Attendees: Ashot, Chao G, Chao P, Dipangkar, Eugene, Haiyan, Kondo, Li, Maxime, Ron, Weizhi, Xinzhan, Zhihong.


Weizhi:
1. Study of radiative tails on HyCal digitization. 
a)Most of the secondary particles are within +/- 50 mm from the scattered electron.

b)External radiated photons are very forwards peaked, most of it will get included in the cluster sum.

c)Internal radiation has two peaks corresponding to along the scattered electron and along the incident electron.

d) With Hycal digitization the simulation should agree better with data, most of
the improvement will come from the external radiation.

e) coplanarity and z-vertex of double arm Moller, data wider than simulation.
<TASK>- need to look at this as a function of angle to identify position of missing material in the simulation.

Hycal digitization is high priority for any comparison between data and simulation.
<TASK>- correlation of internal radiation with cluster asymmetry needs to be studied.

2. Comsol simulation of gas distribution.
a) The Comsol simulated distribution needs to be used in future Geant simulations.

b) The ratio of empty to full is 0.17% much smaller than the observed background
in data. Simulation to study signal to background is underway, using the gas distributions from Comsol. Current simulation still shows factor of 10 difference.
One possibility is halo hitting kapton window.
<TASK>- include beam halo profile in simulation.

c) run 1318 has some problem, although the pressures are similar to empty 
chamber run there still seems to be ep and ee events. Possible reason is that 
the cell was left in the beam and these are from beam halo hitting the kapton windows. 
<TASK>-To confirm need to talk to target group. If true this will help understand background from halo.

Maxime:
1. Study of internal radiation.
a) Two peaks for 1.1 GeV ep, second peak around 6 cm (3 modules) away from central.
 
b) Moller at 1.1 GeV also has a similar peak at 6 cm. 

c) Angle difference between photon and electron fro both ep and ee has two peaks.

d) Energy fraction shows a deviation from 0 is about 2.4% which is same as the energy resolution and hence hard to distinguish.


Xinzhan:
1. a) Data to show position of all the spacers.
Old plot so the transition area problem is because of the old calibration constant.

b) The reconstruction of HyCal collimator using GEM shows that it is slightly rotated. There are Hycal vs GEM mismatches. 

c) The dead area from spacers have a wave like structure.

d) dead area of spacers is about 10 mm in x and 15 mm in y if using simple cuts.
<TASK> calculate what is the fractional loss from discarding the spacer areas.
<TASK> check if there are any difference in spacer positions from beginning of run vs end of run.

e) effect of spacer on efficiency from simulation, shows few % variation (for 3 mm cut) 
<TASK> check with the 10 mm spacer cut.

d) When compared to data there are some differences.

2. HyCal digitization

a) final simulated distributions match well with data.