JACK STEINBERGER DOCTOR HONORIS CAUSA

l niwrsllal Autonorm d? BarcelollJ

UNlvERSrr AT AUTÓNOMA DE BARCELONA

DOcrOR HONORIS CAUSA

JACK STElNBERGER

DISCURS ll.EGIT A LA CERlMONlA

D'INVESllDURA CELEBRADA A LA SALA

D'AClliS DEL RECrORA T

ELDlA 8 DE MAIG DE 1992

BELLATERRA, 1992

La con rerencia pronunc iada peJ proressor Jack Ste inberger s' ha reproduH directament de l'original del mate ix autor.

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DE LA UNIVERSITAT AUTÓNOMA DE BARCELONA

08 193 Bellaterra (Barce lona)

IMPRES PER GRM1CAS UN IÓN Prim, 6 baixos . Terrassa (Barcelona)

Dipo, it legal: B. 4 1.412- 1992

Impres a Espanya

PRESENT ACIÓ

DE

JACK STEINBERGER

PER

ENRIQUE FERNÁNDEZ

Excel·lentíssim i Magnífic Senyor Rector, Digníssimes AutorilalS, Benvolguls Col·legues, Senyores i Senyors,

En aquest acte, la Facultat de Ciencies de la Uni versitat Autonoma de Barcelona, a pro posta de is grups de Física d'A ltes Energies i de Física Teori ca, demana a l'Excel·lentíssim i Magnífic Sr. Rector la in vestidura co m a doctor honoris causa del professor Jack Steinberger.

Ja fa alguns anys que els membres dei s es mentats grups teníem pensat realilzar aquesta proposta, Aixo és degut en primer lI oc a la preeminencia c ientífica del professor Ste inbe rger, ampliament reconeguda entre la comunitat científica de tot elmón. Pero també és degut e n gran manera al pape r que ha ti ngut el professor Steinberger en el desenvolupament i en la conso lidació del grup ex perimental de Física d'Altes Energ ies existe nt en aquesta universitat.

El fet que e l professor Steinberger accept i aquesta di stinció, i que estableixi, per tant, una relació formal amb la nostra institució, és per a tots nosallres un motiu d'orgull i de satisfacció.

El pro fessor Steinberger nasq ué a Alemanya I'any 192 1. El 1934 ell i el seu germa més gran emigraren als Estats Units i s'eslabliren

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a Xicago, on més tard , e l 1938 , hi ana la resta de la família, El 1942 va acabar una diplomatura en química a la Uni versitat de Xicago, Estant a I'exe rcit durant la Segona Guerra Mundial , fou envi at al laboratori de radiacions del MIT, on entra en contacte amb la física,

Després de la guerra va re pre ndre els estudi s de fís ica a la Univers itat de Xicago, Aquesta uni versitat era aleshores, i e ncara ho és, un centre de prestigi, Crec que és suficient anomenar alguns dei s professors i companys de Steinberger per aclonar-se de quina devia ser I'atmosfera que hi regnava, Entre els professors hi hav ia Enrico Fermi , Edward Te ll er, Gregor We ntzel", Entre e ls estudiants, a més a més de Steinberger, hi havia Lee, Yang, Goldberger, Ro senbluth, Garwin, Chamberlain, Wolfenstein , Chew,,, Noms tots ell s prou familiars i que no necess iten presen­tac ió per a molts físics,

Per a la se va tesi doctoral, Jack Steinberger treballa, seguint un suggeriment de Fermi, en un problema que s'havia posat de manifest en ex periments previ s, i que el va portar a la mesura de I'espectre de desintegració d'electrons produüs en desintegracions de muons cos mics aturats en la materia, Aquesta mesura, completada el 1948, establí que elmuó decau en tres partíc ules: un e lec tró i presumibl ement dos neutrins, Aquest resultat fou for~a fonamental en el se ntit gue va ajudar a establir el concepte d'una interacció deb il universal, concepte que és una de les pedres angulars del nostre coneixement de les interaccions fonamental s,

Vull remarcar la paraula fonamental. La majoria de nosa ltres, treball ant en aquest camp avui en dia, estaríem molt sati sfets de fer una o dues mesures d'aguest esti l al lIarg de les nostres carreres, Per a Jack Steinberger, aquest fou tan sois el comenc¡;amem d'una serie, de les qual s esmentaré tan sois alguns exemples, Clarament, els anys en que Jack Steinberger va comen~ar la seva carrera, al fina l deis anys quaranta i comenc¡;ament dei s cinquanta, van ser moll especial s per al camp de la física de partícules, En aq uest període van comenc¡;ar a r uncionar e ls primers acceleradors ; aixo porta a un ni ve ll d'experimentació sense precedents, i, con se­qüentment, a un alt nive ll de co neixeme nt del camp, Malau-

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radament, molts de nosaltres hem de mirar aq uest període des d'una perspectiva hi storiea. Jack Stein berger és un deis prota­gonistes d'aquesta hi stori a.

Després d'un any a l'lnstitu t d'Estudi s Avan, ats de Princeton, la tardor de 1949, Steinberger ana a la Universi tat de California, a Berkel ey, convidat pel professor Wick per ser el seu ajudant. All a, al Laboratori Lawrence Berkeley, va tenir I'oportunitat de treballar amb els acceleradors més importants del món que esta ven en funcionament en aquell moment , el sincrotró d'e lectrons de 330 meV i e l c iclotró de 335 meV. Amb un muntatge ex perimental relativament senzill , que era pioner en I'ús de cente llejadors, Steinberger contribuí a tres experiments, altre cop fo namental s, en tan so is un any: la mesura ac urada de I' es pectre dei s p+ fotoproduHs, que porta la primera indicació de la natura pseudo­escalar de la interacc ió pió-nucleó; la mesura de la vida mitjana del p+ , amb un a exactitud sorprenenl; I'observació de la des integrac ió d'un mesó neutre, de massa similar a la deis mesons carregats ja observats, en dos fotons, i per tant estab lint I'ex istencia de pió neutre.

Tanmate ix, la carrera a Berke ley s'acaba en menys d'un any, a causa del que avui dia es coneix per maccarthi sme. En refusar de signar e l «jurament de Ileialtat anticomuni sta» requerit als membres de la plantilla de la Uni versitat de California, es denega a Steinberger I'autoritzac ió per treballar al LBL. Afortunadament per a la física , Steinberger ana com a professor ajudant a la Universitat de Colúmbia, el 1950, on va poder continuar la seva carrera ex perimental , primer en el cic lotró Nevis de 380 meY i després en e l cosmotró i en e l sincrotó de gradient a lternat del Laboratori Nacional de Brookhaven.

El Departament de Física de la Unive rsitat de Colúmbia ja era for,a prestigiós, i Jack Ste inberger contribuí en gran manera a aquest presti gi en e1s anys següents. Hi ha, als Estats Units, tota una esco la de físics ex perimental s d'altes energies formats a Co lúmbia en e ls anys cinquanta i se ix anta. Que aquests anys degueren de ser molt especials i excitanls científicament es pot

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deduir no tan sois estudiant els resultats c ientífics , sinó també parl ant amb aq uell s que hi foren, Jack Steinberger entre el ls. L'excitació perdura encara avui en dia. Foren anys realment molt especials.

M'agradaria resumir molt breument alguns deis treball s de Jack Steinberger durant els anys cinquanta. Molts expe riments es rea litzaren per estudiar les propietats de is mesons, cosa que fou poss ible gracies a la di sponibilitat d'un fe ix extern de pions a Nevis. Una altra serie completa d'experiments encam inats a l'estudi de les propietats de les partícul es estranyes es va fer al cosmotró de Brookhaven fent servir cambres de bomboll es. Jack Steinberger fou , de fet, un deis pioners en la utilitzac ió d'aquest di spositiu, que va ser una de les ei nes fo namentals de la física de partícules durant quasi dues decades.

Una millora crucial en la tecnica de la cambra de bombolles, que hav ia estat in ventada per Glaser, fou portada a terme per Steinber­ger i tres estudiants (Leitner, Samios i Schwartz) ja I'any 1954. Consistia en una rapida recompress ió, uns deu mil·li segons després de l'ex pansió, que impedia que les bombolles pugessin a la par! superior de la cambra, i així era possible treba llar a un ritme rapid. Entre altres resultats importants obtin gut s per Stei nberger i col·laboradors seus hi ha la demostració de la violac ió de paritat en la des integració de la lambda, la determinac ió de la paritat de l pió neutre i la demostració de la regla ÓS = óQ en la desintegració de f(Ú i de l'hiperó.

Un experiment moll importanl en la carrera de Jack Steinberger es va fer a Brookhaven el 1961-1962, i fou conegut amb el nom d'experimenl deis dos neutrins. La importilncia de l'experiment fou reconeguda, 26 anys més tard , amb la concessió del premi Nobel a Lederman, Schwartz i Steinberger. Aquest ex periment rou molt important per di verses raons. Primerament establia la tecnica per formar fe ixos de neutrins d'a lta energia, que s'ha utilitzat fin s avui . En segon lI oc, era capdavanter en l'ús de detectors de gran area, anomenats cambres spark de capes múltiples , que tot just s'havien acabal d'inventar. 1, sobretot, provava que els neutrins produüs juntament amb muons en les desintegrac ions de mesons produ'ien

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muons en interaccionar amb la materia. Aq uest resul tat fou un pas crucia l per entendre que les partícules elementals s'agrupen en famílies, un fet encara no explicat a un nivell basic.

L'any 1965, durant una estada sabalica al CERN, Jack Steinberger comen~a a treballar en una serie d'experiments basats en I'estudi de la violació de CP en el sistema [(O,f<o. L'experiment dut a terme al CERN mostra entre al tres coses que la dependencia temporal de la desintegració cWl K0 ()'> 'explicava per la interferencia entre les amplituds del K i el K , un efecte de la violació de CP.

, I

El 1968 es va fer membre del CERN i continua amb l'estudi de la violació de CP, aquesta vegada amb dos detectors identics, un al CERN i un altre a Brookhaven, exposats a dos fe ixos diferents de [(O. Per als experiments es va fe r servir la tecnica de les cambres de fils proporcionals , in ventada aleshores recentment per Charpak. AIguns deis resultats d'aquests experiments foren mesures precises d'alguns dei s parametres de la violació CP.

Simultlmiament als experiments de CP del CERN, que duraren fins al final deis anys setanta, Jack Steinberger li dera un gran esfor~, iniciat el 1972, encaminat a construir un detector de 1.200 tones per estudiar les interaccions deis neutrins d'a lta energia amb un feix obtingut a partir del nou gran accelerador del CERN, el SPS. Aq ues! és el famós experiment CDHS que adqu irí dades des del 1977 fins al 1983. Die «famós» perque aleshores jo treballava com a estudian!, en física de neutrins, a Fermilab, i inevitablement sen tia moltes histories sobre la preparació del CDHS. Aquell era <<i'experiment» de neutrins d'aleshores, una amena~a real per a tots els que treballavem en aquell campo Recordo que un deis meus co l·l aboradors, un antic estudiant de Steinberger de Colúmbia, em porta un preprint de Steinberger titulat «Experiments amb feixos de neutrins d'alta energia». L'article tenia una dedicatoria escrita a ma: «Amb els meus millors desitjos», signada <dach. Encara tinc una copia d'aquest preprinl.

L'experiment prova que, en efecte, era una amena~a real: va dur a terme un bon nombre de mesures definitives i precises de les

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interaccions de neutrins, tant en corrents ncutres com carregats. En particu lar va mesurar I'evolució en Q2 de les funcions d'estructura delnucleó, que esta ven d'acord amb les prediccions de la teoria de QCD. A més, també refuta un cert nombre de pretesos, pero no conclusius, resultats en el camp de la física de neutrins.

Al come n9ament de is anys vuitanta, quan va ser aprovat I'accelerador LEP, Jack Steinberger li dera una altra vegada una gran co l·l aboració d 'uns tres-cents fís ic s, per pre parar un experiment encaminat a I'estudi de les co l·li sions e+e- a I'energia de la partícul a Z. Aq uest és I'experi ment Aleph, que act ualment s'esta duent a terme a l CERN i de l qua l som un a institució col·laboradora. Fins ara amb aquest experiment s'han fet mesures precises d'a lgu ns de is pa rametres fonamentals del mode l estimdard , com ara I'amplada i la massa de la Z. La mesura de I'amplada dóna una indicació clara que hi ha tres i només lres tipus de ne utrins, un bon res ultal que també pode m ti til ar de fonamental.

Ara par laré de I'important paper qu e va tenir e l professor Steinberger en el desenvolupament del grup experimental d'aques­ta univers itat. Aixo va passar arran de la nostra incorporació a I'ex perimelll Aleph, i, atesa la meya pan de responsab ili tat en aquesta incorporació, ex plicaré com va comen9ar.

Va ig ven ir aq uí per primera vegada la primave ra del L984 , conv idat per I'aleshores rector d 'aquesta uni vers ilat, el professor Antoni Serra Ramoneda. Espanya s'havia tOl just reincorporat al CERN i molta gent d'aq uí i de la Universi tat de Barcelona, e ls professors Ramon Pascual, Pe re Pascual i Rolf Tarrach entre al tres, volien tenir a Barcelona un grup experimentaL de física d'altes energies . Hi havia un físic ex perimental a la Universitat Aulonoma de Barcelona, el professor Crespo, i al gun s eSludiants novells, entre ell s eLs doctors Garrido, Martínez i Mató, que hav ien estat enviats a l CIEMAT de Madrid per ta l de comen9ar la seva formació en fís ica experimental d'altes energies. M'oferiren de venir aquí i dirigir aquest grup que s'estava forman!. Vaig prendre la deci sió de venir durant I'estiu de 1984, encara que no m'hi vaig traslladar fin s a la primavera següent.

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Després de prendre aquesta dec isió, un a de les meves tasques principals fo u esco llir un exper iment en el qual poguéss im participar d'una manera ad ient. Vaig Ilegir amb deteniment les propostes de LEP i va ig parlar amb col·legues que em podien orientar en aquest aspecte. El que va simpl ificar les coses fou el fet que el professor Steinberger danés una xerrada al Stanford Linear Accelerator Center sobre el detector Aleph, a la qual vaig assist ir. Em vaig quedar molt impressionat per la simplicitat i la c1aredat de la presentació. El que també em va plaure molr va ser I'entusiasme amb que Jack Steinberger va ex plicar e ls problemes físic s i la recnologia escollida per Aleph. No em va quedar cap dubte de quin era I'experiment en el qual voli a participar. Vaig com unicar-ha a Barcelona i el professor Steinberger fou conv idat a venir aq uí la tardar de 1984. Va expressar e l desig d'Aleph de rebre e l nou grup i entrarem oficialment a formar par! d'Aleph pocs mesos més tard.

Per a un grup que rot jusr comen~ava com ara e l nostre, no va ser f¡¡ci l d'esdevenir una part relleva nt d'una gran col·laboració de la importimcia d'Aleph. Des de bon comen~ament I'encorarjament per part de Steinberger fou per a nosaltres moh important. Sempre ha tingut paraules amables per a aquest grup, i ven int d'ell, a ixo ha estat per a tots nosaltres una fo nt de motivació. Pero, més que aixo, ha estat e l seu gu iatge el que ha ti ngut un paper vital en el desenvolupament d'aquest grupo Sreinberger té una gran habi li tar per anar a I'essencia d'un problema d'una manera clara i senzi ll a; per disringir e l que és rellevan! del que no ha és, el que importa del que no és important. Parlant 3mb ell sobre qualsevol cosa, sigui o no de física , la seva primera pregunta, formu lada sempre de manera directa i clara, és normalment la més difícil, potser I'única pregunta. Parser és per aixo que treballar amb ell és un privilegi i ha ringut una gran im portimcia per a tats nosaltres. Avui som aquí per agrair- li aquest privilegi.

Per aixo, ten inr en consideració i exposats tors aq uesrs fets, sol·licito que s'atargu i i confereixi al professor Jack Steinberger el grau de doctor honoris causa per aquesta universitat.

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~t:'r "'-\ . ·0.2·, ..... ,·, \" '. ' .

WHAT DO WE KNOW ABOUT NEUTRINOS? WHAT DO WE LEARN FROM NEUTRINOS?

PER

JACK STEINBERGER

WHAT DO \VE KNOW ABOUT NEUTRINOS? WHAT DO \VE LEARN FROM NEUTRINOS?

J. Steinberger Talk given al Barcelona, May 8, 1992

Each type of particle, by definition, is special. The speciaJ propeny of neutrinos i5 thal they are penetTating. This has made their discovery and me understanding of their properties

elusive, bul il has also made them a userul tool in the study of panicles and their interactions. In astrophysics. on aceQun! of Ihis property, they provide an importan! means ror energ)' transfer and penoi! ¡osight inlo the interior of stars hielden 10 other radianoo. The special cODditions in space permit, in turn, the study of neUlrioo propenies nOI possible in the laboratory.

The 'W'ritten hislory of the neutrino begins with Pauli 's (fig. 1) delicious ¡eller of 1930 10

his "bebe Radioaktive Damen und Herren" (fig. 2)· . He timidly suggests a new partic1e 10

solve two outstanding problems: the apparen! violarion of e nergy conservation in ~ decay, and

the "wrong" statisocs of certain nuclei. for example nitrogen 14. but he does nOl dare to publish it until three years laterl). In the meantime, the name he proposed for it (neutron) was eaten up

by the discovery by Chadwick of the neutral partner of the proton, the discovery which also solved the sratistics problem. At the time [he nuclear energy levels were so uncertain mat Pauli

could only restrict the mass of his proposed neurra) panicle to less than .01 proton masses. The present upper limil is lower by the factor 108, about ten electron v01ls. on the basis of

measurements on me tritium 11 spectrum near its end point. For al] we know t<Xlay, the neutrino

mass may very well be zero.

Figure 1: Pauli .

• Following (soe Ap¡x:ndix) is an english ttanslation, courtesy tIle CERN translation service, as revised by M. SChmelling, R. \\'anke and B. \\'o[f.

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(

MICer Brle! an di_ Qn.¡"pe d_r Radioalctl ven be! dar Oaunre1ns- Tagun g :Rl 'l\ibingen.

Aboehri1't

~1kn118ehee Ina t l tu t d8T EJ.dg. Techniechan Hochech.ü.e ~rioh

L1ebe Ra d1oe.ktive &men W\d Ha:rren,

ZUrlch, h. Dn. 1930 Olor1.alft,rasa_

Wle &Ir U_bsrbrlnger dieeer ZellenJ den 1.cb bnlct.ollat. ensuhOrm bltte, Ihnen das nihe:r.o aua_inandersetaen vird, bin 100 an.gM i cht.s dar "talachen" Statt.tUc del' N. und L1...6 Xerne, ealll1.e dee Ictmt1nu1erUchen be'ta..5pelctl'UlllS eu! oinen T8l"Wd.1'eltc J.naweg YCrt&l..lem '1m deo "Weoheelut.· (1) del' StetistUc und d." !hergieeat. IU r.tten. M8ifu1ch db HOgllchkelt, .., Ic6nnt.ea elelct.rleeh aeutralA Tdlohen, rile lah Heutron., !*mm rill, 1D den lunen e:n.t1enn, Ifelche de Spin 1/2 babee und du Ausachli-.aunfC;8prlndp betolpn UDd. ' ..... - nlQ Lichtq.J.an'ten m.LIe~ DOCh dacmrch unt.enohe1dc, d&eeI 81 .. __ ait L1.oht~¡Ic~t lwtc. Dle Hu,.. der Mictronm ........ dlneJ..b1n ~~~ 111. dI. Uelctron--.._ sen 1IZId jIMafall. a1.ch\ ~C' .la O,al. Pzootca.-••• - ~ kont1m11erllcbll ...... Sp*,,"- vire cknD nnt&ndlich unter dar .Am.abIIe, duI!J b.a ...... Zertall .1t &,. .Ll..Ktron j.,..u. oooh ein lieutron .:1.ttiart , ..... dwart, dese di. ~_ dar !hergien TCID llleutran und tlelct.rcc koruIt.e.nt Ut.

Ifun hMdalt _ 81ch .el tu darua~ .üct. Il'atte &uf d:1 • .IIwtronen v1rkc. CU vehnc:heinlioh.w Hodel1 ~ <Su ""treo eebe1D\ I1.r au.a v.l1arneobl.nbchen oriind.n (alher_ ve:1H de:r U~ d1 .. er Z.llen) di ... :IN .. in, d .. a du Nhende tleutroD e:iA _nurt1echer D1po1 ven ein. gw1B Sin Hcaent /1' ~. Di. kper1JtInW ftrlwlP.en vohl, ck .. di. 1on1al.rende W1rlcun" ..s.n. aolc:heD Nwt.roDA nicht ¡rÓ8aer •• in lcmn. da die dnee err-8trabla uDd dart den ~ v obl nicht &rOes .. "e1n U. e· (lO'" CIl).

Ich traue .teh TOl".l1Utiv, aber n1cht~ etvu Über di .. _ IdMI 1m vubl1.s!.eren UDd vende rrlch ent .,.rtnueDlJ't'Oll an &oh, 11. RadiOll.Ict!.n. 1Iit dtlr P'n.~, vie •• UII. ~ aperlJunt4llc laelwe1A e:1n_ ::;olchen Heutron.l ÑDde, vmn di .... eiD ebenaole_ ~ ... ~ uo.aeree furch~eniógen bultslll VÜrde. v1.e dA -"'trahl.

Ioh ¡ebe SU, du.!" aein J.u ... eg 'fielle1cbt 'tUl ftlmbn'e1A -.te vahnohe1nl1ch enobe1nen vird, v.u un die Jieut.rcm.a., Vem1 ... .ut1.erc, vobl eoboa. rtngst guehen na\t.. Abar II.U' ver va"" ........ 1IDd de- .trn.t dar Si tautioo. be1a k.oIltiDd.rl1ohe ~ drd &rch e:1IMIl lI.1 ...... ~ ftrtIbr\eD Vor~ _ .... , Harrn DIb7e, beleuch\d, ... .u lIInl.1.IIt 111 lr'&Ml ~ ha" · 0, dIIJ"an. aoll lIEl _ ~ pl" n1.ob\ dcIlcm, aC*1.e aa. db MIl_ Stalern.· llanuI ,,011 UD jedcl Ve" sur Rettam¡ ametl10b dloÑu:t!.U"Cl.­Aleo., llebe Bad1oalctin, pritet. 'ODd ~Wt ... W1cMr tum !oh D1.ch\ pn-aOnliob la '11lh1ngc enchdDe, da .cb 1I:lf'olca ~ iD dR Iaolrt Yc:. 6 • .uJIl 7 Des. 111 ZÜr10h I'tattt1nlimdc ~ h1Ar UDat*:&.lloh b1n._ !!1t 'fiahn ~_ lDl .. oh, ac.1e an BC'nl Duk .... ~pt.er-D1 ...

... v. Pa:al1

Figure 2: 1930 Letter of Pauli to me Tübingen congress, suggeslÍng the neutrino_

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In 1934 Fermi proposed a theory of ¡xiecay2), which incorporated the neutrino, and was remarkably simple, successful and long-lived. With the Ferrni theory, the neurrino became a particle like the others. As muon capture and decay becamc understood in the late forties, the Fenni theory became the universal theory ofweak interacoans. It was superseded in !he early seventies by the beautiful electroweak gauge theory wh.ich unified the weak and electromagnetic interactions, bul it!.till survives as a useful approximarion.

The direcl delection of neutrinos was nOI possibJe al the rime, because oC the ver), small inleraction rales, as correctly predicted by the Fermi theory.l\eutrinos are lhe only panicles with only weak interaction. No experiment to detecl them could be imagined until !he advent of the atomic age. The flrst observation of a neutrino induced process, the inverse ~ dec:ay ~crion

v + p --+ n + e+, had 10 wail until 19563), for the development of the hydrogen bornb and the Savannah River tritillm prodllcing reactors, which could generate a sllfficiently large flux of neutrinos. The target was a water tank with sorne cadmium salt dissolved in il The reaction was identified on the basis afthe signal from the gamma rays emitted in the caplure by the C3dmium oC the slowed dawn neutrOn, these gamma rays in delayed coincidence with the gamma rays resulting from the annihilation of the posinon wilh an elecuon (fig. 3).

N A T U R E September 1, 1956 \' 0 . ' "

~FIIQoII ~uz .. (!) OOI.no SCOlfTl .. LAtICMl O(T[CTOIt

1Io0.t.tl, ¡T&IIGlTl 1SCM.

Figure 3: Experimenral arrangemenl ofReines and Cowan fOl' the first derecnon of the neutrino.

The post-war years witnessed the discover)' of whole new and unsuspected worlds oC particles. The discoveries were at firsl in cosmic ray experiments, using nuclear emulsion deteclors and claud chambers, but the field was quickly taken over by accelerator experiments. The avaHable energies increased dramatically with time, opening always new vistas. With lhe consauction, in lhe end oC me fifties, both at Brookhaven National Laboratar)' and al CE&\¡, of proton accelerators in lhe range of 30 billion electron volts, il became possible to contemplate the prodllction of high energy neutrino beams of sufficient intensity 10 perfonn experimenw). The accelerator energy is doubly imponanl for neumno beam experimentanon: lhe cross­sections increase linearly wilh energy, and the beams are more collimated and therefore more

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imense at higher energy. Neutrino experiments opened entirely new possibilities in the study of partic1e propetties and t.he"-'eak interaction5).

The flrst high energy neucrino experimem was performed 31 Brookhaven in 19626).11le

hadrons produced on a targel inside the AGS accelenl!or were allowed 10 enter a 17 meter long decay region (fig.4). The dominant source of neutrinos is me decay ofthe pion lO a muon and a neutrino, and to a somewhat smaller eXlend, bUI with higher neutrino energy, !he decay of me kaon 10 the same [mal State. The decay region was followed by a thick iron shield and a len ton detector consisting of 2.5 on lhick aluminum piares separated b)' spark gaps. The targel doubles as partic1e detector, a feaurre of almos! a1l subsequent neutrino experimems, which is necessitaled by me smallness of the neulrino cross-sections. The sparks are pholographed ; energetic partic1es traverse severa1 piares and can be recognized as trae:ks.

1) ", Ito n S~.eld

Fígwe 4: Arrangement of me fusl acceUerator neutrino experiment, which found !he separate identiry of me muon neunino.

After sorne rnomhs of running, a few dozen evenlS were obtained, and it could be demonsrraled mat these are due 10 neurrinos. One of these is reproduced in fig. 5. The most sttiking featW"e of the events was mal the large majority contained a muan, recognized on me basis ofits large penetration in the alurninum. The muon crack can be seen clearly in fig. 5, Ihe other sparks are due 10 hadronic debris. No events containing a high energy electron could be identified. This demonstrated thal the neurrinos produced in pion and kaon decay, in associarion with muons, are nOI me same as me neurrinos originating in j}-deca)', in association with electrons. The la!ler would necessarily produce electrons in their imeractioo wim mauer7). So, airead)' !he first neutrino experiment observed a fundamental, importan! result. This pairing of neutrinos wilh charged leptons into families is one of the basic fealures of the elecO"oweak theory. Fíg. 6 reproduces a contemporary photo of the experimental team.

- 20 -

Figure 5: One of Ihe events. The upper track is Ihe muon , the lower sparks are due 10 Ihe hadronic debris.

Figure 6: The "two neulri no" collaboralion. From righl 10 left: M. Schwanz, L.M. Ledennan, W. Hayes, G. Danby. ~. Mistry. J.M. Gaillard, K. Goulianos, and myself.

- 2 1-

High energy neurrino experiments have been pursued actively since [hat time, until me presenL Probably the most important resuh was the discovery in 1973 of a new weak interaction, the "neutral currenr". In the late sixties and early sevenlies the eleetroweak meory tOOk formo The ¡heory represen!ed an enormous step (orward in OUT formaJ understanding of panicles. h unified twO of ¡he three panicle in!eraetions, and offered, fo r ¡he first time, ¡he possibility of eakulating weak ¡n teraeríon processes in higher order perturbarion meory, something nor possible in rhe Fermi theory.

Ir was not immediately clear mar me new theory is correcl. All known manifestations of Ihe weak interacnon, almost all of them particle decays, could already be quantitatively understoOO in terms of the old Fenni theor)'. The new theory agreed wÍlh the old on mese processes. but it also predicted two entirely new phenomena: the "neutral curren!" and the existence of the vector basons, partides of a vasll.y greater mass than had been seen before. The frrst of these predictions to be verified was ¡he "neutraJ current". This discovery established the new Iheory beyond any doubt. The vector basons were discovered ten years laler, also a¡ CERN. Unli] the "Gargamelle"- that was the name of Ihe detector---experiment, all observed neutrino interactions. as best one knew, involved the emission of a charged lepton, a muon or electron, in the final stale: one can think of il as the conversion o( me neurrino into the other lepton member of ils "family". The "neutral curren!" permits the scattering of me neunina, with ils reappearance in lhe ftnaJ state.

GargameUe was a large bubble chamber conSCi"Ucted al the Paris Ecole Polytechnique and exposed in a neutrino beam at CERN (fig. 7). lt was (our meters long, IWO melers in diameter, in side a large magnet producing 2 lesla, and fi lled with a heavy Jiquid, freon. "Muonless" eventS were searched for and several hundred were (ound, both in neutt"ino and in antineutrino beams. Such an evenl is shown in fig. 8. 80th of the oUlgoing panicles are identified: one is a kaon, the other is a lambda hyperon, there is no muan. The non hadronic nalure of the beam partiele was demonstrated by the distribution in depth along the chamber, shown in fig. 9. The dismburion is consisten! with being independent of depth, as expecled for neumnos. Neutrons, on the olher hand, would be anenuated wilh an exponential conSlanl roughly equaJ to one~ quaner of the total depth ofthe chamber.

The ratio of rates relative to me more numerous "charged current" events gave a first measure of the weak mixing angle, an importan! free constant in the theory. The ratio of antineutrino to neutrino neutral current cross-sections was predicted by the theory. The measured resull, in agreement with me theoreticaJ prediction . constituted additionaJ, quantitative conflTmation of ¡he theory.

- 22 -

Figure 7: Inside the Gargamelle bubble chamber.

Figure 8: One of me original Gargamelle neulral current events. 'Ole neuronos are coming from the hottom. Al the interaclion ¡x:.inl a neutral panicle and a single charged track are produced. The charged partide identifies itself as a positive kaon by ils decay, afler scatlering in Ihe chamber. The V which points 10 the produclion vertex is a lambda partide, decaying 10 a prOlon and a negative pi meson . There 1S no muon.

-23 -',-' -;,. ¡ . ./ ¡

ti BEAM _ X DISTRIBUTIONS

10 63 NC events

5

0_ 200 o cm

+200

15 148 CC events

10

5

0_ 200 o +200 cm

ratio NC

:: ----- t-----i -- ---~--- -+-~~ .2

o +200

Figure 9: The distribution of the events in ¡he chamber, along {he beam direction, shows ¡hat the

neutral curren{ (non muonic) events, Ihe tOp histogram. are nol produced by neUlroos (see text).

- 24 -

In me years 1969 lO 1972 the inelastic scauering of high energy electrons on protons and deUlerons (neutrons) al SLAC revealed a pointlike constituency of the nucleon. This was a capital discovery. Nucleons were no longer elementat)'. Subsequently, neutrinos proved to be excellent projectiles for complementar)' studies on Ihe nature of the s tructure of the nucleon. On account of the weakness of lheir interaction , neutrinos penetrate the nucleon, and me n~ture of their interaction with the quarks, the primary candidates for me e lementar)' consu luency of nuclear maner, was already predicted by the electroweak theory.

Experiments were carried out wim a ne ..... generation of massive , elecrronic neutrino delectors, al me new 400 GeV prolon synchrotron al CERN. A photograph of the 1000 ton CDHS apparatus is shown in fig . 10. On account of me more massive detector, the higher beam energy, and me more sophisticated beam optics, millions of evenlS were now obtained in com parison wi lh the handful of me first neutrino experiment, and each event contained more detailed and precise information on the scauering man had been possible before. A typica! event is shown in fig. 11. The results. in conjunction with the SLAC electron scauering results, demonstrated the quark nature (quarks had been postulated as panicles of spin 1(1 and of 1/3 integral electric charge, interacting sltongly with each other) ofthe nuclear constituency.

Figure 10: The CDHS 1200 ton electronic neutrino detector at CER.N.

- 25 -

..•. ,. ",., ~ ....... .,..: S[INTILLATOR PULSE HEIGHTS

,.,. ... • '--'{- •• " PROJECTION x I I ~'.U,"I III IUII ,

- _ _ __ _ "UI1l"1 1L!111 - - - -

I 11

-~ ~' '''._.: "" .. fOIIO.O

PROJE[TION u

• ¡ _~x - -- - - - - - - - - -

···u .. .'''·'0;>;1.0 ...... ' ''1.0 PROJEETION V

, , , - - ,- - - - - - - -~ - - - -

O

~~ I! • , , , .- ,% 11 " ..

Figure 11 : A typicaJ charged current evem in the CDHS detector. The neutrino turns into a muon, which is the long track, seen in tmee projections, which penetrates severa! meters of iron . Its energy is measured on the basis of its curvature in the magne tised iron. The accompanying hadronic panic1es are dissipated in the first meter of iron, and their energy is measured by means of scintillation counters sandwiched between the 5cm thick iron pIares.

An additional imponant result of these neutrino studies was their concributlon 10 the experimental confinnation of the now universally accepted theory ofthe strong quark forces, the Quanrum Chromo·Dynamics. This theory pred.iCted small, calculable deviations from the simple point-like scanering which was expected in lhe "naive" quark model. and which resuhs in cross­sections independent of the momentum lransfer caBed "scaling". Scaling was [he basic elernent of the SLAC di~covery, bUl ir is only approximately true. The ne ulrino experi mems8,9) confmned the scaling vioJations predicted by QCD. as shown in fig . 12. and so gave imponanl experimental suppon to the QCD theory.

- 26 -

Figure 12: CDHS rcsults which show the violarion of "scaJing". The observed event Tales are convened 10 "SUUClUrc functions ~ of IWO variables, x and Q2. The variable x can be identified with ¡he fraction of Ihe nucleon's momentum carried by the quark which was suuck. Q2 is the square of the momentum lransfer. For small x, ¡he scattering increases wi!h Q2, for large x i¡ decreases. The result confirmed !he QCD meor)' which predlcled !his behaviour, as shown by me solid lines.

Neutrinos continue to be an imponant tool in the study of nucleon struclure and the propenies of lhe weak interacrion.

Recenuy neumnos p layed an indirect , bUI imponanl role in establishing Ihe number oJ Jermion Jamilies which consntUle maller. In Ihe Slandard Model-lhe Standard Model is !he sum of the elecuoweak. and lhe QCD !heories-"families" consis¡ of fOUT elementary panicles: a charged leptOn and its associated neurrillO, plus a pair of quarks of electric charges 2/3 and -1/3 respectively. Two of these families are known emirely, in ¡he third family the "top" quark is sriU missing, presumably because ils mass is 100 large 10 have been produced in sufficient quantüy for detection so faro The general belief is thal il ""iU soon be found. The Standard Model does nO! predict how many families Ihere should be. Wilh the possible exception of the neutrinos, whose masses are smaller Ihan eouLd so far be measured, the masses of the members of sueceeding families inerease rapid1y, by a factor of lhe order of one hundred from one family 10 the next. If additional famili es exisled, they might be out of Ihe reaeh of present accelerators because of Ihe large possible masses of their conSliluents. But based only on the assumption thal Ihe masses of!he neutrino members of possible higher mass families would also be small, recent experiments at ¡he LEP electron-posicron coJijder have been able te demonstrate lhat there are three families of matter and no more.

- 27 -

The LEP result uses Ihe measurement of the resonance Jine shape of the Z. The Z, the particle wilh Ihe highest mass yet di scovered, about one hundred times heavier Ihan Ihe proton, decays into many different final Slales. Each of (hese consiSIS of a fermion -ano fennion pair. A typical Z decay , here into a quark-antiquark pair, is shown in fig. 13. AH fennion species contribute, wilh probabilities predicted in lhe Standard Model. The width of lhe resonance curve Iherefore is the sum of the conlribulions from aU fennions accessible on energetic grounds, that is, whose mass is less Ihan one-half (he Z mass. The neulrino member of a higher mass family WQuld conuibule, provided onl)' Ihat its mass is less than one-half Ihe very heav)' Z mass. The resonance curve has been very accuralel)' measured at LEPIO). as shown in fig. 14. The widlh is known now with a precision of 0.4%, and is precisel)' me width expected for the known three famUies of matter. The neutrino of a possible fourth family is excJuded with a precision of one Iwentielh of lhe expected contribunon of such a neutrino to the width.

Lel us tum now 10 wha! we have learned abaut slars using neutrino radiation, and, in lum what we might leam aboul neutrinos from (hose which arrive on Out eanh from far awa)'. \Ve will touch on three tapies: neurrinos from Ihe sun, neutrinos from supemova, and neutrinos during Ihe big bang. This is nOI m)' own subject of experimentadon, so r am afraid Ihis discussion will be superficial.

We see Ihe sun dominanuy by means of the visual spectrum. This thermal energy takes about ¡ ()6 years and 1030 colli sions from Ihe time of its creation to gel OUt of the sun, and is modified in the process so Ihat it cannOl lell us much about Ihe conditions which created il. Neuoinos however typically traverse the sun without collision. Al though (he solar neutrino flux on eanh is far from negligible: _10 11 solar neuninos arrive here per cm2 per second, wilh an

energ)' flux as large as several percent of the sun's Ihermal energ)" whie h sustains our life, nevertheless, just because the neutrino interacuon cross-section is so small, their deteclion has been a big chaUenge.

The firSI experiment to delect solar neutrinos, and the only one until just a few years ago, dates 10 197011). It is still running. Neutrinos are detecled by the inverse ~"decay interaction on

chlorine: 37C1 + v -+ 37 Ar + e". The reacuon is observed by means of the argon p-<ieca)', which

has a lifetime of 35 days. The chlorine is in the form of 400 eubic meters (133 lons) of perchloretylene, 1500 meters underground , to gel away from background produced b)' cosmic radiation, in the Homestake gold mine in the US. About on.e. of Ihe }()30 chlorine aloms ~ is expected 10 be converted 10 argon by the solar neutrino radialion! Every coople of months !he radloactive argon is flushed out by means of a smalJ amounl of non radioacnve argon ¡SOlOpe, and counted. The results, which have taken much patience 10 accumulate, have been consistently below lhe expectations of models of nuclear energy production in the sun. They

now stand at 0.4 ± 0.06 atoms per day, aboul one third ofme mte predicted by detai led models of solar nuclear energy produetion.

- 28 -

ALEPH ~":

Figure 13: Decay of a Z into a quark-antiquark pair as seen in the ALEPH detectOr at LEP. The quark and antiquark: materialize as jets, which are typically composed of a doren or so hadrons. The momenta of me charged panicles are measured by the stiffness (in verse curvature) of their tracks. The neutral panicles are measured by means of the "calorimeters " which surround the

traek chambers.

o) ALEPH

35 Hodrons N. '" 2 ._. __ .-JO

1990

" 25 1991 ~::~-~--

S 20

" " " o " 88 89 .,

" 92 93 " " .. b) Energy (GeV)

1.075

I L" • ~1.025

·······t·p + ··~··H··lrlf , " 0.975

0.95

0.92587 .. 89 90 " 92 93 " " " Energy (GeV)

Figure 14: LEP result for me Z resonance, in good agreement with three families of neutrinos. and in disagreemenl with fewer or more families.

- 29 -

In lhe last years, this depletion has been conrlffiled by an experiment using a radicany different melhod of detection 12). The basic reaction is !he e1astic scauering of me neurrinos on electrons, wilh me observation of lhe recoil elecrron. The delectar is a large tank of waler, about 20m on each side, which is viewed byan ruTdy of pholomultipliers. These measure me energy and direction of ¡he liule recoil electron on ¡he basis of emitted Cerenkov light. Again, the detector is shielded fmm cosmic rays in a deep mine, me Kamiokande mine in Japan . Fig.15 shows me distriburion in me angle of the reroil electrOn with respecl 10 the SWl for data obtained in 1040 days ofrunning. The results. which are very clear, correspond 10 0.46 ± 0.05 times the expectations of the solar models.

70

o - 1.0

fe« la MeV

-0.5 0.0

COSC9sun)

/o~od.

T I

0 .5 1.0

Figure 15: Kamiokande results on solar neuninos. The plot shows the observed event role for electron recoils with energy in excess of 10 MeV, as function ofthe angleof the track with

respect 10 the sun. lllere is a large background; the signa] is lhe peak al small angles.

The deviation from lhe expectations of lhe standard solar model of the combined result of me two solar neutrino experiments, by a factor of the order of 1/3 10 1(2, the "solar neurrino puzzle", is of great interest, since the process of nuclear energy prcduction in the SW'l is believed to be adequately underslocd To keep me experimental resull in perspecrive, il should be kept in mind that on the one hand me experiments are difficult, and on the other both experiments are sensitive onl)' 10 the relatively rare high energy component of the expected solar neutrino flux, essentially only 10 the decay of SB, since Ihe neutrino energy threshold is 0. 81 4 Mev for Ihe chlorine reaclion, and about 7.5 MeV for the Kamiokande deteCIOr. The experiments are insensirive 10 the lowerenergy neutrinos from the reaction p + p ~ d + v + e+, which accounts for the large bulk of solar neutrinos. There is a larger theorencal uncertainry for this high energy tail of the solar neunino specuum mm for the pp component

-30 -

For lhis reason 11,0,'0 new experiments are now underway, using me gallium reaction 71Ga

+ v --t 71 Ge + e' which is sensitive 10 Ihe pp reaction neutrinos: an American , Russian

collaboration at Baksan in the Callcaslls as weU as a European collaboration in me Grand Sasso lunnel in lIal}'. )\o positive resulls have as yet been given by eitherexperimenl, bul initial results of me Baksan experirnen( 13) faH weU below me expectalions of lhe standard solar medel. .

Pcrhaps it is too early 10 gel exited about mis new negative result, bUI if it were confmned il would be a demonsrration of new physics in Ihe propenies of neutrinos. Pontecol'vo l4) was lhe flTSllO nOte ¡he possibilil)' of neutrino flavol' oscillation, Wolfensleinl5) poinled OUI that neutrino oscillations would be markedly affecled by maller, and Mikheyev and Smimovl6) used Ihis meehanism !O provide a possible explanalion of me "solar neutrino puzzle". For neumno masses much less ¡han one electrOn voh, i, is expecled Ihal in dense maner, ¡he elterron neutrino. in vinue of it s charged curren! scauering on eleclTons, will have a higher effective mass Ihan Ihe mUQfl neutrino. even if its "free" mass is slighll y lower. An electrOn neutrino bom in me center of me sun would Ihen, if there is ac1equale mix ing between Ihe flavors , leave me

sun as a muan neuoino, impelen! to perform inverse 13 decay. If both the presen! experiments as well as lhe SL1Ildard solar medel calcu lalions are correet, ¡he n Ihe parameler space of neuoino mass differences and mixing angles is very tighlly limited 10 mass differences in Ihe range of a few mousandm of an electron vol, and a substantial mixing angle. The end of this SIOry is nOI ye! told. bUI il is a nice example of Ihe symbiotic relationship bClween particle physics and asrronomy.

Anomer interesting example of lhi s relalionship was the detection of neutrinos from me supemova SN1987 A. Neumnos are me dominant (99%) mechanism by which supemo\'ae are expeclcd to dissipale me energy released in me gravitational collapse of ils core inlO a neutron star. Prior to lhe event of 1987 it was calculaled thal in a typical supemova more man 1()53 ergs should be radialed in me form of neutrinos. These are ¡hermal neutrinos wim rypical energies of Ihe order of 10 MeV. On march 23rd of 1987, al 7:35 U.T., JI and 8 events respeclively, o! such low energy neumno events were regislered in Ihe Kam iokandet7) and 1MBI 8) large underground water Cerenkov detectors. The lime disoibution of me burst, of me order of 10 seconds duration, shown in fig. 16, was in line with the expectations of the supemova coUapse models, as was the energy di stribulÍon and the overall rateo The observanon was usefu] in establishing a new level of confidence in the presenl underslanding of lhe theor)' of supemovae.

The obscr .... ations were serendipilOus in the sense that lhese detectors were built lO srudy an entirely different process, the possibility of Ihe decay of me nucleon. They also provided new information on the propenies of neutrinos, since me time coherence of me events, despile lhe energy differences of the individual neutrinos, pennits an uppcr limil of25 electron volts on lhe electron ncumno ma ss. Other neutrino propenies which follow from ¡he observation were a lower bound of 1.6"'105 years on me eleclTon neutrino lifeome based on the time of fl ight from ¡he supemova, as .... 'el! as an upper bound on its elecmc charge of JO-17 electron charges, and an upper bound on its magnetic moment 10'11 times smalJer Ihan the electrOn magnetic moment, boI:h based on ¡he passage of the neutrinos through the matler of the supemova.

The energy density of neumnos as well as the energy tran sfer by neumnos played an imponant role in the dynamics of me early univcrse. The competition between Ihe expansion Tate (01' the cooling time) and Ihe neurron decay rime is detenninant in lhe fonnation of the primordial helium ruler me lemperamTe has decreased 10 abou¡ 1 Me V, and the weak interaction has frozen out of IhermaJ equilibrium. From Ihe measured cosmic abundances of Deuter1um, Helium and Lithium7 relarive 10 Hydrogen, it has been deduced lhal there should have been of me order of three fami lies of neutrinos, in agreement wilh ¡he panicle physics result. lf one of

- 3 1-

families would have a mass of the order of ten to twenly electron volts, the rem nams of these neullinos from the big bang would be poss ible candidates for the "dark matter" whkh 1S known to dominate the universe.

I hope that these examples make il compre hensible why sorne people spend their time in the study of me most evasive of knO'W1l panicJes: me neurrinos.

Number of counts/sec

Figure 16: Time distributions for (he neutrino events observed in the Kamiokande and 1MB undergrollnd waler cerenkov detectors, and amibuted to me Supemova SN 1987 A. For me

neutrinos, it was all fi ni shed in ten seconds.

- 32 -

Physi.kalisches Insritul der Eidg. Technischen Hochschule ZUrich

Appendix

Zürich, 4. Dez. 1930 Gloriastrasse

Dear Radioaetive Ladies and Gentlcmen.

As the bearer of these lines, lO whom 1 ask you lO lend mos! graeiously your ears, will explain in grealer detail, I ha\'e hit. in view of lhe "false" statisties of the N and Li·6 nucJei and

of Ihe cont inuous I)-speelrum, upon a desperate expedient for saving the "Weehselsalz"t of

staüsrics and energy convcrsation. This is me possibilil)' thal electrically oeuual particies, which I shall call neutrons, mighl eml in me nucleus, ha\'ing spin 1/2 and obeying Ihe exclusion principie. In addirion !he)' differ from light quanta in !hal they do nOI travel at the speed oflighL The mass of the neutron should be of lhe same order of magnilude as thal of the electron and in

any event no greater than 0.01 of the proton mass. The connnuous J>-specoum would then be

comprehensible on the assumption thal on ~ecay a neutron is emitted with the electron in

such a wa)' that me sum of!he neutron and lhe electron energy is conSIilllL

Funhermore lhe questioo arises which forces aet 00 !he neutron. For reasons of W3\'e mechanics (the bearer of these lines knows more aboul this) the likeliest model for !he neutrOn

seems to me 10 be, that the neutron al reSl is a magnetie dipole wilh a eenain moment IJ.. Experiments apparently demand mal lhe ionising effeel of such a neutrOn is no greater than ¡hal

of a y-ray, in wh ich case 11 should be no greater lhan e (10- 13 cm).

For the moment I would nOI venture 10 publish anything on mis notion and should like firsl of all 10 lum tTuslingly to you , dear Radioaclives, with the quesljon conceming the prospects for experimental verificauon of me existence of such a neutron ir it were to have the

same or perhaps a 10 times greatcr penetrating power as a )'-ray.

1 admil thal my expedienl may seem rather improbable from the flrst, because if neurrons existed the)' would have been discovered long since. Nevenheless, notbing ventured nothing

gained, and the seriousness of !he situatiOll ..... ¡!h !he continuous I)-specoum is illustrated by a

statement by my eSleemed predecessor in office . MI. Debye, who recem.ly told me in Brussels: "Oh, it's bener 10 ignore that complelely, JUSl ¡üce the nc ..... laxes". We should therefore be seriousl)' discussing every path (O salvation . So, dear Radioactives, consider and judge. Unfonunately I cannOI come lO Tübingen in person since my presence here is essenrial as a result of a baU held on the nighl of 6th lO 7th December in Zilrich.

With ldnd regards 10 all of you and MI. Back:, I remain , )'our humble servanl,

(signcd) W. Pauli

t This states: Fermi Slaostics and half-numbertd spin rOl' nuclei ".ilh an odd toW nwnba of particles; Bosc. sl31istics and inleger spin fOf nuclei with an evcn lotal number or parocles.

- 33 -

Referenees.

l. W. Pauli, Septieme Conseil de Physique Solvay 1933, Paris 1934, p. 324 ff. 2. E. Fenni, Versueh einerTheorie der ¡3-Strahlen, Zeitsehrift flir Physik 88 161 (1934).

3. F. Reines and C.L. Cowan, Nature 170, 446 (1956). 4. B. Ponreeorvo, JETP 37,1751 (1959), and M. Schwartz, Phys. Re .... Letters 4, 306

(1960) 5. T.D. Lee and eN. Yang, Phys. Rey. Letters 4, 307 (1960). 6. G. Danby et al., Phys. Re\'. Len. 9, 36 (1962). 7. The separale identilY of me muon neutrino was :ulIieipated by G. Feinberg, Phys. Rev.

110, 1482 (1958), on me basis of a meoretieal analysis of me fae t that me muon does nOI like to decay ¡mo an electron and pholOn.

8. BEBC collaboration, Nucl. Phys 8142.1 (1978). 9. CDHS eoll .. J.G.H. deGrool el al, Z. Physik C I , 143 (1979). 10. Eleetroweak Paramelers of the Z. The Four Lep Collaborations, Phys. Len. 8276, 247

(1992). 11 . Homestead Solar Neulrino experiment: R. Davis et al, Proceedings of (he Thirteenlh

Intemational Conference on Neutrino and Asrrophysics. Boston MA 1988. Warld Seientifie. Singapore, 1989.

12. Kamiokande ex:periment: K.S. Hirata el al, Phys. Rev. Letters 65, 1297 (1990). 13. Baksan Neutrino Observalory Gallium experiment. A.I. Abazo\' el al, Phys. Re .... Leners

67 .3332 (199 1). 14. B. Ponteeorvo. Soviet Physics JETP 26 , 984,(1968). 15. L. Walfenstein, Phys. Re\'. d17, 2369 (J978). 16. S.P. rvLikheyevand A.Yu. Smirnov, SO\l. Jour. of Nuel. Phys. 42 (6), 913 (1985). 17. Kamiokande Underground Water Cerenko\l experimento K. Hirata et al Phys. Rev. Lea

58, 1490 (1987)10. 18. 1MB Underground Water Cerenko\l experiment R.:\1. Bionta el al, Phys. Rev. Letl58,

1494 (1987).

-34 -

CURRICULUM VITAE

DE

JACK STEINBERGER

CURRICULUM VITAE

Jack Steinberger

Bom: Bad Ki ssingen, Oermany, 25-05-192 1

Father: Ludwig Steinberger, cantor in the sy nagogue, re ligious teacher.

Mother: Berta Ste inberge r (bo rn May), lang uage teacher, housewife.

Education:

1927-1931 : 193 1-1 934: 1934:

1935- 1938: 1938-1940:

194 1- 1942:

1946-1948:

Employment:

1940-1941 : 1943- 1945:

1945- 1946:

Volksschule, Bad Kissingen. Realshule, Bad Kissi ngen. Elllmig ration to US, th anks to gene ros ity of Allleri ca n-Jewish char iti es.Fos ter rather Barnet Faroll , Winnetka IL. New Trier Township High Scholl , Wilmetter !L. Armour lnstitute of Technology, Chicago, IL. , subj ect: Chelll ical engineering. Uni vers ity of Chi cago, subj ect: Chemislry. B.S. Oegree 1942. Univers ity of Chi cago, subject: Physics. Ph. O. Sponsor: E. Ferllli , Ph . O. Oegree 1948.

Bottle washer, 0 .0 . Searle Co. , Chicago. Radiation Laborato ry, MIT, Cambrid ge, MA, wanime developlllent of radar bOlllb sights, first cha nce lO study sOllle physics, pan time, al MIT, wilh Lazlo Tisza. US Arllly, Signal Corps, Pfc.

- 37 -

1948- 1949: 1949- 1950:

1950- 1968:

1956: 1964: 1965- 1966: 1968- 1986:

1986:

Civil status:

Member, lnstitule for Advaneed Study, Prineeton Ass istant to G.C. Wiek, Univers ity of California, Berkeley , CA. Co lumbia Univers ity , sta rtin g as ass istant professor, endin g IIp as Higgens Professor. Sabatical at Rome, Bologna Uni vers ities. Sabati eal at Uni versity of California, San Diego. Sabati cal at CERN , Geneva. Physiei st, CERN, Ge neva, 1969- I 972: Director, phys ies department. Vi s iting professo r, Seuo la NormaJe Superi ore, Pisa.

1943- 1962: Marri ed lo Joan Beauregard , two chi ldren, Joseph 1944, Richard Ned 1948.

1962: Married to Cynthi a Eva Alff, two children, Julia Karen 1974, Jol1l1 Paul 1977.

Seleetion of researeh papers:

«On th e range 01' e leetrons In muon decay», Phys. I?ev. 76 ( 1949) 11 36.

«On the use of substraetion fi elds and the lifetimes of some types of mesons», Phys. Rev. 76 ( 1949) I 180.

«The deteetion o f artifiei all y produced mesons with counlers », J. Sleinberger and A.S. Bishop, Phys. ReJ!. 78 ( 1950) 802. J. Steinberger, W.K.H. Panofsky and J. Steller, Phys. ReJ!. 78 ( 1950) 802.

«Total cross seetions 01' pions on prolons and several other nllelei», Chedester, 1saaes. Saehs and Ste inberger, Phys. Rev. 82 ( 195 1) 646.

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«The spin 01' Ihe pion», Durbin, Loar anel Steinberger. Phys. Rev. 83 ( 195 1) 958.

<<lntern al pair produclion of y rays of mesonic origin», L inclenfeld. Sachs anel Slcinberger, P/¡ys. Rev. 89 ( 1953) 531.

«Different ial crossecl ion for Ihe scanering of 58 M eV n+ mesons in hydrogen», Bodansky, Sachs anel Sleinberger. Phys. Rev. 90 (1953) 996. 93 ( 1954) 130.

«Absorplion 01' negali ve pions in deulerium: paril y 01' Ihe pion», Ch inowsky and Sleinberger. P/¡ys. Re\'. 93 ( 1954) 156 1.

«Reacl ion 1(+ + el -> 2n + 1(0: parily 01' Ihe 1(0)>, W . Chinowsky anel J. Sleinberger, P/¡ys. Rev. 103 (1956) 1827.

«Propen ies 01' heavy unslab le panic les producecl by 1.3 GeV 1(­mesons». R. 13l1e1de el al. , P/¡ys. Rev. 103 ( 1956) 1827.

«Demonslrat ion of Ihe ex islence or Ihe LO hyperon, and measurement or ilS mass», R. Plano el al. , NuOl'o CimenTO 5 (1957) 216.

«Demonslral ion of parily violalion in hyperon decay», F. Eisler el al. . P/¡ys. Rev. 108 ( 1957) 1353.

« ~ e1ecay 01' Ihe pion». G. Impeclu gl ia el al.. P/¡y s. Rev. Lell. 1 ( 1958) 249.

«PariI Y of Ihe neul ra l pion», R. Plano el al. Phys. Rev. Lell. 3 ( 1959) 525.

«Proel llcl ion 01' pion resonances in n+ p inleraclions», C. Al rr el al. , PhJS. Rev. Lell. 9 (1962) 322.

«Decays of Ihe w and 11 mesons», C. Alrr et al. , Phys. Rev. Lell. 9 ( 1962) 325.

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«Observations of hi gh energy neulrino inle raclions and lhe ex istence of lwo kinds of neutrino», G. Danby el al., Phys. Rev.

«ParilY 01' lhe ne ulral p io!1», N. Samios el a l. , Phys. Rev. 126 (1962) 1844.

«Li felime of Ihe Ol meSOIJ}>, Ge lfand el a l. , Phy.l'. Rev. Le/l. 11 (1963) 436.

«Widlh oflhe cp meson», Gelfand el a l. , Phys. Rev. Lelf. 11 (1963) 438.

«~-decay of lhe L+ and L' hyperons and lhe validity 01' lhe L1S = L1Q law», Nauenberg el a l. , Phys. Re". Lelf. 12 ( 1964) 679.

«Tesl oflhe validily oflhe L1S = L1Q law in KO decay», L. Kirsch el al. , Phy.l'. Re". Lelf. 13 ( 1964) 35.

«LO AO relalive parily», C. Alff el a l. , PraL'. Sienna Con!, vo l. 1, Soco Ilal. Fisica ( 1963).

«Ks- KL inlerference in lhe ¡r+ ¡r' decay mode», C. Alif-Steinberger el al. , Phy.l'. Lelf. 20 ( 1966) 207.

«Measurement of lhe charge asymmelry in lhe decay KOL -> e+ + ¡r' + n», S. Bennel el a l. , Phy.l'. Rev. Lelf. 19 (1967) 993.

«ll+, phase RaE, and Ihe superweak modeh>, S. Bennett e l a l. , Phys. Lelf. 27B ( 1968) 248.

«Co nSlruclion and pe rfoman ce of large proponional w ire chambers», P. Schiliy el al. , Nuc/. /nSlr. and Meelhods 91 (197 1) 22 1.

«Observat ion of lhe decay KOL -> /J + /J », W .c. Carithers el al. , Phys. Rev. Lelf. 30 (1973) l336.

«A new delerminalion of the KOL -> ¡r + ¡r, parame le rs», C. Geweniger el a l. , Phys. Lelf. 48B (1974) 487.

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«Mcasuremen l of lhe charge asymmelry in lhe decays KOL -> 11:ev». c. Geweniger el al.. Phys. Le/l. 48 B ( 1974) 483.

«Measuremcnl of the kaon mass difrerence by lhe lwO regeneralOr mClhod». C. Geweniger et al.. Phys. Le/l. 52B (1974) 108.

«Measuremenl 01' lhe KL- Ks mass difference fro m lhe charge asymmelry in leplonic decay», S. Gjesdal el al. , Phys. Le/l. 52B (1971) 11 3.

«The phase of CP violation in lhe K -> 11:+ 11: ' decay». S. Gjesdal el al. . Phys. Le/l. 52B (1974) 11 9.

«Measuremenl of lhe L O lifelime», F. Dydak el a l. , NI/el. Phys. B 1 18 ( 1977) 1.

«A deleclor ror high energy neulrino interac li ons», M. Holder el al., NI/el. !I/SIr. M eillOds 148 ( 1978) 139.

«Opposile sign dimuon evenlS produced in na rrow band neulrino and anlineulrino bcams», M. Holder el al. , Phys Lell. 69B (1977) 377.

«O bsc rval ion of lrimuon eve nl S produ ccd in neu lrino and antinculrino inleractions», M. Holder el al., Phys. Le/l. 70B (1977) 396.

«Is there a "high-y anomaly" in alllineutrino interactions?», M. Holder el al.. Phys. Rev. Lel/. 39 ( 1977) 39.

«Measuremenl of neutral lO charged currenl cross seclion ral io in neu lrino and antineulrino illleracli ons», M. Holder el al. , P/¡ys. Lell. 7 1 B (1977) 222.

«Swdy 01' inclusive ncutral currenl interacl ions of neutrin os and anlinculri nos». 1\1. Holder el al., Phys. Lell. 72B ( 1977) 254.

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«Origi n of ¡rimuon events in high energy neutrino interacti ons», T. Hansl el a l.. P/¡ys. Lelt. 77B (1978) 1 14.

«Inclusive interactions of high encrgy nculrinos and amineulrinos in iron». H. de Grool e l al .. Zeirsc/¡r. P/¡ysik CI ( 1979) 143.

«QCD analys is of charged curre lll SlruclUre fun clions». H. de Grool e l a l. , P/¡ys. Lell . 82 B ( 1979) 456.

«A measure mCIll o f lhe rali o o f lo ng iluclina l and Iransve rse SlruClure fu nclions». H. Abramov ilz Cl a l. , P/¡ys. Lell. 107B ( 198 1) 141.

«Lim it on ri ghl ha nded weak couplin g paramelers from inelastic neulrino inle racli ons», H. Abramovil Z el a l.. Zeirsc/¡r. P/¡ysik CI2 ( 1982) 225.

«Delerminali o n o f Ihe g luo n d islribul ion in lhe nucleon from eleep inelasti c neutrino sca llering». H . Abramovitz el al. , Zeirschr. P/¡ysik C I2 ( 1982) 289.

«TesIs of QC D anel non-asymplolical ly free Iheories by an analysis of lhe slru clurc funCli ons xF3, F2, and q-baf», H. AbramovilZ el a l. , Zeirschr. P/¡ysik C 13 ( 1982) 199.

«Experime nla l sl udy of Oppos ile-sig n d imuon s prod uced in neulrino and alllineulrino inte racli ons». H. Abramovi lZ e l a l. . Zeirsc/¡r. Pllysik C 1 5 ( 1982) 19.

«Are the re pro ml like s ign d imu ons?» , H. Burkhardl e l al.. Zei rsc/¡r. P/¡ysik C3 1 (1986) 19.

«First ev idence of direcl C P vio larion». H. Burkhardl c r a l., Phys Lell. B206 ( 1988) 169.

«Aleph: a deteclor for e lecron posilron annihil alions al LEP», lhe Aleph coll ab .. NI/el. ülsr r. M erhods A294 ( 1990) 2 1.

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«Determin ation of the number of light neutrino specles», D. Decamp el al., Phys. Leu. 8231 (1989) 5 19.

«TesIs of lhe eleclroweak Iheory al lhe Z resonance», H. Burkhardt and J. Steinberger, Ann. Rev. ofNuel. Gnd Parl. Science 4 1 (1991) 55.

Honors:

US Nalional Meda l of Science, 1988. Nobel pri ze for Phys ic s (w ilh L.M. Ledennan and M. Schwarlz), 1988. Mateuzzi medal, Societa Italiana delle Sc ience, 199 1. Guggenheim fel low. Sloan fellow.

Doctor Honori s Causa:

IIlinois In stilule of Technology Columbia Uni versity Uni vers ital Dortmund Glasgow Uni versily

Member:

Heidelberg Akademie der Wissenschaften US Nalional Academy of Science American Academy of Arls and Sciences Academia Europea

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