SAMPLING CALORIMETER FOR HIGH-ENERGY HEAVY-PARTICLES FILLED WITH ALLENE-DOPED LIQUID ARGON

A hadron calorimeter for investigating relativistic heavy ion reactions, filled with liquid argon doped with allene, has been tested for 1 GeV/n neon and iron ions, and 1.7 GeV/n helium, neon and iron ions. The electrode system of the calorimeter consists of G-10 plates placed in the first, second and third parts, 2 mm thick iron plates in the second part and 6 mm thick iron plates in the third part with a liquid argon gap of 3.5 mm. Some of the ions were stopped inside the calorimeter without fragmentation, which were treated separately. The calorimeter shows a good linear response to the total incident energy of ions for fragmented and stopped ions. The absolute yields of collected charge are consistent with the calculated values. An energy resolution in FWHM of 2-5% is obtained for stopped ions. For fragmented ions, the energy resolution in FWHM is given by [0.9 + 81.1/square-root E(GeV)]% for all relativistic ions and if the datum of helium ions is excluded, the resolution can be expressed by [4.8 + 53.2/square-root E(GeV)]%. The present energy resolution is better than those recently obtained with scintillation calorimeters at BNL and CERN.