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CEPC Physics and detector regular meeting
Attendance: Li Gang, Ivana Bozovic, Ke Li, Paolo Giacomelli, Strahinja Lucik, Suen Hou, Tao, Yaquan Fang, Yuanning Gao, Qing Ming
MDI Status Report by Hongbo
First Hongbo shows the latest machine parameter table. For the main relevant change, it contains the SR power, energy acceptance and bunch related parameters etc.. Second, the magnet design is updated based on 3T, with the improved design of QD0/QF1 and compensating solenoid. He also explains the reason to choose lower magnet field that is based on the requirement to avoid the disturbance to the beam and vertical emittance. Then he shows the magnet layout. Third, he discusses the estimation of background which contains beamstrahlung, SR and beam loss particles. The beamstrahlung is the dominant one. After changing the layout to double ring +3T, the influence of this background is reduced. For SR background, it mainly affect the QD0 and QF1 which have less radiation tolerant. For beam loss particle, it mainly comes from radiative Bhabha scattering. Now they face a challenge for the location of collimator, that needs more evaluation work on it. At last, for the CDR writing, Hongbo and She Bai are the main editors, and many topics will be covered. They try to bring out a preliminary draft by end of September, both considering the timescale of accelerator and detector CDR.
Luminosity measurement at CEPC by Ivanka
Ivanka introduced their LumiCal layout that is placed at the center around the outgoing beam. The reason is that the outgoing beam centered geometry can make the theoretical Bhabha cross-section keep stable, and also reduce the systematic uncertainty from IP. Then she introduce the LumiCal geometry in CEPC and FCCee which has used this outgoing beam centered geometry. She also mentioned the possible cooperation between FCAL and other institute. There are two kinds of ways, one is joining by signing MOU and contributing to the FCAL. This requires some institute to join. On the other way, CEPC could become an observer member of FCAL collaboration. This means once could attend meetings, but would not an author of the papers they produce.
Detector Magnet CDR Related Topics by Zian
The new magnet research is based on 3T environment.
For CDR outline, the 6.3 HTS/LTS Superconductor Options, 6.6 Quench Protection and Power supply and 6.8 Dual Solenoid Scenario are the new chapters. The editor information is also listed in the slides.
Also magnet group has some questions for MDI people.
1.Need detail design of machine magnets to study the field homogeneity
2.Need requirement of stray field both from machine and detector
Machine Detector Requirements
The discussion about each group ’s requirement and questions for MDI.
⁃ For Vertex group, they wants know the occupancy of background. Hongbo said that the bunch spacing is fixed now and vertex people can do the research relying on the geometry and other informations, the actual value from MDI can not give much help. After the discussion, people get the agreement that MDI group give some parameter value with its uncertainty.
⁃ For TPC group, they want know the geometry of MDI.
⁃ For Calorimeter group, the information about the TOF environment and PID is useful.