THE UN I V E R S I T Y OF M I C H I G A N COLLEGE OF LITERATURE, SCIENCE, AND THE ARTS Department of Physics Technical Report No. 30 A COSMIC RAY PROGRAM FOR THE STUDY OF STRONG INTERACTION PHYSICS IN THE RANGE OF 100-1000 GeV (Invited paper prepared for presentation at the X International Conference on Cosmic Ray Physics) Lawrence W. Jones ORA Projects 03106 and 07928 under contract with: NATIONAL SCIENCE FOUNDATION through MIDWESTERN UNIVERSITIES RESEARCH ASSOCIATION STAUGHTON, WISCONSIN and DEPARTMENT OF THE NAVY OFFICE OF NAVAL RESEARCH WASHINGTON D.C. CONTRACT NO. Nonr-1224(23) NR-022-274 administered through: OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR June 1967 Distribution of this document is unlimited.

A Cosmic Ray Program for the Study of Strong Interaction Physics in the Range of 100-1000 GeV Lawrence W. Jones The University of Michigan Since 1962 there have been continuing discussions on the possibility of erecting an ambitious cosmic ray experimental facility at mountain altitudes directed toward the study of strong-interaction physics in the energy range of 100 to 1000 GeV. As the concept crystallized, we formulated several specific objectives for such a facility: (1) that nucleon interactions be studied on free protons, i.e., a liquid hydrogen target; (2) that the identity of the incident particle be ascertained and that momentum analysis of the incident and reaction products be precise to a few percent; and (3) that the total number of events collected at energies well above existing accelerator energies be over 105 per year. In 1964 these thoughts were further developed at a small conference in Cleveland2 and in 1965 they were presented to the government agencies for consideration and support.3 We were encouraged to study the technical and scientific questions encountered in the design of such a facility, and over the past two years the National Science Foundation has supported us in a program of feasibility study. Before presenting our present concept of this research Supported by the National Science Foundation and the U.S. Office of Naval Research Contract Nonr 1224(23). -1 -

-2 -facility, I would like to review some highlights of this interim program. A major concern in the design of an experiment for a mountain top location was the extent to which energetic cosmic ray hadrons were immersed in a flux of accompanying particles, e.g., air showers. Accordingly, in 1965 a small experiment was operated at the summit of Mt. Evans, Colorado, in order to study this question. Two spark chambers of 5x6 ft2 were located above a small ionization calorimeter of 2x4 ft2 area and triggered on calorimeter signals corresponding to incident hadrons of over 50 GeV. The spark chamber photographs were analyzed in terms of the minimum radial separation between the hadron and other particles as function of energy. The results are presented in Figure 1, from which it is apparent that the problem of accompanying particles is not serious at 100 GeV and is sufficient to reduce by one third the useful number of hadrons of several hundred GeV if accompanying particles beyond half a meter may be tolerated. The aboslute flux of hadrons as a function of energy was also determined and found to be consistent with other measurements. In 1966 a larger apparatus was operated with the dual objective of studying further technical questions relating to the major proposed facility and of searching for massive, elementary particles (e.g., quarks). This apparatus contained an ionization calorimeter of 3x6 ft2 area and 1100 gm/cm of iron, a 40x80 in2 wide-gap spark chamber, 6 layers of gas proportional

-3 -counters, and an array of 130 ft2 of shower-detecting scintillation counters around the perimeter of this central stack. This system is shown in Figure 2. The results of the search for massive elementary particles is being presented separately at 4 this conference. Very briefly, the method employed a search for energetic events in the calorimeter delayed relative to accompanying air showers, as originally suggested by Damgaard et al,5 This method has the advantage of being independent of the particle charge. The aperture and operating period were -11 2 sensitive to a flux of 2x10 particles per cm sr sec. Including the possible attenuation of massive particles in the atmosphere and the probability of detecting an accompanying -10 -2 air shower, this flux figure is modified to about 4x10 cm -1 -1 sr sec, although the exact figure depends upon various model assumptions. While one event was detected consistent with the expected behavior of a 35 GeV particle of 6.5 GeV/c2 rest mass, there is also an 8% probability that this event was a nucleono We thus do not regard this as significant evidence for existence of a massive elementary particle, but rather as setting an effective upper limit to the flux of such particles. The experimental questions studied included the nature of cascades in the ionization calorimeter, the behavior of large wide-gap spark chambers in an experimental environment, and the use of gas proportional counters for particle identification. The results of the calorimeter study are generally similar to those of Murzin,7 Cowan, and others. We find average attenuation length of 200 gm/cm2 in iron for the ionization from an

-4 -incident hadron, independent of incident energy (Figure 3). However, large fluctuations in ionization as a function of depth occur in individual events, as illustrated in Figure 4. The wide-gap spark chambers, operated at voltages in excess of 100 kv, contained two gaps of 5 in. spacing and 40x80 in2 area separated by a driven central 0.001" Al electrode. The shielding was such that this pulse was not noticeable in the output of the gas proportional amplifier electronics. As the most probable singly-ionizing particle pulse in the counter gave a signal of 10 1 coulombs on a 400 pF capacitance, the spark chamber pickup was equivalent to less than 5x1016 coulombs input. A detailed study of a similar wide-gap spark chamber of 8 in. gap spacing in our laboratory has shown an achieved resolution of ~103 radians in angle and ~1504 in space. These figures are limits set by multiple coulomb scattering of the cosmic-ray muons, the particles employed in the resolution studies; and the actual precision of the chambers is believed to be significantly better. We have also extensively explored the use of a. number of gas proportional counters to separate positive pions from protons at energies above 100 GeV.9 We have learned that the distribution of ionization of such gas counters is about twice as broad as the Symon-Landau-Vavilov10 prediction, but is in agreement with the calculation of Blunk and Liesegang,l wherein atomic binding effects are considered. From Monte Carlo calculations, we conclude that an array of 12 proportional counters of the

-5 -sort used in the 1966 experiment could be used to separate 100 GeV protons in cosmic rays from positive pions using a maximum likelihood calculation applied to the separation pulse heights. The degree of separation is indicated in Table I. We have also constructed a small superconducting magnet with 8" pole diameter to explore the problem of supporting the magnetic forces exerted by superconducting coils of Nb3 Sn across the required thermal insulation. This realistically models the problem of replacing copper coils on a conventional iron magnet topology with superconducting coils contained in a "donut"shaped cryostato Results of this model program were very satisfactory in that the heat losses through a nylon support structure were reasonable and the mechanical forces at full, superconducting current were satisfactorily sustained. This year we are constructing a new experiment at the Echo Lake station wherein we plan to measure the proton-proton total cross section in the range from 100 to 1000 GeV to a precision of from 5% to 20%. This will employ an expanded version of the system used in our 1966 experiment with the addition of a 2500 liter liquid hydrogen target. The system now under construction is illustrated in Figure 5. Besides statistics, the principal sources of error are uncertainty in the pion-proton ratio and the uncertainty in the ratio of elastic to total cross sections. We expect this system to be collecting significant data this autumn and to accumulate over 5000 interactions in the hydrogen target by nucleons of over 100 GeV within a 6 month period of

-6 -operation. The long-range goal of our group is to construct and operate a major facility at the summit of Mt. Evans. The system proposed is shown in Fugures 6a and 6b. It would contain a 10,000 liter liquid hydrogen target and two large magnets, each with an aperture of 9 m2 and a bending power of 40 kilogaussmeters. The overall system would be 70 feet high and would employ 8 wide-gap chambers of the type we have built, but scaled to areas of 2x4.5 m2 and 3x7 m2 The primary trigger would be provided by an ionization calorimeter of 3.5x9.5 m area and 1000 g/cm2 thickness. Together with narrow-gap spark chambers, it would not only trigger the system at a certain energy threshold, e.g. 50 GeV, but would identify the energies and angles of neutral particles from reactions. It would also largely separate energetic y-rays from neutrons. The momentum resolution would be about 3% at 400 GeV/c, and the resolution in angle achieved with the spark chambers (e.g., scattering angle, opening angle, etc.) would be ~5x10 5 radianso Two matrices containing a total of 22 horizontal layers of gas proportional counters in the incident "beam" would permit pion-proton separation. The spark chamber data would be photographically recorded, while the information from the proportional counters, calorimeter counters, and other scintillation counters would be digitized on magnetic tape with the aid of a small electronic computer. The magnets might be conventionally powered or superconducting. If conventional, they would require about 8.75 MW apiece. At this time

-7 -the superconducting option appears most attractive. It has become traditional that a discussion of a proposed new facility include a statement of the physics to 'be done, In the present case such a prognostication is particularly difficult, as the energy range to be explored is so far beyond current laboratory experience. Exactly the same problems are encountered in discussions of new accelerators. The physics potential of the apparatus is apparent from Tables II and III where the appropriate fluxes, interaction rates, and yields for various strong interaction processes are noted. Total cross-sections and elastic scattering would be easily and accurately measured. Other known specific two-body final state channels would be quite uncommon, 'based on extrapolations from current accelerator data and fashionable theories. An exception would be those processes which proceed through exchange of the quantum numbers of the vacuum, or through diffraction dissociation. Here, cross-sections may be approximately energy independent, and such reactions as pp - pN (1512) may continue to be important up through 1000 GeV. Other processes which may be expected to contribute are boson exchange channels leading to a specific final-state resonance or particle at one vertex but integrating over all kinematically-available states at the other vertex. An example, r p 4 p N (all) (where N (all) includes all final-state nucleon systems), experimentally demonstrates the one-pion-exchange prediction of an almost energy independent cross-section up to 18 GeV.12 A particular

-8 -subset of these processes may be those wherein a virtual exchange particle elastically scatters on the target particle, - -+ p0rrp "Deck effect"p 13 such as TT p p~ p. If this "Deck effect" process lis correctly interpreted in recent accelerator experiments, it would also correspond to an almost energy independent crosssection. These particular channels are cited as interesting subjects for study in the context of current results from accelerator experiments. We also believe that final state systems with the smallest number of particles (or resonances) may be the most readily interpreted theoretically, even though they are relatively rare. On the other hand, such questions as fireball production, studies of correlations, and statistical questions in many-particle final states will be carefully explored with high statistics and precision. As an example, a detailed study of the transverse momentum distributions of secondaries would be very valuable for comparison with recent results of Krisch et al. at accelerator energies.l5 This project is being pursued in the context of intense international interest in high energy strong interactions. Thus the Serpukov 70 GeV synchrotron is nearing completion, the CERN ISR is under construction, and the U.S. 200 GeV National Accelerator Laboratory is being organized. Against this backdrop, this facility will represent a unique source of data on pion-nucleon interactions above 200 GeV for a long period, even though there may be significant overlap between

-9 -this program and the CERN ISR in proton-proton physics. In addition, np reactions and studies of the A-dependence of reactions (coherent effects), can be studied above 200 GeV. There will be a significant number of energetic muon events per year, and, while the triggering is more difficult, the possible results could be very interesting. Support and financing of the facility described here is being requested at this time. It will require four years construction time at a total cost of about $23 million. The logistical questions in establishing this mountain top station, while formidable, all appear solubleo The architect-engineering firm of Skidmore, Owings, and Merrill have studied the costs in constructing a permanent laboratory building of about 50,000 ft2 floor area at the summit of Mt. Evans, and find that a total cost of $5 million would be sufficiento A 300 Megawatt pumped-storage facility of the Colorado Public Service Company is located 7 miles overland from our proposed site. and the U.So Forest Service and power company engineers have agreed on a routing for a 115 kV power line capable of handling a 25 MW load. The Colorado State Highway Commission engineers have appraised the costs of improving the highway to the summit and of maintaining it clear of snow for year-round access. If conventional magnets are used, a closed glycol cooling system would be employed with air coolingo Other logistical questions such as water and liquid hydrogen supply have been satisfactorily solvedo

-10 -This presentation would be incomplete without crediting my colleagues in this program, Fredrick F. Mills of The University of Wisconsin and Bruce Cork of the Lawrence Radiation Laboratory. We have been most fortunate in the participation in our program of P. V. Ramana Murthy and A. Subramanian, on deputation from the Tata Institute. Scientists also playing important roles in this program have included D. Lyon, D. Pellett, R. Roth, B. Loo, and G. DeMeester (Michigan); R. Hartung, R. Reeder, R. March, and S. Mikamo (Wisconsin); E. Marquit and A. Benvenuti (Minnesota); B. Dayton (Los Angeles); A. Bussian (H.A.O., Boulder); P. Kearney (Colorado State University); and S. Snowdon, G. DelCastillo, R. Fast, W. Winter, C. Radmer, and J. Hicks (M.U.R.A.).

-11 -REFERENCES 1, Lo Wo Jones, "A Cosmic Ray Experiment Design to Explore Strong Interactions at 300 GeV," CERN AR/Int SG/63-13, (unpublished); L. W. Jones, "Can Cosmic Rays Replace Accelerators," Brookhaven 1963 Super-High Energy Summer Study AADD-10. 2. "Proceedings of Conference on the Interaction between High Energy Physics and Cosmic Rays," Case Institute, Cleveland, Ohio, September 25-26 (1964). 3o "Proposal for an Ultra High Energy Physics Experiment Using Cosmic Rays," Midwestern Universities Research Association, January 11, 1965. 4o "A Search for Massive Particles in Cosmic Rays," L, W. Jones, D. Eo Lyon, Jr,, P. Vo Ramana Murthy, Go DeMeester, Ro Wo Hartung, So Mikamo, Do Reeder, A. Subramanian, Bruce Cork, Bo Dayton, A. Benvenuti, E. Marquit, Po D, Kearney, Ao Eo Bussian, Fo Mills, C. Radmer, and W. R. Winter, June, 1967 (to be published in. The Physical Review). 5. Go Damgaard, Po Grieder, K. H. Hansen, C. Iverson, Eo Lohse, Bo Peters, and To Rengarajin, Physics Letters 17, 152 (1965). 6. "Design of Ionization Spectrometers Using Iron and Scintillators, for the Detection of Hadrons in the 100-1000 BeV Range," Do E. Lyon, Jr., and Ao Subramanian, May, 1967 (to be published in Nuclear Instruments and Methods)o 7. Vo So Murzin, "The Ionization Calorimeter," preprint,

-12 -Moscow, 1965 (to be published in Progress in Cosmic Ray Physics.) 8. E. L. Cowan and M. K. Moe, California Inst. of Technology, Preprint, 1966. 9. "On the Problem of Distinguishing Protons and Pions in the Cosmic Radiation at Energies > 100 BeV," P. V. Ramana Murthy and G. DeMeester, MURA TN-641 (unpublished), June 1967, (to be published in Nuclear Instruments and Methods). 10. B.-Rossi, "High Energy Particles," (Prentice-Hall, 1952). 11. 0. Blunk and S. Liesegang, Zeitschrift fur Physik 128, 500 (1950). 12. L. W. Jones, E. Bleuler, D. 0. Caldwell, B. Elsner, D. Harting, W. Co Middelkoop, C. R. Symons, and B. Zacharov, Nuovo Cimento 44, 915 (1966). 13. R. T. Deck, Phys. Rev. Letters 13, 169 (1964). 14. L. Stodolsky, Phys. Rev. Letters 18, 973 (1967). 15o L. G. Ratner, K. W. Edwards, C. W. Akerlof, D. G. Crabb, J. L. Day, A. D. Krisch, M. T. Lin, "Production of Pions, Kaons, and Antiprotons in the Center of Mass in High Energy Proton-Proton Collisions," June 1967 (to be published).

Table I Proportional Counter Study: Separability of protons and pions in an array of 12 proportional counters by the likelihood ratio method with enhanced widths To Select Proton Beam L >lo0 >3.0 >5.0 >8.0 E 83 % 60o7% 50.3% 40o7% P ~ 19.2% 6,0% 3.4% 18% Contamination 6. 5 2.9% 2.0% 1.3% To Select Positive Pion Beam L <1o0 <0o5 <0o3 <0,1 c 14.1% 6.9% 3.7% 0.5% Ely T78.4% 60.1% 48.1% 19.1% Contamination 37.4 2708% 20.6% 8.3% These efficiencies and the rr+/p ratio (.0.3) in the cosmic radiation would imply a certain amount of contamination by the wrong kind of particles whose values are given in the 4th row.

I Co C\J 0 -1 HH H H I I I I I: oq oq ~- - 1 1 1 0000 1I I I?HH!D oO0 -d HHHH -O 000 HI cr p_0O>0C\J 0 ~I~~~ HHH ci~ HH ~~~ ~o o ^ X X X X C; H H H (D 1 ~~~~~~~~~~Hr- 0 0 c ~ L P>C x c\j t ' LC> -t0 0o o fn 0 — 0 0 0 + + H HH H - 0 0 0 0 = 0 C\J- h y - <P-ci)D I Lr>0zn y -LC i- -d TJ ^~~~~~~~~~~~~T 0 C\J C CO CO P-C I I I + 0 0000 tHHHH- *'H H H- H CC-CIZ 1.-!0 q-.' i I I cO0CYq r-i~~~c-i r-i( (nc ^ Oii i oo o I~ IXl XlI I I0 0 0 0 'Q D 0C\J O Ln0 000 0 ci) ci+ -i HOO0 0 0OC\Jcf 1 H H H U ) )c-tU ci O. HOH 1 o 000^0 -— 1-L nQ0 I e ~. ^ I I I I Q) I L~~~L\LCk0 0000 H1 0 CU CxJ CC);t II xCU-;- 0 ~~~~~~~~~~ i CM Ln _-^t Cm <; 0D I I I I I- I 0000 Z H r H H H 0 H Pft4o 4 0 C H U) r-L0HHHH 0> o00 C JCY I I I I H Hr-i a00 H j g H O1 H H I I I Q >> t*~is H. o 000 00 US ~ ~ ~ ~ ~- ~! HH 0 2ttYh\ 5 H ci 0 H 4 000 bTj.)Hc ODOKO HHHH -!. O 0 C%1 00. -, I H ~ I r-I _ 0A03 OO -H 3.II X X X~ U) tZlf LPK L n n (CM 10 CD " L(>LC\? ^* * * - O D 0-. qO t X d > 0 0 a H 0 LCn L o Q00 c Z C\J QJ C m 0 *r-H * * * ft 0 US -H -P 0 0 00 -P cU bD 0 -P ^ P^ CQj 0 ^ H 0 0 C\JCJCCO (4H 000OU)OUOU)OU I II — I.DI LO ES H H H US c CH H 0000 *o-p x x 4~-=t^ — L( ^ U HISxIxi l HH H 00 0L 0 -P 0 H tCa -H0:0:00 0 0 C * * * U H HHH ( 1 0 E- H KOJC\jLC> l HHH ^ xxx -- 4 _t~ Lhk 0h L. \L( OJ. o '.... b o GH CdCJCY0CY O 00 -H O o0H -P Od 04 0q -~ 0 0 0 ~0 u~-P o o o...H ~! OO^OO IH H xl-d.d d'L 0 ~P ~ ~ ~ ~ ~- 4- ~.C0 0..~~~~~~~~~~~~~~~~ ~ O ~~~~~~~~~~U) ^~~~~~~~~7 4 -P 0 rH 00 H 0:14 00 H 00 00 00 P 000 H 0000 O O O ~-~ OO O OOO'O000 4 OOOO 03 OOOO 0000 000 0000 0 0000 K Fzl H r 41 H-i H H H H 0<~ ~ A I A I I Q) A I I I A d~~~~~~~~~ - -~ ~I COO 1~ —, I — d ~ '%O l I-~ 0 '

Table III Rates for Various Reactions A. Reactions predicted to be approximately energy independent Process Cross Section Events/year >100 BeV >300 BeV 1. Elastic scattering 4+p 4 mb 760 100 r p 4 mb 760 100 pp 8 mb 5800 np 8 m'b 5800 2. Elastic scattering with It |<0.01 (BeV/c)2 (region sensitive to Coulomb-Nuclear interference and hence for the real part of the scattering amplitude) Ur-p 0.3 mb 35 4 r~p 0.3 mb 35 4 pp 0.75 mb 550 70 3. Production of Isospin ~ nucleon isobars N 1520, 1690, and 2190 pp4pN 2 1.0 mb 700 100 4o Production of p meson integrating over final states at the nucleon vertex ~r pp N (all) 0.5 mb 100 12 5. Deck effect or production of the Al boson p4 TT~p 0.1 mb 20 2 Tr+p4r+p p 0.1 mb 20 2

Table III (continued) B, Meson Exchange Reactions Energy Dependence Events per of Cross Section Cross Section Year over -N at Energy 100 BeV a s N a E 1. pp-pN3/2 1.3 100 ib at 15 BeV (t exchange) 8 ib at 100 BeV 5 2. ~-p4n~n 1.3 25 pb at 18 BeV (p exchange) 4 ib at 100 BeV 1 3. T p-K A~, K~Z~ 1.4 140.'b at 4 BeV (K exchange) 15 Ib at 100 BeV 2 4. n+p-N ++ O 1.1 1.1 'b at 1 BeV 7 'b at 100 BeV 1 5. t p4p nn 600 b at 4 BeV 4.8 i'b at 100 BeV T P-4p~p 1.5 450 tb at 4 BeV 3.6 4b at 100 BeV 1-2 T+ p4P P 375 'b at 4 BeV 3 Ib at 100 BeVJ

FIGURE CAPTIONS Figure 1. The radial distribution of the nearest accompanying particle as a function of total energy from the 1965 M.UoR.A. experiment on Mt. Evans. The ordinate is the probability of occurrence of an accompanying particle within a radius of R meters of the detected energetic hadron. Figure 2. Design of the 1965 Echo Lake experiment to search for massive, elementary particles and to explore the properties of proportional counters, wide gap spark chambers, and the total absorption spectrometer. Figure 3. Averaged shower curved for some selected energy bins, Figure 4. Individual event shower development in the total absorption spectrometer. The curves are drawn only to guide the eye. The X's are the actual data points. Figure 5. Design of the 1967 Echo Lake experiment for the determination of total cross sections over the energy range 100-1000 GeV.

Figure 6a. Front view of the overall experimental assembly. The overall height is 836 inches. The magnetic field is normal to the plane of this section. An extreme diagonal ray is indicated illustrating the aperture subtended (e/2 = 21.8~). The phase space admittance of the system is 0.55 m2 sr. Figure 6b. Side view of the overall experimental assembly. The overall height is 836 inches. The magnetic field is parallel to the plane of this section. An extreme diagonal ray is indicated illustrating the aperture subtended (cp/2 = 8.7~).

RADIAL DISTRIBUTION OF NEAREST ACCOMPANYING 0. PARTICLE AS A FUNCTION OF TOTAL ENERGY 0.9 -cn - - A: 8 BEV < E < 120 BEV w: 0.8- B: 120 BEV<E <180BEV z C: 180 BEVE <300BEV 0.7 D: 300BEV< E w3 o 0.6 cCZ aX. MO Z. 0.5 g- ID 0 0.4 i 0.4 -co -I}' Bt A ~w 0 rCa A. 0.1 -a- _i 0 0.2 0.4 0.6 0.8 1.0 1.2 R (m) Figure 1

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0 0 E *- 0 w< cr, C, 0:C IDO~~~~~ 0C o8 1* S> gY l-S3-1 U8Vd,,:lO t0 3BIynN C 2 2 0 w w -,4 o COD N _S3,.1S301cIVdld, dO d3""fN __ 8 u E> E S iido S39z.N - ^ " ^, I i po~~~ 0 C,S,3"0.18Vd, JO 83ewvnN > OD-.Sr-3 S1.Ud t.-I0 83gnNuy C~W j I ' ' ' Is J,~~~~~

1967 TOTAL CROSS SECTION EXPERIMENT FRONT VIEW MARCH 1967 t,.. 0 ~ --- I ll I 11 1 -20 THIN FOIL SPARK CHAMBER -t / \ SHOWER 0) COUNTERS HYDROGEN COUNTERS:'Eizzz"'"""'' TARGET AN [[A ~~~~~~~~~~ \ i~~r<ANTI= _ \V~~~~ / ~COINCIDENCE 0 0 -- 0 "1. K |LEAD PLATE CHAMBER ^n pIRON PLATE CHAMBER 80 g/cm2 V A__________ __________1!. ~ I IRON PLATE CHAMBER 80g/cm2 I o i ' _ 1................... J..,,,,, ', - -,,.I o0 i | IRON 120 g/cm2 W |-0o ||IRON 120 g/cmn2 g/cm2 \ I,,,R,,,, N,,,,.,,,,,,,,,....-.....,,,,,. ' ' iTOTAL,0) IRON 120 g/cm2 it r,.,...-,....,...~,........,...,...,..........r ---.I N CAL. =U. IRON 120 g/cm2 Approx. Wt. 8.34T IRON 120 g/cm2 IRON 160 g/cm~ Approx. Wt. 11.12 T IRON 160 g/cm Figure 5

VERUclHEIC. IN, ESs, FRONT VIEW PRX)I[VI IALS EIk.l\) i% c555[K i cT C*R~ -- /..... P ITID.\I C AdTD _ / SPARKP / oS ~~~~~~~~~~~~~~~/ SPA AK - Ci W T f alit [/V T i I Figuree^^^ /a WIDE GAP; /! CHAMBEt I _R iLA YERS OIF j /,COUNTERS LER/ / SWSSPARK CHAMMER | — A ER OR FCR STROAS IS R CO NTER I s Ilonic~ WDAG E GA An, x 180, / / /. S PARK lCOMB R /. I... [IOR l Imr / HYDROGEN *StPLRKb S SPA R C1AM'ER O Lh / GAPt 9 o R. SPARK. HAMBYER _ / I DmCTORS

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Unclassified Security Classification DOCUMENT CONTROL DATA - R&D (Security classification of title, body of abatract and indexing annotation must be entered when the overall report ie clarified) 1. ORIGINATING ACTIVITY (Corporate author) 2a. REPORT SECURITY C LASSIFICATION The University of Michigan Unclassified Department of Physics 2.b GROUP Ann Arbor, Michigan 3. REPORT TITLE A COSMIC RAY PROGRAM FOR THE STUDY OF STRONG INTERACTION PHYSICS IN THE RANGE OF 100-1000 GeV 4. DESCRIPTIVE NOTES (Typ of report and inclusive date) Technical Report No. 30 5. AUTHOR(S) (Lost nnam. firt name. initial) Jones, Lawrence W. 6- REPORT DATE 7. TOTAL NO. OF PAGES 7b. NO. OF REFS June 1967 25 15 Ga. CONTRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(S) Nonr-1224( 23) 05106-50-T b. PROJECT NO. NR-022-274 c. b. OTHER REPORT NO(S) (Any other numbera that may be asalgned lai report,) d. Technical Report No. 30 10. V A IL ABILITY/LIMITATION NOTICES Distribution of this document is unlimited. 11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY Invited paper prepared for presenta- Department of the Navy tion at the X International Confer- Office of Naval Research ence on Cosmic Ray Physics Washington, D.C. 13. ABSTRACT D 1 JAN 64 Unclassified Security Classification

Unclassified Security Classification 14. LINK A LINK B LINK C KEY WORDS ROLE WT ROLE WT ROLE WT INSTRUCTIONS 1. ORIGINATING ACTIVITY: Enter the name and address imposed by security classification, using standard statements of the contractor, subcontractor, grantee, Department of De- such as: fense activity or other organization (corporate author) issuing "Qualified requesters may obtain copies of this the report. report from DDC." 2a. REPORT SECURITY CLASSIFICATION: Enter the. over-t 2a. REPORT SECUTY CLASSIFICATION: Enter the. ov (2) "Foreign announcement and dissemination of this all security classification of the report. Indicate whether "Restricted Data" is included. Marking is to be in accord- report by DDC s not authozed ance with appropriate security regulations. (3) "U. S. Government agencies may obtain copies of this report directly from DDC. Other qualified DDC 2b. GROUP: Automatic downgrading is specified in DoD Di- urs hllt re t D ther qualified DDC rective 5200.10 and Armed Forces Industrial Manual. Enter users ha request through the group number. Also, when applicable, show that optional." markings have been used for Group 3 and Group 4 as author- (4) "U. S. military agencies may obtain copies of this ized. report directly from DDC. Other qualified users 3. REPORT TITLE: Enter the complete report title in all shall request through capital letters. Titles in all cases should be unclassified., If a meaningful title cannot be selected without classification, show title classification in all capitals in parenthesis (5) "All distribution of this report is controlled. Qualimmediately following the title, ified DDC users shall request through 4. DESCRIPTIVE NOTES: If appropriate, enter the type of.__ report, e.g., interim, progress, summary, annual, or final. If the report has been furnished to the Office of Technical Give the inclusive dates when a specific reporting period is Services, Department of Commerce, for sale to the public, indicovered. cate this fact and enter the price, if known. 5. AUTHOR(S): Enter the name(s) of author(s) as shown on 11. SUPPLEMENTARY NOTES: Use for additional explanaor in the report. Enter last name, first name, middle initial, tory notes. If military, show rank and branch of service. The name of the principal author is an absolute minimum requirement. 12. SPONSORING MILITARY ACTIVITY: Enter the name of the departmental project office or laboratory sponsoring (pay6. REPORT DATE: Enter the date of the report as day, ing for) the research and development. Include address. month, year; or month, year. If more than one date appears on the report, use date of publication, 13. ABSTRACT: Enter an abstract giving a brief and factual summary of the document indicative of the report, even though 7a. TOTAL NUMBER OF PAGES: The total page count it may also appear elsewhere in the body of the technical reshould follow normal pagination procedures, ie., enter the port. If additional space is required, a continuation sheet shall number of pages containing information, e attached. 7b. NUMBER OF REFERENCES: Enter the total number of It is highly desirable that the abstract of classified reports references cited in the report. be unclassified. Each paragraph of the abstract shall end with 8a. CONTRACT OR GRANT NUMBER: If appropriate, enter an indication of the military security classification of the inthe applicable number of the contract or grant under which formation in the paragraph, represented as (TS). (S). (C). or (U) the report was written. There is no limitation on the length of the abstract. How8b, 8c, & 8d. PROJECT NUMBER: Enter the appropriate ever, the suggested length is from 150 to 225 words. military department identification, such as project number, subproject number, system numbers, task number, etc. meaningful terms or short phrases that characterize a report and may be used as 9a. ORIGINATOR'S REPORT NUMBER(S): Enter the offi- index entries for cataloging the report. Key words must be cial report number by which the document will be identified selected so that no security classification is required. Identiand controlled by the originating activity. This number must fiers, such as equipment model designation, trade name, military be unique to this report. project code name, geographic location, may be used as key 9b. OTHER REPORT NUMBER(S): If the report has been words but will be followed by an indication of technical conassigned any other repcrt numbers (either by the oraf^mnator text. The assignment of links, rules, and weights is optional. or by the sponsor), also enter this number(s). 10. AVAILABILITY/LIMITATION NOTICES: Enter any limitations on further dissemination of the report, other than those Unclassified Security Classification

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