Around the Laboratories

The UA2 experiment at CERN's - Collider - big companion for a series of smaller studies.

(Photo CERN 84.9.81)

CERN Two more Collider experiments The unique physics conditions provided by the SPS proton- antiproton Collider (see also page 229) are explored by experiments jiounted in the two large underground areas where the beams of and are brought together. In one underground site sits the mighty UA1 detector, described as the most complicated piece of electronics in the world. The other is the home of the UA2 detector which complemented UA1 in the famous hunt for the W and Z particles (see November 1983 issue, page 370). In this second underground area, UA2 alternates with the UA5 visual detector which provides a fast survey of new collision conditions (see May install silicon/lead sandwich the same behaviour also occurs at issue, page 131). detectors in UA4's 'Roman Pots' to small angles. (The UA6 experiment at the detect the photons coming from After UA7 completes its running Collider works in a different way, the decay of neutral pions which this year, a new experiment, UA8, providing its own protons in the emerge from the proton- by a Los Angeles (UCLA) group form of a of hydrogen gas antiproton collisions close to the will install a new 'mini-drift' wire which squirts across the path of collision axis. chamber system in the Roman the circulating antiprotons - see UA1 and UA5 have revealed pots vacated by UA7. The UA8 April issue, page 102.) interesting suggestions of new team will look at the special In the same underground area behaviour in the numbers of 'diffractive' reactions which as the large UA2 apparatus is charged particles emerging from produce a fast forward proton (or another experiment - UA4 the collisions. These suggestions antiproton) together with large (Amsterdam/CERN/Genoa/Naples/ are interpreted by some as hints transverse energy which may be Pisa) - which studies elastic of the onset at SPS Collider in the form of 'jets'. The fast scattering, when the colliding protons and antiprotons 'bounce' energies of a long-awaited change forward particle will be detected in off each other like billiard balls of phase when matter containing the wire chamber system, as was (see October 1984 issue, page particles 'boils', producing matter done by UA4, while the transverse 336). containing quarks and gluons (see, energy will be picked up by Its initial aims accomplished, for example, the article by W. courtesy of UA2's large detector. UA4 will serve as a springboard Willis in the January/February The fast forward particle most for UA7 - a brief new study this 1982 issue, page 179). Clues have likely contains the three valence fall by a Naples/Japan group of been seen with particles coming quarks (antiquarks) of the beam neutral pions produced along the off at large angles to the collision proton (antiproton). Therefore, the collision axis. The UA7 team will axis, and it is important to check if particles with transverse energy

CERN Courier, July/August 1985 237