|
|
| Line 38: |
Line 38: |
| | *Pengjia | | *Pengjia |
| | **Comparing asymmetries determined from the MAID model to those calculated from data.<br>Last time he showed a factor of 6 difference between the two results. He determined the <br>scattering angle and Q<sup>2</sup> by fitting the data and compared them to the quantities calculated <br>from MAID. He also showed the results of calculating the quantities g<sub>1</sub>, g<sub>2</sub>, F<sub>1</sub>, F<sub>2</sub>, A<sub>L</sub>, A<sub>T</sub>,<br> dXS<sub>L</sub>, dXS<sub>T</sub>, XS<sub>tot</sub> andXS<sub>mott</sub> using MAID. He hasn't included radiative corrections in his <br>calculations, but this probably won't account for the factor of 6. More details can be seen <br>in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/07012015/MAID_20150701.pdf here]. | | **Comparing asymmetries determined from the MAID model to those calculated from data.<br>Last time he showed a factor of 6 difference between the two results. He determined the <br>scattering angle and Q<sup>2</sup> by fitting the data and compared them to the quantities calculated <br>from MAID. He also showed the results of calculating the quantities g<sub>1</sub>, g<sub>2</sub>, F<sub>1</sub>, F<sub>2</sub>, A<sub>L</sub>, A<sub>T</sub>,<br> dXS<sub>L</sub>, dXS<sub>T</sub>, XS<sub>tot</sub> andXS<sub>mott</sub> using MAID. He hasn't included radiative corrections in his <br>calculations, but this probably won't account for the factor of 6. More details can be seen <br>in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/07012015/MAID_20150701.pdf here]. |
| − |
| |
| − | ==6/24/2015==
| |
| − |
| |
| − | Present: JP, Min, Chao, Jie, Jixie<br>
| |
| − | By Phone: Vince, Toby, Ellie, Pengjia, Karl <br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Toby
| |
| − | **Presented some asymmetry plots which Ryan will show in the Chiral Dynamics conference.<br> The plots can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/asymplots.pdf here]. All statistics has been included in these plots along with<br> the dilution and the polarizaiton results. The calculated asymmetries is compared with fully<br> radiated MAID model. Toby will continue working on the physics asymmetries of all the<br> kinematics settings.
| |
| − |
| |
| − | *Jie
| |
| − | **Gave an update on his study of the acceptance. He studied the multiple scattering effect<br> of the incoming beam. The standard deviation of this effect is ~0.07mm for position and<br> ~0.7mrad for angle. He also studied the influence of the beam position to the acceptance.<br> There was a large dependence on y_tg (horizontal direction) but not on x_tg (vertical direction).<br> 2-D plots shows that the acceptance is not uniform along the vertical direction. JP suggests <br> that the horizontal target field may be a reason of this effect. More details can be seen in <br> his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_06_24_simulation/2015_06_25_Simulation_update.pdf here].
| |
| − |
| |
| − | ==6/17/2015==
| |
| − |
| |
| − | Present: JP, Min, Jie, Chao, Melissa<br>
| |
| − | By Phone: Alex, Ryan, Toby, Ellie, Pengjia, Vince <br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Ryan
| |
| − | **Working on inelastic polarized radiative corrections, based on the formalism by Akushevich, <br>Ilyichev and Shumeiko. Since there is no polarized proton data yet, he is using models to <br>understand the systematic error on the radiative corrections. He used the MAID 2007 model to <br>generate the polarized cross sections, and went through the same iterative process he used for <br>the unpolarized radiative corrections. To do the systematic study he took the MAID 2007 cross <br>sections, radiated them using the POLRAD code, unfolded/radiatively corrected the cross sections, <br>then compared them to what he started with; the difference is attributed to systematic error. In <br>general, the ratio of unfolded/radiated cross section is close to 1, but there is a jump when Δσ <br>crosses zero. JP suggested an alternate method of doing the corrections is the correct on the spin <br>up XS and spin down XS separately, since neither will be zero. Ryan will look into this method as <br>a cross check. More details can be seen in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_061715.pdf here].
| |
| − | **Working on his talk for Chiral Dynamics, he will send out his slides to the collaboration later <br>this week.
| |
| − |
| |
| − | *Toby
| |
| − | **Working on fixing the scattering angle dependence on the cross section. His original method <br>was to plot the calculated scattering angle, take the central value and plot it versus HRS <br>momentum. Fitting this with an exponential function (originally provided by Jixie), he could <br>then use the fit parameters in the Bosted model to calculate the cross section. The problem <br>with this method is it forces the scattering angle across kinematics to be continuous, but our <br>data is not continuous. He generated the model at all scattering angles within a momentum <br>setting and combined all resulting models with a weighted average. This causes the model to be <br>discontinuous over an energy setting, but this method of generating the model may be necessary <br>since the continuous model doesn't represent our data well. JP cautioned that the acceptance <br>could have an effect on the scattering angle, so we must be cautious using this data until <br>optics/acceptance studies are finalized. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/anglecorrection.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her acceptance study. She divided the data by the Mott cross section before <br>comparing it to the simulation results for an empty dilution run (just helium). For the scattering <br>angle she is using the survey result, which has an uncertainty of 0.7mrad. JP commented that we must<br>be cautious in how we determine the scattering angle, particularly the effect of the septum magnet <br>on the angle. For next time, Min will work on tuning the apertures to have better agreement between <br>data/simulation. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/06172015/06172015.pdf here].
| |
| − |
| |
| − | *Chao
| |
| − | **Gave a status update on optics, specifically the offset problem he has discussed previously. He <br>treats the matrix elements separately and uses the center hole to determine the offset and 2 first <br>order matrix elements. He then uses the beam position scan data to determine matrix elements that <br>are not related to x<sub>fp</sub> and delta scan data to determine the matrix elements related to x<sub>fp</sub>. <br>However, using the updated matrix (for the 1.7 GeV data) still has a 3mm offset. JP questioned <br>whether the effect of the septum is being taken into account properly. Once we understand how to <br>treat the septum well, we'll know whether to attribute problems to the septum field, target field, <br>etc. Chao will go back and look into the effect of the septum before moving forward on the offset <br>problem. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/Chao_WeeklyMeeting_06172015.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *The abstract deadline for DNP is July 1st.
| |
| − |
| |
| − |
| |
| − | ==6/10/2015==
| |
| − |
| |
| − | Present: JP, Min, Chao, Jie, Kalyan, Melissa<br>
| |
| − | By Phone: Vince, Ryan, Toby, Ellie, Pengjia, Karl <br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie
| |
| − | **Gave an update on his study of the change in acceptance/yields due to shifts in the <br>beam position using simulation. Last time he showed the number of events blocked by <br>different components such as the collimators, and magnet entrance/exit planes. He looked <br>at the change in acceptance/yields moving along BPM Y and X and found that there was <br>not a large dependence on Y, but the dependence on X was significant. In addition, <br>removing the Q1 exit plane aperture while moving along BPM X showed a large effect on <br>acceptance/yield ratio on the positive x side. He also looked at the effect of extending <br>X to +30mm. He found that moving the target ~10mm gives the largest acceptance at the <br> Q1 exit endplane. There was some confusion about coordinate definitions, Jie will clear <br>this up for next time. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_06_09_simulation/2015_06_10_Simulation_update.pdf here].
| |
| − |
| |
| − |
| |
| − | ==5/27/2015==
| |
| − |
| |
| − | Present: JP, Min, Jie, Chao, Jixie, Melissa<br>
| |
| − | By Phone: Pengjia, Ryan, Toby, Ellie, Alexandre<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Pengjia
| |
| − | **Comparing calculated asymmetries from data to asymmetries calculated from the MAID model. <br>He looked at the 2.2 GeV, 5T settings (both longitudinal and transverse) and used a dilution <br>factor of 0.15. He needed to scale the MAID model as it was 6X larger than the asymmetries <br>calculated from data. He also included a plot of Q² vs W for each setting. JP commented <br>that the distribution was a little strange, since Q² and W are directly correlated the <br>distribution shouldn't decrease or stay flat. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/05272015/maid_asym_20150527.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on acceptance studies, specifically the 3rd septum setting. In this septum <br>configuration, the entire second coil is gone. She looked at groups of runs where the beam <br>position was stable to determine the uncertainty of the focal plane measurement. She compared<br>the y and φ at the center sieve hole at the focal plane determined from data to the SNAKE <br>result. The center sieve hole was defined by survey results. JP suggested using the no-target <br>field setting as a starting point to determine the offset, then look at the transverse effects. <br>More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/05272015/05272015.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *There will be no meeting next week due to the Users Group Meeting.
| |
| − |
| |
| − |
| |
| − | ==5/20/2015==
| |
| − |
| |
| − | Present: JP, Min, Jie, Jixie, Melissa<br>
| |
| − | By Phone: Pengjia, Ryan, Toby, Kalyan<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Pengjia
| |
| − | **Calculated asymmetries using the MAID model. He used the total cross section output from <br>MAID 2007, then summed the cross sections from two channels to extract the asymmetry. He <br>calculated the longitudinal/transverse asymmetries and g1,g2,F1 and F2 for several different <br>values of Q². Ryan pointed out that the calculated asymmetries cannot be compared directly <br>to our data, since our data is not at constant Q², and the MAID model is not radiated. More <br>details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/05202015/maid_asym.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Investigating the field overlap of the septum and Q1 fields in the SNAKE model. Currently, <br>no overlap is assumed between the two fields. He looked at different points in the space <br> between the septum and Q1 entrance to check the field from each magnet. Although the Q1 <br>field goes to zero close to the septum, the septum field extends to the entrance of Q1. The <br> current septum field map is too small to cover the full area in the x,z direction, so a larger <br>field map is needed. JP also suggested looking at how this will change the particle <br>trajectories; Min will work on estimating this for next time. More details can be seen in <br>Jie's slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_05_20_snakefield/2015_05_20_hrsfield_update.pdf here].
| |
| − |
| |
| − |
| |
| − | ==5/13/2015==
| |
| − |
| |
| − | Present: JP, Chao, Min, Jie, Melissa<br>
| |
| − | By Phone: Pengjia, Ryan, Toby, Karl<br>
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *Jie posted a draft of a technote on radiation effects in the g2psim package [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_05_13_simu_rad_technotes/radiation_simulation_technotes.pdf here].
| |
| − |
| |
| − | *Toby posted a draft of a technote on dilution analysis [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/dilutionnote.pdf here].
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa
| |
| − | **Looking into packing fraction runs for the 1.1 GeV setting, taken with the short ammonia cell.<br>She doubled checked the normalization constants used to calculate the yields and didn't find <br>anything strange. She also looked at the s1 and Cherenkov channels for each of the four runs, <br>and found some small differences, but this is probably due to the fact that the runs were taken <br>at significantly different beam currents. Two of the runs (5197,5198) were taken with a beam <br>current of 20nA (compared to 40-50nA that the other runs were taken at), which means the BPMs <br>are not reliable for these runs, so the beam position may be significantly different for these <br>runs. It's possible there is some effect due to the high rate with a beam current of 40-50 nA <br>that is not being accounted for. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_05_13.pdf here].
| |
| − |
| |
| − |
| |
| − | ==5/6/2015==
| |
| − |
| |
| − | Present: Chao, Min, Jie, Melissa<br>
| |
| − | By Phone: Pengjia, Ryan, Ellie<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Chao
| |
| − | **Gave a status update on optics analysis. He found that using the 2.2 GeV 5T longitudinal matrix <br>to replay the 1.7 GeV 2.5T transverse data resulted in an overall offset. Because of this, it is <br>useful to do a full check of the relation between the reconstructed kinematics and the beam position. <br>If there is a correlation between the beam position and reconstructed kinematics, a linear fit will <br>be used to determine the correction. The fitting result for φ for the two different settings is added <br>directly to the first order matrix element P0000 (constant term). These matrices will be used to <br>replay the two data sets, and then the fitting procedure can be applied to improve higher order terms. <br>Next he will work on checking other energy settings. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150506/Chao_WeeklyMeeting_05062015.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Showed an updated on focal plane matching. For the 2.2 GeV, 0T setting with the "good" septum <br>(484816), the data and simulation match well at the focal plane. However, data from the same setting <br>but with the target field at 2.5T do not match as well. She tried adjusting the beam position to find <br>a better match, but the correction needed was larger than the uncertainty on the beam position, so <br>JP suggested looking at the discrepancy starting from the central hole. By adjusting the beam position <br>and dipole field, she was able to match data from the central sieve hole to simulation results, within <br>uncertainties. Next she will work on fitting the other sieve holes to match the data. More details <br>can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/05062015/05062015.pdf here].
| |
| − |
| |
| − |
| |
| − | ==4/29/2015==
| |
| − |
| |
| − | Present: JP, Chao, Min, Jie, Melissa<br>
| |
| − | By Phone: Alex, Pengjia, Toby, Ryan, Ellie, Karl<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Pengjia
| |
| − | **Looked at the effect of different raster cuts on the asymmetry. He looked at the 2.2 GeV 5T <br>settings, both longitudinal and transverse configurations. First, he placed a cut on the center <br>of the raster (50% of total radius), which didn't have a large effect on the asymmetry. He also <br>looked at the effect of splitting the beam spot into 4 quadrants; for some asymmetries there was <br>a considerable difference between the quadrants. He also found that the yield is larger on the <br>left side of the beam spot. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/04282015/Asymmetries%20for%20different%20raster%20cut.pdf here].
| |
| − |
| |
| − | *Melissa
| |
| − | **Showed the results of packing fraction analysis for the 1.1 GeV setting. There is some <br>discrepancy in the yields for some materials, and the ratio of the rate/current is not consistent <br>in some cases. She showed the effect of applying acceptance and PID cuts to each run; the <br>makes the largest impact is the cut on single track events, which cuts out ~50% of the total <br>events in some cases. She will continue trying to figure out the cause of the variance in the<br>yields. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_04_29.pdf here].
| |
| − |
| |
| − |
| |
| − | ==4/22/2015==
| |
| − |
| |
| − | Present: JP, Chao, Min, Jie, Melissa<br>
| |
| − | By Phone: Toby, Ryan, Ellie, Karl, Vince<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Chao
| |
| − | **Gave an update on optics analysis. Using data from the single foil target does not provide enough <br>constraints for optics analysis, but there are two other methods to additionally constrain the data. <br>One way is to look at the relation between the kinematics and beam position for beam position scan <br>runs, and the other way is to include data from the aluminum window into the fitting procedure to <br>directly correct the reconstruction matrix. The second method is what was tested for this week. To <br>improve the fitting routine, he first fits the k=0 matrix elements without the Aluminum window data, <br>then fixes the other matrix elements and fits the k=l matrix elements after adding in the aluminum <br>data. He found that he couldn't get a good fit using the aluminum window data, even if only the y-fp <br>matrix elements are allowed to vary. JP commented that, since y and φ are coupled, they cannot be <br>fit separately. It's possible that a higher order polynomial is necessary for the fit. More details <br>can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150422/Chao_WeeklyMeeting_04222015.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Put together a summary of the data quality checks on the yields (detailed [https://hallaweb.jlab.org/wiki/index.php/G2p_data_quality here]), including the <br>number of useable runs and percentage of useable statistics in each kinematic setting. Overall, the 5T <br>settings look the best, with the exception of the 3.3 GeV setting, which has several settings with yield <br>drifts that appear to be unrelated to beam position changes. Karl suggested checking the stability of the <br>dipole for settings with bad runs. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/qualitychecktalk.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Pengjia posted a draft of a technote on beam charge measurements [http://hallaweb.jlab.org/experiment/g2p/technotes/bcm_technote.pdf here], and would appreciate feedback.
| |
| − |
| |
| − |
| |
| − | ==4/15/2015==
| |
| − |
| |
| − | Present: Jixie, Min, Chao, JP, Jie, Melissa<br>
| |
| − | By Phone: Vince, Pengjia, Toby, Ryan, Ellie, Karl<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie
| |
| − | **Gave a simulation update, specifically looking at acceptance and yields. Last time, he used a point <br>beam a moved the position from 0-10 in x and y to see the effect on the acceptance and the yields. This <br>time, he looked at the acceptance at each endplane using a point beam at (0,0) and (-10,0). One big <br>difference is the number of events blocked by the Q1 exit for these two beam positions. He went step by <br>step through the simulation to compare the number of events that reach each enplane to the number of <br>events that pass through the plane. He found that the shift of the beam position by 1cm caused a drop of <br>~20% in the acceptance. JP and Vince commented that this drop seems too large. It's possible the septum <br>is also playing a role in the decreased acceptance, not just Q1. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_04_15_acc/2015_04_15_Simulation_update.pdf here]
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave an update on packing fraction analysis. She extracted pf values for numerous elastic runs for <br>several settings. For settings where there is a drift in the yields, the pf also varies. The most <br>variation is seen in the 2.2 GeV, 2.5T setting. The raster size was changed part way through this <br>setting, so it may not be possible to compare runs with different rater sizes without first correcting <br>for this difference. She will continue working on trying to understand the discrepancies in the yields, <br>and finish extracting the values for the 1.1 GeV setting, for the regular and short ammonia cells. More <br>details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_04_15.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Gave an update on radiative corrections. He took a closer look at the systematic error on the <br>inelastic radiative corrections, which are different now that he has removed the interpolation from the <br>unfolding procedure. He replaced the interpolation with a direct call to the Bosted Model. Comparing <br>the two methods, he found that they are consistent with each other. The interpolation will be the <br>largest contribution to the systematic error. He also wanted to test if there was a faster way to <br>radiate a model. There are two ways to do the integration within the Stein equation, Romberg or Simpson <br>integration. The Romberg method is more accurate, but takes longer. The results from using both methods <br>to radiation the Bosted model are nearly identical, but the Simpson method is orders of magnitude faster, <br>particularly for finer ν binning. Next he will work on setting up polarized radiative corrections. <br>More details can be seen in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_041515.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Gave an updated on dilution analysis. He showed a central fit to the scattering angle compared to the <br>model prediction done by Jixie. This is used to scale the angle between different run types, such as <br>scaling carbon dilution to nitrogen production. Since the optics isn't complete yet, this scattering angle <br>is just a place holder until we better understand the scattering angle. At large ν, the dilution factor <br>(and packing fraction) starts to drop off, which he thought could be due to a problem with the scattering <br>angle correction. JP commented that this might not be the case, since this is a ratio, but due to the fact <br>that at low Q squared the DIS cross section is small. This will probably result in a large statistical <br>uncertainty on the dilution factor. Next Toby will extract the dilution factor for the 1.1 GeV and 1.7 GeV <br>settings, and finish writing a technote on this analysis. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/diltalk_041515.pdf here].
| |
| − |
| |
| − |
| |
| − | ==4/8/2015==
| |
| − |
| |
| − | Present: Chao, Min Kalyan, Jie, Melissa<br>
| |
| − | By Phone: Alex, Vince, Toby, Ryan, Karl, Ellie, Pengjia<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Chao
| |
| − | **Gave an update on optics analysis. Previously he showed that there is an issue with the horizontal beam <br>position changing the dp reconstruction. Since there aren't enough constraints to do the reconstruction, it <br>is necessary to do a full check of the relations between the beam position and the reconstructed kinematics. <br>He looked at delta scan runs and beam position scans to check the correlation between the beam position <br> and reconstructed variables. To correct for these effects, he used a linear fit to determine a correction factor<br>for θ, φ and dp. To test this method he used a production run, and placed cuts on the raster pattern in <br>different areas around the center of the beam spot. While the "old" reconstructed dp variable shifted based <br>on the location of the cut, the "corrected" dp variable was stable. Next he will work on applying this method <br>to other settings. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150408/Chao_WeeklyMeeting_04082015.pdf here].
| |
| − |
| |
| − |
| |
| − | ==4/1/2015==
| |
| − |
| |
| − | Present: Min, Chao, Kalyan, JP, Jie, Jixie, Melissa<br>
| |
| − | By Phone: Ryan, Toby, Pengjia, Vince, Alex<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave an update on packing fraction analysis. She started extracting the pf for the 2.5T settings, but the biggest <br>lingering issue is the discrepancy seen in the yields for elastic pf/production runs. Several suggestions were made <br>to check for a possible problem, such as the septum field drifting over time, looking at the raster pattern, and <br>checking the scalar rates and normalization values (specifically the charge). More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_04_01.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Gave an update on automated model tuning for determining the carbon/nitrogen cross section ratio. Previously, the <br>tune was optimized in the order dip-region, inelastic, quasielastic. For this time he swapped the order to inelastic,<br>quasielastic, dip-region. The final overall tune represents an average of each settings parameters. He found that <br>the best average reduced chi-squared was found after the second iteration, and the fit is good to within 10%. Next <br>he will look at saGDH nitrogen data, but is waiting on updated cross sections from Vince. More details can be seen <br>in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_040115.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on acceptance studies. Last time she compared the data from a delta scan in the 2.2 GeV, 2.5T <br>setting (with good septum) with simulation results and found some differences. This time she adjusted the beam <br>position in the simulation to match the data, which was quite different from the original beam position. Kalyan <br>suggested looking at just the center hole of the sieve slit to determine the offset. It seems the offset is seen <br>in the data, but the simulation shifts the events in the opposite direction. Min/Chao have a plan to check each <br>part of the simulation, and Pengjia will check the beam position calibration for this setting. More details can <br>be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/04012015/04012015.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Gave a simulation update, specifically checking the target center compared to the position given by the BPM at <br>the target. His goal was to test if the target was centered, whether the BPM could have an offset? Or if the <br>target was centered and the BPM position was correct, could the raster size be scaled incorrectly? Looking at <br>several runs he saw a shift of 1cm in the target center. However, as the runs were at different energy settings, <br>the beam position wouldn't necessarily be the same. Kalyan suggested looking at the carbon hole runs nearest to <br>these runs as a check. For next time he will focus on simulating the shifts we see in the yields. More details <br>can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_03_31_bpmpos/2015_03_31_Simulation_update.pdf here].
| |
| − |
| |
| − |
| |
| − | ==3/25/2015==
| |
| − |
| |
| − | Present: Jie, Min, Vince, JP, Chao<br>
| |
| − | By Phone: Ryan, Karl, Toby, Alexandre, Pengjia <br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie
| |
| − | **Gave an update on simulation package. The elastic radiation tail include soft photon contribution is compared with <br> the result from the predication calculated using Mo/Tsai. The tail matches at ΔE~6MeV. He also looked at the effect <br>of the beam position on the acceptance. The simulation covers the full angle acceptance to test the aperture cut <br>in the SNAKE model. The simulation shows that φ acceptance has large correlation with the horizontal beam position. <br>JP suggests the aperture setting in the model may be not sufficient to represent the real situation. Chao suggests <br>that to use the simulation to determine which aperture stops most particles. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_03_23_rad_effects/2015_03_25_Simulation_updae.pdf here].
| |
| − |
| |
| − | *Chao
| |
| − | **Gave an update on the optics calibration. As Jie points out before, the reconstructed dp does not agree with the <br>prediction very well when horizontal beam position changes. The beam position scan runs are used to fit a correction <br>to the dp reconstruction matrix. The correction could correct the dp reconstruction result for optics runs. However, the <br>reason of this correction is still not clear. After discussion, the suggestion is to add the correction back to the dp matrix <br>and redo the fit of higher order terms. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150325/Chao_WeeklyMeeting_03252015.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Gave an update on dilution study. He showed dilution results for all completed settings. The tech note of the dilution <br>study is in progress. He also mentioned an alternative way to calculate the packing fraction. The method only works in <br>DIS region but a 0th order polynomial fit at large ν can be used to find the packing fraction everywhere. All packing <br>fractions seem about 5-10% larger than typical values. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/pf_dil_talk.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Presented some preliminary results of asymmetry and yield for RHRS. He compared the right arm asymmetry and yield <br>with left arm for two kinematic settings. The asymmetry results agree quite well but the yields has some deviation for <br>the 2.2GeV, 5T longitudinal field setting, perhaps caused by acceptance effect. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/03252015/asym_lr.pdf here].
| |
| − |
| |
| − |
| |
| − | ==3/18/2015==
| |
| − |
| |
| − | Present: Jixie, Chao, Jie, Min, Kalyan, JP, Melissa <br>
| |
| − | By Phone: Ryan, Karl, Toby, Alexandre, Vince, Pengjia <br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave an update on packing fraction analysis. For each setting, she tried to identify ammonia runs that could <br>be used for the analysis, ideally runs that were taken in close proximity to the dilution (dummy/empty) runs, or <br>at least where the beam position is similar. In addition, the fitting routine (to understand the level of <br>contamination from the 2nd peak) was adjusted for each energy setting. The 2.2 GeV, 5T settings (longitudinal <br>and transverse) have ammonia runs taken close in time to the runs to helium. The 1.7 GeV setting has some <br>variation in the ammonia yields, but they are not too large. The 1.2 GeV energy setting has significant variation<br>in the elastic yields; she will look more into these runs to see if there is an obvious reason for the variation. <br>She also showed the fit results for the different energy settings; JP suggested checking the hydrogen fit, as it <br>seems a bit wide. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_03_18.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Working on an automated model tune, which will be used to determine the ratio of carbon to nitrogen for dilution <br>analysis. Last time, he showed an automated tune of the Bosted model, which assumed that the quasi-elastic and <br>inelastic channels are independent one another and can be optimized independently. The caveat to this is that the <br>tune is only valid in the Q<sup>2</sup> range and for the target type of the input data. For this time, he updated the<br>automated tune procedure to include an adjustment for the "dip" region. The Bosted model parametrization of the <br> dip region is a Gaussian that is calculated as part of the inelastic channel. Including the dip region improves the fit <br>to carbon data for each individual setting, however the overall fit it worse. JP suggested that fitting the dip region <br> first may be the problem; Ryan will try to swapping the order of the fitting routine to see if it improves the fit. <br> More details can be seen in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_031715.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her acceptance study. To improve the simulation, she included data from the windows into the <br>calibration and updated the results for the delta scan runs. This new function was applied to both horizontal and <br>vertical beam scan runs. This improved the agreement between the data and simulation, especially for the horizontal <br>beam scan run. She also looked at beam scan runs with the target field on, this time adding an additional constant <br>on y and φ. For the fit of the focal plane, JP cautioned not to use too high-order of a fit, as it can become <br>non-physical. For next time, she will adjust the fitting function. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/03182015/03182015.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Looked at the effect of raster cuts on the yield. He looked at several kinematic settings with consistent yields <br>and a applied a raster cut with a diameter of 6mm. He found that applying the raster cut had a negative effect; <br>meaning the spread in the yields became larger after the cut was applied. He also showed the x and y positions at <br>BPM A and B for each set of runs. In some cases, the x-position at BPMA is stable, but it varies at BPMB, which <br>could be the source of the variation in the calculated scattering angle. It may be more useful to do a relative <br>study, (similar to what Jie has shown previously) for individual runs than trying to compare separate runs. More <br>details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/03112015/Raster_Cut_201503011.pdf here].
| |
| − |
| |
| − |
| |
| − | ==3/11/2015==
| |
| − |
| |
| − | Present: Chao, Jie, Min, JP, Melissa<br>
| |
| − | By Phone: Vince, Toby, Ryan, Karl, Alexandre<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie
| |
| − | **Working on updating the energy loss model in the simulation package. Previously it was found that the energy loss <br>model in g2psim does not match the prediction calculated using the Mo/Tsai formulation. He found that the soft photon<br>contribution was missing. This term could have a large contribution, up to 20%. He also looked at the effect of <br>changing the scattering angle on the dp distribution. Over an 80mrad change in the scattering angle, he saw only a <br>~0.16% change in the dp distribution. He also looked at 5 different areas of the beam spot, to see how the dp changed <br>in that region. The simulation results show no change in the dp distribution in the different regions, but the data <br>shows that the dp distribution shifts as you move around the beam spot. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_03_06_xs_ratio/2015_03_11_Simulation_updae.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Ryan sent around an abstract for the upcoming Chiral Dynamics workshop, comments are appreciated.
| |
| − | *JP sent around the latest version of Pengjia's BPM paper, feedback is appreciated.
| |
| − |
| |
| − |
| |
| − | ==3/4/2015==
| |
| − |
| |
| − | Present: Chao, Jie, Min, JP, Melissa<br>
| |
| − | By Phone: Vince, Toby, Ryan, Karl, Pengjia<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Toby
| |
| − | **Gave an update on dilution analysis. He finished tuning the Bosted model in order to obtain cross section ratios used <br>for radiation length matching for dilution runs (for example, scaling a helium run to match the radiation length of a carbon <br> run). He showed the calculated background over the full kinematic range for the 2.2 GeV, 5T, Transverse setting. The <br>dilution factor can then be extracted using the ratio of the background yield to the total yield. Eventually he will be able <br>to update the dilution factor using material specific packing fraction values (when they are ready), and an improved tune <br>of the XS model. Next he will work on other settings and compiling a technote. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/diltalk_030415.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Working on a method to automate model tuning for the QFS and Bosted models. For dilution analysis it is necessary <br>to scale carbon data as a replacement for nitrogen yields. Since there is no nitrogen and carbon cross sections available <br>from the same experiment, it is necessary to use to model tune of saGDH data for nitrogen, and a model tune of data <br>from UVa archives for carbon. Previously, this tuning was done "by hand", with a reduced χ<sup>2</sup> to determine the <br>quality of the fit. A problem with this method is that it could result in inconsistent results for different people tuning the <br>same data set; an automated method could solve this problem. JP commented that a possible problem with an automated <br>method is that the physics is simplified. He showed results for tuning the Bosted model to carbon data, next he will work <br>on saGDH data, and then will repeat the procedure for the QFS model. More details, including a description of the code <br>structure, can be seen in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_030415.pdf here].
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave an update on packing fraction analysis. Previously, she described an update to her method to include cross section <br>input. Elastic form factor models were used to determine the cross section ratio σN/σHe. To obtain radiated cross sections<br>two methods were used. First, using the g2psim energy loss model, and second, using the Mo/Tsai formalism to calculate <br>the correction to the elastic peak. There is a discrepancy between these methods, specifically that the results suggest that <br>the correction is smaller than it should be. This will have to be resolved to get an accurate value for the cross section ratio. <br>She is also working on fitting the data for dilution and production runs for other energy settings to extract packing fraction <br>values for other materials. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_03_04.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her acceptance study. Last time she found that the focal plane variables for production runs didn't <br>match well with the simulation. Production runs have a rastered beam, as opposed to the point beam used in optics <br>calibration runs, so this effect must be corrected for. For this week, she looked at events at the target window in the focal <br>plane, and used these events to improve the fitting at the virtual plane. She also looked at events from the carbon foil at <br>the focal plane, and saw a reasonable match. Next she will work on further improving the fitting and incorporating the <br>results into g2psim. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/03042015/03042015.pdf here].
| |
| − |
| |
| − |
| |
| − | ==2/25/2015==
| |
| − |
| |
| − | Present: Chao, Jie, Min, JP, Melissa<br>
| |
| − | By Phone: Toby, Ryan, Ellie, Pengjia<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie
| |
| − | **Working on understanding the yield drifts due to changes in the beam position. He used beam position information <br>as input to the simulation, and applied loose acceptance cuts to determine the yield. He looked at several momentum <br>settings that had a drift in yields >3% in the 1.7 and 1.1 GeV energy settings. In general he found that the effect was <br>opposite of what is seen in the data. JP suggested doing the study independent of data, so as not to bias the results, <br>and to show the dependence of the yield on each parameter (x,y,θ,φ) individually. He also suggested checking to <br>make sure the acceptance effects are included properly, as it is difficult to get them to agree at the boundaries. Jie will <br>keep working on this, and will start working on the septum SNAKE model for the 403216 septum configuration. More <br>details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_02_24_yields/Simulation_update_2015_02_24.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Trying to determine if applying a raster cut to the data will fix the spread in yields. The difficulty is in determining <br>the total charge after this cut is applied. To determine the charge, he used the calibrated charge info from both the <br>happex and fastbus, and applied the same raster cut to each. He was then able to use the happex raster cut info to <br>get the charge from the happex bcm. JP pointed out that, since the happex and fastbus aren't synchronized, this <br>method may only work if the beam is stable, so it is important to quantify an uncertainty on the charge. He suggested <br>trying this method again with a much smaller raster cut, so that whatever effect this method will be magnified. Pengjia <br>will first look at a setting where the yields are stable to see the effect of this cut, then will move on to settings that have <br>issues. The raster cut library and testcode is available on the work disk, see his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/02252015/Position_Cut_20150225.pdf here] for more details.
| |
| − |
| |
| − | *Chao
| |
| − | **Posted the draft of a technote on target field mapping [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/technotes/Chao_TechNote_TargetField.pdf here]. Any comments would be appreciated!
| |
| − |
| |
| − |
| |
| − | ==2/18/2015==
| |
| − |
| |
| − | Present: Chao, Jie, Kalyan, Melissa<br>
| |
| − | By Phone: Vince, Ryan, Toby, Min<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her acceptance study. She showed a comparison of simulation results with data from a production <br>run. As was suggested previously, she expanded the acceptance range when generating events. She found that the <br>focal plane variables still don't match very well. One possibility is that the production runs have a raster beam, but the <br>optics runs she had looked at previously used a point beam, so this effect needs to be corrected for somehow. More <br>details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/02182015/02182015.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Chao mentioned that a problem was found in the most recent BPM package, and it may have caused a problem <br>in the replay. Toby will discuss this with Pengjia offline.
| |
| − |
| |
| − |
| |
| − | ==2/11/2015==
| |
| − |
| |
| − | Present: Chao, Jie, Min, Melissa<br>
| |
| − | By Phone: Pengjia, Toby, Ryan, Ellie, Vince<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Toby
| |
| − | **Gave an update on dilution analysis. The dilution factor is define as one minus the ratio of background yield over<br>total yield. The background yield includes contributions from nitrogen, helium and the foil endcap on the target cell. <br>To extract the dilution factor he must tune the Bosted model (for helium and carbon) to match cross section data, <br>radiate the simulation results and take ratios to obtain necessary scaling constants, and then apply these scaling <br>constants to calculate the background yield. For tuning the Bosted model, he is currently using cross section data <br>from the UVa quasi-elastic database. The kinematics do not match ours exactly, but this will work until g2p cross <br>sections are available. He used a χ-squared minimization routine to determine the scaling factor for each kinematic. <br>He also showed the resulting cross sections ratios, which are used to determine the scaling factors α, β and γ.<br>Next he will apply the cross section ratios to yields from dilution runs to calculate the background yields and dilution <br>factor for the 2.2 GeV, 5T transverse setting, after which he will move on to other settings. More details can be seen <br>in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/dilution021015.pdf here].
| |
| − |
| |
| − |
| |
| − | ==2/4/2015==
| |
| − |
| |
| − | Present: Chao, JP, Jie, Min, Melissa<br>
| |
| − | By Phone: Toby, Ryan, Pengjia, Karl<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Chao
| |
| − | **Gave a status update on optics analysis. For the 2.2 GeV, 5T settings (longitudinal and transverse) there was<br>limited optics data taken. Instead, the 1.7 GeV optics matrix matrix was used for this setting, with a 0th order <br>correction for the longitudinal setting, and a 1st order correction for the transverse setting. He showed the <br>longitudinal setting as an example, applying the 1.7 GeV matrix and including the 0th order correction to center <br>the sieve holes. JP commented that, if the offset is large, there may be higher order effects to consider. There <br>are no optics runs for the 3.3 GeV setting, so he plans to use g2psim to determine the optics matrix. He is <br>working on an optics technote, and a technote summarizing the last target field measurement. More details can <br>be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150204/Chao_WeeklyMeeting_02042015.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her acceptance study. For this time, she improved the fitting at the virtual plane (for both <br> x/y and , and θ/φ) and projected the results onto the focal plane. The corrections on the forward transport <br>function were incorporated into g2psim. For the reverse transport function, the fit was done using all dp scan runs. <br>The simulation does not match with the data at the edges; this is due to the boundary conditions in the simulation. <br>Min will try expanding the boundary to see if it better matches the data. More details can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/02042015/02042015.pdf here].
| |
| − |
| |
| − | *Melissa
| |
| − | **Updated the data quality check for the 2.2 GeV, 2.5T setting to include RHRS runs. In general the problem <br>settings on the RHRS are consistent with the LHRS. She also gave an update on the packing fraction analysis; <br>there was a problem in the previous definition of the packing fraction. The updated method requires some input <br>from cross section models. The resulting packing fraction is slightly larger than the result from the previous <br>method. Next she will work on extracting packing fraction values for other settings. More details can be seen <br>in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Yields/Yields_02_03.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Calculated the energy loss using two methods; using his energy loss model (Monte Carlo, step by step), and <br>using a radiated cross section model (from Stein). He used a fixed initial energy and fixed scattering angle for <br>a carbon target, and didn't apply any acceptance cuts. He compared the dp spectra for the two methods and <br>found that his energy loss model agrees well with the radiation model. Next he will work on a full simulation <br>for a beam dependence study (once the acceptance is ready). More details can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_02_04_radiative/2015_02_04_Simulation_updae.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Starting next week we will change the meeting start time to 9:30am.
| |
| − |
| |
| − |
| |
| − | ==1/28/2015==
| |
| − |
| |
| − | Present: Chao, JP, Jie, Melissa<br>
| |
| − | By Phone: Vince, Ryan, Toby, Min, Pengjia, Ellie, Alexandre<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Ryan
| |
| − | **Gave an update on data quality checks for the 1.1 GeV setting. He found that the spread in yields ranges <br>from 0.01% - 6.1%, with an average of ~2%. For this setting we also took runs on a short target cell (material <br>14). For settings with a large spread, there was a correlation between beam drift and yield drift. Overall, this <br>setting seems ok. Next he will move back to working on polarized radiative corrections. More details can be <br>in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_012815.pdf here], and a detailed summary <br>of the data quality check can be seen [https://hallaweb.jlab.org/wiki/index.php/G2p_1157_25T here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Gave an update on data quality checks for the 1.7 GeV setting. For settings with a large spread in yields, <br>he looked at the correlation with the calculated scattering angle. He found that in some cases the change in <br>yield was proportional to the change in scattering angle, but for some settings it was inverse proportional. <br>He also showed an example of a setting where the yield was drifting, but there was no change in the scattering <br>angle. He tried applying raster cuts to see the effect on the yield, but first needs to find a way to calculate the <br>charge while including the raster cut. There was some discussion how this could be done; it may be possible to <br>use the Happex DAQ, as it is triggered by helicity. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/01282015/yield_drift_20150128.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Toby will start replaying RHRS runs today, hopefully they will be done by the end of the week.
| |
| − |
| |
| − |
| |
| − | ==1/21/2015==
| |
| − |
| |
| − | Present: Jie, Min, Chao, JP, Kalyan, Melissa<br>
| |
| − | By Phone: Pengjia, Vince, Ryan, Toby, Karl<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave a summary of data quality checks for the 2.2 GeV, 2.5T, transverse setting. There are several momentum <br>settings with a significant spread (>2%) in the yields. In most cases, the spread in yields seems to be correlated <br>with a change in beam position, which often corresponds to beam down time during the run period. Examples of <br>problem settings can be seen in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Yields/Yields_01_21.pdf here], and a summary of all settings is available [https://hallaweb.jlab.org/wiki/index.php/G2p_2254_25T here].
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| − |
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| − | *Chao
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| − | **Gave an update on the status of optics for the RHRS. For the longitudinal and transverse settings at 5T, only a <br>few optics runs were taken, so the plan is to use the 1.7 GeV optics matrix for these settings. He also included a <br>summary of the RMS value of each kinematic variable (δ, θ and φ) for each setting, and commented that <br>the RMS value for y_tg is around 3-4mm, but this is a rough estimation as the fitting is not as good for this variable. <br>Next he will test 2.5T transverse optics matrix on the 5T settings to see if it works. His slides are available [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150121/Chao_WeeklyMeeting_01212015.pdf here].
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| − | **The simulation package has been updated to cover the RHRS and include some upstream geometries. The most <br>recent version of g2psim is available through github here: https://github.com/asymmetry/g2psim
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| − |
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| − | *Min
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| − | **Gave an update on her acceptance study. For this time, she combined all dp scan runs in order to do the <br>corrections at the virtual plane, which was then projected onto the focal plane. The agreement at the virtual <br>plane looks good, but there is still some disagreement at the focal plane. Next she will fit the reverse transport <br>functions and compare target plane variables. More details are available in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/01212015/01212015.pdf here].
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| − |
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| − |
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| − | ==1/14/2015==
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| − |
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| − | Present: Chao, Jie, JP, Melissa<br>
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| − | By Phone: Pengjia, Ryan, Toby, Ellie, Karl, Min, Vince, Alexandre<br>
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| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
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| − |
| |
| − | *Jie
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| − | **Gave an update on the dp simulation, specifically trying to understand why the simulation result for elastic dp was <br>narrower than the data. Comparing the data (with just PID cuts) to the simulation result (using full acceptance, and <br>a raster diameter of 2cm), the simulation is narrower than the data. However, if he applies acceptance cuts to the data <br>and simulation, and uses a beam size of 4mm (which matches with the data), the results show a better match between <br>data and simulation. He also tried dividing the beam spot into 5 different zones, and looked at the resulting dp <br>distribution for each. He did see a shift in the central value of dp between zones, however this shift was not seen in the <br>simulation. He also compared the shift in θ and φ for the 5 zones. JP commented that the θ distribution in<br>the data is symmetric and centered around zero, while the simulation result is not. It is possible that this is due to the <br>fact that Jie is using the old SNAKE model; he will get the updated version from Min and see if it makes a difference. <br>More details can be see in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_01_12_dp/Simulation_update_2015_01_12.pdf here].
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| − |
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| − | *Pengjia
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| − | **Posted his false asymmetry results to the ELOG.
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| − | **Working on data quality check for the 1.7 GeV, 2.5T setting. It looks like the spread in yields in some settings is <br>strongly dependent on the scattering angle. JP suggested looking at beam position or other raw variables, since the <br>scattering angle is a calculated value and depends on optics. It seems most settings with problems correspond to a <br>break in time when the runs were taken, which may suggest a problem with the spectrometer. Pengjia will look into <br>this next. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/01152015/data_quality_20150115.pdf here].
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| − |
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| − | *Toby
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| − | **Gave an update on his yield drift study for the 3.3 GeV setting. For this time, he looked at the target field (central <br>NMR value) over the 2.34 GeV momentum setting, a period of about 6 hours. While there are some jumps in the signal, <br>there isn't a consistent drift like is seen in the yields. However, there is a period where the signal jumps significantly; he <br>will look into a possible cause for this. He also looked at the scaler BCM counts and trigger rates for these runs. There <br>was no noticeable drift in the scaler rates, but the beam current was not stable during this time.. He also computed the <br>"scaler yield" by dividing the total triggers by the BCM counts and saw a drift similar to what is seen in the normalized <br>standard yield. Previous to these runs being taken, there was a flood in the hall resulting in a power outage. It's possible <br>that the drifting is a result of systems not being stable while these runs were taken. More details can be seen in his <br>slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/scaler_yield_drift_talk.pdf here].
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| − |
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| − | *Ryan
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| − | **Working on a data quality check for the 1.1 GeV, 2.5T setting. In general the setting looks pretty good; the maximum <br>spread is 10% and the minimum is 0.01%, with an average of ~2% spread. Fewer runs were taken in this setting, and the <br>runs were taken consecutively, resulting in smaller spreads overall. In addition, there was data taken at this setting at <br>3 different momentum settings, all looking at elastic, and all on the same material. Next he will try to determine the <br>problem for the settings with a large spread (~10%). More details can be seen in his slides [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_011415.pdf here].
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| − |
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| − |
| |
| − | ==1/7/2015==
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| − |
| |
| − | Present: Chao, Jie, JP, Min, Kalyan, Jixie, Melissa<br>
| |
| − | By Phone: Yunxiu, Vince, Pengjia, Toby, Ryan, Ellie, Karl, Todd, Nilanga, Haiyan<br>
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| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | Each student gave a short update on their analysis projects since the last collaboration meeting on November 14th:
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| − |
| |
| − | *Melissa
| |
| − | **Method for packing fraction analysis is complete; the packing fraction values for each material still need to be <br>extracted. This will probably take ~1 week, but the yield discrepancies need to be understood before it can be <br>completed. She is also working on data quality checks for yields, specifically the 2.2 GeV, 2.5T setting. After these <br>projects are complete she will work on the PbPt check using elastic asymmetries. More details can be seen in her <br>slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/talks/MCummingsCollabMeeting_Jan.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Focusing on data quality checks of yields for production runs. He has completed the 2.2 GeV 5T settings, both <br>longitudinal and transverse, and the 3.3 GeV setting. The 2.2 GeV 5T settings have few problems, but the 3.3 GeV <br>has many momentum settings where the yields drift over time. He sees a similar drift in the left and right arm data. <br>He is still trying to figure out the cause for the drift. In addition, he is working on tuning the Bosted model to helium <br>and carbon dilution runs to simulate the background for dilution analysis, with a goal of finishing the dilution analysis <br>by mid-march. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/01.07.15.pdf here].
| |
| − | **Information on data quality checks can be found on the wiki [https://hallaweb.jlab.org/wiki/index.php/G2p_data_quality here].
| |
| − |
| |
| − | *Jie
| |
| − | **Looked at the effect of changing the scattering angle on the cross section for carbon, nitrogen, helium and hydrogen. <br>This may help explain the discrepancy we see in the yields, but is problem not the only cause. He is also working on <br>finishing the dp simulation, which should be done soon, and will begin working with Min to learn more about the acceptance <br>study. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2015_01_06_pbosted/2015_01_06_Simulation_update.pdf here].
| |
| − |
| |
| − | *Chao
| |
| − | **Gave an update on the status of optics analysis. He is finishing up the 2nd iteration of the optics calibration; the LHRS <br>is complete and the RHRS has one setting to go (1.158 GeV). For the 2.2 GeV, 5T, transverse setting, there is no full <br>dp scan, so the longitudinal data taken at that energy setting will be used. Once the 2nd iteration of the calibration is <br>complete, he and Min will compile a technote on the optics study. He has also modified the geometry part of the g2psim <br>package to make it more configurable. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20150107/Chao_WeeklyMeeting_01072015.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Working on the acceptance study. In the focal plane, there seems to be good agreement between simulation and data. <br>In the target plane, in the θ vs φ plot, there seems to be a shift in φ for all dp settings; it seems to be a linear<br>correlation with dp. Next she will work on a correction for φ-target vs dp and compare target plane variables. To finish the <br>good septum, straight through setting it will probably take 1-2 months, then an additional 1-2 months for the other 2 septum <br>settings. More details can be see in her slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/01072015/01072015.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **He has completed a draft for a PRC paper on unpolarized He3 cross section data. He still needs to complete the He3 radiative <br>correction analysis for saGDH, but is waiting on updated nitrogen cross sections for saGDH. He is also working on the carbon/ <br>nitrogen ratio for saGDH, but is waiting on updated analysis from Vince before continuing. He is also working on data quality <br>checks for production runs for the 1.1 GeV setting, and is starting to look into polarized radiative corrections. More details can <br> be seen in his slides [https://userweb.jlab.org/~rbziel/CollabMeeting_12015.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Calculated the false asymmetry by comparing the asymmetry before and after applying detector cuts. He found the false <br>asymmetry to be small; less than 200 ppm for all energy settings. He's also working on a data quality check for the 1.7 GeV <br>data set. More details can be seen in his slides [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/01072015/false_asym_20150107.pdf here].
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Yields stability/overall data quality check is the main issue at this time.
| |
| − | *Progress of acceptance study looks good, but could become an analysis bottleneck.
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| − |
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