Study on Meson Spectroscopy-Search for Exotic States

The collaboration project of the GAMS experiment among CERN，IHEP(Protuino)and KEK took shape promoting the occasion of the 2nd International Conference on Hadron Spectroscopy held at KEK in 1987.GAMS is a nickname of the electromagnetic calorimeter hodoscope of a total absorption type which detects gamma rays decaying from a neutral meson state.The GAMS experiment started as an international collaboration between CERN and IHEP in 1978 in the framework of the 6th joint CERN-IHEP experiment。The GAMS program covers the research activity that is taking place around two Electromagnetic Spectrometers which are GAMS-2000/4pi at IHEP and GAMS-4000(NA12/2)at CERN。The collaboration activities are supported by the following institutions；LAPP of France，IISN of Belgium，Pisa Univ.Of Italy，LANL of USA，IHEP of USSR and KEK of Japan.The main line of the GAMS project is a systematic search for new neutral light meson resonances including exotic states(glueballs，hybrids and others)and…More for new rare neutral decay modes of known meson resonances.These neutral mesons which decay into multi-gamma rays are produced in two exclusive processes；pi^-p charge exchange reactions and central collisions of hadrons.Pions and protons ranging between 100 and 400GeV/c produced by the 450 GeV SPS at CERN and pions between 30 and 40 GeV/c produced by the 70 GeV PS at IHEP have been used in the reactions.GAMS has already observed several new states，among which G(1590)/f_0(1590)is prominent。It is a scalar state which decays into etaeta，etaeta‘and 4pi and is considered as a candidate of a glueball。M(1405)is an important object which has been found in etapi^0 decay mode。Its quantum numbers are J^&lt；PC&gt；=1^&lt；-+&gt；which are qq exotic。Activities in the same direction have been also pursued at KEK.Meson states including exotics are searched for by using the charge and gamma spectrometer，Benkei at the 12GeV Proton Synchrotron at KEK。The GAMS collaboration forms，now，a combined experimental program performed by the three institutions.During1988-1990，the GAMS collaboration executed machine time runs in June-August at CERN and in November-December at IHEP in each year.The data summary tapes have been delivered to each institutions。Analyse are under way.Meanwhile，the data acquisition system has been improved by using a VME system in order to filter events and to maximize acquisition time in both GAMS-4000 and GAMS-4pi。GAMS-2000is upgraded to GAMS-4pi augmenting the solid angle coverage by adding the guard system around the hydrogen target and the wide angle calorimeter system。Large drift chambers have been installed for detecting charged particles.The GAMS project is scheduled to continue to accumulate data till1993。Less：Less

The collaboration project of the GAMS experiment among CERN, IHEP (Protuino) and KEK took shape promoting the occasion of the 2nd International Conference on Hadron Spectroscopy held at KEK in 1987. GAMS is a nickname of the electromagnetic calorimeter hodoscope of a total absorption type which detects gamma rays decaying from a neutral meson state. The GAMS experiment started as an international collaboration between CERN and IHEP in 1978 in the framework of the 6th joint CERN-IHEP experiment. The GAMS program covers the research activity that is taking place around two Electromagnetic Spectrometers which are GAMS-2000/4pi at IHEP and GAMS-4000 (NA12/2) at CERN. The collaboration activities are supported by the following institutions ; LAPP of France, IISN of Belgium, Pisa Univ. of Italy, LANL of USA, IHEP of USSR and KEK of Japan.The main line of the GAMS project is a systematic search for new neutral light meson resonances including exotic states (glueballs, hybrids and others) and … More for new rare neutral decay modes of known meson resonances. These neutral mesons which decay into multiーgamma rays are produced in two exclusive processes ; pi^-p charge exchange reactions and central collisions of hadrons. Pions and protons ranging between 100 and 400 GeV/c produced by the 450 GeV SPS at CERN and pions between 30 and 40 GeV/c produced by the 70 GeV PS at IHEP have been used in the reactions. GAMS has already observed several new states, among which G(1590)/f_0(1590) is prominent. It is a scalar state which decays into etaeta, etaeta' and 4pi and is considered as a candidate of a glueball. M (1405) is an important object which has been found in etapi^0 decay mode. Its quantum numbers are J^<PC>=1^<-+> which are qq exotic. Activities in the same direction have been also pursued at KEK. Meson states including exotics are searched for by using the charge and gamma spectrometer, Benkei at the 12 GeV Proton Synchrotron at KEK. The GAMS collaboration forms, now, a combined experimental program performed by the three institutions.During 1988-1990, the GAMS collaboration executed machine time runs in June-August at CERN and in NovemberーDecember at IHEP in each year. The data summary tapes have been delivered to each institutions. Analyse are under way. Meanwhile, the data acquisition system has been improved by using a VME system in order to filter events and to maximize acquisition time in both GAMS-4000 and GAMS-4pi. GAMS-2000 is upgraded to GAMS-4pi augmenting the solid angle coverage by adding the guard system around the hydrogen target and the wide angle calorimeter system. Large drift chambers have been installed for detecting charged particles.The GAMS project is scheduled to continue to accumulate data till 1993. Less