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Editorial discussion of Physics and Detector CDR.
CDR Editors Email List: cepc-cdr-dp-editors@maillist.ihep.ac.cn
CEPC detector CDR meeting
Monday, July 23, 2018 from 13:50 to 17:45 (Asia/Shanghai)
at IHEP ( B424 )
Attending: Joao, Dan Yu, Wei Zhao, Zian Zhu, Feipeng Ning, Hongbo Zhu, Manqi Ruan, Yunpeng Lu, Mengran Li, Kewei Wu
1. Status of Muon chapter
1) Joao suggested that for the muon-chapter introduction part, we can not only mention the PFA, because the muon detector is used for both PFA calorimeter and non-PFA calorimeter concept. Paolo and Manqi suggested adding some general statement for the muon detector, since it can not only improve the muon efficiency and also has advantage to detect the long living particle. Liang agreed with this solution, and Paolo and Liang will improve this chapter by turns. Paolo will do the first round and Liang make the second round.
2) Charlie suggested to reduce the number of layer from 8 to 4, but in this way, all the related concept in the CDR would have to be changed, and it will not be consistent with magnet geometry. Considering the baseline for muon detector is RPC, which needs 8 layers for high momemtun resolution, people decided to keep 8 layers and just add a statement for other options. (After the meeting Joao discussed with Charlie about this topic. Charlie acknowledge it was too late to change this and he was not proposing that. He just wanted to make the case that we should be able to justify these choices. Four layers would also have to be justified).
3) For the beginning of muon chapter, we should firstly mention the possibility of different technologies and then clarify that the RPC was chose as the baseline.
4) Then one problem is the information for RPC is not enough comparing with other options. It is better to add some R&D status of RPC. There is some research on going on glass RPC in China. Could something like that be added?
5) The text mentions 100 Hz/cm^2 at muon chambers. Should find out where this number is coming from. In order to understand this rate, someone should do some simulation for the muon detector performance, at least we can count how many muons. The maximum muon rate per area can be checked by simulation of Z->mumu. Mengran will help to do that, although that misses other sources of muons.
6) Paolo will shorten the text of the muRwell chapter and improve the resolution of Figure 7.4. He said he will try to finish this part today.
7) Manqi suggested to Paolo to reference in the text that the inner radius of muon detector for IDEA is larger than the inner radius for baseline detector.
8) The future muon R&D section should add some hardware R&D.
9) Liang and Paolo agreed to get a new version by Wednesday morning.
2. non-isolated muon efficiency study
DanYu and Jifeng Hu gave the update of muon efficiency study saperately. From Dan’s talk, the conclusion is for the current Muon Identification in the b-jets: the efficiency in high energy region is 80%, but for low energy (E < 5), the efficiency is much lower ~60%. The Muon chambers could help to improve it. After that, Jifeng showed his results for the cross check. He is using some standard likelihood cut for the muon identification. This seems to be the one for high-pt muons. So, his muon efficiency is lower than Dan’s results for low-pt muons, but about the same ~80% for high-pt muons. People suggested them two to cross check the configuration and selection, to better understand the difference.
3. Status of Magnet
Magnet group agreed with Charlie’s comments, except some comments need to be discussed with Joao.
1) From Charlie’s comments, the compensation magnet should be clarified. The solution is to add one sentense, just make the reference to the MDI section, the MDI section will explain this in more detail and it will have reference to the Accelerator CDR.
2) Don’t mention 3.5T in the text.
3) There are too much details in magnet chapter, please simplified the contents. We should define the baseline at the beginning of this chapter, which is the iron yoke with baseline LTS, then simply mention the other choices for future R&D. Move the details to an appendix.
4) Add an overall introduction before 6.1
5) Magnet group concerned about the statement for low magnet option (2T). Joao suggested them to contact with Franco for IDEA, to discuss the details for 2T. The principle would be using the LTS you can get the coil with 30cm, however using the HTS, it can be more aggressive and the solenoid could be thinner, which has more advantage. Chapter 3 and chapter 6 should be in sync.
6) Magnet group will try to get the new version before wednesday meeting.