I":

'"_' DOE/ER/10713--10

OCT DE91 000682

Progress Report

Study of Electron-Positron Interactions,,_

A. ABASIlIAN_ PltlNC, ll'AL INVESTI(;ATOI_

I(. Go'row, CO-PI{INCIPAI., ]NVI_S I'IGATOI{

L. PI1LONEN, C,O-I'II1NC, II'AI, IN\,,'I.?,STIGATOI(

Virginia. Polytechnic Institute and Sta,te UniversityBlacksburg, Virginia 24061

September 15, 1990

DISCLAIMER

This report waspreparedas an accountof work sponsoredby an agencyof the United StatesGovernment. Neither the UnitedStates Governmentnor any agencythereof, nor anyof theiremployees,makesanywarranty, expressor implied,or assumesany legal liabilityor responsi-bility for the accuracy,completeness,or usefulnessof any information,apparatus, product,orprocessdisclosed,or representsthat its use wouldnot infringeprivatelyownedrights. Refer-ence herein to anyspecificcommercialproduct, process,or serviceby trade name, trademark,manufacturer,or otherwisedoes not necessarilyconstituteor imply its endorsement,recom-mendation,or favoringby the United States Governmentor any agency thereof. The viewsand opinions of authors expressed herein do not necessarilystate or reflect those of theUnitedStates Governmentor any agencythereof.

,(

i *

I. Introduction

,

For tile lm.St .seven years, this group has be('n int.er(.,st,('d ill tlw st._ldy of t,ests of the

Sta,nda.rd Model of Electr(,wcak interactiolls, Tile ln'¢_grnln li_|s ccl_tcred abcmt. l,lie AMY

exl)eriment, wMch exaynines tlie na.tm'e of the fina.1 state l)roduct, s produced in elect, rol,_.

positrori collisions in the center of mass energy ra.ilgc llear G0 G(,\,'. R_'sult, s c,f these lll(:'.a-t . , . ,

, ,

sm'ement, slm,_,e shown a, rcnmrkab]e consist, ency with the prcdict, iollS of tlle minin_a.1 nloclcl

of 3 qua,rk a,nd lepton genera,fions and single charged a.nd lmutra,l intermedia.te bosons, No

new pa.rt, icles or excited st a.tes have been observed nor Ims relY evidence fin' delmrt, ures ini

•

cross sections or angular assvmetries ft'ore expecta,tions been observed. Tl_ese c.onclusi(ms

have been even more firmly est, a]:fiished ]:)5' the higher energy result, s ft'ore ,the LEP _lndJ

SLC colliders a,t center of mass energies Of a.bout 90 GeV.

,

The Virginia. Tech pa.rr of the AMY colla,boration is in the process of a.nalyzing da.t,a.

a,ccumula,ted up to the end of July, 1990 m_d expects t,o tmve completed a, number of

theses during the forthcoming year. A portion of the effort will begin to address new a,rea,s

of investiga,tion rela,ted in part to our continuing interest in tlm subject of electroweak

intera,ctions. It is clea,r tha,t the extension of our pa,st endeavours t,o l,igher cent, er of mass

energies using electron herons will not, be possible in the rea,sonably near filture inasmuch

a,s no electron type colliders beyond LEP m-e envisioned. Our focus is shifting to t,he ottler

pa,rticle which probes the electroweak intera,ctions; namely the neutrino.

There are a number of .rea,sons why the cosmic rays may be a rea.sona,ble Sora'ce for

the study of neutrino intera,ctions, First, energies of cosmic ra,y particles are known to

extend to at lea,st 102°ev, which corresponds to cent, er of ma.ss energies of about, l()_Gc.-:l,:,

fa,r beyond present ra,nges of labora,t, ory st,udy. Second, results emerging from ex!)eriments

which study the emission of neutrinos from the sun give a,hint t,ha_, the neutrino may ha.re

,'3

prc)])ert.ie._ ()t,her tlla.n t,lm,t of a l)oint a11<Ima,s._h:_ssl_m"cle. This intr(_(luc(-;s t,llc l_¢>ssil_ilit,5'

t,llat ll('ut.rin()s will at s()ln(' cliergy ilit,era.ct with a sul)st.anti;dly high(.'r l)r(_btd)ilit.y t,ha l_,i

(:,xtrapolati(ms fi'orn l,,l'eS(:'nt day mt,;tsurenl(,nts I)redict,

The .rel_,.tive merit, olt'ai,i,enlll)/,irlg t,o observ(:' 1-1ellt,rillos fl'Olll point sources versus ()bscrving

neut, rin()sgener_dly is not (_asy to lm, dict, The irnl)rovcd ability t,o il_t.('rprct is offset l)y,,

t,he ll)ro])al)ly el)is()(lic lmt, ur(:, of t.h(: (,missi()n _llil irrt'l)r(_)ducibilit.y of t.lic r(,sl_ll.s. Ill t,llis

pha),se of development, it, is best t,o be sensitive to l:_ot,h sources of neutrinos.,,

As a s(.'cond plrose of our program a.t Virginia Te.ch, we are st,udyillg ttle feasil)ility of

dct, ecting cosmic ray neutrinos in a proposed e.',:perinlent which we have call(xi NOVA. Tlle

results of the 'test, set,up will be instrumental in developing a._l Ol:)timmml' design.i

A (,l_ird program we axe il_v()lved in is (,he MEGA exp('rirnent a,t Los Alamos, a,n experi-

ment, to piace a, limit, on t,he ra,tc ofn_on d(-'cay t,o electron l:)lus l:)lmt.on which is fc)rbidden

by the St,_mda.rd Model.

J

II. REPORT ON TI,-IE AMY EXPERIMENT

A. AMY STATUS

Tile AMY exl)erin:(mt a.t TRISTAN cont, inues to st,u(ly t,ll(:, 1,hysi(':J of ('.'l(:,cl,r(m-l,()sit,r()n

collisions a.t' center oi" mass energie.s bet, wcen.50 a.nd 64 GeV, Irl t,his (.,r_,.,rg_'range, the

electroweak cross sect, tori lla.s n. loca.1 nfininmnl of _ 10()l)b as t,h(, t'alling QED aml)lit, ud(_,,

b(_corn(.:s conq)arable to t,he rising; weak amplitude nem' t,ll(., Z ° l_olc. Tlms, t,ll(.: AMY

eXl:)erinmnt.ca.n make sensitive CC)lrq:)a.risons with the predictions of tllc St_m(lard Model of

t,he electrowea.k intcra,ction.

In the surnmer a,nd fa,ll of 1989, the (.'ndc_l,p regions of AMY were rcillstrumcnt, e(l with new

'cndca,p shower counters (ESC) covering 0.799 < cos 0 < 0,98:2 a.lld small angle count, ors

(SAC) covering 0.982 _< cos0 < 0,9994. These detect, ors ha,v(-' substalfl, ially inq:)rovecl

AMY's solid angle coverage a.nd its energy a,nd a,nguln.r resolutions in t,lle fln'wa.rd regiolr

the ESC, energy resolution for 32 GeV" electrons is 8.4% _1.1_(.1t,hc a,ngula.r r(_,._;ol_lt,i()n a.re

ao = 2,4 mra,d a,nd a_/, = 80 lnrad.

Testing of the rebuilt synchrotron X-ra.y detector (XRD)continued in 1990. This de-

tector, sa.ndwiched between the centra.1 drift, chamber (CDC) and the ha.rrc1 ca.h.)rimet(,.r

(SHC), is to clist,inguis!_ electrons from other clm,rged pa.rticles such a.s l:)ions by the presence.

or a.bsence of associa.ted synchrotron ra.dia.tion a.s t,he l)a.rticles a,re bent in the 3 Tesla. m_g-

netic field of AMY, Ba.,'s_edon a. very prelimina.ry, a,na.lysis, of isolated muons a,nd el(-,ct,rons,

the XRD has a. muon misidentifica.tion proba.bility of 6.2% and a.n electron identific_,t, ion

efficiency of 44%, hnprovement will require a. better knov,,ledge ()f the cha.rged lmrticle

position a.s it passes througll the XRD; most of the work is going into understanding the

position resolution.

TI_.ISTAN a.chieved a. (ehf.el of mass energy oi' 64 Ge\, in late 1989; 1,5 pb I of (l_m._.were

4

4

rc'.,c¢_rd¢.'dl)y AMY at t.hi_¢'i_,_:'_,v.Tl_¢, (,ll(-H'_v wti.s 1'(,(h.1('(-_,(I t,()t.rJS GI-'\," f()1' I.ll(' F_']II'Ii_II'3 ......

July 1990 run to maximize the lunfilmsity of TRISTAN, Al_out 271fl, -l of data w_rc

rotor(led 1)3'AMY in t,lfis period, The lif(-,tinl(, int.egrat(,d l_ulfill¢_sit.y¢_t'AMY il_w st,an(ls

a.t 601)b -1. .

B. PHYSICS RESULTS

'Tlle AMY colla.bora,tors (:ont,inue t,(.)l_c activ(-: in extra,ct,ing useful reatllt, s fi'olil tlw limit,_,(l

da.t,a sample, A complete list, of new pul)lica.tions since t,lle la.st progrc, ss report a.pI.x:aa'sin

the BiMiograpl0,; new cont,ributed lml.>ers a.n!, list,(,(l in ,i,lie C.:¢mfcrenc.(-'Sublnitt,_,d Pal)ers

sect,ion. Some of the resuli;s art:, ::::::::::::::::::::: below,

1. C',ompa.rison of Qua,rk a.nd Gluon Jets' In co_lt,rast wit,h t,he (la.ta. taken a.t lower

cent,ct of masses energies a.t PEP and PETI:I.A, we see dist:inct difl'e.rences in t,hc pr()pcrties

of hadronic jets. produced from qua.rk and gluon pa.rents. These difl'erences a,re a.li_l)_l.rent,

for inst,a,nce, iri t,llc higher concentra.tion of energy near t,lle ,jet axis for qum'k-induced jets.

,,..,, 10 " ,") Multiha.dron Event Properties' C, mparlson of multiha,dronic event, s in the TRISTAN

energy ra,nge with t,he predictions of the LUND 6.2, LUND (3.3 and HEI1WIG phenomeno-

logical models of e+e - _ha.ch'ons shows tha.t, the LUND 6,3 model best reln'oduces a.ll of

the event sha.pe distributions mea.sured by AMY.

3. Forward-Ba,cl_wa.rd Asymmetry in e:+c- _ 1,1,a.nd c+ c- _ha.dron jets: The St,a.ndm'd

Mode] predictions of a. forwm'd-bacl_ward asmnnlet, ry in these processes is collfirlncd in

mea.surernent, s of hadronic event production in AMY,

4., Mea.surernent, s of Hadronic ]?: We see no evidence for l)l'()duction (_' new quark flavors

beyond the five known t,o date, .However, the va.llle of I_, t,he rat,to of t.lle hach'olfic cross

section to the lowest.-order QED preclict, ion for dinmon l:)roduction, is si,ill higller than

expected from t,he St,a.nda,rd Model predict, ion wit,h Mz = 91 Ge'\: and .sin2 011, = 0,231.

5

TI_(' r('_s(_l_ i'or this discr(.'l)al_cy is n()t kl:()',vl_,

5, Observati(.m (_f An(,nmhms Producti(m of 1VIu(m P_lirs in 4-h,1)t(ni Filml Stl_t,('s' We S(,(,

an excess over t,lic QED prediction of c+c - _ e+C-/l+/l- wh(:ql _1]] f()lll' _[illld-st,_l,t,(' lq)t,(nis

are see:: in' AMY, We observe 7 events and expect 1.9. The st,a tisl, i('nl 1)r,)l,_ll)ility ()f such

.a.n excess is 0,34%, No sn(',ll excess a.1)pcars in the untagge(l or single-t:_lgge(l f(nu'-l('l)t()n

data sam _les, or i1_ the (l(ml)le-t, aggdd c+e: - _ c+c-c+c - All ()t' t,lw (li:ll_u)n l)_drs lm v(_

inva,ria.nt mass below I Ge\;/c2; any 1)ossiMe excess in tile double-tagg(:,d 4-(.'.lectro:_ signal

in t,]:is :lla,ss l'a,lige c:l,l:not ].)(' distinguisll(:'d fl'i)n: t,l:e higll r_l.diniiv(.'-Bl:_d.)lla 1)a('l:grou{l(l,

All of the dimuon p_firs emerge along t,lle dir(.'cti(m of t,ll(' (.)rigil_n.11,()sit,ton b(!,a.,ll, Tlm

' 's for the excess is unknowl,_,1Cd.,. Oil.

6. Nev,' Pa.rticle Sem'che_;: We lla.re ruled out, procluctioll (>f fourt, l:-ge.:mration qum'ks

a.nd lel)t, ons, non,-mil:i:na.1 Higgs bosons, vm'ions supersymnmt, ri(' lm.rticl('s, lel)t, ocl_n.rl:s

and colored leptons in the TRISTAN energy region, From the n(m-()10s(::rv;i.t,i()n of tlm,.'sc.,

processes, we ha.ve set, limits on new pa.rticle masses a.nd/or couplings, In g(m(-:ral, t,hese

,. _ "a i ,* )limits ha,re been superseded by the la,test result, s from the LEP colliding bea,m a,ccch_.:a,t( 1,

C. OPERATIONS OF THE VIRGINIA TECH GROUP

The Virginia Tech group continues to be a,ct,ive in ali aspects of the AIvlY exl)eriment,

Our n'la,il: responsibilities a,re in the operation of the barrel calorin_el,er a:_(:l i:_ da.t,a m:alysis,

, 1. Calorimeter Operation

The VirginiaTech g.:'c)::l?contixmedit,sresp()nsibilit,y fin'day-t,o-d_lyopera.tiona,ndma,in-

tenanceoftheAMY barrelc.alorin:ct,er.This i:_cluclesrout,inema,int,e::a,::(:eof thel:nrdwa,re

a,s well a,s softwm'e ca.llbra.t, ion of the det, ectc)r respo:,se, As a. result of t,l:c insta.llation of

redesigned ircm pole t,ips in c(mjm:ction wit, h the ESC and SAC:, t,ll.,,:'ml_.gnet, ic fi(..'.ldin t,l_e

shower counter region wa.s affected, Als(:), in a.n at, t,eml:)t, to lm?Vent f:u't,her loss of wires

6

f

,i

I

af't.('r t,ll(' I,rcmcn&ms rq)_dr effort i1_ S_11mll(.u'1989, t,lic, higli v¢,lt,ILgic,sc_li t.lli., wire's wt,rc• ,

, . ,

7ro¢hlced 1)i" 50 \ olt,s, Tiros, a lal'ge ofl'¢,rt Ims 1_(,¢:,11eXl)mltlod in r('cldil,:_lt, illg i,ll(:, d,'t.(:,ct.¢,r,,

resp(mse illt, llc l)resence (_f t,lle modified ma_lJ(,t.ic tic,Icl _11(1with l,lle ]¢m,,er wire v_)ltilg(.,,

\'Vit,h tlm .rcpa.ir of tile slmwcr c(mnt,cr and t,tu_,r(!ca.l{ln'at,i(_ll ('fl'(_rt,, t.he det,('('t()r rcsoluti(ms

ha.re recovered to t,he lovcls t,llat, were achicv(,d l_cfl_re t,lu, 1.nu'liill_ of _2()% of tllc SHC

wires (discussed in t,lic 1;isr, l)rogl'ess l'el)orI,),

, \¥e ha:v(, had o11o fa.cult,y member, one ilesearch Associate, and one U.S. graduate st,llch'nt

SUPlmrt, ed 1.)3'the cont, r;_ct in c(mtinua.1 rcs'ichnlcc _lt, KEl,( (l_u'illg t,ll(:' (:l;_t._lI,_l<i_g l)criods

fron_ November 1989 t,(_ ,July 1990,

2. Data Analysis

Aria.lysis of cia.ta by the Virginia. Tech group is now ca.rried out primarily a,t.Virginia Teel l,

with a. sma,ll fftf.ct,ion (prinm.rily event selection) st,iii done using t,lie KEK COlnlmt,ers,

Our st,udent, s t,a,ke a.dvaa_tage of t,he ability to use l,lw KEK FAC,O]_4 llla,illfl'a,nleS, t,l_e

Virginia. Tech AMY VAXClust, er, a,nd the Virglnia Tech Inst, it,ut, e of High Energy Pl_ysics

C,0nvex minisul)ercomputer in their st,udies, Ali of the 1)rograms for event general, ion,

sinmla,tion a.nd analysis a.re nmint, ained on ali three comput, er syst, ems, Tiffs gives us t,hc

flexibilit, y to ba.hmce our comput, ing needs with the loads on a,ll three systems; in particular,

it significaa_t, ly lessens our dependence on t,l._eover-subscribed KEK COmlmt,er,,_,

Four Virginia, Tech student, s are present]:," working on their t,hes_:_sft'ore t,he AMY exper-

iment, They a.re I(a,ngping Hu ("Search for Monochroma.t, ic Gamma. IR,a.ysa.nd rr°''), Anzhi

Lai ("St, udy of e+e- --+ c+e-''), Mark Ma.ttson ("Sl,ucly of Mult, iqua.rk aet, Producti_i")

a,nd Kevin St,erner ("Sea,rch for Sul._el'symmetric Pa.rticles" ), All l_;_ve resided ;t.{.KEK for

v_.rying l)eriods in 1989-1990, _'a.milia,rizi_g then_sclves wit,h t,l_e A _.'Ih: (let,ect,or, providi_ E

a.ssist, ance in running t,l_c exp_.._", "_-._nc.nt,_ a_ad discussing t,hci". data _ds"sis with t,l_c, ()t.l_er

7

nlclnl_cu's of t,ll(, AMY gr(ml),

I/ese_,rch Associ_lte E, Low left. in la.t.c 1990 t,(_ tak(' a 1,osition a,t t.lle University _f

Pe'nnsylva.nia.. Her dut, ie,s a.t,KEl( (rf'c_l()rimet.cr m_lint_-,n_111c<'_LI_(1C_l)(,r_'lt,iol_ and of det.ect.(_r

ca,lil:)rat.io.u will be a.ssuln(,d by Profess(_r S. Selmet, zer c_fIlutgers Ulliversit,y a n(l ot,ller AMY

collaborators a.t, KEK, one of v,,hcJm (Z,P. M.ao) will be 1-mrt,ially S_ll_p_rt,ed by (.nlr gr_mt:,

Bib liog rap lly

N,M. Shaw _:1,a,1,A Searci: fc_:'Unst._,l_lettel:vy Ncu.tral L¢?l?t(msi:l t.+t- Anldllil_,ti¢_lls

at. _ from 50 t.c_60,8 GeV, Pliys, Ile',', Left,. 63, 1342 (1989).

Y,I(, I(im c_',a,l, A C,(nnl)arisou of Q_mrl¢ lind Gluon Jct,s Pr<),.luc(,d iii ttigll Ell(,rgy c'+_-

Annihila,t, ions, Phys, Rev, Left, 63, 1772 (1989),

S, Eno ct al, Sem'eh for I_'om'th-Gellcn'ati(_ll Cll_rg¢.'d-1/3 Qum'k, Pllys, Rev. I.,ett. 63,

1,9,_0 (19s9),

II, Saga,wa. tC,a,l, A Measurement, of c+(,- _ bb N_rward--B_l.ckwa.rd Cll_lrge Ass'm.nlet,ry

between _ = 52 t,o 57 GeV, Phys, llev, Le.tr. 63, 2341 (1989),

E,H, Low c_ a,l, Sc'm'ch fc_r Non-Millimal Higgs Procluct_ion ilJ t +c- Amlillil_J, ions a.t

= 56 GeV, Phys, Left,, B228, 548 (1989).

Y, Saka.i ct a,l, A S(:'a,rch f¢_l' SUSh." Particles ill c+c- Allrlihila.t,icms _{J,_ = 50 60.8

GeV, Phys. Lett. B234, 534 (1990),

Y,I,_, Li t:¢,a,l, Mult, i-lladron Event, Properties in c+c - Anldillh_t, ion a.t _ = 52 to 57

GeV, Phys. 12.ev. D41, 2675 (19901).

D, Stuart, t:t,a,l, Forwm'd-Backward C,hm'ge Asymmetry in c+c - _ tlmll':n: ,Jets, Pl_ys,

R.ev. Lett,. 64, OS3 (199(1),

G,N. 1,2im e_,a,l, A Sem'eh for Lept,oqua.rl¢ m:d Colored Lept.on Pair Producl, ion in c+e-

Annihilations a,t TRISTAN, Phys. Let,t;, B240, 243 (190(1),

L. Piilonen, E.ecent 1--lesults from TII.ISTAN, Nucl, Phys, B (Proc. Suppl.) '13, 4S

(1990).

T, Kumit.a e_,a,l, Mea,surements of/?, for e:+ e- Annihila.ticm a.t Trt,ISTAN, submitted to

Phys. Rev, D.

Y.H. Ho c1,a,1,Observat, ion of Anomalo'_ls Product.ion of Muon Pa.irs il_ c+ c- Annit_il_,tlon

irit.o Four-Lepton Fina,1 St.a.tes, submit, t,ed t,o Phys. Let,t,. B,

3, Smith e_,a,l, Ma.ss Limit.s of C,htlrged Higgs a,t. Lm'ge tan/i_ frown e+ ¢:-"Annihila.t, ions

at, _ = 50--61.4 GeV, submit, ted to Phys, 12.ev. D.

H,W. Zlleng c_, a,l, Cha.rged Hadron Mult.iplicities in c+c:- Annil_ilat, io_s a.t _ = 5(1 l,o

(;1.4 GeV, submit, ted t,o Phys, Rev. D.

Y. Saka.i e¢, a,l, Semeh for C,harged Hea.vy I,ept,ons wit,h Arbitr',:tr_" N¢,__trino Ml_.sses in

c'+e:- Annihilt._tions a.t.v/gs- 50_G0.8 Ge\,', s_dmdt.t.ed t.o hat,l, ,]¢_u'l_tl _A'Mocl¢,r_lPl_ysics,

), i

C,onference Submitted Papers

Recent, 1-_,sllll,s _l,t,TRISTAN, sul,lnit, t,ed t,c, Les ]-tell¢'cmt,l,_,s _h, PllS',,d<l_le(h' ,1_1V_lll_'_'

D'A_st, c,, La Tlluih,, ]t,_l,l,v(h,'I_lrcll1990),

Bose.-Einstein C_rrt,lat,i(ms 111Pi(m Pr(,(luci,i(_al I_t TRISTAN,' s_lli111ii,i,('(1t,(, 25t,ll 111t,1,

Conference oil High Energy PlG,";ics, Singal)Ore (Aug_lsI 1990).

Measm'ement. of t,he e+ e - _ bb C,rc'_ss Section mid Forw_Lrd-B,tckw_tr(l Cll_lrge Asyllllll_'-

try a.t,_l C.,ellt,el-()f-Mass Ellergv of _" o ' ,,. o_,. Ge\' s::l_:::it,t,(_(lt,(,25t.1_11:t.1,C'.(,::f(':'('::('('I,:_ Higl_

" ' E_mrgy Pl_ysics, Sing_l_lW(' (:\_g_st. 1990),

Mcasm'ement of Heavy Q_mrl_ Fr_gine_tat, ion at. TRISTAN, subl_lil,_,ed t,o 25rh I1_t,1,

C,onference on High Energy P1Gsics, Sil',galmre (Aug_ist. 1990),

Test 'of t,l_c'Next-to-Le_.ding-Log_lrit, ln_l QC,D Apl.n'oxilna.t,i(m using AMY Dr, t,a., sul.,mit,,

ted t,o 25t,h Int,1, Corlfercncc (m t-Iigl_ Ell_-rgy PlGsics, Si_lg_lp,,w(,(Aug_lst. 1990).

Sem'di for Cha,rged Higgs Particles wit,l_ AMY, sul.nnit,t,ed t,o 25t,li Intl, Conference on

High Energy Physics, Six_g_pore (A_gust, 1990).

10

III. Progress on NOVA Experilnent

Tlu: foil(hying is a brief sumnl_ry of NOVA l_r(_gress; _l lng,r(, <lot,_dl_,d(l('scril)ti¢,11 is giv!,ll

in A1)l,en(lix A.

A. Background

Tlu, NOVA act,ivit,y is (_1'i(,nl,od t,mvards Iillswerillg illll,Ol't,_lll, ast, r(,l_hysicnl an(1 lilt, ni

)(:,clfi('n,lly, it, llns t,ll(: g(ml <d'lligh ene.rgy pa.rI;iclc, ])hysics quest, ions related t,()llmlt, rilu,s, S1 ''

nddressing the follc_wing l)hysic.s issues:

1. C,n n t,he lieut, rtll rt_clittt,icnl report,ed to hwee been det, ect,ed by exl,ensive ,i.il' sll(nvm' ro'rays

' 9fi'cnn t,he direction of CYGNUS X-3 be neut, nlu:,s.

2. Can the muons rcport, ed t,o have been det,ect.ed by underground detect, ors ft'ore

CYGNUS X-3 be due to neut, ra.1 pm.'t,icles wit,h int,era,ct, i(m Cl(_SS"_ " st'ct,lollsbetween those

of p]iot,ons and convent,iona]st,m_clardmodel neut,rillOS?

3, Wl-latlimit,sca,n be placedupon fluxesa,ndcrosssec'tionsof ncut,ri1_osinc.iclcnt,upon t,he

eart,llft'orenon-specificsources?

Beta.use t,he processes beil-ig st,udied _l:'e expect, ed tc, bc ra.re, t,he experiment, must have

t,he clua] features of rejecting effectively convent, iona.1 backgrounds f'rom cosmic ray prot, on

a,nd pitot, on int,era.ctions in t,he upper levels of t,he cm't,h s a.t,mospllere, and enhaaming the

1)roba.bility of det, ecting ll(:'ut, rillOs a.lld other wea.ldy interact, illg l}art, icles, The concel}t,

involves t,he set, t,ing u 1) of a.rl ext, ensive m'rny of scinl_illa,t,ors and drift, cllmnl){,rs loca.t,{:,{l

on a mounta,in side so as t,o der, ect part, icles moving a.hnost, para.lM I,o t,lle enrt, ll's sm'time,

The a.t,nlosphere dept, h present, edt{} t,he experilnent, a.1geon_etry will serve a.s a.t,t,enua,t, ing

sl-fields i'or backgrounds an{l target, ma.t,erial for weakly iilt,era.ct, ing lm.rl, icl{.,s. \'Vit,h the aid

of excellent tinring ft'ore t,he scintilla, tots _lnd position resolution from the elrift, cha,nfl)ers,

mlgula.r res()lut, ions of t,he order of 10 lili'ii,till.illS for direct, ion resolut, ion _re ant, icipat, ed in

11

To d('_n()nst, rat,(' til(.' s()ulldness <)I't,h(., l)r<)l:)osed eXl)(?rim¢,llt, _ m1_)_lll)ilrt ()f ()_ii' Nr()uI) h)is

b(,on in','<)lv('d i1_c()nd_lct.ing ,, f(:asil)ility st,udy. The g())tls of t,l_(.,st,_lcl',' )_r(, (h(, f()ll()wing'.

1, Measure (,11¢-,m:gul_lr (lis(,ribui.i()ns ()f sillgle C()SrlliCnlys in (,lie z(.:ltit,h ,ulgttlttr i11(,¢-u'val()f

75 dog t,() 1()5 (leg,

2. Mea,sur(? the angulm' (lis(,ribut, i()ns ()f mul(.il)le lmrt, iclc (w(,ni,s ill (.h(_ td)()vc ini.crv_:l.

3. St,udy tile relative comp()sit, ion ()f'soft, mid lm.rd cor).ll:)onellt.s a.s a fllri(',t,ion of'(, 'z ..m t,h _mgle.

,4. St,udy the t,ime vm'ia,t,ions in sign_ds as a, f:.uict, ion of direct, i(nl _nd t,rigg(.r t,ype,

5, Ut,ilize t,he n_east_r(:_ment, s of t,rigger ra,t.es wit, li vm'5'ing l:>_lran_et,crs such _:s d(,t.ect,or Sel.)-

a,ra,t,ions, part.icle mult, il_licity, shiclclil_g, etc. in opt, in fizing t,l_(:,(h!,sign ()f an ext, ensive

a.rra,y.

G. Perfo,rm extensive Monte C,arlo simula.t, ions utilizing the Convex 210 COml)ut,cr of ln'Ot,o:_

a,ndneutrinointera,ct,ionsin t,he l:orizont,tfla.t,mosphere a.ndeal.ri,h'sc.r::st,t,:)(l(,t,crmine

optirnal design cha,ra.ct.erist, ics of t,he a,rra.y,

B. Apparatus Acquisition

During the past severa,1 lnOni, hs, t,he group ha,s bem_ busy acquiring equipment, from

various sources t,o conduct the study. Tlle following is a summa,ry of those effort, s:

1. From Professor L. Mo a.t Virginia Tech, sixt,een }m x lm scintillation c_mnters.

2. From Professor B, Richter a,t, SLAC',, a.bout, 30rr_:_ of scint.illa.t, ors,

3. From Professor B. Blumenfeld a.t, Johns Hol:)kins, ten ,-}m × 5.3m 4 cell drift, chambers.

4, Fro:::T, I(irl:a.t,Argom:(?,about,2()'___._ ofsci:tt,illa,t,or m:d assort,(:,dcl(.'.ct,:'o:ticsand power

supplies.

5. N'on: Professor T. O'Ha,llora,n a.t, Illinois and Wonyong Lee a.t, C,oh:n:l_ia., about 42'm '2of

4 cell drift, cha,lnbers. We a.:'e proposil:g t,o acquire m:ot, lier 30()()'rr__ of drift, chmnbcrs

12

II [

q

: ,

from' these groups by ' end."_'(:!_.l,r s ,,,,: .q.

.

In addition t.o t,hese acquisitions, we intend t.o supplement the SUl@y of scintilh:lt(n's a:ld

electronics from our'involvemer:t in the AMY experiment, wh(,l: t,ha.t, eq.uilmmnt bec(m:les

a.va.ilable, hopefldly by ea.rly 1992: Smnma.rizing, ahnost, a.ll of the equipnlellt being used..

for the feasibilit.y study c.onsists of e(lUil?nmnt used previously in high <:!lCl'gyl)hysics ex-

l_eriment, fun(led l.,yt]:.,'..'federal agencies. E(luipm(:nt, CXl.)endit.urc'_llavc 1_(:'(.'11ln()(l(:st a.ll(l.

for items of general la,l:,ora,tory.usage, ..

C, NOVA Personnal

During tlle pa,st, severa.1 months, the follov,'ing 1)ersonncl ha.rc been invoh,ed with tlm

NO\:a_ feasibilit,y study,

r.'

_ PhD_s

Dr, Norma.n ]VIorgarl full timeProf. A. Aba.shian 25% timeProf. K. Got,oy,, 10% timeProf. L. Piilorlen 15% time

Gradua.te StudentY.D. Zheng 50N time

Undergra,dua.t,e StudentsT. Dut,y (Aca.demic Year) 30% timeE. Leckner (Sun:trner) 100% timeP. Shifter (Summer) 100% time

As seen, the fea,sibility study is being staffed with a very minima.1 effbrt. The group is,

however, enthusiastic a.bout the project, a,rld dedica.t.ed t,o demonstra.ting the soundness of

the proposed experiment.

D. Feasibility ,Test Setup

The idea, behind the fea.sibitity t,est is t.o study the behaviour of coslnic rays ln<Mng in

directions close t,o zenith angles nea.r 90 deg. \'Ve have set. up in the Physics Building a.t,

Virginia Tech in t,he renovat, ed room previously used a,s t.he rea,ctor vault,. The room is a

13

' L

I

45' X 4.5_ two st,dried roonl wlth era.n(, coverage a.nd with w_dls ()f c¢mc'r('te b(,twccll abo_lt

1_,and 3_ thicl:. The set, up is shown 'in Figure 1. Oll the wall whicll t';w_'s northwest,(,rlv

(West (W)wail), sixteen ½mx 1;, ..':int,illa.tors arranged ili 4 grcmps of 4 are at:tix(,<l. (),_

ihe opposite wall (East (E) wall), six }m × lm s(:int,illai.ors are a.fl=ixed.

1A third ha,nk (M)of five s'cintillators, ca.eh gm x 3.57_ is sit.ua.t,ed a,b.out 1½m west of t,he

ea.st banli, To define a. region of a.ngula.r acccpta.nce of AO (zcnitli) = 4 dcg and &¢ =4 0 dog

(a,zimutl_), a. broad three fold coincidence E, M a.nd 14;0 com:ters is required. Bee,mst of

the differences in vertical heights of the W ha,nk (4m) a.nd the other ba.nks (lm), pa,rticles

moving ft'ore west t,o ea.st ma,y have zenith angles between 75 deg a,nd 90 deg while single

tra,cks moving from ea.st to west, mas" ha.re zenith a,ngles between 105 deg a.nd 90 deg., ,

E. Data Analysis . .

For m:y trigger, the differentia.1 in transit time between the west, and east pla.nes is

recorded a,s weil as the time of da.y for each event. For each run of a.bout 20,000 triggers,

a. time delay cre're is ma.de a.s shown fc)r example in Figure 2. \Ve see two na.rrow peaks

a.t :i:45nsec corresponding to single pa.rticles moving in the two opposite directions. In

a.ddition, a. broa.d pea.k centered a.t 0 nsec is observed whict: corresponds to the detection

of a cosmic ra.y shower with proba.bly three different pa.rticles striking the E, W, a.nd M

planes.

The a,ngular distribution of the cosmic rays is shown in Figure 3. For a.ngles less than

90 deg, the da.ta, exhibits a cos _-0 distribution a.s expected. For angles beyond 90 deg, the

distribution a.ppea.rs to be essent, iaily flat. The solid curve is a. cos 2 0 del)endence norma.l-

ized to the cosmic ra.y flux reported a.t 0 = 0 degrees from the pa.rticle d;_.t,a.book toget, hr'.ri

with a, const, a,nt a.ngula,r ir,.lependent ba.ckground,a.s determined f'ronl t,lle mca.surenmnt, s

for 0 > 90 deg. The fit, is remarl:a.bly good.

14j,

Naively,:me might belim':.'t,l:_.tthe events beyond 90 (legare l_m'ti('h:'s_'n:ergi::gf'ro1:, .

b:,nca.tllthe floor'ssurface,Tlie:'cis,howeverl a.naltc,'na.tiveCXl:)la,::._.ti¢mwliid:isth_l.t

these are not single track events but arc i._lst,ead horizonta.1 showers ¢>f l>c:'hal_S sm, eral

particles moving a.t mlglesless.tlmn 90 degrees, Under these circmnsta.lwcs, the evcllts

might a,ctua,lly be one particle in .F, and M banks with another tta.ck in the W l:mnk. The

nra'row wave ft'on: for .the shower stillinsures :,lie sa.me timing a.s f¢_r a single track. ._

If the events a.t 90 deg a,nd beyond do consist of multil>le particles, l,]l¢.':iperha,1)s .the rat,es

would be affected by a,bsorbing materia.1. Mcasm'e:nents ill(leed show i_ selisitix:ity to 8:'Irt.

of lead a,bsorber pla,ced between tl:e W a.ild _4 pla.nes a.s shown inFigm.,e 4, Furtller studies

of these horizon:a,1 showers a.re continuing with the inclusion of drift, chmnbers 1oetween M

a.nd E a.nd ADC's which together will record the directions a.nd numbers of pm'ticles for a

given trigger.

The times of a,rriva.1 dm'ing the da5' is shown for a typical '.2?4hcmr 1':111ill Fig:lr: 5. If there

were a, point source,, it might mm:ires: itself as a.n increased number of events sometime

&.ring the da,y. The sta,tisties are too meager to expect to see any sources alt this time.

For a,ngles nea,:' 90 deg, the trigger ra,te in either the EW or WE direc.tions a,re of the

order of IO-2Hz. If we were to extra,pola.te these results to a detect, or 200 tin:es as lm'ge

and with a,ccepta,nc.e a,ngles of .50 = 20 and Ag) = 90 °, the trigger rn,te would a,pproa,cl:

lOHz, a, ra,te close to wha,t we consider to be a,ccepta,ble. Furt, her studies should determine

the optimum trigger requirements a,t each station

I s, ) .Our prelinaina.rvconclusionsbasectupon the data acquiredtc,da.teare the iollcw1:_g:

1. Ba,cl:ground ra,tes for zenith a.l:gles ::.lose t,o 90 ° are low. Accidental c oinc.idenccl_ of

vertically descending showers ca.n be managed througl: time of flight t,eclmiques

2. Clea,r signa.ls of single pa,rticles tra,veling a,t la,rge zenith angles a,re ea,sily n:easura.ble,

The rat,es a.rc lmv a.lld (.';_.silynm.n;_e:_],!e with (mr (m-line c(,lqmt,cr.

3. Pa.rt, iclcs a,t. vm: l_l,lej¢.'zenit, h _l.nglos (_ft,('n at(' t_,cconll._a,nicd l_y ot, ll(,f' lm.rl,iclcs, Tills

introduces the 1._0ssibilit.y of requiring niore t,lmn one lm.ft,Jolt a,t ast, a.t,itni as _:.fm't, lmr

.metals ()t"i'educi:lg the effect, s of vertically descending.showers,

F. Monte Carlo Simulationst

Mon*,e C,a,rh_ calcul.tions ll_:\,(:'b(,'cn underwa,y for some time utilizing the C,onvcx 210

super mini comput, er a,nd t,he GEANT simula,tion progvmn,

Our hope in I,he NOVA exl)eriln(:,nt, is t,o defect neutrino iilt,er_llct,ions i.:l t,lic ea,rt,h s

a,t,nmspl:ere for 0 nea,r 90 deg and in t:he t,op la,yet of t,he ea.rt,h's surfil,c,c. Our prima,ry

ba,ckgrounds a,rise ft'on,: protons interacting a,t, t,he edge of the a,t,mosphere sevend hundred

kilomet, ers a,wa,y. For these dist_lnces, t,ile ba,ckgrounds consist domin_mt, l.v of very higla

energy muons, t,he electrons and phot, ons ha,ring been a,bsorbed by t,lle a,pproxinla,t,ely 1000

r_-:_.dia,tionlengths of a,tmosl)i_ere, Figures 6 and T show simula,t, ion res:llt, s for energy vs

density of muons due t,o 1Pe1'" incident, protons a,nd t,ra,nsverse (list,a,ncc of muon dcnsit,y

produced by 100Tc:l: 1):'ot,ons, respectively. On t,he a,verage 10 and 00 muons, respect, ively,

ea,rth s suri'a,ce,reach t,he ' '

Figure 8 shows simula,ti0ns i'or t,he case of lpci,' neutrinos int,era,cting a,t dista,nces of

30/c.m,, a,ssuming the St, anda,rd Model va,lues for :v a,nd Y dist, ribut, ions a.nd neglecting muon

'q ,, " ":_bremsst, ra,l,'lung. C,lea,rlx,, neut, rinos give rise t,o mms. muons, 133, than t,he ba,ckground

protons oi" the same energy.

The_e conclusio:_s need t,o be modified, based upon t,he calcula,t, ions of St,a,nev a,nd

\;a.nl:o'/lwho ha,reshown l,lm,t,muons of 101eev ca.::I'n.dia.t,epl:ot,ons so as t,ohave a.n

average a,ccoml)a,nying105 electronsa,ta.nyloca.tiona.longtiremuon's tra.ject,ory, For

E,, = IPcV, the cha,rged curl'ent, n-luo:l _lso 1._asE t, =lPcl'" since < i) >'" 0.03 wl:icl:

lT. SI,a,nev and H.P. \,"a,nkov, Phys. I-{ev. _D4(___).1472 (19gq),

IG

t,ra,nsla.tcs into 10 2 clectrt}lis a ccollll}t_nyillg t.h_tt. {,xi,rciiw]5' ¢:,n_,rg(-,t,ic ln_1oli f'r{ml the 1,1,

illtera.ction,i

Muon l}remsstrahlullg introduces a furt, h{,r T, ry i1111){}rt,_mt1}(}ssil}ility for t,ll{, NOVA

exl}eriment; namely the potential {'apsl:}ilit,y of observing tlm ros_dt s {}fn(.,_lt.l'inos illI{:'ractillg

below the -' 'ca,rth s surface. Figure 9 is ft'ore t,llc_pa.per of St,an(,v ,.k"\:_ml¢(}v a.l_d shows {,lie

effect of muon i}relnstra,hhmg giving use t,{}Ul}Ward g{}ing show¢,rs in t,lic {,artll's a.tmOsl)ticrc,

If these numbers prove to give rise i,o subst, a,ntia,1 showers accomI}a,nying the muon, the

detection a,rea for NOVA cxp{,rimcnt b{,comes the surface:, area of t,h{:' arr_,lv and ll{}t the,

detector a,rea,, Tiffs would mca,n t;lmt, t,h(:, (:_q)M}ilit,y {}f t,hc NOVA (:Xl}(.'rilll(:nt in t,enns (,)f

intera,{'tic}n volume a,nd (i{:.t,{Bct,ion {:al:}al)lilit,5"are COlnl}ara,l:}le to DUMA ND.

]7

I

IV. TIlE MEGA EXPERIMENT

A. INTRODUCTION

A ,i t ¢ ¢The MEGA eXl)f,riln(:nt" al d_( C,hnt,(_llP. Anderson Mes(m Physl('s F_cility (LAMPF)ill

Los Ala.rnos, New Mexico will searcll for the rare decay .jt+ -, c+') ' wit,li 1111 m_ln'(.'c(:,dcllte¢l

sensitivity of (.mcpart in 10la. This exlmriment, t'ul_(led prin_arily by D()E alld t,o n lesser

degree by NSF, is being m(mnt.('d by a group of l_llysicist.s frcml 12 inst,it,lit,ictus: Los Alilm(_s

, ' - . o', Tech University ofNa,t.iona.1La.bora.torv, Fenni Na.tiona.1 Accelera,tor La.bola.t 13, Virginia ,

Virginia:, Princeton University, Yale University, Sta.nford University, University c)fChic_lg(_,

Texas A&M University, University of Houston, UC,LA alld Va.ll_l.r_ds_ Uaiversit,y.

The. fa.milv-numb(-,r-nonconserving 1)roc,ess p+ _ c+')' is t'(n'bi_ld(.nl l_y fia.t in tlw St,_m-

da.rd Model. Ol_s(-,rv_:l,tionof t,his as-yet unseen decay would be t,he first clcn.r indi('ati(m of

new physics l._CyOll(l the St,andnrd Model of the elect,rov,,eak i11I,eracti(m. S(:'v(:,l'a.l previ(:nis

Cxl)eriments lmve sea.rclled for the sa,lne ()r similar forbidden d(:,c_.ys, a.n(1c(mq)el,ing e,',:l.)er-

iments axe phmned (_r being mounted a.t Brooklla.verl Na.tiona,1 L_.bor_.tory, TI-I,IUMF and

'! i .PSI (formerly SIN), MEGA is designed to ,)e 500 times more sensitive t,(.)seeing p+ -_ c+')'

tha,n 't,he la.test published limit set, by the Crystal Box exl)eriment a a,t Los Aln,mos.

B. DETECTOR DESCRIPTION

The experiment consists of a.n electron detec.tor inside a. photon detector inside a la.rge

superconducting magnet (Fig:::'es 1 a.nd 2). The lnagn(::t,ic field confines a.ll cllal'ged decay

products (electrons and positrons) to the central region of the a.pl)ara.tus l.]m.t conta.ins the

electron detector's eight M'WPCs m_d two scim,illa.tor barrels. Any plmt(ms arc un_fl'ectod

by the magnetic field and traverse' tl_e nea.fly massless electron arm MWPC.s to the 1)hoto_

:_M, D, CI,ooper et al,, "'MEGA--Sea.I'cl_ for the lC/are Decay t t ---+c3'," Prol_OSa.1969, Los

Alamos Meson Physics Facilit,v, ,]uly 1985,al2., D. Bolt,on et a.l,, "Search for the Decay i_-t-+ c+.), ,, Phys, 1]ev, L(:'t.t,,56, 2{;4.1(1986).

18

l)t_ir _pc,ctr¢_Inc-,t<,rswlJ('r(' t. Ixc,yhay(' _l,¢ml 10% c.ha.nc,(,(_f]_(,i_ (,I:,serv_,<lx'i_L">,_ _+c -_,

Til(' intrinsic res(_lut,i(.m ,:)f t,ll¢.,(l(,t(,ct,()r(,l(:,111(,11t.swill _lll(_w_ls t.o x'(.'j('('t,ali lmu_ll,d(.,c,,ays

t,lJat (1()n(,t r(,sult in r'xtlct ly _,11(,l_()sitr(_lJ1)ilck-t.()-l_acl¢wit,li ()11(,I,illl('-('()in('i(l(,nI. l_llc_t,oli

in the '/hua,lst,m,e (%1)1('I).

A hm'dwm'c, t,riv;_.,_('rm()(l-tfi_,('()_t.ilmally monit,(:,rs t.he 1)lll.t(u.n (,f l_it,s iii rh(' 1.)ll()t.(:)_llmir

sp(;('tron_(,t,(_rs, l_Jl)(m s('('i_l_q_ l)_t,t.t,crl _ i_(li('_ti'v_.'of _ lfigh _'_'rgy 1)l_(,t,(,_,t,ll(, r_w (l_,t.af'r_)_

t.ll(:,ehf.ire detector (_d_out 700 words) i,'-t,ra,nsf(.,rr(:'dt,(_one ()f 32 ('()n_lmt_u's fl)r int,en_'(,dlt_t,(.'

writ, t,e_ on 1-nagneti(' t,ap(_, f¢u'm()l'(:' st.ring(:'lit ()fl'-lin(, _nalysis. W(' (,Xl)(,(,t,t(_ wl'it.(, ab(mt

2000 tapes of <,m_di(ll.t,t,r'ex-(:,nt,s _1_(.1t,o r@'Ct nl(.,st,, if not ,_11,(,f t,h('se ('v('nt.s in t,lie (,ff-lill(:'

m mlysis a,s not being du(., t,()tt _ c')'.

C. STATU S

The MEGA dct,ect,()r c(:)aa_l:)Vnents arc presently under c(.)listrnct,i(ni _,_(1 t,(,st.iiig; tlm c×-

perim(:'nt, will run i_l 1991-1992. S(-,veral t.echnica,1 challenges liax'(, l,(,(,_ s_c('(_sshflly ad-

dressed in designing l.)ot,h tl_e electron arm M'WPCs and the phot,(m arm drift cba,tubers,

The' innermc)st pair spect,x'(u.not,er of the phot.on m'm und(n'w(:,nt,b('_ma tests in t,l_(:,MEGA

magnet dm'ing 1990, Sex:,era.1electron arm M'vVPCs have becn built; four of these were

tested wit,h muon t)emns i:_ the magnet in August-Sept,(nnl)er ].990,

Det,ect,or const,ruct,i(:m ,,x-'illcontinue int,o 1991, wit,h ali of th(:' electr()l_ m'm m_d two pair

spectromet, ers ofthe ph(.)t.v.)r__.lrmexpect, cd to be re_:_dyfor 1)l_vsic,s da.t,a acquisition in the

stare'net of 1991, The (.'.on-_.l.)lct,edetect, or is expected t,o l,e r(:,ady in 1992.

19

Table I

Parameters of p _ e_ Experimentse

Proper ty MEGA CrystalBox

(ref, I) (tsf, 2)

Fractional electron energyresolution 0,005 O.0B

Fractional photon energyresolution 0,02 0.08

Photon-electron timing (ns) 0.5 I.I

Electron position resolution

at the target (mm) 2,0 2.0

Electron angular resolution-

including target scattering(deg) 0.6 1.3

Photon conversion point

resolution (mm) 3 25

Electron-photon angle (deg) 0.6 8.0

Photon angle (deg) I0 --Inefficiency of

bremsstrahlung veto O.2 O. 5

Fractional solid angle

times detection efficiency 0.I 0.2Muon stopping r_te (s") 3 x 107 _ 5 x 105

Ru=nin_ rime (s) 1.2 x i I 2 x l0b 'Branching ratio sensitivity 9 x I0 "_ 4 x I0-II

Number of background eventswith +_2_ cuts 0.9 -50

Ali resolutions are TWH.M

Elements Type Number of Elements

Electron chamber planes 3Electron chamber anode wires 1950

Electron chamber cathodes 3900

Electron timing scintillators 200 ,

Bremsstrahlung veto scintillators 24Photon MWPCs iO

Photon MWPC wires 3400

Photon drift chambers IO

Photon drift chamber anodes 2300

Photon drift chamber cathodes 4600

Photon scintillators 425

Photon scintillator PMTs 850

Primary trigger modules 5

Data memory modules 30

Microprocessors 326250 BPI tapes 2000

Display Curves 9

_d_y,Aegis!.3,_97Io....!5_ 9oFront Panel

-_- i i ii I I _ • -- _ J I II . _ II III - _ II illlll ' - -- i III Illlll II

I'l'otal Ratel East to West Rat_ Shower Rate West to EastRaI 7..,..I

0,024 iE Ven t Rat e ( Hz ,o62 o,oll

r__:4,seo_'I 0,005

0,0040 .............................................

IMIM_ I lll

all- ,' " i_ ,

0,003 I 'I

IShow_sl.q_, i '

[_t20_5"o8-_ 0,0020 ..............................

I.Sho_?,"M_ I

0,001 .........................AeleE i

I

iI

0,00206256 iI

0,000 i ,0,00398005

I_ nanoseconds

MEANSQUARED IReadError:] FYl.es Read] _--__ - ___ - 'I

19,I425E'?,9I ! 0 i _ _ ,,

Fig. 2

q+

Fig. 3

EFFect oF lgo g/c_.,2 Absorber

_'_' '"'...._-_"-i...._ _ ' i .......i ''_'' __ -6 6 WAitto J_6',t "

t. O,3 --

L L. _ -C

ep 6 b -

c u,, -6 "r.

80 go Ioo 110_et_tth Anqle (de(l,)

Fig. 4

86'DEGREES: WEST TO EAST 86 DEGREES: SHOWER

40 L_ 40

o _0 - _ o 20 -,q** Nk,

0 I_ t0 15 _0 0 fi 10 ll_ 20TIMB OP DAY TIM_ O!p DAY

86 DEGREES: EAST TO WEST

•-,_,,_]_,-,-,,,, _-r"[,,_ , ,'"v,

I]0 r

_' lo-1lh

o 8 i0 15 eoTIMil OF' DAY

Fig. 5

I _,l

I

100 EVENTS OF i PEV PROTON /

l '|''l II 1'' 1 I I" J l 1 .... 1 1 " l - I '"1 'l '| _"_1- _

10 2 - -_SOLID:70 DEll,N(MUON)= 1575 :-

_. ol DASH'. 80 DE]G,N(MUON)= 59g -z i --=m DO_S :gO DHO, N(MUON)= 58 "-

_ 100_4

>

W ',, ,_ %1o-I 7",__ . _=

' "'i:I' ':,":',.:',,,':',"",

{ o Boo 1ooo IBoo 2000ENER(_Y (GEV)

Fig. 6

i t': lFg 7

100 EVENTS OF I.PEV NEUTRINO WITH 90 DEG

i

m

DI_=JT=30LM N(MUON)=133z I0-3 --

° "_ -

.-g _0-_- %___ -Z

O

o L:10-5

0.2 0.4 o.e O.BRAD[U_ (KM)

Fig. 8

•.,' Fig.ii