Particle Physics research at Birmingham began when the 1 GeV proton synchrotron was brought into operation in 1953. During the ten years or so after that, research was carried out at Birmingham by groups using counter techniques and bubble chambers. The Birmingham Synchrotron was the only high energy accelerator in the UK until 1963, when the 7 GeV machine, NIMROD, was commissioned at the Rutherford Laboratory. Effort was gradually transferred from the Birmingham machine to experiments on NIMROD, which offered superior facilities, and, in 1968, the Birmingham Synchrotron was closed down.
A 28 GeV proton synchrotron was brought into operation at CERN , Geneva, in 1960. Most of the bubble chamber work had already been transferred to CERN in the early 1960s and the counter experiments were transferred after 1971. The Birmingham Film Analysis Unit was set up to support the analysis of the bubble chamber experiments. It played a leading part in several important collaborative experiments and established itself as one of the strongest and most productive in Europe. These experiments typically analysed millions of photographs by using teams of scanners and computer operators working on shifts round the clock to find and measure the interactions of beam particles in the bubble chamber. A spectrum of new resonances (unstable particles, excited states) was discovered, heralding indirectly as atomic spectra had done for the atom, the existence of a new substructure in physics. In Europe, the equivalent of Rutherford's direct evidence for the atom's substructure (known as `deep inelastic scattering' or DIS), and much more, came with the commissioning in 1976 of the 400 GeV Super Proton Synchrotron (SPS) at CERN. Responding to the discovery of charm in 1974, the bubble chamber group moved on to a series of experiments in the Big European Bubble Chamber at CERN and the 15-foot Chamber at Fermilab. With high energy neutrino beams, a wide variety of Standard Model features were explored. In particular, DIS with the weak probe provided information on the distribution and nature of quarks in the nucleon; charmed mesons and baryons were produced, their decays then revealing properties of the charmed quark.
The Birmingham group played a central role in the first observation of the J/psi particle in Europe, providing some of the earliest evidence for the charm quark. This was achieved through the creation of a Beam Dump experiment at the CERN SPS, absorbing the vast bulk of particles produced, so that only muons penetrated into the Omega spectrometer, from which the J/psi's were reconstructed. This was the first experiment to be completed at the SPS. The group participated in many later experiments with the Omega spectrometer, including searches for glueballs and the quark gluon plasma.
The CERN SPS antiproton-proton collider started operation in 1981 with a collision energy of 540 GeV. Most of the Birmingham group worked on the UA1 experiment which together with UA2 reported the discovery of the W and Z bosons in 1983. The group contributed to many aspects of UA1 from the early detector design in the late 1970's through to the final analysis of the collision data. The group worked on the hadron calorimeter, calorimeter trigger, muon and jet identification and the then state-of-the-art Megatek event display. Our analysis work focussed mainly on W/Z and J/psi production and properties and the first observation of b-bbar mixing. By the mid 1980's most major experiments involved much bigger collaborations and took data for much longer periods. Later in the 1980's the Birmingham group focussed most of its efforts on two major experiments, OPAL and H1.
The OPAL experiment constructed one of four general purpose detectors at the LEP electron-positron collider at CERN which took data from 1989 until 2000. The initial collision energy at LEP was ~100 GeV to make precision measurements of the Z boson which established that the number of 'light' neutrinos was three. The collision energy increased steadily to 209 GeV in the late 19 90's to measure W pair production and conduct searches for new massive particles including the Higgs boson. The Birmingham group, together with Rutherford Laboratory, were responsible for al l aspects of the Muon Endcap detector (12 metre by 12 metre) including its trigger system. The group also made many important contributions to the long term operation of the experiment and t he precision electroweak analysis of the collision data.
The H1 experiment was one of two general purpose detectors at the HERA facility at the DESY laboratory in Hamburg, which collided 27.5 GeV electrons with protons of energy up to 920 GeV. HERA operated between 1992 and 2007. From the outset, Birmingham led the design, build and operation of the ASIC-based trigger for the Forward Muon Trigger and also contributed to two upgrade projects - the 'Very Forward Proton Spectrometer' Roman pots and the 'Fast Track Trigger', one of the first FPGA-based devices used in high energy physics experiments. The group's analysis work included a very strong contribution to the study of `diffractive' processes in which the proton remains intact, as well as work on inclusive deep-inelastic scattering and the corresponding extraction of proton structure functions, charm and beauty production and quasi-elastic J/psi production.
Between 1998 and 2009 the Birmingham group was one of ten UK institutes in the BaBar Collaboration, working on an experiment at the SLAC National Accelerator Laboratory in California. The BaBar detector was situated on the PEP-II asymmetric collider facility, or B-Factory, in which 9 GeV electrons collided with 3.1 GeV positrons. BaBar recorded and analysed about 500 million pairs of B and anti-B mesons, and made precise measurements of CP violation in B decays. Birmingham physicists contributed to software development and studied charmless three-body B decays using the Dalitz Plot technique.
Some group photos taken over the years can be found here
Last update 13 July 2020