CDR organizational meeting
Thursday, July 27, 2017 from 09:00 to 11:00 (Asia/Shanghai) at B410
A. Introduction from Costa
This meeting is about the CDR organization discussion.
First, we plan to produce an integrated CDR on November international meeting, and there will be many convenors in the meeting to review it.
We decide to move to weeklyy meeting, after different options discussed, people prefer to choose night at 9 pm, and we will make a doodle for deciding which day for the meeting. We make a git repository for the CDR text, everyone can register for it.
For the possible CDR outline, we presented before, after discussion, we decide to move the chapter 2.3 “Basic description of Detector Concepts” outside the chapter 2, treating it as a independent chapter. We showed agreement on it and this new chapter will contain 3 concept: TPC tracking system (baseline), All-silicon tracking and Drift chamber and DR calorimeter. Then the following chapter will introduce the details of R&D of detector. For Chapter 5.1, Particle flow calorimeter, Haijun suggests to change the ECAL before HCAL, everyone agree with that.
Then we decide to give short summary table in chapter 1, which includes some important parameters of detector and give the reference to the specific chapter for details. At last, we made a common view that the CDR need to integrate work done in detector subgroups with work done by simulation subgroup.
B. detector status and remain questions from Manqi
Manqi shows the status of the preliminary detector simulation, he present situation of new geometry and performance study for PFA Oriented Detector, then he went through each detector (TPC, Silicon tracker, ECAL, HCAL, LumiCal) about the status and remain questions to be answered. Also DAQ, trigger and cooling system havn’t been considered.
during the talk, several discussion happened:
For P6, Jianming asked the performance of particle resolution for TPC with 3T. Manqi answered that the particle resolution is good, also the resolution for single Higgs performs better in high field than low field.
For P7, Jianming asked about the main source of radiation for Z-pole. Manqi answered that it mainly comes from beam pipe. People agree that we should do the simulation for radiation tolerance in Z-pole consideration.
Also Hongbo add that the radiation background for Z-pole can come from the beam-induced background, e.g. the beam lost particles (radiative Bhabha scattering, beam-gas scattering) and synchrotron radiation. There is no estimate yet as the machine design is still in progress. Regarding radiation tolerance and detector occupancy, physics processes (Z->qq, large angle radiative Bhabha scattering) of high cross-sections matter as well and may play even larger roles here.
For P9, the mentioned hadron energy resolution refer to the single hadron, the total resolution should be better.
For P11, Jianming asked about the collision rate. Manqi answered that the collision rate is 10 ns. Jianming asked whether we can use Z to gamma gamma events to calculate the luminosity. Gang answered that the luminosity measurement is usually based on Z to qq events.
Also Hongbo add that the bunch spacing for Higgs operation (filling up half of the ring) can be 0.3 us (high lumi) or 0.8 us (low lumi), and for Z-pole operation the bunch spacing will drop to 20ns (high HOM power) or 5 ns (low HOM power). 10 ns as Manqi mentioned might comes from the constraint of the TPC operation. Luminosity measurement is expected to be carried out the small angle radiative Bhabha events with the dedicated LumiCal. Sue Hou (SINICA), Kai Zhu (IHEP) and Strahinja Lukic have proposed the design and Chengdong Fu has implemented the geometry in simulation. They are working to understand the performance. In principle, several other processes recorded in the main detector can also be used for lumi measurement but with lower precision and can be only complementary.
At last, people mainly discussed the issue that whether we should add the cooling system in silicon tracker. Manqi said that adding cooling system may result in the change of geometry and power consumption etc., and we should find manpower to do the simulation. So for this question, more discussion and communication is needed.
C. Conclusion of the meeting
According to Manqi’s talk, we still meet a lot of questions to be solved. In this way, we should answer all questions in no more than 2 weeks, so that the procedure of CDR will not be influenced. After that, the simulation group should determine the final design and begin to test the performance and write CDR. So Manqi will send the request with questions to every sub-group and each sub-group returns the corresponding answers to Manqi in two weeks from today.