PRad-II/X17 Software Meetings

A page dedicated to meetings for simulation-related tasks for PRad-II and X17.
Meeting time: Monday 8PM EST Weekly (Yes 8PM at night...)

Zoom link: information [1]

Meeting ID: 161 6338 6292 Passcode: 921642

2024

Dec 16

(1) Files for GEM efficiency is done for the default setting, students can download the files here on the farm for three beam energies: /volatile/hallb/prad/xiongw/GEM_eff/default

(2) Yuan has checked the G4 simulation for the dose rate, by increasing the target length and scaling down the density, while keeping the target thickness the same. The results are all consistent. This study should be enough to answer the question, whether G4 can properly simulate situation, for which the material thickness is at the level of 1um. Relevant slides are here: [2]

(3) Various solutions were discussed to lower the dose rate. No conclusion yet, and further simulation studies would be needed.

Dec 2

• Meeting Minute

(1) Yuan presented radiation damage on HyCal for the X17 search experiment (see slides here [3]). For 4.4 GeV beam with 150nA current, the first open layer of PbWO4 has radiation damage of ~140 Rad/hr, which is rather significant. Typically, a radiation damage level of 15 Rad/hr is preferred. Such high radiation levels will result in a noticeable impact on the energy resolution of these modules. Possible solutions were discussed and some need to be evaluated, including:

   (i)   Enlarge the absorber size to cover the first open layer of PbWO4. This should effectively resolve the problem, but will result in loss of acceptance, need Eric and Tyler to take a look.
   (ii)  One may still operate the calorimeter under such a condition but needs to make sure the deteriorated resolution is acceptable (maybe with 2-3 times worse energy resolution), also need Eric and Tyler to evaluate. 
   (iii) One may need to re-consider the run schedule. As X17 has over an order of magnitude radiation damage on HyCal. Should we run PRad-II in advance?

(2) Yuan presented the new X17 window and beampipe added to the simulation (see slides here [4]). There is a new bellow appear right downstream of the vacuum window, and got in the way of the first GEM. We will need to shift both GEM and HyCal downstream by another 9cm.

(3) A technical discussion about the GEM efficiency calculation was appended in the meeting today. Weizhi will provide simulation files, with one of the GEMs rotated by 90 deg, to see if there is any improvement on the GEM efficiency calculation.

Nov 19

• Meeting Minute:

List of Important tasks to be finished before ERR and the available workforce:

(1) Scintillator simulation (Yuan and Buddhiman):

   (i) Finish simulation studies to determine the rejection efficiency
   (ii) background rate under a more realistic beam with a halo
   (iii) study alignment tolerance, how much we can tolerate the shift in position and tilting angles?
   (iv) finalizing the geometry of the scintillators, what should be the size of the central hole
   (v) effect of beam spot position on the detector

(2) X17 with 4.4 GeV (Tyler, Erik, Yuan, and Weizhi):

   (i) Background study: ask TongTong Cao to generate background events, run through the simulation, and then analyze and study the output. In addition, see if we can use the GEMs to reject backgrounds from the fringe and downstream beampipe (Tyler, Erik and Chao)
   (ii) Radiation damage on HyCal (Yuan)
   (iii) HyCal energy resolution (Weizhi)
   (iv) vertex-z resolution (Tyler and Erik)
   (v) update the geometry for the X17 vacuum tank window (Yuan)

(3) GEM efficiency (Yining, Xinzhan, and Weizhi):

   (i) GEM efficiency uncertainty estimation with the current GEM design
   (ii) explore the possibility of adding a third plane of GEM, and how much it can help suppress GEM efficiency uncertainty

(4) Update projected results (Yining and Weizhi)

   (i) Update and finalize the projected results

Presentation from today: (1) Scintillator simulation study by Yuan Li [5]