Conducting targets for p production of ACOL past experience and prospects

The Antiproton Collector (ACOL) project at CERN calls for a production target providing at least twice as many antiprotons into a given acceptance as the present passive target. The pulsed target under study must be able to withstand large current pulses of a hundred kiloamperes or more for 10 to 20 μs whilst at the same time it is hit by the proton beam of up to 2 - 10¹³ ppp. Because of the very high radioactivity of the target region this new device should show a sufficient reliability before it is put into operation. Previous experimental work with an active target, both in the laboratory and in the AA proton beam line, has shown that such a target gives a measured gain of 50% in the p production yield, although the problem of making an assembly to withstand many weeks of pulsing has not been solved. A comparison of the main features of the four tests made in the AA is given. The mechanical and thermal behavior of a conducting metallic, solid or liquid target is studied, with particular emphasis on the shock wave, the thermal expansion and the magnetic unstable pinch effects, by means of computer calculations. A preliminary design of a metal conducting target is reported.