G2p Analysis Minutes

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Minutes of the weekly analysis meetings

2/02/2011: Present : Kalyan, Jixie, Alex, Min, Pengjia, Jianping, Karl(phone)

  • Kalyan:

1) Kalyan is searching for possibility to place a 3rd arm to detector either the elastic electron or elastic proton (or both). This time he showed the estimate rates to detect the electrons at 42 degrees. Please refer to https://hallaweb.jlab.org/dvcslog/g2p/11 for details.

2) He also showed some real data at 45 degrees from BigBite http://www/~kalyan/g2p/meetings/02feb2011/

Summary: a) Electron detection at 42deg is only good for 1.1GeV, for rest of energies the rates are very low(its hopeless) b) Protons can be detected around 75deg but the S/N is very low. So may need to put a small scintillator at small angle to give coincidence with hadron arm and reduce background.

JP: 1) Discuss if we need to run Compton at such a low current. Considering the facts that A)tuning the beam through the Compton chicane always takes time, B)the Compton may not work efficiently in such a low current and low beam energy c)It takes longer time to run moller if the beam go through the Compton chicane we may not want to run Compton during G2P. But we may run it for 3.3 GeV beam at the end if time allows.

2) Discuss about the NMR coils. We did not understand the uncertainty and effects of the "uniform" NMR or that of the "edge" NMR. He suggested to verify which is better and what is the effects compare to the EG4 data. We need to run simulation to understand the radiation effect of that. A quick way i


  • Pengjia:

1) Plan to write tech note for the Beam Position Measurement 2) He gave a presentation about beam position calibration, see the slice here: http://www.jlab.org/~pzhu/report0202.pptx


  • Min:

1) Will work on the 3rd arm with Kalyan, she will look into the Bigbite performance in the SRC experiment 2) Continue working on snake and MUDIFI program

  • Jixie:

1) Show some visualization figures for the Geant4 simulation. Currently there is some bug on the transverse configuration. Jixie is working on that. 2) Will simulate the NMR coil for radiation.


1/26/2011: Present : Kalyan, Jixie, Melissa, Alex, Min, Pengjia, Jianping, Karl(phone)

  • Jixie:

1)The coil will block almost half of the acceptance of one arm for the configuration that the field is 80 degrees with the beam and HRS at 6 degrees. Refer to https://hallaweb.jlab.org/dvcslog/g2p/9 for details. For HRS at 12.5 degrees, only single arm data will be available. Need to mention this to Doug and Guy. Alan is waiting for the decision to finalize the design for the scattering chamber entrance window. 2)Still waiting for input of beam dump for the Geant4 simulation

For 74 degree and solid angle 60 mSr: The elastic Pr rate is about 4 kHz; the total inelastic rate for Pr in momentum range 0.25-0.4 is about 270 kHz.

Need to find out a way to reduce the inelastic rates. Increase the momentum range to 0.280Gev/c may help...

  • Jp: About the BCM|BPM of the beam line, Jlab may pay 60K for it???
  • Pengjia: Talked about the target cooling took place at UVA. The

maximum field provided by UVA solenoid is 5.0032 Tesla. He showed some pictures of the solenoid, the microwave generator, the pump system. The target was cooled down pretty smooth. He will summarized it and put it onto the web for next meeting.

  • Min: Working on the MULDFI program. Discussing the effects introduced by the 2cm raster. Angle resolution is more important than the position resolution.


1/19/2011: Present : Kalyan, Jixie, Melissa, Karl, Min

  • Kalyan : Working on third arm elastic rates. Looking at 2 options,

both on beam left: 1) Bigbite detecting protons at 74 degrees. Issues: manpower to install, no identified power supply and possible issue of overtaxing the power budget to the hall (Ed Folts). Guy may have power supply at Berkely. Jixie will follow up to see if power budget is real problem. 2) A small calorimeter at 42 degrees to be used as electron detector on the platform about 2 m from the can. Pros: simple design, little tech support needed. Cons: rate will be very low. PMTs near target field might have problems. Goal is to have a decision to present at the next collab meeting.

  • Jixie: Working on the Geant4 simulation. Has created scattering

chamber and included the UVa target field map. Waiting for more information on the beam dump design. Initial goal is to look at radiation in the hall. Intermediate goal is to look at acceptance blockage by the target coils. Later, will be able to look at physics and issue of radiative tails at low Q2. Jixie will talk to Whitney Armstrong from Temple who created a geant 4 simulation of the target for SANE. Jixie is working with Min on SNAKE. John having difficulty to transfer code from solaris to linux. Will talk to Doug about impact of acceptance blockage on gep (target at 80 deg) for 12.5 degrees scattering.

  • Min: Working on the fitting for SNAKE. Also interested to get

involved with the 3rd arm study.

  • Melissa: Starting to look at target and detectors.
  • All: Discussion of manpower and projects in need of manpower.
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