Saxon Fest:A Celebration Beams and Bubble Chambers The World of Baryon Physics R.J.Cashmore...

Saxon Fest:A CelebrationSaxon Fest:A Celebration

Beams and Bubble ChambersThe World of Baryon Physics

R.J.CashmoreBrasenose College and Dept of Physics

Oxford

30-May-08 DHS_Glasgow 1

A Brief CVA Brief CVBorn 27 Oct 1945Education Manchester Grammar School 1956 - 63 Balliol College Oxford 1963 - 68Employment

JRF Jesus College 1968 - 70 RA Columbia University 1970 - 73

SO,PSO RAL 1973 - 90 Kelvin Prof at Glasgow Univ. 1990 - 2008Honours FRSE 1993 FRAS 2005 OBE 2005


Manchester Grammar SchoolManchester Grammar School Very able and conscientious No games player,secretary of

Philosophical Society,trombonist Apart from a scholar .. Very sound

commoner Paid 30 shillings to enter and …….

Awarded a Brackenbury Open Scholarship


Balliol CollegeBalliol College

Took Prelims in March 63 … cost 5 pounds Thereby avoiding exams for 3 years Jenkyns Prize 1965 Scott Prize 1966 Travelling Scholarship to NERC Canada Where he was ‘most impressed by the

vastness’,studied laser interferometry,and found ‘the Canadians most friendly’


ResearchResearchThesis Oct 1969‘A Study of Elementary Particle Interactions using the Bubble

Chamber Technique’ Pi- Proton -> Pi Pi Nucleon at 456/505/552 Mev/c

Thesis Adviser John Mulvey ( & Willie Chinowsky)

Acknowledges DHW for pleasure of working in NPL Balliol for occasional support

and Scanning Girls for their support


Why the Topic ?Why the Topic ?

Kirz anomaly ….. pi pi mass bump that changed with incident beam energy

(In fact Norman Booth had also been implicated in this debate)

Was it an I=J=0 pipi resonance?An S wave resonance?

Was it due to a baryon resonance?A P11 nucleon resonance?


The BUBBLE CHAMBER and The BUBBLE CHAMBER and the BEAMSthe BEAMS

Beams 456/505/552 MeV/c 400/590/660/740 MeV/cNeeded clever design to get rid of electrons

Saclay 80cms hydrogen chamber used at RAL (NIMROD) and SACLAY (SATURNE)


ComputersComputers

PDP 8 to record all the measurements and produce mountains of paper tape KDF 9 to read the tapes and reconstruct

and kinematically fit the reactions


Graduate Students ActivitiesGraduate Students Activities Designed and tuned the beams Scanned and measured the film Processed all the results Developed New Analyses Wrote the paper

All chasing the energy dependence of phase of the pipi s-wave interaction30-May-08 DHS_Glasgow 13

Baryon ResonancesBaryon Resonances

Only the ground state multiplets and a few beyond were known

In fact piN,pipiN final states were to pave the way for the spectrum we now know SU(3) and SU(6) structures existed Baryons qqq and Mesons q-anti q30-May-08 DHS_Glasgow 14

pn

+

0

0

-

-

0

The Baryon Octet

- 0 + ++

- 0 +

0-

-

The Baryon DecupletThe Baryon Decuplet


uu 2/3 2/3dd -1/3 -1/3

ss -1/3 -1/3

The u,d and s quarksThe u,d and s quarks

pn

+

0

0

-

-

0

u,d,s quark structures

uududd

dds uds uus

dss uss

- 0 + ++

- 0 +

0-

-

ddd udd uud uuu

uusudsuss

ussdss

sss

u,d,s quark structuresu,d,s quark structures

Baryon ResonancesBaryon Resonances

Only the ground state multiplets and a few beyond were known

In fact piN,pipiN final states were to pave the way for the spectrum we now know SU(3) and SU(6) structures existed Baryons qqq and Mesons q-anti q30-May-08 DHS_Glasgow 20

OXFORD at that TIMEOXFORD at that TIME

Dick Dalitz ,the father of ‘real’ quarks, was the ‘great man’

The language was quarks

and no one else in the world believed in them

until DIS(1969) and PSI’s(1974)30-May-08 DHS_Glasgow 22


The Particles of the Standard ModelThe Particles of the Standard Model

( )e~0.0 MeV 0 e

0.5 MeV -1 e

e

( )~0.0 MeV 0 e

0.1 GeV -1 e

( )~0.0 MeV 0 e

1.8 GeV -1 e

( )uuu5.0 MeV +2/3 e

10.5 MeV -1/3 e

ddd

( )ccc1.3 GeV +2/3 e

0.2 GeV -1/3 e

sss

( )ttt0.175 TeV +2/3 e

4.3 GeV -1/3 e

bbb

Lept

ons

Qua

rks

In ConclusionIn Conclusion

It has been great having you and Margaret as friends

It has been great working with you over these many years


Saxon Fest:A Celebration Beams and Bubble Chambers The World of Baryon Physics R.J.Cashmore...

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