Gestion INIS LAPP-EXP-Q^ m Doc. enreg. Io : /.3.[f3.yfl.H JUIN ÎWJ N" TRN : ^LaJi Destinriicn .

1973-DISCOVERY of NEUTRAL CURRENTS

B.AUBERT CNRS-IN2P3 LAPP-ANNECY

^ It is difficult to speak on "1973 -Discovery of Neutral Currents" without first mentioning earlier events, mainly 1953 in Paris the July 1st, signing of the convention setting the basis for the creation of this place "CERN in Geneva", and 1963 in a trattoria of the Siena's Palio the birth of the HLBC Gargamelle, on a napkin on a warm summer day.

I must also apologize that I am not able to pay any special individual tribute here to each one who acted for the good of this enterprise : engineers and technicians from the machine and the beam, the bubble chamber physicists, theorists and experimentalists, administrative personnel and scanning girls. The only names I would like to honor are A.Lagarrigue who was the real leader of the Heavy Liquid Bubble Chamber (HLBC) active community and P.Musset who acted as the convener and the driving force behind the neutral current analysis.

I will spend few minutes on the status of the weak interaction theory and the search for neutral currents in the late 1960's, and on the tooling available at this time. Then I will review the analysis of the Gargamelle experiment and finally I will give a brief look on what happened elsewhere.

Status of the weak interaction theory. The current theory for weak interaction, able to represent p decay, \i decay and the decays of strange particles, called the Universal Fermi Interaction (UFI), was "local", which means a priori, it does not need a propagator. All interactions were adequately described by the phenomelonogical (current x current) Lagrangian :

where G is the Fermi constant and the lepton current is:

Then one can write all lepton currents (ev) (v|i) or hadron currents (np) (KJC) . This description was completed with many assumptions,which were not in contradiction with experiments, such as :

1. The two component neutrino theory, (Vn ve have the helicity+1 ) 2. Lepton conservation ' 1 I 3. Absence of neutral current . 4. (ie universality ' 5. |AI| = 1/2, AS = AQ, AS = ± 1 6. Charge symmetry of AY = 0 7. CVC 8. PCAC \ - S» _

9. CPT invariance Experimental programs in the sixties were largely based on tests of such rules .

In this UFI theory , the possible existence of a neutral current was often ignored as not needed, experimentally or theoretically. The local Fermi interaction suffers several difficulties: first radiative corrections divergences, and second it is not renormalizable when we go to a higher energy domain.

The next step, by analogy with the electromagnetic interaction, was to add a propagator called IVB( for Intermediate Vector Boson ). At such a point, the absence or presence of neutral currents became a question because the multiplet of IVB was in question.

Based on the absence of K decay such as K° -» Ji+Ji" or H decay such as |i+ -» e++ e" + e+, the common belief was the absence of neutral currents. The difficulties faced by the IVB theory are different in detail but the overall pattern is not altered,when we want to go to higher energy we found a lack of renormalizability. To overcome the problem of renormalization , several gauge theories were proposed in the 1960's , constructed as extensions of the YANG-MILLS theory for the electromagnetic field Ajx. But in all those, neutral current, heavy leptons or both are needed. In the simplest gauge theory, GLASHOW, SALAM and WEINBERG propose only two new particles.The Lagrangian is extended. Charged currents are coupled to the charged massive field W and neutral currents are coupled to a mixture of Z and Aji '.I field.Two new coupling constants are introduced, g and g'. A mixing angle is defined , i - ] (the WEINBERG angle) by : j tan 0\v ="^" , e2 -'2 sin^ 6\v = ~2 = " S fe T6 e2 1 where — is the fine structure constant = TT13= 4JI '

*'. *• -

The masses of the new particles are related to the Weinberg angle: 2 e2 2 4V2 G sin 6W e2 Z 2 42 G sin 26W and this model gives measurable predictions concerning neutrino interactions:

2 2 4 + e' -> Vn + e") = — me E[(2sin GW -I) + i sin Gw] 2K 2 — G A 1 ? 2 + + e" —» Vi1 + e') = — me E[(4 sin^ Gw) ï (2sin^ Gu/ - 1) ]

n NeutralCurrent NC .1 . i. 20 . 4 Rv = Charged Current = (2 "sin 6W + 27 sm

" D Neutral Current NC .1 . 2 « 20 . 4 V Charged Current = (2 ' sin 6W + T sin

But because in 1970 several limits existed on neutral currents, the direct consequence was that in the proposals for new experiments, especially in neutrino physics, more emphasis was given to search for W and for heavy leptons (deviation of linear increase of the cross section and presence of dileptons events). Table I show the limit for neutral currents as measured in K decay physics, which at that time, was the main tool for probing of weak interaction theories.

Table 1 K* -**e*e~ <9xlO"7 Camerini,... (1964) K* -. it* it* n~ < 3x 10"' Camerini,... (1965) K+-** w < 1,1x10"* Cline (1965) + K5 -e c" < 3.5 x 10"* Bohm (1969) 7 K1 -p*/i" < 3,1 XlO" Gjesdal (1973) ,

KL -»/i*/T < 1,8x10"* ClMik (1971) I0 f Kt -A«*/»" - ll*, xl0- Carither (1973) + r K1. -it e < 1,6x10"* Clark (1971) + KL -c e"

In the early neutrino experiments the flux and the size of the chamber precluded a realistic ., 5**. neutral current analysis. In 1970 the result published by the 1.1 m HLBC group 1

.n-»|i-p=0.12±0.06 4) ? \ and v^ p -» v^ n 7t+/V|i p -^ ^- p Jt+ = 0.08 ± 0.04 j acted as dissuasive data, both for experimentalists and theorists. It may be worth mentioning that the 1.1m HL bubble chamber experiment group noticed a very high rate of neutron stars and ^ . called for a better understanding of the sources of so many neutrons. But the size of the chamber \ ' r did not allow for a complete understanding of this effect. H

\ \ •-:.*.

Nevenheless, shortly thereafter two major theoretical developments occurred, in 1970 the GlM mechanism demonstrated that the absence of AS = ' neutral weak current could be overcome and in 1971 G.'t HOOFT's proof that a class of gauge symmetric theories are renormalizable. In 1972, Weinberg remarked that his .nodel prediction for the elastic reaction :

0,15 <

was not so far from the experimental limit.

This led to a growing interest in the search of neutral current but balanced by the fact that if you have to choose where to put your money, you give more emphasis on the search of heavy lepton.

Neutrino beam and HLBC program. In the early 1960's the first neutrino experiment with the HLBC built at Ecole Polytechnique, BP3 ( 3001), and a counter experiment gave no events. During this decade many improvements were made, mainly on the beam. In 1963-1964 the CERN 1.1m HLBC (5001 ) provided some 450 neutrino interactions.The main limiting factor was the neutrino flux. The source of neutrinos and antineutrinos are the decays of K and K produced in a pp collision. So in

any neutrino beam we have a mixture of neutrino and antineutrino both from ve and V^ . The average neutrino energy, is only about 1/10 of the incident proton energy, and the spectrum for the existing accelerators was :

ANL 0.5

One of the strengths of CERN and on what I will present as the Gargamelle experiment, is the neutrino beam. Let us review the components of such a beam. The most intense primary proton beam hits a target and produces a secondary beam of pions and kaons . A focusing device, the "Simon VAN DER MEER horn", focuses particles of a given sign and in a certain (m. momentum range. Those particles pass through a decay region where K and Jt decay, then » j through an iron shield which kills all remaining particles but muons and neutrinos. If the shield I j'.j is long enough only neutrinos remain. Monitoring devices in the shield tag the flux of muons in ^i .J depth and allow us to reconstruct the shape of the flux in energy and profile, but because of the J rapid fall-off of the flux the precise monitoring poses difficulties. The flux is always a mixture of

Vn and ve, but with the v coming from Jt or from K decays having different spectra.(Fig-l ) I \

••••M One other important tool in this search was the availability at CERN of the largest heavy liquid bubble chamber ever built. The first neutrino experiment with BP3, a chamber of 300 liters, showed that the use of heavy liquid had much potential. The drawback of a complex target instead of H is largely compensated for by the increased mass and by the particle identification capability. This was the main reason in the decision to build a 4.8 m long, 1.8 m diameter cylinder which allowed for a large fiducial volume as target with several tons of freon embedded in a large magnetic field. The two main technical challenges were the use of a large membrane for the pressure control ( the pressure must drop from 20 bars to 10 bars in 60 milliseconds, once every 1.4 seconds ) of the large volume and the optics (direct lighting with 21 flash lights and the use of 8 large angle lenses for the track-recording cameras ) to guarantee the uniformity of the illumination. But what was also of real value was a large community of HLBC physicists which for ten years not only learned the problems of HLBC but also learned how to work together. The Gargameile Collaboration, which included 7 laboratories, was the first large collaboration in high energyjihysic. Fifty physicists constituted the first sociological experiment of group meetings, conveners, memoranda and "choice process" initiation.

While engineers were building Gargamelle, one part of this community worked on K physics and weak interactions. The other part worked on the 1.1 m chamber built at CERN in a second neutrino experiment. Both groups merged on neutrino physics in Gargamelle. In a such large group all sensitivities were represented and very lively discussions took place.

In 1971, the data taking started with the GGM neutrino beam. The pictures were sent to all institutes of the collaboration and scanned and measured on dedicated tables. Each event was identified, the number of prongs recorded. In 1972 the presence of events showing stars without muons was noted in several meeting . The time had come to start a complete analysis of such events.

Neutral current in semi leptonic processes. The reaction here is :

Vj1 + Nucléon -4 Vj1 + hadrons )*» The large size of the chamber, the density ( 1.5 g/cm-*) of the freon, the short radiation *j* I length (11 cm) and interaction length (70 cm) permitted the unambiguous identification of the 1 \ j secondary particles in most cases by interactions, by stopping or decay. 83000 pictures in v beam % ! and 207000 in v beam are scanned . To be considered events must originate in a restricted fiducial volume of 3rri3 within a 7m^ visible volume. (Fig-2) Three categories of events are defined ( Fig-3) : *NC all outgoing tracks are identified as hadrons, by interaction or by stopping with a , range momentum criterion. *CC typical neutrino events with an identified \i leaving the chamber without interaction or stopping. *AS candidate for the reaction v+N -» n+n+X ' —» neutron star where both vertices are visible in the chamber.

v beam NC=102 vbeam NC= 63 CC=428 CC= 148 AS= 15 AS= 12

A cutoff of 1 GeV on the hadronic part (totality of the event in NC, all tracks but the muons in CC),was applied. The background could come from several sources: 1 -Neutral particles produced at the target.The comparison of rate of NC per incident proton in neutrino and antineutrino beam must be identical if the origin comes from protons on the target. 2-Neutral particles produced by pions or kaons. The same ratio must be one half, ratio of negative to positive particles. 3-K° produced by neutrino must also produce strange particles A0. 4-Cosmic rays, no UP/DOWN asymmetry was observed, in position or in momentum. 5-Low energy muons escaping identification, not compatible with the extrapolation of the muons spectrum. 6-The only main source of background remaining is the neutron star coming from neutrino interaction in the surroundings of the visible volume.

To study such background we used several methods : 1-study of the spatial distribution (Fig-4). 2-topology of NC event compared to hadron part of CC event (number of 7t° in both cases)(Fig-5). 3-study by the Bartlett method of the mean free path of the neutral particle giving the star.This provide a length of the order of 2 meter as for CC and not 70cm as for neutral ' j star in AS events. 4-If the neutrons are produced by neutrino in the vicinity of the visible volume, the - ' neutron flux must be in equilibrium with the neutrino flux. So a simple method could be used to deduce the ratio of background neutron star B coming from non visible neutrino interaction to the associated neutron star AS coming from visible interaction.

••'••M .i.. . -.*.'• 5-To be complete a simulation of the flux of neutrons produced hy neutrino interactions in the surrounding of the visible \ olume (Fig-6) must be calculated . The data going in to the Monte Carlo takes account of the flux of charged particles produced at the target and follows them in the beam. The kinematical hypothesis for the neutron produced by neutrino in the shielding is checked by the associate event AS. The "rich man's " Monte Carlo including several effectes like the cascade, and data from a special proton beam exposure in GGM, would only be available in 1974. Finally, the ratio Background to Associate star is 0.8+-0.4.

Like in a puzzle,all those internal and external pieces of evidence built a complete representation, where even if you dont have all the pieces in hand, you can easily see the image. Finally we found that the neutron flux could account for only 10 % of the NC events after correction and in a CERN seminar July 19th 1973 P.MUSSET announced the result:

_v" beam R = NC/CC = 0.217 ± 0.026 v beam R = NC/CC = 0.43 ±0.12

2 These two values are compatible with the value 0.3< sin 0Welectrons ( from purely leptonic interaction).

ve + e" -> ve + e" is allowed in all theories, but the Weinberg model expects the reaction

Vu + e' -> v"u+ e"

With the pictures of GGM a search was made for single electrons, positrons and e+e" pair with E > 300 MeV and an angle with the beam line :

The ve beam is only 0.1 % of the v ^ flux. The main source of background is from the process '

ve + n —» e" + p Ji The angular distribution and the absence of a visible recoil proton in the channel Vp + n —» \i~ + p ' j provided a limit on the background. • I

In February 1973 a sample of 375000 v and 36000 v pictures gave one event with Ee of 385

MeV and a 8e of 1.4° and 15 ve standard events. The background from that was estimated to 0.3 ± 0.2 event in the neutrino film and 0.03 ± 0.02 in the v film - 1 event e+e" at angle < 5° was observed in spring 1973 in the v film and none in the v film.

Table- H

Number of single e~ events of £e > 300 MeV, «e < 5° Weinberg predictions Flux Mini- Maxi- Background Observed neutrinos/m 3 mum mum

1S v 1.8X 1O 0.6 6.0 0.3 ±0.2 0 v 1.2 X 10IS 0.4 8.0 0.03 t 0.02 1

The comparison of this rate with the Weinberg prediction (Fig-7) is in agreement with the observed'result in the semi leptonic mode. Two more events were later found - the three events proved without ambiguity the presence of leptonic neutral current. But in 1973 only the one event was more a confirmation of the work on semileptonic than a proof in itself.

What happens in the rest of the world. Three other places were able to perform neutrino experiments : - Argonne, with a low energy beam and a hydrogen buble chamber (12').An experiment of 800000 pictures with two different fillings, hydrogen or deuterium looked for the neutral current in the one pion production channel. 13 events were found with a background estimate of 3. - Brookhaven, with spark chambers experiments and a beam of the same range as CERN. Lack of visible detail and the influence of aluminium nucleus precluded unambiguous identification of reaction. The number of events recorded was 12 in the standard one-pion channel. - NAL was just at the beginning of the 300 GeV operation with two counter experiments, one ( HPW ) in a broad band beam and another ( Caltech ) in a narrow band beam.In March 1972 NAL had 5.109 p/p in July 101 Vp , in November 4.1012. But the energy of the neutrino was 10 times higher than at CERN. HPW ( which later emphased neutral current searches ) was in 1973 mainly devoted to a heavy lepton search. Most of those experiments suffered from rate and from misidentification of secondary particles in the neutrino interaction or from both. The only experiment which in 1973 presented some capability was the HPW at NAL.

This experiment (Fig-8) was built in order to operate in the broad band beam with a sensitive target of 16 tanks of scintillating mineral oil (20 tons) followed by a (i. spectrometer, built with optical spark chambers and iron toroids.The early design required a signal in the trigger *i rnnntpcounter nnanHd eson rnnlcoulHd accepflrrpntt nnlonlyv mnrimuon pvpnevents.ThK Th*e» triaopitrigger- u/owacs r*»Hf*ciernpredesigneHd crso* that thpe r1f>tf*rmrdetector *< ' would fire if either the hadron energy was above a threshold or a muon passed into the f spectrometer. A signal above 6 GeV ( for 300 GeV primary beam) in the calorimeter triggered the , spark chambers (Fig-9). 1116 triggers were recorded at 300 GeV and 368 at 400 GeV. The beam was unfocused. The sensitive target covered 9 interaction lengths. A veto counter in front of the calorimeter, provided protection from neutron background. Events originating in tanks 7-12 and 50cm away from the edges of the target,were selected for both 300 and 400Gev proton runs . ' One "out-of-spill" trigger allows for comparison with events of cosmic ray origin. In such an experiment, the only correction is the Ji detection which comes from angular measurement (muons missing the spectrometer in direction) and from low energy muons which do not go to the first identification chamber. The correction here is large ( estimated by Monte Carlo ) and depends on the neutrino energy. It suffered from the fact that the knowledge of the beam was only rudimentary at the beginning.The particle production would only be measured in early 1974. The number of events recorded was 93 with muons and 76 with no visible muons. The estimation of the purity of the sample was 50%. The conclusion at this stage was an excess of muonless event coming from several possible origins : neutral current, contamination from ve, kinematic effects at the neutrino interaction and a new type of lepton. In order to be less dependent on unknown quantities, a second run was performed with layout modification to improve the flux and the muon identification (Fig-10). The 300 GeV proton beam was steered on to an aluminium target included in a horn device and the detection was modified a) to get an earlier u. identification, by adding 35 cm of iron in front of the spectrometer b) doubling the size of the original (1 identifier counter system. This new design needed a new evaluation of the muon identification as well as a punchthrough correction. Those two corrections E^ ( Fig-1 l)and Ep (Fig-12) are function of the position x,y,z

of the vertex and of the energies Ejx andEn. They can be evaluated from the data itself.The comparison of two different beams, one from a bare target and one with secondary hadrons focussed in such a manner as to get a beam enriched in neutrinos would increase the redundancy of this search. In the fall of 1973 , 535 trigger were recorded . The data were corrected for (X identification (of the order of .7 - .9 ) and for hadron punchthrough (of the order of .1 - .5). The

corrected ratio R (NC/CC) is deduced from the measured number Rm by the formula [Ep. + Ep - En£pin + Rm) " 1

1-Ep(l+Rm) J* Finally, R = 0.20 ± 0.05. STANDARD MODEL"

The condition of the discovery of Neutral Currents in 1973 at CERN, allows us to draw several others conclusions, still very valid today. It is more difficult to prove an unexpected result than to confirm one which is widely anticipated. To make a discovery, you need the best tools at the right time. To have the best tool often requires taking a wise decision long in advance.

Î

-it. - Table-m

rod) « n(u Ntaiund Quantity Pradlctlos Valu» leurca (aln'e - 0.27) OW. 0.28 0.29 t 0.012 OOT. CaIT-HU.. 0.38 0.38 * 0.02J (StR-WEBC 0.S0 0.48 £ 0.17 DUL-I -RIF-tttcii

0.33 0.49 t 0,14

Csl-tl.l-B0dk. 0.10 0.1» t 9.(n DH-BU.

O.U 3.2 * 0.1 Vp • I»*» VW * VCT* 0.24 0.21 t 0.07 Cal-Ill-Racfe. OBM, A-*

vit • 0.3 0.37 t 0.08 •111-Back, vn • p*Xw* OON vp -» vnw* 0.07 0.13 t 0.06 ML 12' B.C. vp -» p-p»+

vp •»• vpw* 0.17 0.40 t 0.22 AML 12' B.C. vp -• ti~p»* vn * voir~ 0.07 0.12 t 0.04 AML 12' B.C. vp • iTpir+

J • /CaV) 5.2 «10-* (5.7 11.2) Balnaa »t al.

") /t^em1 /CaV) 1.4 K 10"" (1.2 11.0) CGH ~)/E,,(c«2/CaV) 1.6 K 10"* (1.911.1) A-P

12 Figure captions

Fig-1 Neutrino spectra in the CERN neutrino beam with focussing Horn and two reflectors in the secondaries decay path. Fig-2 Visible volume and fiducial volume in the GARGAMELLE experiment for search of semi leptonic neutral cutrrent. Fig-3 Topology of different classes of events. Fig-4 Ratio "neutral star/ neutrino event" function of the spatial distribution. Fig-5 Pion multiplicity for the 3 classes of events. Fig-6 Layout of the environment of the chamber as Background target. Fig-7 Weinberg model predictions for purely leptonic neutral current. Fig-8 Layout of the first HPW experiment. Fig-9 Spark chamber picture of a muonless event. .Fig-10 Layout of the second HPW experiment; Fig-11 Muon detection efficiency Fig-12 Punchthrough probability Fig-13 1973 GARGAMELLE and HPW results on semi leptonic neutral current. Fig-14 1978 overall final result on semi leptonic neutral current.

Appendix I

List of authors for the GARGAMELLE and the first HPW experiments

Appendix II PICTURE BOOK

Picture -1 Neutrino event with identified muon Picture • 2 Neutrino event with identified electron Picture -3 Semi leptonic neutral current with all secondaries identified as hadrons Picture -4 Neutrino event with an associated neutron star Picture -5 "THE" event, electron identified as evidence for leptonic neutral current i'l

\ 13 ] rcuxc* *va*S0M£ ova* r. o.* —

-

— • ' - ' A— [ j N J. i I ' ~ y I -. Jf _^ S j- i— " T ! * i

\ • - • - — -r .i i —. * i

,J-Jc j-j r i t s- * \ T < p* i i _ ; I =c .J- J I ^s ! _ = ¥=T= É IMS T "i ^•^ / 1 '!• C" T . I V \ • ni -t > T T i , ^, J i •' -t J—U 'Sri TTi CX - T I J r- --.^ ! ' ' I I T it T • • J I •: Ji : : i K À — :s;_3

in j i -r E ^i -i: Zi —--*- = HTI—i—Tr

• i 1 i ; . ! ' i i ; { i

I 1 4 , « ? ê • • » 'r :~±" Hmrf H. WmI* 4êê H» 9 m Vm — m

Figure -1 i.

Side viow

Chamber body

visible volume

Beam F idu cial volume

Figure -2

E >1GEV

NC CVCNT

EH>1GEV

CC EVENT

S*. 'J r

AS EVENT CAMKKTE V

Figure-3 beam - X V baarn - R

NC

-m -•» o «• a

CC

. o -ta o 0) too OL _ o iooo

NC CC _#__J___f__4-4- t___JL. Ja.

•un -iooo too too an 10» 2500 wi*

Figurc-4

ÎÎ

V Figute-5 i

»-•& .._ • . Side view

Yoke _ Fiducial Volume

Top view

Figure - 6 :,*.

8 /

7 /

6

5 / / Z Ul I il 2

1

1 ' ' • o!s ' ' • 2 sin ew

5*

Figure - 7 PROTON SWITCHYARD . HAORON (a) I k-ORIFT MUON SHIELD »1 I EXTRACTED PROTON "EGON BEAM Î NEUTRINO TARGET DETECTOR 500 -MAIN RING OF THE NAL 300GeV ACCELERATOR SCALE (METERS)

OPTICAL SPARK JT" T 1 ï i I CHAMBERS I IROWCORE TOROIDAL MAGNET (b) 5" PHOTO MULTIPLIERS /

ANTICOINCIDENCE CALORIMETER TARGET DETECTOR COUNTER,A COUNTERS EVENT #.04-69630 0 I 2 MUON CHARGE NEGATIVE 1 i i MUON MOMENTUM 27+2 GeV/c SCALE (METERS) HAORON ENERGY ~0.l GeV

Figure-8

SPARK CHAMBERS XX&XÏ "" SPARK CHAMBERS "xx xx», 2 3 4 XX

5

>

«««„ XX XX

10

585351-IS * VIE W xx xx xxxx xx {• Figure-9

«« XX TARGET- DETECTOR MUON SPECTROMETER BC D I 4 5 8 9 12 13 16

v, v BEAM

I 0.5, SCI SC2 SC3 SC4 SC5 SC6 SC7 SC8 h l il O I METERS (a)

2 - a) — CM PO O O O O V) CO CO 1 1 I ... .J] ol 4 5 8 9 12 13 16 TARGET SEGMENT NUMBER (b)

SCl SC2 SC3 SC4 SC5 SC6 SC 7 SC8 (C)

Figure - 10 1.0,

•1.0 ë (d) T O ZOO 400 600 I..

.6 T • -

5 6 7 8 9 IO Il 12 ^VERTEX «MODULEI

Figure-11

1.00 0.50 . Iy r (o) 0.5 (b%) —b 0.20 _L 0.4 C i A I l/li-B ORSC4 Cp 0.10 £P 0.3 0.05 O 2 T-4-'' SC4 ONLY 0.02 - O.I > O 4 8 12 O 20 4O Z OF VERTEX (MODULE NO.) HADRON ENERGY (GeV)

Figure-12 0.8 -

0-6 ïï TK' CERN

R -N\ l Q I 0.4 d \ N V "\ C 0.2 - N

I 0 0.2 0.4 0.6 R" ft ?

Figure-13 { 0." 0 GGM (EH > OGeV) - ES HPWF (EH >4GeV) Q CITF (EH > 12GeV) R O BEBC (EH > 15GeV) O CDHS77(EM>I2G«V) • CDHS 78 (E > OGeV). 0.6 N • CHARM (EH>2-l7GcV)

0.4

0.3

0.2 0.3 0.4 R Vi

Figure -14 { Appendix I

List of authors for the GARGAMELLE and the first HPW experiments •HYSJCSUTTEIlS

OBSERVATION OF NEUTRINO-LIKE INTERACTIONS WITHOUT MUON OR ELECTRON IN THE GARGAMEUE NEUTRINO EXTERIMENT

FJ HASERT. S KABE. W KHtNZJ Von KROCH. D LANSKE. J. MORFIN. K SCtIULTZE ind If WEERTS ftwt *» Ttdi'Uc*** Hoekickule. GH 8ERTRAND-COREMANS. i SACTON, W Vm 0ONiNCK vté P VJLAlN" Mmmrmrniy /xn*u# far H*h £**#«. UL K. V VB JjWHi BtEkF 1 U CAMEWNI* .DC CUNDY. R BALDU-DAN'CHENKC**', WF FWV".D HAIDT1 S NATAU**. P MUSSET. B. OSCULATI, R PALMtMM-MI PATTISON. DH PERKINS". A PULUA. A. ROUSSCT. W VENUS*'ml H WACHSMUTH ggg. Gmnw Swltittim* V BRISSON, • DECRANGE. M HAGUBNAUEIt, L KLUBERG. U NGUYEN-KHAC in* P PETlAU I^botmKHft de fftyrif m Nmti44rt «Vi Hmm Smt%k*. btoêt Mrtrdt*ique. ft".'.- Frmc* E BEU)TTI. S BONETTI. O. CAVALLI. C CONTA** E F(OR(NfMdM ROtX(ER lttuufQ4iFiactêrtlW**r*ti.MUxoë*ilNFN Memo. Italy B AUBERT. D BLUM. LM. CHOUNET. P. HEUSSS. A LAGARK(^UE. A.M. LUTZ. A ORKIN LECOURTOIS snd J P VIALLE

FW BULLOCK. MÏ ESTEN. T W WNES, J McKtNKIE. AC MICHETTE* G MYATT* m4WG SCOTT*»-*» Umiwmty C

t venu induced by Muiitl pwiickf **4 #«oéi*ctai fcrfnmi. Irai no "IIMMI CERN ncvinoo *«p«f*B»ni THm «««• Nfcw» •• tif«^*4 tf lhiy «rt» (ro. Mntnl «ffi«l TIu met reUim ia Hw connpon** CkW1^ rarmil *rac»SM> w«nlwi

We have icarchett for (he nc ual current (NC) and CC • (2) arged current iCC) retenons which ire diiiinfulahtd ra«|MCUv«l> by the ibfence of any po«iMe muan. or On ptemnc* afooe. tad on- ly one. ponible muon A ttnili coatwninatian of vtlvt emill In Irn *>M Im0 beam! gfvln| tome CC evenu * ' C hcidtiui «trar de L'lruiiiui Inicrutuvcmiairc d which are esatly ncofniKtl by ^e c Ie ugrMutt The S*.nmei* Nudcnm, tVtttqiM •l Alto «i HiTBCi OtçirtmcBi. UnrvtMlr of WlKor imlyjii ii bucd on 83 000 » pKiurei and 207000» •* Now u Scipukhv* picture» taken *( CERN in the CtigtmQc bubble •* Now ii UiKTCiNty or tan chamber nileii wiih freon of densty I SX lOUi/m1* *' Now ii BiookhtMn NaiioMl Labotuory The dimeniiom or this chamber are iuch thai moit •* AJw •> Uni«i»tr ofOnfort •' Now •! Rutherford Hiah EiwttV Uboriiair *• On !*•»« of absence ftom Unmmiy ino INFN » A mot* deiaied account of the arwlyui of iKn •* Suppori^ br Science lteieuch Counnl ftmi •ppetri M * pap» io be tubmtiied Io Nudeu rhyaci

>•] OBSEKV.'.TIO" OF HUOSLESs NEITBINO-INDUCED INELASTIC INTEKAr i IONS

At Benvenuti, D.C. Cheng, D. Cline, W.T. Ford, R. Imlay, T.Y. Ling A.K. Mann, F. Messing-, R.L. Piccioni, J. Pilcher ', D.D. Reeder, C. Rubbia, R. Stefanski and L. Sulak

Department of Physics, Harvard University.**) Cambridge, Massachusetts

Department of Physics, University of Pennsylvania.**) Philadelphia, Pennsylvania

Department o£ Physics, University of Wisconsi.•_**n ) Kadison, Wisconsin

National Accelerator Laboratory, Batavia, Illinois

ABSTRACT

He report here the observation of inelastic interactions induced high-energy neutrinos and antineutrinos in which no muon is observed i the final state. A possible, but by no means unique, interpretation o this effect is the existence of a neutral weak hadronic current. ft fc .

Appendix II

PICTURE BOOK

Picture -1 Neutrino event with identified muon Picture -2 Neutrino event with identified electron Picture -3 Semi leptonic neutral current with all secondaries identified as hadrons Picture -4 Neutrino event with an associated neutron star Picture -5 "THE" event, electron identified as evidence for leptonic neutral current if» «I i

Picture-1 V- ••*&•*. Vt-.

Picture-2 \ \ *

-~ v-:>*p.~

')

Picture-3 Piciure-4 Picturc-5