Search for non qq mesons-GAMS Collaboration

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The GAMS international collaboration consists of two independent experiments at CERN and IHEP (Protvino, Russia). At CERN,the WA91/102 experiments with the GAMS4000 spectrometer combined to the OMEGA one were performed using the 450GeV SPS,and at IHEP the SERP-172 experiment with Gams-4pi spectrometer was done using the 70 GeV PS.Both experiments aim at searching for new meson states including exotic non-qq states. The process pp->ppX of central pp collisions is mainly studied at CERN and that of charge exchange reactions pi p->Xn with X-> multi-photons is at IHEP.Data taking runs were performed from May to July, 1995 and 1996 at CERN,and was done from November to December, 1996 at IHEP.Japanese collaborators visited CERN and IHEP to join the data taking run. They also visited there to proceed the analysis and R&D works when it was necessary.In the frame of GAMS collabration, physicists of CERN and IHEP visited KEK to discuss about the data analysis, publication of papers and also abou … More t the next plan of the collaboration.Many physics outputs were issued. pi^0 pi^0 and eta pi^0 systems were studied in the pp central collisions reaction. omega pi and eta pi pi systems were studied in the charge exchange reaction. In particulary a bump of low mass region (500-800 MeV) in the pi^0 pi^0 mass distribution was studied carefully and it was shown that it has characteristics of an isoscalar scalar state. The new data of WA91/102 was analyzed and published in the journals. Many papers were submitted to the HADRON 95 international conference at Manchester, in July 1995. The possibility of whether the scalar low mass bump of pi^0 pi^0 system could be regarded as a long awaited sigma particle was studied in collaboration with Nihon University.On the other hand, the detector R&Ds are also done successfully. A new calorimeter using heavy crystal of PWO (PbWO4) was studied at KEK,IHEP and LAPP.The result of test of a prototype PWO hodoscope at KEK was published. The new material PWO is enough good for the next high intensity experiment (COMPASS). High speed, high resolution (QVC and ADC were developed for the new electromagnetic calorimeter.New proposal COMPASS (COmmon Muon Proton Apparatus for Structure and Spectroscopy) was approved by CERN.The GAMS collaboration agreement between KEK and IHEP was prolonged for another 5 years in October, 1995. Less