The fast luminosity monitor counting the γ photons above a given energy threshold emitted from radiative Bhabha scattering has been operated in the BEPC Ⅱ to measure the relative luminosity bunch by bunch for the fi...The fast luminosity monitor counting the γ photons above a given energy threshold emitted from radiative Bhabha scattering has been operated in the BEPC Ⅱ to measure the relative luminosity bunch by bunch for the first time and used successfully in beam tuning of BEPC Ⅱ. In the relative mode the monitor is able to deliver the relative luminosities with an accuracy of 0.8 %. By steering the electron beam while observing the counting rate changes of the monitor the horizontal and vertical sizes of the bunch spots can be estimated as： Sxe＋ =Sxe =0.356 mm, Sye＋ =Sye- =0.011 mm.展开更多
To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle ...To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle Bhabha scattering events,the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb-1,where the first uncertainty is statistical and the second one is systematic.In addition,the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV,where the first uncertainty is statistical and the second one is systematic.展开更多
基金Supported by BEPC National Laboratory (BEPCⅡ-UDEC-326-HT193/2004)
文摘The fast luminosity monitor counting the γ photons above a given energy threshold emitted from radiative Bhabha scattering has been operated in the BEPC Ⅱ to measure the relative luminosity bunch by bunch for the first time and used successfully in beam tuning of BEPC Ⅱ. In the relative mode the monitor is able to deliver the relative luminosities with an accuracy of 0.8 %. By steering the electron beam while observing the counting rate changes of the monitor the horizontal and vertical sizes of the bunch spots can be estimated as： Sxe＋ =Sxe =0.356 mm, Sye＋ =Sye- =0.011 mm.
基金Supported in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11235011,11322544,11335008,11425524,11635010,11675184,11735014)+18 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)the Collaborative Innovation Center for Particles and Interactions(CICPI)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1232201,U1332201,U1532257,U1532258)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CASNational 1000 Talents Program of ChinaINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(Collaborative Research Center CRC 1044,FOR 2359)Istituto Nazionale di Fisica Nucleare,ItalyKoninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Natural Science Foundation of China(NSFC)(11505010)The Swedish Resarch CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069)U.S.National Science FoundationUniversity of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),DarmstadtWCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle Bhabha scattering events,the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb-1,where the first uncertainty is statistical and the second one is systematic.In addition,the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV,where the first uncertainty is statistical and the second one is systematic.
