# G2p Analysis Minutes

Minutes of the weekly analysis meetings

## Contents

## 2/17/2016

Present: JP, Jixie, Chao, Ryan, Min, Ellie, Jie

**Feature Presentations:**

- Chao

Gave an update on the optics study. He finished the matrix recalibration on right arm. The database is updated and is ready to use. The RMS values for angle and momentum calibration are summarized in his presentation. JP and Jixie has some concern about the broken septa seems to cause worse effect on left arm comparing with right arm. They suggested to check this more carefully. More details can be seen in his slides here.

- Ryan

Gave an update on his cross-section analysis of the small angle GDH data. Based on the discussion from the last week's meeting, he removed the extrapolation part in RADCON and then test the code with some test cross-sections from Pbosted Model. There is no problem in this case. So he compared the Pbosted model with saGDH data at large <math>\nu</math>. He is waiting for the response from Vince about the uncertainty of the saGDH cross-section at large <math>\nu</math>. More details can be seen in his slides here.

## 2/10/2016

Present: JP, Karl, Alex, Jixie, Toby, Chao, Ryan, Min, Ellie, Vince

**Feature Presentations:**

- Ryan

Gave an update on his cross-section analysis of the small angle GDH data. He is dealing the problem that after doing the tail subtraction and radiative correction the cross sections go negative at high <math>\nu</math>. He did a refit of the few low <math>Q^2</math> points using a charge form factor fit. The results still deviated from the PBosted model at high <math>\nu</math>. However, JP and Karl suggests that the code RADCOR code should not give negative cross section result. There might be some problems in the extrapolation part. Karl suggests to check the input data to see if there are constrains at the high <math>\nu</math> region. More details can be seen in his slides here.

## 2/3/2016

Present: JP, Karl, Alex, Jixie, Toby, Jie, Chao, Ryan, Ellie, Vince

**Feature Presentations:**

- Min

Gave an update on her acceptance study. She continued to compare the simulation result with data. Since the optics database is updated with the vertical beam position correction. The result suggests that the delta distribution is improved however the phi distribution still shows large discrepancy. She used this result to calculate the acceptance factor and applied it to the cross-section calculation. The result shows a factor of two difference. JP suggests that the acceptance calculated from the compare between the simulation and the data could still be influenced by the cross-section difference at small scattering angle. More details can be seen in her slides here.

- Toby

His presentation on 1/12 is reviewed. JP mentioned his concern about the uncertainty propagation. Toby is going to check it again and update his tech note about it.

**General Discussion:**

- The replay package is restored on the work disk.
- Toby will talk to Melissa and take over her packing fraction study.

## 1/26/2016

Present: Jixie, JP

By Phone: Jie, Chao, Ryan, Ellie

**General Discussion:**

- The analysis meeting will be moved back to
**10 am Wednesday**starting from next week. - There is no meeting room available thus everyone will join by bluejeans. The meeting ID is 4828802914.

## 1/12/2016

Present: Melissa, Jixie

By Phone: Jie, Chao, Ryan, Toby, Ellie

**Feature Presentations:**

- Ryan

Gave an update on his cross-section analysis of the small angle GDH data. yield study using simulation. He is working on the problem that after doing the tail subtraction and running the inelastic Radiative Correction code the fully corrected cross sections go negative at high <math>\nu</math>. To solve this, he did a fit on the Nitrogen form factor. During the fitting, two models is considered: the oscillator model and the Fermi Model and the Fermi Model is proved to be better. He will complete the calculation of the elastic tail by using the form factor in a few weeks. More details can be seen in his slides here.

- Toby

Gave an review on the polarization uncertainty estimation. He claimed that the reason of the small uncertainties for the target polarization is because we took large amount of TE for each material. Thus the uncertainty of the calibration constant is reduced by average. Jixie suggests that the error propagation still need to be carefully checked. More details can be seen in his slides here

**General Discussion:**

- Chao updated his optics technical note.
- There is no meeting next week due to the Hall A collaboration meeting.