2015-04-27 Alan Astbury R. Keeler Scienst 1934 -- 2014 1 Scientiic Antecedents • Graduate of Nantwich and Acton Grammar School • Alan told me he was parcularly lucky to have excellent teachers • First Class Honours degree in physics at the University 2015-04-27 of Liverpool • PhD research supervisors (University of Liverpool): R. Keeler • Sir Alec Merrison, • Hugh Muirhead (was a member of Powell’s group that discovered the pion and an acve member of UA1). He wrote a well known textbook. 2 Outline Overview of Alan’s scienfic work in historical order. • His worked covered nuclear physics to high energy parcle physics 2015-04-27 Two themes emerge: • Alan worked on the leading scienfic problems of his me. R. Keeler • He used the most technologically advanced apparatus that was available 3 Liverpool Synchrocyclotron Photo of the rotang capacitor used to modulate the RF at the 400 MeV proton accelerator. An external beam could be extracted. 2015-04-27 R. Keeler 4 Liverpool (graduate Student) Capture Rates for Negave Muons in Various Elements Proc. Phys. Soc. 72, (1958) • Physics interest was tesng the theory of universal weak 2015-04-27 interacons • External negave parcle beam (86 % pions, 11% electrons, 3% R. Keeler muons) • Muons stopped in target and decay me measured 5 Liverpool ( Leverhulm Research Fellow) Angular Distribuon of Neutrons Following Nuclear Capture of Polarized Muons Phys. Rev. Leers 15, 1959 Tesng V-A weak coupling Results support parity violaon µ− + p → n+ν 2015-04-27 ! ! ! Harwell neutron counter with N(θ)∝1+ασ i p/ p gamma ray suppression R. Keeler 15% polarizaon for stopped muons in sulfur target !⊗!magnetic!field Asymmetry in direcon of n emission 6 Liverpool ( Leverhulm Research Fellow) A measurement of the Total Cross Secon for the Producon of Neutral Pions in Proton-Proton Collisions at 383 MeV Proc. Phys. Soc. 78 (1961) Uses a measurement of gamma rays at a special angle 2015-04-27 γ dσ (θ ) R. Keeler σ = 2π ppπ 0 dΩ where cos−1( 1/3) {37° ,102 ) !θ = ± = ° Result: 59±9 μb Mandelstam Resonance Theory 7 cannot account for all of the producon cross secon Berkeley Search for Neutrino-induced Reacons Physical Review Leers 11 (1963) p + n ν µ + → µ + ! 2015-04-27 • W mass > 1.1 GeV OR R. Keeler • cross secon less than 4x10-32 (~10-40) 8 Berkeley Using the 184 inch synchrotron Commissioned a bent-crystal spectrometer Measured 2015-04-27 Pionic X-rays R. Keeler Results presented at conferences. 9 Rutherford Appleton Laboratory RAL (Research Associate) Nimrod Weak Focusing proton synchrotron 2015-04-27 7 GeV, 1012 protons / pulse R. Keeler 0.5 Hz pulse rate. Start operaons 1963 10 CJSD/JD retirement/July 02/pg4 RAL Nimrod Two Pion Decay of the Meson K 0 2015-04-27 ! 2 Phys. Rev. Le`. 14 (1965) Throughout its life, physics programme was directed mainly to studying baryon resonances • Nimrod beamlines in 1964 R. Keeler • First generation experiments measured π ±±pKp,and pptotal cross-sections, differential Confirmaon of CP violaon in K-long decays cross-sections and polarisation • Also Kd± total cross-section, ππ− pn→→0 and η nnppn and charge exchange processes momentum spectrum 1.5 < p< 5.0 GeV/c K 0 CJSD/JD retirement/July 02/pg5 ! 2 5 m evacuated decay chamber Decay parcles are momentum analyzed by two 11 spectrometers with bending magnets and sonic spark chambers RAL CP Violation • 54±9 2pi events observed • BR = (2.08±0.35)x10-3 Today’s value=(1.967±10)x10-3 2015-04-27 K2pi R. Keeler K3pi Ke3 Kmu3 pions in the forward 12 direction RAL (Tenured PSO) Measurement of the Electron Asymmetry Parameter in the Decay of Polarized Hyperons. Σ− Nucl. Phys. B39 (1972) Cabbibo Theory • 1.13 GeV/c pions − • Measured polarizaon is small Σ 2015-04-27 P=-0.32±11 R. Keeler − p+ − K + π + → Σ + Σ− → n+ e− +ν 43 decays observed g Result: A = −0.4+0.52 g −1.5 ! V g 13 A = +0.3 Predicon: g ! V RAL Nucleon-Nucleon Small Angle Proton-Proton Scaering at 7.85 GeV/c Phys. Les. 14 (1965) Measure the cross secon in the very forward direcon. 2015-04-27 Strong-EM interference region will give phase Total cross secon can be calculated from the opcal theorem R. Keeler 14 RAL Another group reported anomalous result that violated the Opcal Theorem 2015-04-27 Results here are consistent with other data and predicted dispersion relaon R. Keeler 15 CERN PS Antiproton Physics CERN Yellow reports: 71-25, 72-10, 74-10 Papers _ + − + Differenal Cross Secon for between 0.8 and 2.4 GeV/c !pp → π π ,K K Phys. Le` B 47 (1973) 2015-04-27 _ Interpretaons of the Differenal Cross Secons for . !pp → π π R. Keeler Phys. Le`. B 47 (1973) − + Some Observaons on the Differenal Cross secons for . !pp → K K Phys. Le`. B 49 (1974) 16 CERN PS Electrostacally separated anproton beam Wire chamber based magnec spectrometer 2015-04-27 R. Keeler 17 CERN PS Angular distribuons measured at 10 incident 2015-04-27 momenta. R. Keeler Phase shi analysis done. 18 CERN PS Phase shi analysis There are many more states available in 2015-04-27 anproton proton annihilaon than there R. Keeler are in proton-proton interacons. This table keeps track of various fit results 19 RAL Kaon-nucleon interacons searching for a forbidden S=1, I=0 baryon state Polarizaon in K+n Charge Exchange Scaering Between 0.851 2015-04-27 GeV/c and 1.351 GeV/c Phys. Le`. B R. Keeler No forbidden states detected. 20 UA1 (co-spokesperson) Anproton-proton collider 540 GeV Centre of Mass 2015-04-27 R. Keeler 21 UA1 Hadron Calorimeter UK provides: • Hadron Calorimeter (Iron-Scinllator with wavelength shier readout) • Return yoke for a transverse magnec field 2015-04-27 • Inside the box were a: • Lead-Scinllator R. Keeler electromagnec calorimeter • Central Dri Chamber 22 UA1 Hadron Calorimeter 0.8 Resoluon = E(GeV ) ! 2015-04-27 R. Keeler Missing Transverse Energy Resoluon of each component is Gaussian σ = 0.4⋅ E i !!E!measured!in!GeV with ! ∑ i T where the sum is typically < 100 GeV 23 UA1 Trigger 50 kHz event rate Reduced to 3Hz • Tape wring speed Calorimeter trigger was combined with a muon trigger 2015-04-27 Eventually a 168E (emulator) was used as a high level trigger R. Keeler 24 UA1 startup Enormous Group 2015-04-27 R. Keeler !< n >= 6.57 25 T !is!the!probability!of!observing!n!charged!tracks ! n UA1 W Missing Transverse Energy (Martyn Corden – U. Birmingham) 2015-04-27 R. Keeler 26 UA1 W Experimental Observaon of Isolated Large Transverse Energy Electrons with associated Missing Energy at √s=540 GeV. Phys. Les 122B (1983) 2015-04-27 R. Keeler M = 81+5 !GeV/c2 ! W −5 27 Telegram to CERN DG from 2015-04-27 Margaret R. Keeler Thatcher, PM UK 28 Margaret Thatcher 29 R. Keeler 2015-04-27 British PM 2015-04-27 telegram R. Keeler to Alan 30 W discovery 31 R. Keeler 2015-04-27 UA1 Z Experimental Observaon of Lepton Pairs of Invariant Mass around 95 GeV/c2 at the CERN SPS Collider Phys. Les B126 (1983) 2015-04-27 2 M = 95.2±2.5!GeV/c R. Keeler ! Z 32 UA1 W & Z Electron angular distribuon W is spin 1 parcle ρ and Sin2(θ ) measured W 2015-04-27 R. Keeler 33 UA1 Di-Jets Spin 1 Gluon exchange Factorizaon à leading order structure funcons 2015-04-27 R. Keeler Bill Sco RAL 34 UA1 3-Jets Scale breaking Running of the strong coupling constant 2015-04-27 R. Keeler 35 UA1 3 Jets 2015-04-27 Gluon R. Keeler Bremsstrahlung 36 Alan arrives in Victoria (1983) Earliest group photo I could find 2015-04-27 R. Keeler 37 UA1 Ramping Run SPS cycled between 200 and 900 GeV. 2015-04-27 R. Keeler 38 UA1 Bose-Einstein Correlations First Student in Canada - Margret Fincke-Keeler Bose-Einstein Correlaons in An-p p Interacons at √s=0.2 TeV to 0.9 TeV Nucl. Phys. B 226 (1989) 2015-04-27 R. Keeler 39 TMP 2,2,4,4 tetramethylpentane • Does it compensate? 2015-04-27 R. Keeler 40 No, it does not. SLD Designed and built liquid argon- lead electromagnec calorimeter in collaboraon with Caltech. 2015-04-27 R. Keeler 41 OPAL (Director of TRIUMF) LEP: Electron-positron collider Z pole and then above the WW threshold Victoria Group worked on: • Silicon microvertex detector upgrade 2015-04-27 • Responsible for near-real me data reconstrucon Our tau physics work started with three technical notes that Alan took R. Keeler a very big interest in: TN 139 (1993) A New Clustering Algorithm for tau Decays A. Astbury et al TN 186 (1993) A New Clustering Algorithm for tau Decays : II R. Sobie TN174 (1993) A Study of Electromagnec Shower Profiles in the Electromagnec Barrel Calorimeter 42 M. Vincter, A. Astbury, R. Keeler, R. Sobie OPAL Some thesis topics that Alan was involved with: 1. The W Boson Spin Density matrix at OPAL (I. Bailey – Lancaster) 2. Search for Excited Charged Leptons in Electron-Positron 2015-04-27 Collisions (B. Vachon – McGill) 3. A Precision Measurement of the Rao of the Effecve R. Keeler Vector to Axial-Vector Couplings of the Weak Neutral Current at the Z0 Pole (M. Vincter – Carleton) 4. Measurement of the Neutral Current in the Standard Model using the Tau Polarizaon Asymmetries Determined from − − the decay (M.