dN/da , were then used to form the sum defined above for each value of (,7 at which a value of (dN/dCP )6, was desired. The upper limit of the summation is set at 0° ; in practice, however, this series converges very rapidly since (dN/da )9 decreases by five orders of magnitude by about 14 degrees. 01 also decreases monotonically for larger angles. The set of values for (dN/da)“; obtained as described above constitutes a series of points on the differential scattering distribution for projected angle single scattering. In order to be directly com- parable with the results of the Cooper—Rainwater cal— culation and those of the experiment, it is necessary finally to make a multiple scattering correction to this single scattering theory. This was done by cal- culating the function g(y), the differential distribu- tion for single scattering from an extended nucleus developed in the Cooper-Rainwater paper9. : .J_- 2 2 '3 2 saw) 230' + ym ) / fimy) where B = Q/ 002, y = (“P/CPO or x/xo, and ym =Ctom/CPO. 0, ($0, 61m, x, and :T&(y) were defined in part A., of this section. A ratio of multiple to single scattering probability from Cooper-Rainwater was then formed by dividing'MC’R(y) by g(y). This ratio was formed for each of the 260 values of y for which values of MC-R(y) and g(y) are obtained during the course of the computer 68 calculation. This set of ratios was then employed as a correction factor to the Drell-Schwartz projected angle distribution obtained as described above. The Drell-Schwartz distribution, corrected for multiple scattering is plotted in integral form in Fig. I"? along with the theoretical distributions of Moliere and Cooper-Rainwater and the results measured in the present experiment. Appendix G gives a review of the computer program, written in CDC-3600 Fortran, by which each of the theoretical predictions described above was calculated. V. RESULTS AND CONCLUSIONS A. Discussion of experimental uncertainties Experimental uncertainties are present in the meas- ured values of the scattering angles determined for each muon event represented in the data here reported. These arise in two general areas: 1) failure of the track, made visible by the series of spark discharges in the chamber, to lie exactly along the original path of the particle 2) inability to transfer with complete exactness the coordinate positions of the series of sparks com- prising the visible track to IBM data cards to be used by the analysis program. The major cause of (l) is taken to be a random displacement of individual sparks in the track due to the secondary ion- ization effects in the helium atmosphere of knock-on elect— rons. This effect results in a "scattering” of the points along the track which in turn causes an apparent scattering angle in the observed track not caused by any real physical scattering phenomenon. This apparent scattering is often referred to as "noise level scattering". The uncertainty of (2) is caused by the inability of the scanning operator to position the reference indicator on the Hydel Scanner over the exact center of each spark in the track for each event. The random distribution of measured positions about the actual positions on the film introduces an additional 69 70 ”scattering” of the points along the track beyond that of (1) above. The overall error distribution resulting from both of the above causes of false scattering can be treated by the method developed by McDiarmidl“ for anal m3 is of cloud chamber tracks. From his method the standard deviation can be obtained for the overall noise level scattering from all such causes as the above. The following scattering distribution is developed in his paper for the case of pep—9e», i. e., negligible real scattering: 2 2:: (< r¢>M): [_ (c ¢>,.)] P(C ¢7M) =F:) (4)/ 3 XP 3' a- 1 For the case n = 2 which pertains to the present experiment as described below, this reduces to __J-(< ¢>4)e ((46);!) PC< $7.1): a" x’o-a‘l' Setting the derivative cf this expression equal to zero defines the location of the peak of the <¢ >n distri- bution in terms of 0' Nil-I (C ¢> n)2 most prob. 0" 2 This relationship may then be inverted to yield a value for 0" once the value of (<¢>n)(most prgb.) is identified from a plot of the experimental results. In this manner 0" = V3- (4¢>n)most prob. 71 Numer -——-1 of events I - 20 V4::), I / l—- '18 l 11 l l l I l I | l _J 16 -—-— 1 I '2 I I I c¢ >n (in degrees) \\ l l 2: 1. 6 as 1.0 1 a: l 1 Figure V-l. Plot of.100.fideublesv events- Two groupings or the data are shown..Sal£d curve represents theoretical predictions for noise-level scat- tering. I 71 NMth ———9 of events I— I — 20 I I , I l I / l I" [16 -——-I I _ '13 1l —_——l I I2 I I I 4¢ >n (in degrees) \\ I 2 u 6 s 10 1 1:1; J l I l l I Figure V-l. Plot of 100 "doublesv events. Two groupings cf the data are shown- Saltchuree represents theoretical predictions for noise-level scat- tering. 72 The identification of (< ¢>n)(most prob.) is carried out here as in McDiarmid's paper by measuring events obtained under a "doubles” counter criteria in the apparatus. That is, these were obtained with the anticoincidence counter disabled, thus accepting particles having any momentum greater than 1.56 Dev/c in order to re- duce the contribution from real scattering to a low value. A plot is given in Fig. V-l for 100 such events upon which two measurements of the scattering angle were made, corre- sponding to n = 2 in the above expressions. A separate histogram for each of two groupings of the data is given. From these histograms the most probable apparent scattering, (< ¢> n)(most prob.) is 0.37 degrees at the location of the peak of the histogram. The solid curve in Fig. V-l is a plot of the distribution P(<: ¢>n> above for peg—9 0° and n = 2. The fact that this curve is a good approximation to the data establishes the assumption that the data used here had in fact negligible real scattering and thus pro- vides a valid means of measuring 0'. The value of 0.525 obtained for CF was then used in the determination of the theoretical distributions presented in Fig. V-2. B. Comparison of observed scattering with predicted values In the present experiment a total of 2,266 usable events identified as muon events were obtained upon which track measurements and deflection angle calculations were performed. Many events beyond this number were identified a: tc Dri 73 as muon events but were not usable due to subminimal track quality of one type or another. Most of the events re- jected in this way either failed to pass through the entire chamber (i.e., entering or leaving through one side), had too few sparks present to obtain an accurate line fit, or had too many displaced sparks due to knock-on electrons set in motion along the track. Figure V-2 shows the resulting integral scattering distribution for the 2,266 accepted events. The curve is normalized to unity. This is a plot of the relative number of events displaying a measured projected scattering angle equal to C? or greater. These measured projected scattering angles were calculated from.the data for each event in the manner described previously in Section III—C and.Appsndix F. .Also shown in Fig. V-2 by solid lines are the predicted integral scattering distributions for this experiment which follow from the theories of Cooper and Rainwaterg, of Drell and Schwartzl7, and of Molierelo. These curves were obtained from calculations done as described previously in Section IV and in.Appendix G. The error bars shown on the experimental points are statistical only. The effect of other measurement uncertainties, discussed in Section VeA, are accounted for in the calculation of the predicted dis- tributions. The contribution to the scattering distributions due to multiple scattering are as follows (evaluated for the Drell-Schwartz theory): 74 [Scattering angle ] l.0°l 2.00 [3.00 l4.00|5.oo j [Multiple scattering]69% l27.4% llZ.6%|9.5% l8.2%] In comparing the experimental results with the theories as shown in Fig. V-Z, it is apparent that the data are in best agreement with the predictions of the Drell-Schwartz calculation within the statistical uncer— tainties shown. This calculation gives predicted values about 10 percent higher than those of Cooper-Rainwater for angles greater than 2 degrees. The Drell-Schwartz calcu- lation represents a slightly better fit to the experimental data than does that of Cooper—Rainwater. The Moliere distribution, while differing from that of Cooper-Rainwater only by a factor of 3.2 at the highest angle use, nevertheless does not represent a suitable fit to the data. A x 2 test was made on the data with respect to each of the theories from the relationship exp M: N1 ‘ - N1 X2=Z i=1 Vfiifififiir This gives values of 4.76, n.92 and ll.#0 respectively for Th. 2 the Drell—Schwartz, Cooper—Rainwater, and Moliere theories. The X2 tables38 give the following predictions for these values. The probability is approximately 92.5 percent that the data are consistent with the first two theories, as com- pared to a no percent probability that the data are consis- tent with the Moliere theory. 75 1.0 L-2 a 10-1 \\ Moliere N gall-Schwartz \ e \ (d in degrees) .0 l -— 2 Cooper-Rainwater r 10-3 0.5 l 1.5 2.0 2.5 3.0 3. ll» 0 I l I L l b Figure V-2. Normalized plot of experimental and theo- retical integral scattering distributions. C. Summary and conclusions The work presented herein was an experimental investigation of the scattering behavior of 1.60 Bev/c muons experiencing momentum.transfers up to 190 Nev/c in the aluminum.plates of a spark chamber. Cosmic rays were utilized as the source of these muons. Details of the experimental equipment constructed for operation of the spark chamber, particle detection and identification, and automatic track photography have been presented along with details of the computer programs developed for data analysis and theoretical predictions. The muon track data obtained was analyzed to yield measured values of projected angle scattering. It was found that within the uncertainty limits shown in Fig. V-2 the observed scattering was in good agreement with the extended-nucleus theories of Cooper and Rainwater9 and of Drell and Schwartzl7, rather than with the point- nucleus theory of Molierelo. Thus the results of the present experiment are in good agreement with the results 13 and of Fukui, et al.1]- .At the same of Mbsek, et al., time the data and results of the present experiment are given with somewhat firmer bases, with respect to improved momentum determination and particle identification as described earlier, than those upon which the results of the latter were felt by some12 to have rested. 76 77 Having observed no identifiable ”anomalous" scat- tering in an experiment where both the momentum determina- tion and particle identification were good, it is concluded that upon careful investigation the similarity of muons and electrons with respect to electromagnetic scattering indeed holds for cosmic ray muons as has been shown for machine made muonsl3. The present experiment represents the best cosmic ray muon scattering experiment to date with respect to the above critical features. APPENDIX A: Spark chamber system The spark chamber system consists of three prin- cipal divisions: (l) the spark chamber structure itself, (2) the helium gas flow system, and (3) the thyratron pulsing unit. 1) Spark chamber As mentioned in the text and as shown in Fig. 11-3, the spark chamber used in this experiment is constructed in three sections: the upper, main, and lower chambers. The main chamber is composed of S/32-inch aluminum plates 10 l/2-inches square with a tab on one corner of each for electrical connection. These plates were assembled with tabs alternated with respect to location at front and rear of the right-hand chamber face to facilitate the connection of alternate plates to the thyratron pulser and the remaining ones to ground. To handle the high current pulses without excessive voltage drop, oneuinch copper straps were used to connect the chamber plates together, and one-inch braid carried the current from the thyratron circuit. The gap spacing between plates was formed by plexiglas spacing strips sliced from 3/4-inch sheet stock and machined to 0.25-inch within a ten thousandth. A close gap tolerance was necessary in an attempt to obtain uniformly high spark efficiency in each gap. The spacing strips were assembled to form a square around the outside of each successive plate. The next plate was 78 79 placed upon the spacing strips forming a closed cell, and then another set of spacing strips was placed upon it in the same manner. Twenty-two such gaps form the main chamber. The entire assembly including the upper and lower chambers is held together by tensioning bolts at each corner bearing upon a l/2-inch thick aluminum plate on top and bottom. The upper and lower chambers were each constructed by milling l/l6—inch grooves in plexiglas pieces at 0.25-inch spacing in such a manner that the pieces are assembled into a closed box having continuous grooves around the inside wall at every 0.25-inch increment. The 3/64-inch thick aluminum plates used for these chambers were inserted in the box grooves just before the final side was mounted in place. Both the upper and lower chambers were built with four gaps in pairs of two, separated by a distance of l l/l6-inch. Elec- trical connections to the plates were brought out in a similar manner to that described above for the main chamber. 2) The helium gas flow system The gaseous medium for spark production decided upon for this experiment was helium with a trace of ethyl alcohol vapor as an additive. Of the gasses commonly used for spark chamber work, helium was chosen since it is the only one economically feasible in a free flow system which exhausts into the atmosphere. 80 This flow method was chosen because it is mechanically impractical to attempt to seal for evacuation a chamber constructed as described above. Helium, of the grade most readily available from welding suppliers, was first run through a cold trap containing liquid air. This procedure was adopted when after only a few months' operation a noticeable deter- ioration of gap efficiency was observed. It was determined that a trace of both oil and water as well as some hydrogen was present in the welder's helium. The latter could not conveniently be eliminated, but the liquid air trap effectively removed the oil and water before it entered the system. The result was a considerably longer time period before disassembly and cleaning of the chamber again became necessary to restore gap efficiency. The helium flow control panel consists of two Hoke metering valve and flow gauge units, one on each branch of a two-way flow path. Most of the helium passed through the main branch and on to the distri- bution manifold on the spark chamber. A flow rate of 2.5 liters per minute was maintained in this branch. A small amount of helium, however, was diverted into the second branch through a second metering valve and flow gauge to a l/32~inch orifice at the base of a glass tube containing ethyl alcohol. The tube was filled to a depth of 2.5 inches and helium was bubbled 81 through the alcohol at a rate of one bubble per second. The purpose of the alcohol is described in the main text. The gas flowing in the two branches was again com- bined and sent to the chamber. Each of the three sections of the chamber was fed from a separate flow control valve to its own manifold block. At this point individual flow control to each of these divisions was necessary in order to keep the helium flow rate per cell equalized among the three sections, since each contained a different number of cells. 3) The high voltage pulsing unit As described in the main text the spark chamber was fired by discharging into the chamber a bank of capacitors charged to 15 KV. The discharge of each capacitor bank was controlled by a separate 5022 hydrogen thyratron being triggered ultimately by the coincidence circuit. The Amperex 6279/5022 version was chosen because of its superior rise time charac- teristics and higher voltage handling capabilities. Biasing the grid of each thyratron at +15 V (adjustable to best operating point) further decreased the rise time into conduction. An Amperex EFP6O secondary emission tube, used in a single-shot blocking oscillator circuit, delivered a fast-rise 150 V pulse to the grid of the 6279/5022. The EFP6O was triggered by the positive pulse delivered to it from its respective 6688 cathode follower stage. The three cathode followers, each 82 'driving its own EFP6O and 6279, received their signals from the coincidence circuit via a 6688 input amplifier- inverter stage. A negative pulse having an amplitude of 0.1 V or greater triggered the spark chamber discharge, but a larger input pulse was desirable for reducing the rise time to a minimum. A negative input pulse of one volt or more produces an overall spark discharge delay time of :3 200 nsec. The circuit of the thyratron unit is shown in Fig. A-l. This unit was constructed in 1961 following the general plan of a similar unit just com- pleted at that time by Prof. D. Meyer and Prof. K. Terwilliger of the University of Michigan, Ann Arbor. 83 F—MZOOV 10mm 5 250 {smut/w 050V ‘ j} P um “89 INPUTS or IIIPI/T REMAINING CHANNELS To Top NALfOF '0’“ TO BOTTOM HALF AM R C L or mm camera ”M” c” 8‘ 500 DOOPNOB CAPACITORS or CHAN. ’ z TO APLATE OF on nm 2 mmmzon T0 METER /: usrnm cmulttz ' 3 i 11'];- room 500%,!» |N3|96 : 20W .IL A- . '1l 12m 501% EH} 6‘88 EFF 60 627965622 CAPACITOR (— amt *— DR'VEP a WM’TGEKN 53‘}? 1: +. Lu... —— “.53 u. chenrben 6‘88 EFP 60 6279(5C22 —' CATHODE '_ DRIVER '— HYD OGEN #- IL : FOLLOWER THYRATRON “mm CABpfifilK-EOR main chem. 6638 EFPGO 627 5622 H CATHODE #— DPIVER — HYISQSOGEN ‘ FOLLOWER THYRATRON é‘l’op he” charm; I M l+:-Vib +or L 772: “15% 3’ "I... 5?. "5 AMPLIFIER —"f5 <—‘ a..i+;.+. H. A )H.v.a..§,.+ INVERTER : {Zimmem camera cycle _: HV. METER 5:90!“ 5kv SPARK CHAMBER PULSE CIRCUIT FIGURE A-l. APPENDIX B: Circuit description of the counter telescope system The counter telescope system consists of two divisions: (l) the scintillation counters with their circuit boxes and power supplies, and (2) the tunnel diode coincidence circuit. 1) Counters and phototubes The three scintillation counters in the telescope system are fitted with one, eight, and four 6810A photo- multiplier tubes corresponding to the aperture, stopping, and anti counters respectively. Each phototube was wired for negative pulse output according to a suggested circuit found in the data sheet supplied with each tube, except that the bleeder resistances were multiplied by a factor of 6.5 to conserve power supply current. This was feasible only because of the low average count rate involved. The DC operating voltage for each phototube circuit was supplied via a distribution panel from two Hamner N—h035 power supplies. One of these power supplies was associated with the eight tubes on the stopping counter; the remaining one supplied both the aperture and anti counters, via a second distribution panel. Each phototube voltage could be adjusted to a desired level below that of the power supply voltage. A voltage drop ranging to minus 20 per cent in 16 steps was provided by this method. 84 f3 85 The purpose of this arrangement was to allow independent voltage adjustment of each tube to equalize pulse heights among the several tubes on the same counter. The aluminum mounting sleeves of each phototube were connected to the power supply at negative cathode potential to reduce dielectric stress on the glass walls of the phototube. It has been the experience of many that failure to do this causes noise in the phototube output. 2) Coincidence unit The tunnel diode coincidence circuit constructed for this experiment (see Fig. B-l,hD was designed from the basic circuit given by Whetstone and Kounosua‘. Basically it consisted of an input module for each scintillation counter with a number of tunnel diode univibrators cascaded to provide a high degree of isolation from the input signal as well as standard- ization of signal shape. Once the input signal is standardized in this manner, the coincidence function may then be performed by merely feeding the signal from each coincidence channel into a current adder, which in turn triggers another univibrator whenever there is a signal present in all inputs at the same time. Anticoincidence operation is also available by arranging that the signal from the "anti" input module be used to gate the coincidence channel at a subsequent stage in the circuit. It is necessary in this mode of 86 operation that the ”anti" signal arrive in the circuit before the coincidence signal. For this reason the signals from the aperture and stopping counters were each delayed 60 nsec by means of additional cable length. As shown in Fig. 11-4 the entire unit was con- structed in a copper chassis to minimize troublesome effects arising from pickup of RF radiation from the spark chamber. Use of silverplated finger stock on the tight-fitting bottom plate provided a highly effective closed conducting shell for shielding of the circuit. Within the chassis are copper dividers to decrease signal pickup from one point in the circuit to another. The necessity of this measure was evident from experience with a pilot model in which the degree of singles rejection was limited by dependence on the amplitude of the input signal. Partitioning the chassis effectively eliminated this problem. 560.0 IONA Figure B—l. Coincidence circuit diagrams. 88 I § 9 I: 8 :5 § 9 ‘ E3000 ' I u‘rc-u-eo an E f '-? : COINCIDENCE SECTION 'IIV . 3 OUTPUT SECTION am": we 3 s i. 9 Figure B-la. Coincidence circuit diagrams, cont'd. APPENDIX C: Modification of Tektronix 517 oscilloscope for 7T—y-e d isplay As described in the main text, more than one method of identifying 77-}1~e decay pulses on the 517 was attempted. The one which proved most reliable in the presence of large quantities of RF radiation from the spark discharge consisted essentially of programming the sweep of the 517 to produce a characteristic Z-trace as described in the main text. To accomplish this several rather extensive modifications were made to the sweep gate and sweep amplifier circuits of the 517. A diagram of the most crucial modifications is given in Fig. C-l. These are the circuits responsible for (l) automatic sweep speed change after the first trace and (2) trace separation and marker pulse presentation. As may be seen in Fig. C-l the automatic sweep speed change was accomplished by using a 5727 thyratron to switch in a new timing capacitor (1200 pr) for the slow sweep, after completion of the fast trace. The original timing capacitor 0129J is adjustable to cal- ibrate the fast trace, while the 25K rheostat shown serves to calibrate the slower trace. The 150 ”pf capacitor serves for the duration of the first trace to effectively short the two resistances across which it is connected, but becomes of negligible effect in comparison with 1200 Rpf by the time the second trace 89 90 is fully underway. The use of this 150 ppf capacitor proved to be an effective means of providing the proper charging resistance for each timing capacitor, in order to maintain a linear sweep. The delay required before switching in the 1200 uuf capacitor for slow sweep was provided simply by the inherent delay involved in establishment of conduction in the thyratron, following application of plate potential. The plate potential is simply the potential appearing across C129J as it charges during the first sweep. The firing delay is a function of the bias potential present on the control grid of the 5727. Thus a variable bias potential was provided by the 10K rheo- stat by which it is possible to calibrate the firing of the thyratron to occur precisely at the end of the first trace. When set for double sweep operation, the action started from the initial trigger pulse proceeds on its own, including horizontal retrace between sweeps. Auto- matic horizontal retrace is a direct consequence of the fact that in the 517 the sweep voltage appearing on the deflection plates is simply an amplified version of the instantaneous potential across the timing capacitor 0129J as it charges with time. Thus when the uncharged 1200 upf capacitor is switched across the fully charged 0129J at the end of the first trace, the potential across it is reduced to approximately 1 per cent of its "full- 91 sweep" value. This action is passed along by the DC sweep amplifiers to the deflection plates as a very effective retrace (limited slightly by stray capacitance in the amplifier and deflection plates). The second trace begins immediately after retrace since the lZOO‘upf begins to charge immediately upon being connected by the thyratron. A ramp and marker generator was designed to produce a step voltage by which to separate the slower trace to a position on the screen below that of the fast trace. A schematic for this circuit is given in Fig. C-l. The rise time of this negative step function produces the vertical movement in the cross bar of the Z-trace as the beam is lowered after the first trace at the same time that the change of the timing capacitors is causing horizontal retrace. By the time the sweep speed change and retrace are complete the negative step function will also have reached its full amplitude where it remains throughout the slow trace. The negative step function for sweep separation was obtained from the square negative pulse present at the first triode section of the 6D38. The leading edge of this wave form was delayed by a two-section RC delay network and then fed to the base of 2N501 transistor. TThis transistor was connected as an emitter-follower to provide a low impedance output to drive the vertical input of the scope. The purpose of the 1N67 is to clip the signal into 92 the 2N501 at ~10V. This method of signal limiting retains the short rise time associated with the high amplitude signal from the 6DJ8 circuit without overdriving the 2NSOl. The purpose of the 1N39 is to block passage of the negative step function back into the differentiation circuit attached to pin 6 of the 6DJ8. A negative marker spike was obtained by differen~ tiating the negative-going trailing edge of the wave form generated by the 6DJ8 monostable multivibrator circuit. The 2.5K trimpot which controls the period of the circuit was used to set the time of the marker pulse to be pre~ cisely lO‘psec.after the arrival of each phototube pulse accepted by the coincidence circuit. The appearance of this marker pulse in each scope picture served as a con— tinual calibration monitor on overall sweep time. In addition to the modifications described above, several other incidental changes and additions were made in the 517. The two 6AG7 clamping tubes V112 and V113 used to discharge the timing capacitor following each trace were replaced by eight 6CL6 tubes for greater discharge current capacity and hence faster retrace. Two additional 6CL6 clamping tubes were inserted between pin 8 of V117 and ground to more quickly discharge the effective shunt capacitance of the positive deflection jplate during retrace. This treatment should in principle Thave also been applied to the negative deflection plate. Trhis was not done since sufficient benefit was obtained 93 from clamping the positive deflection plate as to make it no longer mandatory that it be done on the negative plate as well. Also because of the reversed polarity on the negative plate, clamping is difficult without arranging a more sophisticated circuit to control conduction in the clamping tubes than was required for the ones that were installed. The R126 and the L105 in the trigger amplifier were increased by a factor of 5, to 160012 and 604ph respectively, to increase the trigger signal for more stable triggering of the sweep gate circuit of V111 and V119. The circuits added required power supply capa- bilities exceeding that of which the 517 power unit was capable. For this reason a supplemental power supply was constructed and installed in the scope to supply 6.3 V AC at 12 amperes, 6.3 V AC at 1 ampere, and ~90 V DC regulated with 9001 VR tube. All of the above equipment was constructed on chassis plates and installed within the case of the 517 indicator unit. Subsequently, however, it became apparent that the 180 V DC regulated supply within the scope was being overloaded by portions of the modification circuits. Therefore an additional 180 V DC supply was used to supply the new circuits. No further overload symptoms in the main power supply were encountered. 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Nm. eaves oe em Amz. mas .mems :sz ez mN m:. N .xem game am can mas mNu E" Ezi m H 02 122 ZDmNiNN t NN¥ZDmX n Xfi z u Z< NN + N*«AHVmmm mm mH<_ox.z vmsmom n >mam Ho.N I zmv\mem u > mom + HHemmm u «em N¥*avam n avamm mom + HHemm n mem HvaNImmmIom I Hvam u HHemm z.H u H mm on NN\xe u mH< :mmNon I N: n me mm\m< u o: n mm NN¥EDmN I NN¥Z< Om mN 121+ mzm zmmsmm Hm + o.oemnHm 3 es oe . . . Hm +.o.eeHuHm oH Hm: m: H: H: waves oe HmIHemN.NmO I Hm Hsvmzmsm u Hm mmmH4\/z. The values of J%h(y) obtained in this manner are stored in an array under Labelled Common for later use. Subroutine RAIN, called successively for each value of x, controls the remaining operations involved in calculating the differential scattering distribution M(x). Function TXIAM is called a number of times to furnish, for each value of x, an array of Values of the function T(x,)\) as defined above. Function QLX is called to evaluate the function Q(L, x) as defined above. The integral represented by N(L, g) is evaluated by means of‘Weddle's rule in Function WEDL.' The value of MIX) then is merely the sum of each of the terms whose value was just calculated. Each value of Mix) thus obtained is entered in an array in Labelled common containing the set of.MKx) values that correspond to the set of required values of x. MIX) is also printed out at this point along with the corresponding value of 6? and.x. Printed out also is the value of Q(L, x) and the number of terms found necessary for convergence of the series used to calculate (KL, 3:)? w B. The corrected differential scattering distribution The next step in the calculation is to obtain a differential scattering distribution corrected for noise level scattering. This is done as discussed in in the main text by evaluating the following integral .0 -x—X’)a My) 5 JV CJX g(X') : .1-77'0' -00 where g(XI) is the correfteq distribution, x' = . ox’ measured deflection, c. ‘r" is the normal distri- bution function used as a weighting factor upon M(X) as a method of obtaining the expected value of the differential distribution function at x' due to the total of all the contributions from deflections having all values of x. This integral is evaluated by numerical integration in Function GPTHTA, which in turn calls Function FNTGRL to do the actual inte- gration using an extended five-point Newton-Cotes quadrature method. A set of g(xt) values is obtained by repeating the above procedure for various values of x' by which a corrected differential distribution g(xt) for each x' needed is made available. These values of g(xv) are printed out at this point together with their corresponding (4" and x' values. 128 C. The integral scattering distribution From the set of g(x') values obtained in Function GPTHTA an integral distribution is obtained by numerical integration of these values in Function GTHETA. This is done to evaluate the integral '9 Gag) "y/zjo") “(X For purposes of normalization this may be rewritten as 1 w I :: —-——— I dX/ G, 09) 6(0) Z7“) The integration of this expression is performed by the same Newton-Cotes function routine mentioned above. Normalization is performed after integration by dividing each value of G(XL') by C(O) to obtain GN(XL') for each value of XL' to be used. The values of XL: were gen- erated stepwise in the machine upon reading in values of the step size and upper limit on XL'. The calcu- lated values of C(XL') and GN(XL') were printed out at this point together with the corresponding values of 6? IL and x'L. 129 II. Calculation of the Moliere scattering distribu- tion The Moliere differential scattering distribution was calculated using the same program as described in Section I. above, making the proper identification concerning .3& in the calculation of M(x). (FNC)% is the Fourier transform of the nuclear charge dis- tribution. Thus the point charge nucleus which is assumed in the Moliere theory will, since it has negligible extent, have a corresponding FNC-—+ 1.00. From the expression for .3% = FNC + —%— (1 - FNC) we see that J$fi -——9 1.00 also. Thus to calculate the Moliere differential distribution, the integrand of NCL, N) was merely rewritten with the fill} factor omitted--effective1y setting ffik = 1.00. The Moliere corrected differential distribution and the Moliere corrected integral distribution were then calculated in exactly the same manner as described in B. and C. above. 130 III. Calculation of the Drell-Schwartz scattering distribution To obtain the Drell-Schwartz predicted distribution, a subroutine DRELL was written in a straight-forward manner to calculate the function JN/Jo developed in section IV.-C. Values of this function were obtained at 260 points in the range of the experiment. Printed out at each of the 260 points were the following quantities: 6 , qo(in Mev/c), f2(qo), Fqu): quO)’ jmagmo), dd‘o/dfi. , dr/dJL, dN/dg. A second subroutine MSCOR was written to calculate the multiple scattering correction factor required to correct the single scattering law of Drell-Schwartz to one which includes the effects of multiple scattering. This was done by calculating the ratio of the multiple to single scattering laws of Cooper-Rainwater at each point. This ratio was then stored in the memory until after the following step. Next a third subroutine DRELPR was written to cal- culate dN/dCP from the appropriate linear combination of the dN/dO values, as developed in Section IV.-C. Values for dN/dCP were obtained at each of the 260 values of d as above. These values were then corrected by using the correction factors generated in subroutine MSCOR, giving a differential distribution for multiple scattering based on the Drell-Schwartz single scattering results. Printed out at this point were the following quantities: 6? , x, “HQ/(14%, (dN/d (WM- , 7oMS. The terms (dN/d ens and 131 132 (dN/dCTXM, are respectively the single scattering distri- bution of Drell-Schwartz converted to projected angles and this distribution corrected for multiple scattering. The set of values obtained for (dN/dOZ Imm .m.Hvo.Humose«m :mom eszsmm sm omzHesmo onssmHmsmHm mmmHHo: .onsmmHmsmHm mmmHHo: :omm H mmx mo Hum ZHID¢mm mom .BmHD .mmHQ mMHUWMMOU Awi mo ZOHH X mo Bmm ZHIQ .xezHee HHee H u me N .No: meme cm H\ ezHeesseee eHeHH sHm: eee onsmeHeseHe HeHszeeeeeHe eesezzHemIeemooemee .omHe se:moe see see szHem m oooH. n .OOHHH I :pzveH mooe HHee N 00.0 0.0 0.0 0.0 «I 135 H\ onsmeHeseHeH ezHeesseem .sHm: HeeeeszH aeseemeoe NseemmeeIHHeeemme .omHvse:eoe woe woe szHem mH NH es oe H\ H .onsmeHesmHe ezHeesseee HeeeeszH oeseeeeoe eeeHHe:mom .omHese:eoe woe eoe szHee :H mH. :H .NHHmI:sz eH emszzoe ee xHee + e u m HHm.:mz.xHee.:HHm.e:eHm.ersmsme u Hmvesme : u He smez.H u e 3e cm H + mHee\:HHm u see: 0.0 u : HH HH.NH.HHHe I :mzveH 0H 00H os oe N e.N.N 3:83 I ee:HszemH H + .383 u szmoeH HH:.:mz.eHeo.:HHm.e:eHe. eexeesmsmeu see H + :Hee\emqu H: emx .Noe eeee e HH os oe eeSbSezN 85.0 + x u x Hze.:mz.eHee.:HHm.Heex:e.Heex:e.eveeHeee HHee e u :: eeezH.Hue :N on H + xHee\:HHm n 5.55 o. o u e H\ .ezHeesseem eHeHsHm: eoeH eeseeeeoe .onseeHeseHe HeHszeeeeeHe Nseezme eeIHHeeemeN 6mHOse:eoe Noe Noe szHem H:mz. xHee .:HH:e HHeeo HHee oN OH. e 6ooHHNI:mzeeH me oN 6N 6eHeIzmzeeH eefibseae 136 eme mosm OOOH OOH os oe eon eH os oe m u me:mz H\ onsmeHeseHe ezHH messeee eHezHe HeeeeszH eeseeeeeeze mesezzHeeIeeeoeemON.omHese:eee NHe NHe szHem omH eH os oe e u meme: H\ onseeHesmHa ezH Heesseee .sHm: HeeeeszH eeseeeeoezm eesezzHeeIeeeooemme.omHVse:eoe HHe HHe szHem oeH eH es oe m u ee::z H\ onseeHmseHe eH szesseee eHezHe HeeeeszH aeseemeoezm NseezmeeIHHememee.oeHvse:eem eHe OHe szHem ONH 3 es oe N u mezmz H\ onsmeHesmHeH ezHeesseem .sHp: HeeeeszH eeseemeeezm NsmezmeeIHHeeemNe.omHvse:eoe moe see szHem oeH ee:mz.Hooe.omH.oeH.oNH.oeHeos oe emH oom.omH.oomHeI:mzveH eefimaeeN HeHem + :HHe u :HHm H\mH N "HeeeszN.xs.:.HHe. “.meoeHOIHmmeemeH .em.:.HHe.uHOIHmmeemm .mmH .N.ee. ueIe H.e.vaHH.ee .m.Ne. "H.eee zHeeIHmmemH . mHese:eoe Nee HmeezH .Zeze .mze .:HHe . onm .Noe szHem :eoze\mze u zeze NN mze u :eoze.eN NN.eN NNH:HHmOeH Hoeee.NeeseoeeHemN.vae:HHe u onm Hme:m2.H:eozH.:mz.:HHm.e:eHm.xHee.:HHmeesemse u mze HeeezH.HnH eN on H+HeHee\H:HHmuHeeemH 0.0 n :HHe eH H n mezmz NH 137 .meme eIeNoe.H "HmHIeNoe.HO.Hmoe\.Hmoe e+eu>e: H eeszO:eI>e:wmo mstm zs eH ememm meNmmHeH.m u Hm 0H HHonezs oneze:He xe:z .e .o .HHoevzs .Hee .Hx \e\ zo::oe :Hos .Hm .Hos zo::oe mooe eszmommmm O U 138 Xe:v em mNm.omHO se:moe see szHem HOHH.me.m.eHevm . mHO se:eoe xe:z .Hos .Hee .Hx .Noe szHee H H Hos Hen H mNe.omHv sezeoe eoe szHem. emszzoe HN\HHHOezeI.HOO + HHOeze n HHOze mHNz.H u H e on H + xezz u mHNz Heze .Hee .He.oeeNxO e:eom HHee :smee\eNHmm u oeeN: Haseeeveseom.u :seee O¥O¥.N n :mem mseeeeHe\N:e:e.mNeNo.eeHHee.:vv u o em.NeeeHmsezee u N:e:e NssNfixxm u MBMmm Hem\HHm.ovseHIeeHe.N.Hesee\Nv u Nseee H:ees + ee.m u mNeme.o«HHseeeveeOHeeN.H u Hzmes :ozee\eos u Hseee em.N«zee«eeHms.HH.e\.:v.«NO u mos <¥AaNssA.NNH\NVV¥ON.M# .szHee eszmoeeOm Oze zemsee emszzoe OOOH Heeeeeev\.NH u :mom : OOOH os oe HHe I HN.O\eeeVO*HHmmHOseeee I HemeHOseeeev I HemeHOseeee_u :eoe N + H n mmH H + H u emeH H u He N.\eee u H m e.e.m HO.: I eeeOeH N OOOH es oe HHvseeee u :moe H N.H.N HeeeOeH HHNOseeee \e\ zo::oe Heeee :eoe onsezme eze messee emszzoe OH Hse:moe u HHVeze OeeNx\x u s H: + HeOeH.HIHeO u x H u He eHNz.H n H OH on H + xezz n mHNz xe:z.e.O.HHOevze.eO.HmO\e\zoz:Oe HHOeOeze onmze:HO Heze.HeO.Hx.OeeNxv e:moe eszmoeemm llIl Oze zemsee HaH. "He.HOO zH memzmeH.e:.e.HHe. "He.HeomN.ee.e.HHe. uHeO:meH .xe.N.ee . nx H.e.HOmO.xe.e.Ne. uH.eeO zHOesemsmeH. mHO se:eoe aoe Oxe:z .x:O .mN:> .x .esems .eoe szHem Hoee..NOeseOe«HemN.NeO.e u esems Nmees + Hzees u eN:> N :eeseHHHmseee.O.:O\O.HO u N :ees u N HHeO.xe:z.sOHoe3 :mes eseeeeHeeOe u H:ees Hese\HmexIOemxe u Heeoe HHmOeseOm u Hmsm HHHe.O.:O\e:OO + O.HO u eseee Home:z.x.HerHOn::O emszzoe e. HevzeeHszfis u HO; N e Os oe 2.;sz n HO; e .sHe>Hseemeee .onsmeHeseHO eeeHHO: eO eIe eoe e OeOeez me .HOOze moseee e>HseeHHmHsHm: smomst mo msH3 meOHe> ozeeeeszH :mOe e eeN.NH: I :mzv eH mHNz.H u e e on emszzoe ON H:eHx .xvzeHms u H:Oe:Hs HeOeH.H I :eO + He u :eHx : u :e mHNz.H u : ON on HH H + xemz u mHNz HHOeOO .HHons .HHOeOesz .HeHvzH oneze:HO Ne:z .e .O .HHOeOze .Hee .Hx \e\ zo::Oe :Hos .Hm .Hos zo::oe .1 D A a O o 4 H. .e ’1 . r. I H. 4 ,, ' \' I H— I '1 4 v 1 a ~I a 4 0 .1 . A v -, _ i . I ,1 . 0 i "I . 142 .e>Oee me .:e emee>zH eO OeesezH eH:eem eeee>zH 3 see me seaeoo eeem e HHOOxNeeHHHINeeN + N u HHOHeNe N:eeseH:ees n HHOOmNm eeH\HOe«OeO«H.eO+ .me\Oe.H.eHO I .H u N:ees HH.N\O:OIOemee u H :ees .N\HN*.HHHOOO.eeOO u Ox H.N\esemsvezHe«HOee.H.NO u HHOOO . H u He . . eeO2w.HwH e OO . . . . .H\.emstOme.xN. oeHemmm eN. ee:NmmeN me HeNeme xe OeNmm: NN OeHeOme eN OONeme :OH OomN eeH . esemsme.mN\ .onseHmeHee NseezmemIHHeeO eO esHmeeemem.OmHOse:eoe Noe Noe szHem OOH\HeHee u esems H+mHeO\:HHmuxemzH Hoee«.NveseOmexHeo u HeHea emeem\Oee n Home em u Oee .Hu eeee>mH eO esHmm zH eH HOee .>e: eO estm zH mH Oee e eHIeee.H n ee O.Omumees Hm.HI u zO:e MON.N u mm:e e.eeO u e:e e.O u e:e mHIeHe.N u em mNeNO.e u oze eIeNoe.H\NHIeNmeH.e u eeeem .>e: mes eeee eIeNoe.H e uHN+eO.HOeHeHIeNOe.HO.HmOe\eH:OO e+eu>e: H eezHeO:eI>e: me est: zH eH eeeem e HOOeOee:Ne.HOOeVeeHeOH .HOOeOOeHeO.HOOeOHeNe.HOOeOOeNe.HOOeOOO.HOOeOeesOZO \e\ zo::oe HOOOON:O.HOOmOeOee.HOOer:e.HOOmOe:e.HOOmOx:e \e\ zo::Oe :Hmm.zee.:eHms.N.e.em.me:z.e.o.HHOeOze.HeO.He \e\_zo::Oe Hm.HOs zo::oe NseeszeIHHeeO eO onsmeHesmHO ezHeesseee eHezHe HeHszeeeeeHO e H:mz.eHee.:HHmO HHeeO eszmOeeme \I n \I (I lLI3 Oze zemsee HmHeO.:HHmOeOem: HHee eBSESOe HeHeO«He n esems HHNN.e.OHeOe.me.e.Ne. mHOse:eoe HOe HH emsezo .HHOeeHeO .HHOee:NeH HHOHeNe .HHOOeNe .HHOOeHmO OONe .HOO.mesems.Hoe szHee HemN.NeOeesems u mesems HHOeeHeoeN:eeseH:mes u HHOemseze e\meHms«:e.Nezemeoze u N:ees HesemseezHeeHmeH.NOnH :ees eeHeO :Ome Hemsezme esemsmzm eO onseHmeHee HHHOee:Ne+HHOHeNeveooNeeHHOOeHmOuHHOeeHmO He:eese::mes + m:mesOeN:ees + H:mes u HHOee:Ne zm:eezm:e«HNIeO + mm:eeem:eeN n e:ees Hz:e«z:ee.:O\HOOeHOo u e:mes Hz:eee«.mv\mees«Ne.N u e:ees H I HNeeHH.N\esemsOeeonO\.N u N:ees Hz:e«z:e.ee.NO\HOOeHOOeN u H:ees emeemeHHOOO u HOO He\>e: zH eemmzees .:o: u sHHeeHeezsz>e: eo estm zH eH HOO N:meseHzees u HHvoeHee N:eeseN:mes u N :mes HNeeHH.N\esemsvezHeOO\H.N\esemsveeoe u N :ees H:ees..H:mes .I. H spies HOeee.NO\e:eeeeu H:ees e HHOONeeOIOeeNe u OONe m e os oe O.H u OONe N N.e.mH.OOeIOONeeOeH H.e\HeNIe.H«HHOOO«HHOOOO u OONee f.) 4"" .H. . I. H e I I . , 4 a o I [I 7 u I O . Q 0 o 7—\ I v I N. _, , L U . .. II . x. I \ C N. H; x, . D . I _. Ht » .) H: \l . ._v I.. . e N \l — \r s. I.. .. I. .r , . . . ll\ I.I e; x, x . x I I I_~ .\ e. N, \ ‘ 7-. .| [—1 .i x. e. D ,H. \I r . O.HOHeOzH .aéoze .e§oze .OOe szHeO eOszzoe O:moze\HHOx:e u HHOx:e erzH .H u H eN OO Hee:mz.eerOzH.:mz.:HHe.e:eHe.xHeO. :HHOOesemse u e:eoze NN Os oe eume:Oz eOszzOe :N Os oe xHeOeHe u :HHe mN.HN.HNHO.HIHHOe:eOeH NHMQ+OHN HH:eese. NO\HOOezm.OOI HOON:O “NesmNHmmv\Ou H. N\. eeesHN««:s + Neese n H :ees mNHmm\:HmO n :s .oeeNe\:n eeOzH .H n O ON OO O. O u x emszzoe e:moze\HHO::eu HHOm:e eeOzH .H n H eH OO Hme:mz.erOzH.:Oz.:HHm.e:eHe.xHeO. :HHmOesemse u e:eoze eH os OO O u ee:mz O. OI :HHm H + :HeO\:HHmn meozH HOOOON:O. HOOeOeOee. HOOmOm:e. HOOnOx:e. HOOer:e \e\ zo::oe eNHme .HHoeexme .HHoneeze .omeNmH .HHOeOeze. :Hme. zeO. meHms. N. e. em. me:z. e .O.HHOeOze. HeO. H: \e\ zo::oe .ezHeesseem eHezHe Oze eHOHsHm: eoe .eHee mIe eszeO:Oe NO eZOO llIlI» ma ..mHMBmHO min O.H. ZOHHOMMMOO OZHmMBBHVUm MAMHHHDE mo ZOHHEOAHNO 33mm .ZHHDvmoomZ HZHBDOMODO O 145 H + OH H Hmoq .OH ZOOH OOHOOOO H mom «mma mo onHOOHmHZOO HOZOHBOOOO o HmzmmH«HOv\mzmmH«HzOma u NIHHHHOVOZOHV I «IIHHHOHVOzoo O Hzx.ZOz.meO.zHHO.mHmOOZO.HmOO2O.meOHOmO OzHHOOmOOm sz zmafimx E2 H 9200 o m xqma + x u x HHOsz\HHHOxzm I HHOxzmm HmmHO OOH 9mm HHOOOxm .HHOOOO zOHmzmzHO HHOO.x¢zz.xOO HOmz oneOzOO sz 150 OHsz.x.OO.Oxz«.x.mmx.H.NOO HszO mHH.OON.mHHHm.HImOxVOH OON.OO~.HONHO.OImOxOOH OOH.OON.HONHm.:ImOxOOH :ON.OO~.HONHO.OImOxOOH mHH OH OO NHO OH OO ~O~.OON.HONHm.HImOxOOH mHH OH OO .OHsz OzHHszO Hzm>mmm HHHB Ommm OOHmOmzH mHH OH OO OzHOamx HZOZOHOHO HHOOHsz u OHsz Hxvxz< u Oxz< HOOIOHOHOIHxsz< u HHVOHsz HOZOHOIOZOHOI.NO\NIIHH + mmxv n mm H + H2 n x H + Hm I meO\zHHO u Hz HuHm Hz.OH n H OH OO H u OH OH OH OO HOzHHzOO xHOOIx u x O.O n HOOOHsz OH OH OO O u OH N.H.OHOOOIOOOHH HOZOHOIOZOHOI.NO\NIIHH + mOxV u Om Hz.H n O O OO O.O.OHH.OOOIHOOOOH HOZOHOIOZOHOI.NV\NIIHH + szO u HOO HOzOHmIHHOI.HVOHmOnV\.H u zmozx NHO wON OON :ON NON HON OON NH OH OZ¢ZGMBZH HEB mm¢mmmm meO\zHHO u Hz zHHO u x HOOmOxz< \O\ zozzou O HO.H0.00H.OOO I OOOOH HOZOHOIOZOHO¥.OO\OIIHO I OOOO u OO H:.HHO. uHHOOHszOO.xO.OH. . onvszOH.xO.O.OO. ume.x0.0.00. Oz.OH u H OOH OO Hz u OH OOzHHZOO xHOO + x u x nme.xO.:.HHO. "OOOO.OO.:.HHOH "OOOOO.OO.OH. "HOO. OHOHOZOOO OHsz.O.OO.Oxz<.x.OOx.O.OOO HzHOO .OHZHN OZHHZHmm Bzm>mmm AAH3 mamm OMHMMWZH 151 OOH.OOO.OOHHO.HIOOOOOH OOO.OOO.HOOHO.OIOOOOOH OOO.OOO.HOOHO.:IOOOOOH :OO.OOO.HOOHO.OIOOOOOH OOH OH OO OHO OH OO OOO.OOO.HOOHO.HIOOOVOH OOH OH OO OOH OH OO OzHOOOO HZOEOHOHO HOOOHsz u OHsz Hxvxz< u Oxz< H + H2 I O n O O.O u HOOOHsz OO OH OO O u OH HO.HO.OOHOOO I OOOOH HOzOHOIOzOHOI.OO\OI«Hx I OOOO n ma H:.HHO. ”HHOOHszOO.xO.OH. . "HOOOZOOH.OO.O.OO. ume.xO.O.OO. Oz.Hz n O OO OO OO.OO.OOHOOO I HOOOOH H + Hz u Hz Am~E 41:3 mmmm OmflmmmZH Om OH. 00 UZHDOHMM BZMSHH¢Hm HHOOHsz u OHsz HHOxz< n Osz HOOIOOOOOOHHOxEO nHHOOHsz H + H2 I H u H OO OOOH OH OO 0.0 n HOOOHsz OO Oz.H u O OO OO HO 153 O0.00.00 HzIzOOH OIOOOI.OH+HHHIOOO+HOIOOOO*.OO+HHOVO+HOIOOOOO.H+OuO n2 :.z.OuO OO OO 0.0uO HOOO onOzmzHO HzHOO HOz OOOO HO OOHOHOOOH OZOOOOHzH u H OHzHOO HOz zmmzHOO HzszOOzH u OHHOO HOOOOOOIOHHOOOOOO OHzHOO HOz OO OOOzOz HOHOH u z znszHO OO zszsz OOOHOOOO HOHZOZOHOO OOOOOOIOHOOOO OOH HOOOO OOOHOOOOOO OOHOOIZOHBOz HzHOOIO>HO OOOZOHOO HO.