The main goal of the NA50 experiment is to study the J/psi suppression pattern in PL-rb interactions, at 158 GeV/c per nucleon at the CERN SPS. We present here the results from the 1996 (final) and 1908 (preliminary) data taking periods. They confirm and extend our previous observation that the J/psi is anomalously supressed from peripheral to central collisions. With new event selection procedures and different analysis techniques, we observe that in peripheral collisions the J/psi cross section per nucleon-nucleon collision agrees with the pattern inferred from a wide range of measurements with lighter systems, from pp up to S-U. When the collisions become more central a clear departure from this behaviour is observed. The 1996 data show a sudden drop in the J/psi production yield for E-T values above 40 GeV, where E-T is the neutral transverse electromagnetic energy released in the colision and measured in the EM calorimeter. The 1998 data provide a big improvement in the study of the most central region, where a second change in the pattern becomes visible.
Latest results from NA50 on J/psi suppression in Pb-Pb collisions
Cicalo C;DE FALCO, ALESSANDRO
1999-01-01
Abstract
The main goal of the NA50 experiment is to study the J/psi suppression pattern in PL-rb interactions, at 158 GeV/c per nucleon at the CERN SPS. We present here the results from the 1996 (final) and 1908 (preliminary) data taking periods. They confirm and extend our previous observation that the J/psi is anomalously supressed from peripheral to central collisions. With new event selection procedures and different analysis techniques, we observe that in peripheral collisions the J/psi cross section per nucleon-nucleon collision agrees with the pattern inferred from a wide range of measurements with lighter systems, from pp up to S-U. When the collisions become more central a clear departure from this behaviour is observed. The 1996 data show a sudden drop in the J/psi production yield for E-T values above 40 GeV, where E-T is the neutral transverse electromagnetic energy released in the colision and measured in the EM calorimeter. The 1998 data provide a big improvement in the study of the most central region, where a second change in the pattern becomes visible.
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