MachineDetectorInterfaceSummary.pptVIP

Machine Detector InterfaceSummary Junji Haba, KEK Beam background Another very important issue in a high luminosity machine other than L. Where it comes?. Lifetime Effects Quantum lifetime Not a problem as the RF voltage is high. Residual gas Bremsstrahlung Elastic scattering Small change as the gas is only a few times worse. Touschek effect Luminosity Bhabha e+e- ? e+e- Radiative Bhabha e+e- ? e+e-g Beam-beam tune shift Study of Touschek Effect Touschek lifetime versus RF voltage Background parametrization based on February 2002 data SVT Background from HER It was noted that it may be difficult to distinguish “beam-beam” effect from “luminosity” background. KEKB experience: “beam-beam” effect make HER beam size larger and hit the smallest acceptance of the ring resulting increase of background. What is wrong with the background? 1 Degradation of the detector itself. Light yield of scintillation crystal Gain drop of DC wire Damage in the readout electronic 2 High occupancy degrades the event reconstruction also. 3 Very high data trasfer rate Resolution degration with occupancy Example in Decrease of hits @ x20 occupancy The electronics Shaper/QT deadtime is clouding out proper track hits under the high occupancy. Thus tracking efficiency and resolution depend on the readout system. Do we understand the current beam background? G. Wormser from BaBar O. Tajima from Belle S. Stanic form Belle Conclusions for short term issues We have to look far ahead: Minimum 3 years Look for worst case scenarios! Look for end-product effects! BABAR issues Immediate concerns: SVT ATOM chip, IFRForward endcap Next on-line: DCH DAQ Longer term issues: SVT and EMC in 2008 Changes in background issues Beam-beam tails injections trapped events Conclusions for short term issues We have to look far ahead: Minimum 3 years Look for worst case scenarios! Look for end-product effects! BABAR issues Immediate concerns: SVT ATOM chip, IFRForward endcap Next on-line: DCH DA