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| Line 27: |
Line 27: |
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| − | ==12/11/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Chao, Min, Jie, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Alexandre, Moshe, Pengjia<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Ryan:
| |
| − | **Working on comparing elastic cross sections for carbon and nitrogen using form factor data. It's clear there is a strong angle <br>dependence on the cross section. He also looked at the ratio of the cross sections, and saw a strong dependence on Q<sup>2</sup>. Next he <br>will look at the GDH carbon data, once he has access to it. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_112713.pdf here].
| |
| − |
| |
| − | *Toby:
| |
| − | **Gave an update on dilution analysis. He is working on reconstructing the total background from the dilution runs. When looking at<br>the elastic region, there was some strange structure when the calculated background was subtracted, but the method of scaling the <br>carbon cross section tonitrogen will be less accurate in the elastic region. In the quasi-elastic region, he will need to reproduce the elastic <br>radiative tail so that it can be subtracted off. Moshe has a simulation for the elastic peak and radiative tail for nitrogen, which he will give <br>to Toby. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/12.11.13.pdf here].
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Gave an update on BPM analysis. Described his improved method for determining the calibration constants, which includes rewriting the <br>diff/sum expression to account for the fluctuation of the pedestal throughout the run period. By assuming a linear response in the receiver,<br> he uses harp scan data to determine the offset value. He also uses the absolute beam position found from harp scans to examine the <br>nonlinearity of the diff/sum method. The biggest issue is with the fluctuating pedestal, as it seems to change even within the same gain <br>setting. Details on his method can be seen in Pengjia's slides,[http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/12112013/bpm_status_20131211.pdf here].
| |
| − |
| |
| − | *Jie:
| |
| − | **Gave a practice talk for his upcoming talk at the Hall A Collaboration meeting, his slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/talks/jie_g2p_hall_A_collaboration.pdf here].
| |
| − |
| |
| − | ==12/04/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Min, Chao, Jie, Jixie, Melissa <br>
| |
| − | By Phone: Karl, Ellie, Toby, Ryan, Pengjia<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Chao:
| |
| − | **Gave an update on optics analysis, with target field on. He started with the "best" septum configuration, 48-48-16 and looked <br>at dp = 0%. He used the simulation to determine the theta and phi to be used in the fitting routine, and used a point beam, set <br>to the average of the BPM readout. The reconstructed sieve pattern is decided by the beam position and reconstructed angle. <br>Improvements from last time include using the direct BPM readout as input for the beam position (since the y-target calibration<br> is not very good), and using the calibrated matrix for the angle reconstruction (as opposed to the straight-through version). The <br>results look good! There seems to be a slight offset in all the points, though this can probably be tuned using the data. Next he <br>will work on calibrating the y-matrix using a similar method using beam position scan data. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20131204/Chao_WeeklyMeeting_12042013.pdf here].
| |
| − |
| |
| − | *Min:
| |
| − | **Gave an update on optics analysis. She is doing a comparison of target quantities between data and SNAKE. Previously, she was <br>using the wrong database, correcting this has fixed the offset seen in phi. For the March 4th run, there is no beam scan data, so <br>she used the y-calibration from March 14th. There seems to be some contamination in the dp data (from other materials, such as <br>upstream windows), so JP suggested placing cuts on other acceptance variables to minimize this contamination. Next Min will look <br>at the other dp scan runs. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/12042013/12042013.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *We will have a dry run next week for Jie, who's giving the g2p update at the Hall A meeting. Chao will make his slides for the Analysis <br>
| |
| − | Workshop available at that time as well.
| |
| − |
| |
| − | *Melissa will post a draft of the g2p update for the Hall A report by Friday, so comments can be made before the deadline (Dec. 13th)
| |
| − |
| |
| − | *Next year we will have a new meeting time, Thursdays at 10am.
| |
| − |
| |
| − | ==11/13/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, Jie, Min, JP, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia, Moshe<br>
| |
| − |
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Toby:
| |
| − | **Gave an update on dilution analysis. Showed a general expression for the background contributions, written in terms of <br>yields from dilution runs. Also showed the normalized yields for each background contribution. The results look reasonable <br>for most kinematic settings, but the elastic setting is questionable. Specifically, the "missing" quasi-elastic peak. Toby will <br>check his method, especially the assumption he is making to determine the nitrogen cross section. He also showed an estimate <br>for the dilution factor of ~0.2-0.3, which agrees with what we expect. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/11.12.13.pdf here].
| |
| − |
| |
| − | *Ryan:
| |
| − | **Working on radiative corrections for nitrogen data from GDH experiment. Showed nitrogen cross section data for two different <br>beam energies compared with the Dally parameterization. For GDH kinematics, there is a strong angle dependence on the cross <br>section. Also showed a detailed diagram of the radiation lengths for the GDH experiment. Finally, he compared the raw, subtracted, <br>and elastic radiated cross section for GDH data at 6deg. He did a quick calculation to convert this to 5.66 deg, again showing that the <br>scattering angle plays a large role. He still needs to get the GDH carbon data from Vince. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_111313.pdf here].
| |
| − |
| |
| − | *Jie:
| |
| − | **Gave an updated on the g2p simulation package, specifically the energy loss calculations. There are three contributions to the <br>energy loss; ionization, internal bremsstrahlung and external bremsstrahlung. To check the calculations, he compared the energy loss <br>for g2psim to the Geant4 simulation (set up by Jixie) results. There is a significant discrepancy between the two methods. Jie will <br>check his method and discuss with Jixie to determine what is causing this difference. The details of the energy loss calculations can <br>be seen in Jie's slides, [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_11_13_simulation/Simulation_update.pdf here].
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Gave an update on the status of the BPM calibrations. In order to test the method he presented last week, he looked at runs taken later<br> in the run period, which didn't have issues with BPMB. The method seems to work well for these runs, but JP urged Pengjia to be cautious <br>in making assumptions using this method. Pengjia will continue to check his method for any potential problems. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/11132013/bpm_status_20131113.pdf here].
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *Jie will be giving the g2p update at the Hall A winter collaboration meeting
| |
| − |
| |
| − | *Melissa will write the update for the Hall A status report
| |
| − | **Each student should send a 1-2 paragraph summary of their subsystem to Melissa
| |
| − |
| |
| − | *Please post all technotes to the wiki!!!
| |
| − |
| |
| − | ==11/6/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, Jie, Min, JP, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa:
| |
| − | **Gave an update on packing fraction analysis. She improved her fitting routine to account for the contribution from <br>the quasi-elastic peak (in the case of the dilution runs) and from the hydrogen elastic peak (for the packing fraction runs). <br>For this setting (2.2 GeV, 2.5T, transverse, target material #7), there seems to be significant difference in yield for each of <br>the four packing fraction runs. She will look into what is causing these differences. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_11_06.pdf here].
| |
| − |
| |
| − | *Chao:
| |
| − | **Gave an update on the status of the optics. There are two different settings for straight-through optics; with and without <br>LHe. Both are aligned quite well, and the straight-through optics matrix can be found in the following directory: <br>/g2p/chao/optics/matrix. This matrix will be used to finish the angle calibration to finish up the straight-through optics <br>analysis. Next up is optics with target field, starting with the "best" septum configuration (2.5T, 2.2GeV). The method starts <br>with using the straight-through matrix to reconstruct to the target plane, then projecting from the target plane to the sieve slit. <br>The final step is to do ray tracing from the sieve slit to the target. After ray tracing the sieve slit pattern has an offset of ~40mrad <br>(~3deg). Chao's slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20131106/Chao_WeeklyMeeting_11062013.pdf here].
| |
| − |
| |
| − | *Min:
| |
| − | **Gave an update on her results from last week (see [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/10302013/10302013.pdf here]) of comparing target quantities. By including the energy loss contribution <br> that Jie has added to the simulation package, there is now agreement between the reconstructed delta and the data. There is <br>still an offset in phi, which Min will work on correcting. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/11062013/11062013.pdf here].
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Working on BPM calibration for the 3/14 optics runs, as his results do not agree with Chao's fitting results. He is trying to use <br>the harp scan runs along with BPMA information to determine the calibration for BPMB. JP voiced concerns over the non-linearity<br> of the harp scan runs. For next time, Pengjia will use this method for a situation where there were no problems with BPMB to show <br>that it gives a good result for the calibration. Chao will try to estimate the uncertainty on his result from fitting the data to better<br> compare to Pengjia's result. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/11062013/bpm_status_20131106.pdf here].
| |
| − |
| |
| − | ==10/30/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, Jie, Min, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie:
| |
| − | **Working on updating the simulation package. He has included the energy loss due to the various materials in the <br>target (Al, LHe etc.) and from the HRS entrance window. He showed a comparison of the energy loss at the sieve, with no <br>target field, for the case with and without the energy loss due to multiple scattering. The results are consistent with each<br> other. Next he will work on extracting the packing fraction by tuning the rates in his simulation. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_10_30_simulation/packing_fraction.pdf here].
| |
| − |
| |
| − | *Ryan:
| |
| − | **Compiled a list of the information he has on the nitrogen data from the Small Angle GDH experiment, which includes a <br>technote describing the radiation lengths and collisional energy loss and cross sections for several different kinematic settings. <br>He also showed an example of the cross section data closest to our settings, which is 2.135 GeV at 6 degrees in both 2 and <br>10 MeV bins. Next he will work on running the radiative corrections code. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_103013.pdf here].
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Working on BPM calibrations for the 3/14 optics run. For this time period, the "div" (attenuation) was changed from 4 to 2, <br>which had an affect on the BPMB calibration but not BPMA. The only harp scan data for div=2 with the target field on is from <br>the 3/16 optics run. To get the center position for BPM B, he will use BPMA and harp data. To determine the raster size at BPMB, <br>he will used the raster size and BPMA and the raster at the target. To check the rotation, he will look at two runs; one with only <br>raster x on and one with only raster y on. The results look promising, however the offset that Pengjia found (1.456 mm) does not <br>match with Chao's result from fitting the data (-3.5mm). He will check his method to see what could have caused this difference. <br>His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/10302013/bpm_status_20131030.pdf here].
| |
| − |
| |
| − | *Min:
| |
| − | **Showed a comparison of target quantities for the SNAKE transport functions and optimized data (using Chao's matrix) for a <br>straight-through run. The beam position used was determined from Chao's fitting of the data, but is also consistent with Pengjia's <br>results. The comparison for theta seems ok, though the mean of the peaks is off in some cases. She will check to make sure there <br>isn't a negative sign missing between the data and SNAKE variables. There was a considerable shift in the delta distribution, which <br>may be due to energy loss, since the SNAKE model currently does not include this. There was also a shift in the phi distribution; <br> after manually shifting the data by 0.004 rad the results seem to agree. Min will check for possible inconsistencies of variable <br>definitions that could have caused this shift. Next she will update her results using the latest optics matrix and will compare with <br>other delta scan runs. Her slides <br>can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/10302013/10302013.pdf here].
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *Chao:
| |
| − | **g2p simulation is currently being compiled by several different people. Once it is ready it will be distributed for everyone's use. <br>He will give more details about this next week.
| |
| − |
| |
| − | ==10/16/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Jixie, Jie, Min, Chao, Melissa <br>
| |
| − | By Phone: Karl, Ellie, Toby, Ryan, Pengjia, Moshe<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Working on calibrations for BPMB for the optics run on 3/14. He is using BPMA and harp scan data (from 3/16) to <br> get the center position at BPMB. To deterime the raster size, he is using the raster size at BPMA and the size <br>calulated from the carbon hole. Currently, he is trying to find a method to fit two circles in a 2D histogram; one <br>for the hole size, and one for the raster size. He still needs to figure out how a deviation from the circular fit <br>will relate to the uncertainty. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/10162013/bpm_status_20131016.pdf here].
| |
| − |
| |
| − | *Melissa:
| |
| − | **Showed a method to get the packing fraction using dilution runs. The estimate for the packing fraction found using <br> this method seems very low, even with the approximations made. The most likely reason is that her expression for the <br>yield does not account for the atomic mass of the target. She will update her calculations to include this and compare<br> the results with other energy settings. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_10_16.pdf here].
| |
| − |
| |
| − | *Melissa & Toby:
| |
| − | **Showed a comparison of their asymmetry results for all energy settings. While the results overall look good, there <br>are some discrepancies. They will chose one kinematic setting to focus on and determine the cause for these differences. <br>The slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Asym/AsymCompare.pdf here].
| |
| − |
| |
| − | *Moshe:
| |
| − | **Showed his progress on comparing cross section models to Vince's data. The data does not seem to match well with the<br> QFS or Bosted model, but these models may not be valid in this kinematic region. He will continue to use a cross section <br>model in his simulation until the radiative corrections for the nitrogen data are completed.
| |
| − | **Also showed his method for extracting the packing fraction. To avoid quasi-elastic contributions, he does a simple <br>background subtraction by subtracting a helium dilution run from a production run. By taking the ratio of the heavy elements <br>peak and the hydrogen peak, he can extract the packing fraction. His preliminary results look good, with a packing fraction <br>of 0.46 (0.43) from the lhrs (rhrs) data. This result will be used as an input for the GEp event Generator, which will then <br>provide a better estimation for the packing fraction through further iterations. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/moshe/MFoct1613.pdf here].
| |
| − |
| |
| − | ==10/9/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Jixie, Jie, Min, Melissa <br>
| |
| − | By Phone: Karl, Ellie, Toby, Ryan, Pengjia<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Toby:
| |
| − | **Described his method for determining the dilution factor. He expressed the number of scattered electrons in <br>terms of the background contributions, specifically in terms of known quantities which can be determined from <br>our dilution runs. There may be small contributions from other materials (target cup plastic, target nose, etc.),<br>which Toby can include as corrections later on. JP pointed out that, while this method works well in the DIS region,<br>it may be less valid in the resonance region; we will need to use Vince's nitrogen data to determine the nitrogen/carbon <br>cross section ratio. Toby's slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/10.09.13.pdf here].
| |
| − |
| |
| − | *Ryan:
| |
| − | **Looked at yields for 2.2 GeV, 2.5T, transverse setting. He looked at the first few momentum settings, with the <br>goal of correcting for the "gap" that appears between momentum settings. He started by making narrower focal plane <br>cuts to cut out any "junk" on the edge of the acceptance. The result was that the gaps between momentum settings <br>actually got larger, and that making tighter focal plane cuts reduced the "strength" of the elastic peak. He will try to adjust <br>the cuts (wider y-cut, narrower theta cut) to see if this improves the result. There seems to be good agreement for the yields<br> between runs in the same momentum setting. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_100813.pdf here].
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Working on BPM calibrations. Showed the change in pedestal for each channel of the BPM throughout the run period. Most <br>of the "jumpy" periods seem to occur when settings were changed. Also showed the results of calibrating BPMB based on BPMA <br>and harp scan information. The resulting raster pattern does not have a uniform distribution of events; there seems to be a hot-spot <br>near the center. Pengjia says this is a result of the happex DAQ, as is the hole in the center of the raster pattern. He will reconstruct <br>the same plot from HRS results to see if it looks the same. Also, he will show the raster pattern from BPMA to see if the distribution is<br> the same. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/10092013/bpm_status_20131009.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Working on determination of t0 for VDCs. Last time he showed two different methods for determining t0. The first used the<br> maximum slope of the VDC time distribution as the t0 offset. The second method used the maximum slope to extrapolate to <br>zero on the TDC channel axis, using the intercept as the t0 offset. This time, Jie compared the two methods and looked at the<br> effect on the tracking variables. The effect is small, with RMS ~10e-5. He is also working on updating the multi-track efficiency <br>code using tight acceptance cuts. Next he will work on the simulation package. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_10_07_t0_final/VDC_10_07_2013.pdf here].
| |
| − |
| |
| − | ==10/2/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Jixie, Jie, Min, Melissa <br>
| |
| − | By Phone: Alex, Ellie, Karl, Toby, Ryan, Pengjia<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Melissa:
| |
| − | **Looking at elastic yields for dilution runs, specifically the 2.2 GeV 5T longitudinal setting. The results so far <br>don't make sense, but it seems there is a problem with the definition of the yield. Due to the way the livetime <br>information was calculated, the prescale must also be accounted for in the yield formula. Her slides can be <br> seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Elastic/Elastic_10_02.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on optics analysis. She determined new transport functions using trajectories from the latest <br>SNAKE simulation. She incorporated the new transport functions into the g2p simulation and compared the thrown <br>and reconstructed results. Overall the results look good, with some discrepancies that she will look in to. Also, she <br>needs to check if the code accounts for energy loss. Next she will compare variables at the target plane for runs with <br>out the sieve. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/10022013/10022013.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Working on BPM calibrations. Jixie talked to the survey group and provided Pengjia with updated survey information, <br> but there is no uncertainty given for the angle. Pengjia showed a table of the resolution and uncertainty for the entire <br>run period. The resolution at the target seems suspect; he will check his calculation and provide the formula he used next <br> time. He is still working on calibrating BPMB using BPMA and the harp scan data for the "bad runs" listed in the table. His <br>slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/10022013/bpm_status_20131002.pdf here].
| |
| − |
| |
| − | ==9/25/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Jie, Jixie, Min, Melissa <br>
| |
| − | By Phone: Chao, Ellie, Karl, Toby, Ryan, Pengjia<br>
| |
| − |
| |
| − | '''Feature Presentations:'''
| |
| − |
| |
| − | *Jie:
| |
| − | **Showed a summary of the t0 calibration for the VDCs. He used two different methods to find t0. The first <br>method uses the point where the slope is steepest as t0. The second method looks for the point where the slope <br>is steepest, then extrapolates to the TDC channel axis to find t0. The remaining question about both methods is <br>how to deal with events that have t < 0. Jie will provide more details of how these events are dealt with. His slides <br>can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_09_24_multi_track_notes/VDC_summary.pdf here].
| |
| − | **Also wrote up a technote for the multitrack analysis, which can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_09_24_multi_track_notes/vdc_eff.pdf here]. Feedback would be appreciated.
| |
| − |
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Still working on BPM calibrations, will hopefully be done in the next couple of weeks. He will also provide a <br>global picture to describe quality of BPM information throughout the run period.
| |
| − |
| |
| − | *Ryan:
| |
| − | **Updated the trigger efficiencies to use actual PID cuts (previous cuts were estimated), and results are in the mysql<br> database.
| |
| − | **Got nitrogen/carbon data from Vince and will start looking at radiative corrections. The carbon data may not be <br>reliable due to ice build-up on septum during the run period.
| |
| − |
| |
| − | ==9/18/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Jie, Jixie, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Chao, Pengjia, Karl<br>
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − |
| |
| − | *Pengjia: Discussion on BPM calibrations, specifically the period in March when the calibration for BPMB is bad. <br>For the new calibration, Pengjia is using harp scan data to determine the position, and is determining the <br>radius by using either the "carbon hole" target or the BPMA raster size. JP says he needs to use both pieces of <br>information to determine the size. Pengjia needs more information from the survey group, JP/Jixie will talk to <br>them to get more details.
| |
| − |
| |
| − |
| |
| − | *Toby: Working on setting up replay on new ifarm machines. Chao has already setup Root/Analyzer. There are <br>still some problems with replay, which will hopefully be fixed by the end of the week.
| |
| − |
| |
| − |
| |
| − |
| |
| − | *Analysis Tasks:
| |
| − | **Optics and BPM calibrations are still ongoing (Min, Chao and Pengjia)
| |
| − | **Next step is looking at elastic runs and determining the packing fraction and dilution factor. An important <br>contribution to this will be the nitrogen/carbon data from the small angle GDH experiment (from Vince).
| |
| − | ***Ryan will work on radiative corrections for GDH nitrogen data
| |
| − | ***Toby will work on determining the dilution factor
| |
| − | ***Melissa will look at elastic data to understand spectrum, and will do a cross check of PbPt (once dilution factor is ready)
| |
| − | ***Jie will work on setting up simulation program to get packing fraction
| |
| − | **For reference, the analysis flowchart can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/kalyan/g2p_analysis_flow_feb2013.pdf here]
| |
| − |
| |
| − | ==9/11/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, JP, Min, Melissa <br>
| |
| − | By Phone: Alex, Moshe, Pengjia, Ellie, Toby, Ryan<br>
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Pengjia:
| |
| − | **Gave an update on the status of BPM calibrations. At one point during the run period, the "div" <br>(attenuation) was changed from 4 to 2, which did not affect the calibration for BPMA but seems to have had <br>a large affect on BPMB. To solve this problem, Pengjia is using a "brute force" calibration, where he finds a <br>reliable beam position from BPMA, then uses the carbon hole to determine the target center. From there he <br>can adjust the calibration coefficients to optimize the calibration for BPMB. JP suggested using a different <br>method to determine the center of the hole, as using the carbon is not a reliable method since the target will <br>move slightly during cool down etc. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/09112013/bpm_status_20130910.ppt here].
| |
| − |
| |
| − | *Toby:
| |
| − | **Showed raw and physics asymmetry results as a comparison to Melissa's results. However, there are still <br>some problems with the pass 2 replay, specifically the insertion of the helicity into the rootfiles, so these<br> results do not contain the full statistics. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/09.11.13.pdf here].
| |
| − | **Also, the computer center will be upgrading to CentOS 6.2 by the end of the month, so Toby will work <br> with Jixie and Chao to rebuild all the g2p software on the new machines.
| |
| − |
| |
| − | *Moshe:
| |
| − | **Gave an update on the status of the GEp event generator. He is using models for elastic hydrogen, helium-4 and<br> nitrogen-14 cross sections, and is using P. Bosted's model for non-elastic cross sections. JP suggested looking at <br>data (from Vince) for nitrogen, as the Bosted model will not be enough and the quasi-elastic nitrogen contribution is <br>quite large. He is also working on calculating the energy loss using a Geant4 simulation, but first he will need to <br>determine a value for the packing fraction (for each target material) by using HRSMC. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/moshe/meetingSep11_MF.pdf here]
| |
| − |
| |
| − | ==9/4/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, JP, Jixie, Min, Jie <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl <br>
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Chao:
| |
| − | **From last meeting we start to doubt the beam position. So Chao modified the program optimizor<br> such that it can also calculate the beam position at the end of the fit. The detail is that chi^2 <br>is now defined as Chi^2=dX^2+dY^2, where dX and dY are the distance of projected-back-position to <br>beam position, and this projected-back-position is based on surveyed sieve hole position and reconstructed theta | phi angles. The program is ready to run and the result shows that the beam position given by BPM<br>on March 4 is OK while on March 14 is not correct. The uncertainty of the beam position fitted by this program <br>is about 1.5 mm.<br>
| |
| − | **His talk can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130904/Chao_WeeklyMeeting_09042013.pdf here].
| |
| − |
| |
| − | *Min:
| |
| − | **Gave an update on SNAKE tuning. The focal plane variable of March 4 can match the real data with uncertainty <br>when select only the center row. But can not match well with March 14 data. The septum current ratio optimized by <br>matching focal plane of these data set agrees with Jixie's Geant4 prediction. <br>
| |
| − | **Mannually shift the BPM horizontal position of March 14 optics runs, she found that the focal plane variables <br>can be matched within unsertainty when shifted from 4.5 mm to -3 mm or -4 mm. This indicates that the BPM position <br>of March 14 runs are not reliable.
| |
| − | **Started to adjust aperture on SNAKE. JP suggested also using reconstruction matrix to do reconstruction and then <br> match the target plane variables.
| |
| − | **Will tune quartroples later.
| |
| − |
| |
| − | *Jie:
| |
| − | **Just back from China. Will work on writing the multi-tracks-analysis-note.
| |
| − |
| |
| − | ==8/28/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, JP, Jixie, Min, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia <br>
| |
| − |
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Ryan
| |
| − | **Looked at livetime asymmetries for all production runs over each momentum/energy setting and determined the mean <br>value, error and standard deviation for each resulting histogram. The livetime correction to the yield is done on a run-by-run <br>basis, but this method will allow Ryan to look for any overall systematic shifts in the livetime. JP suggested correcting the <br>livetime asymmetry within each momentum setting with the "expected value" so that all runs can be combined to increase the <br>total statistics. Also, each run should be weighted by statistics to make the standard deviation a meaningful representation of <br>the uncertainty. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_082813.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Gave an update on the status of the BPM calibration. Showed the uncertainties provided by the survey group, which gives an <br> uncertainty at the BPM of 0.25mm. He needs to contact the survey group to better understand the values provided.
| |
| − | **Also showed a timeline of calibration settings for early in the run period (March). Looking first at BPMA, it seems that the <br>calibration is fairly stable over this period. However, the calibration for BPMB is not very stable. It seems that using different "div" <br>settings (2 or 4) caused the BPMB settings to change but did not affect BPMA. JP suggested looking at runs immediately after the <br>calibration is done to see when the calibration for BPMB goes bad. Pengjia's slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/08282013/bpm_status_20130828.ppt here].
| |
| − |
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==8/21/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, JP, Jixie, Min, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Pengjia, Alex <br>
| |
| − |
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Melissa
| |
| − | **Updated previous asymmetry results to include charge/livetime/prescale normalization for all energy settings. Also <br>showed the corresponding physics asymmetries. The 1.1 and 1.7 GeV settings need some work, as the scaling from raw <br>to physics asymmetries doesn't quite make sense. Also need to look at asymmetries run by run to identify any possible bad <br>runs. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Asym/Asym_08_21.pdf here].
| |
| − |
| |
| − | *Chao
| |
| − | **Last time he found an offset between two sets of straight-thru data and is working on determining the reason for this <br>offset. He first tried using only first order matrix elements for the optimization, but the resulting sieve pattern was not <br>aligned very well. Next he tried including second order matrix elements in the optimization, using the data from a run with<br> liquid helium. Using this database to look at the run without liquid helium revealed a horizontal offset of 7.3mm. A possible <br>reason for this offset is that the BPM information is not quite correct. To check this he looked at simulations for two different<br> beam positions. The results looked suggested only a -0.3mm horizontal offset. Finally, he compared the focal plane plots for <br>settings with and without liquid helium. The bpm tells us there should be a ~7mm offset (~8mrad) difference between the <br>settings, but the data shows only ~2mrad difference. Chao will work with Pengjia to try to determine if there is a problem with <br>the bpm information. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130821/Chao_WeeklyMeeting_08212013.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Merged the db_run.dat and db_run.dat files for left and right HRS into one file to fix problems with replay on batch farm.
| |
| − | **Working on tuning the SNAKE parameters. She found the best results by adjusting the position of the septum and HRS along <br>the beam direction. Looking at the focal plane distribution for SNAKE and the data, there is a point where the SNAKE model "turns" <br>away from the data. Moving the HRS from its original position (1.96mm) to 0 does not seem to help, but moving the HRS and <br>septum both in the negative-y direction seems to correct for this "turn". Looking at a run with a large beam offset, there seems to be <br> a much larger difference between the data and SNAKE. Further, the plot of x vs y doesn't seem to match at all. It's possible that the <br>issue with bpm information that Chao found is causing similar problems for Min; she will try fixing the magnet positions and adjusting <br>the beam position to see how this effects her results. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/08212013/082113_min.pdf here].
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==8/14/2013==
| |
| − |
| |
| − | Present: Kalyan, JP, Chao, Min, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia, Alex, Guy <br>
| |
| − |
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Pengjia
| |
| − | **Showed an update on the status of BPM calibrations. He is currently using a method where he looks at the linear <br>portion of the BPM current vs. signal, and extrapolates the fit to determine and offest. This offset is used instead <br>of the pedestal value. JP is concerned about using this method - he and Pengjia will discuss it more offline.
| |
| − | **Also mentioned the makeup of the uncertainty for BPM calibrations. It will come from the BPM hardware resolution <br>(plus addition noise from radiation), uncertainty in the survey, and possibly a third contributer. The Beampackage is <br> ready to calibrate bpms and rasters for all run periods, with the exception of the fast raster which still has some issues. <br> His slides can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/08142013/bpm_status_20130814.pdf here]
| |
| − |
| |
| − | *Toby
| |
| − | **Presented raw asymmetries from pass 2. The results looking promising but still need to be corrected for charge, <br> livetime and prescale, and should use focal plane variables for acceptance cuts instead of "gold" variables.
| |
| − | **Also, there are still a few issues with the replay for pass 2 that need to be corrected. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/08.14.13.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Showed the results of livetime asymmetry analysis. He cross checked his results using scalar totals from both the <br>TTree and hel_ring tree, which also turned out to be a good check of the helicity decoder. In general, he found most <br> runs had a livetime asymmetry of less than 200 ppm. He will check to see if the distribution of his results is gaussian. <br>The results are also in the mysql database. His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_081413.pdf here].
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==8/7/2013==
| |
| − |
| |
| − | Present: Kalyan, Jixie, Chao, Alex, JP, Min, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Karl, Pengjia <br>
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Karl posted a couple of new papers to the wiki, they can be found [http://prd.aps.org/abstract/PRD/v87/i5/e054032 here] and [http://prd.aps.org/abstract/PRD/v85/i1/e016012 here].
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Melissa
| |
| − | **Showed raw asymmetry results for 2.2 GeV, 2.5T setting. JP suggested only using focal plane variables (not <br>reconstructed variables) for acceptance cuts until optics with target field is completed. Also, the prescale value <br> needs to be included to account for total statistics. Once the issues with the second farm pass are resolved, she <br>will include the normalization for charge/livetime and complete the analysis for all energy settings. Her slides can <br>be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Asym/Asym_08_07.pdf here].
| |
| − |
| |
| − | *Chao
| |
| − | **Showed an update on first order matrix calibration for the straight-thru conditions. Min did a study where there <br>was helium in the target nose, now Chao is doing a similar study but using runs where there was helium in the target <br>nose. Using the most updated BPM information, there is still a ~1.5mm offset in the horizontal direction. He is able<br> to clean up the data by cutting on focal plane and y-target, then makes a dp cut to distinguish between helium and <br>carbon peaks. Comparing his results for the first order matrix to the results without helium, the matrix changes quite <br>a bit. He will try to figure out what is causing this change and will compare the results to the SNAKE model. His slides <br>can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130807/Chao_WeeklyMeeting_08072013.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Working on matching SNAKE model to the data. Showed the results (for two sieve holes) of moving the septum and/or <br>HRS magnets by 1-2mm. There seemed to be some improvement, but she will continue to study this. She will also look <br>at the rest of the sieve holes to see the distribution/acceptance. Her slides can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/08072013/080713_snake.pdf here].
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==7/31/2013==
| |
| − |
| |
| − | Present: Vince, Kalyan, Chao, Min, Jixie, Melissa <br>
| |
| − | By Phone: Ellie, Toby, Ryan, Pengjia, Alex <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Pengjia
| |
| − | **Gave an update on the status of the BPMS. Showed plots of current vs raw BPM ADC values for several different <br>beam positions and saw that the distribution is linear above 30nA. Using the offset of the fit to the current, <br>he can determine the pedestal for each channel. Overall, the results look much better using this method, <br>although BPMB may still have some issues. Also showed a plot of raw current vs entry number. The spread in <br>position looks better then before using the new values for the pedestals. Next he will try to improve his <br>method to minimize current dependence and will try to use a non-linear fitting of calibration data. His <br>presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/07312013/bpm_status_20130731.pdf here]
| |
| − |
| |
| − | *Toby
| |
| − | **Working on pass-2 of farm replay. There were some issues using the batch farm, but they seem to be fixed now. <br> Rootfiles should be ready soon!
| |
| − |
| |
| − | *Ryan
| |
| − | **Was delayed by problems with helicity decoder, but should be able to finish helicity dependent deadtime analysis soon.
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==7/24/2013==
| |
| − |
| |
| − | Present: Vince, Kalyan, Chao, Min, Jixie, Melissa <br>
| |
| − | By Phone: Moshe, Pengjia, Ellie, Toby, Ryan, Guy <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − |
| |
| − | *Chao:
| |
| − | **Gave an update on simulations using the straight through optics conditions. He showed results comparing <br> the reconstructed and thrown variables for 3 cases. First, assuming an uncertainty in bpmA/bpmB of 0.2/0.4 mm. <br>Second, assuming no resolution in the bpms . And third, using only bpmA. From this he concluded the BPM <br>resolution will contribute 2e-4 to the delta reconstruction. A question was raised as to why the phi distribution was <br>so wide. Chao will check this for next time.
| |
| − | **Also updated the simulation package. The most recent version of the event generator uses a “random walk” <br>algorithm to generate particles following the cross section distribution. The simulation code is available for use, <br>and Chao will work on producing some documentation.
| |
| − | **Next up is working on optimizing the optics matrix for March 4th data to help Min, since the simulation package <br>will need input from her SNAKE model. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130724/Chao_WeeklyMeeting_07242013.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update on her SNAKE model. Using the most updated beam package and looked at the distributions of <br>the current, bpmA, bpmB and target variables versus entry for run 3185 (for both x and y). The distribution of the <br>target variables seems to follow the bpmB distribution. She selected a region of events in this run to remove <br>oscillations. Looking at the results for the uncertainty from the first order matrix, the uncertainty seems to be smaller <br>then before with delta-y = 1.90mm and dela-phi = 0.68mrad. However, looking at the current results for tuning the <br>septum field, the comparison between SNAKE at the data is not much better.
| |
| − | **Next she will try moving the location of the quads by 1-2mm and comparing the trajectories of runs 2725 and 3185. <br>Her presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/07242013/072413_snake.pdf here].
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==7/17/2013==
| |
| − |
| |
| − | Present: Vince, Chao, Min, Jixie, Kalyan <br>
| |
| − | By Phone: Ellie, Alex, Toby, Moshe, Pengjia, Karl <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − |
| |
| − | *Pengjia:
| |
| − | **Present the pedestal as a function of time for the whole data set. The pedestal were <br> drifting along time. They were not stable at all. Currently Pengjia subtracts only the averaged pedestal <br> of a period of time to reconstruct beam position for that period. He will need to do the subtraction run by run. <br>
| |
| − | **Also presented are the BPM calibration against Harp position for 100, 75 and 50 nA. It seems that the <br> calibration for 50 nA need to be redone. He also shown that the calibration constant is sensertive to <br> beam current. Whenever the beam tripped and then the beam position is not stable during the current was <br> ramping up.
| |
| − | **See detail [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/07172013/bpm_status_20130717.pdf here].
| |
| − |
| |
| − | *Moshe:
| |
| − | **Working on an event generator for simulation. Right now he is working on the energy loss caculation <br> using both EStar and Geant4. He mentioned that the energy loss result from EStar <br> does not agree with that from Geant4. <br>
| |
| − | **He is also trying to get cross section models for helium-4 and nitrogen-14. He has QFS model <br> in hand but this model is known to be poor. Vince agreed to provided him with some N-14 <br> data and Moshe will try to compare P.Bosted's model with Vince's data. Then decide which model to use.
| |
| − | **See his presentation [http://hallaweb.jlab.org/experiment/g2p/collaborators/moshe/meeting_Jul1713.pdf here].
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==7/10/2013==
| |
| − |
| |
| − | Present: Vince, Chao, Min, Jixie, Melissa <br>
| |
| − | By Phone: Ellie, Ryan, Toby, Moshe, Pengjia, Karl <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Chao
| |
| − | **Gave an update and summary of the helicity decoder There were a couple of bugs that needed to be fixed, <br>including the one bit delay. Also, the ring buffer creates a set of unused, extra events at the beginning of each <br>run, which will now be marked as an error. Finally, there was an alignment issue when inserting helicity information <br>back into the rootfile. These issues should all be fixed now. When using the decoder, the variable that should be <br>used to obtain the correct helicity of an event is "hel_act", and all events with hel_error /= 0 should be cut out.
| |
| − | **Also working on improving the decoder to deal with beam trip cuts. The cut should be made in units of helicity <br>patterns, so time information (from the fast clock) will be added to help make these cuts. His slides can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130710/Chao_WeeklyMeeting_07102013.pdf here].
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave a summary of her method to determine raw asymmetries including the applied cuts and method for extracting <br> the asymmetry. However, the issue with the helicity decoder described in Chao's talk means that the results shown are <br>not reliable. Concern was expressed over the error bars shown, she will carefully check this when she re-does the <br>analysis with the correct helicity information. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Asym/Asym_07_10.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Updated the LHRS optics calibration by including beam trip cuts and using the latest bpm information from Pengjia. <br> The results seem better! Cuts still need to be applied for when the beam moves. Since BPMB is not always stable, she <br> thought about just using BPMA to calculate the beam position at the target. Vince suggested that by correcting for the <br>beam movement the poor resolution in BPM B might be less significant and Min could still get reasonable results. Her <br>slides can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/071013/07102013_LHRS.pdf here].
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==7/3/2013==
| |
| − |
| |
| − | Present: Kalyan, Chao, Min, Melissa <br>
| |
| − | By Phone: Ellie, Ryan, Toby, Pengjia, Alex <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Ryan
| |
| − | **Updated the MySQL database to include Jie's results from multi-track analysis and Toby's results from target <br>polarization analysis. This information is also now included in the ROOT library. Also fixed several bugs that caused <br>missing information for some runs in the database. He is also working on helicity dependent deadtime analysis. <br>His slides can be seen [https://userweb.jlab.org/~rbziel/Weekly_Meetings/g2p_070313.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Gave an update on BPM analysis. He compared two techniques to reduce noise in the pedestal; applying a filter <br>and taking the average of every two seconds of data. The two methods seem to give similar results. For next time <br>he will look at how the change in current affects the position, and how using a 2Hz filter affects the mean value of <br>the BPM. His slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/07032013/bpm_noise_wfilter_20130703.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Finished writing a technote for the target polarization analysis and will be looking for feedback soon. He will also <br>start preparing for a second round of farm replay, since no event-type information exists in the rootfiles currently.
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==6/25/2013==
| |
| − |
| |
| − | Present: Karl, JP, Chao, Kalyan, Min, Melissa <br>
| |
| − | By-Phone: Ryan, Toby, Ellie, Pengjia, Alex, Moshe <br>
| |
| − |
| |
| − | '''General Discussion:'''
| |
| − | *Ryan will submit an abstract for a general g2p talk for the DNP meeting this fall.
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Chao
| |
| − | **Gave an update on optics simulation package. He showed the results of comparing the reconstructed and thrown <br>variables from simulation to see if he could reproduce the central value of delta, theta and phi. He determines the <br>average for each variable by taking the average of each point and weighting by the cross section. Currently, his <br>reconstruction stops at the target plane with z=0, which assumes that the target is symmetric along the z-direction. <br>He needs to find a careful way to correct for this. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/chao/20130626/Chao_WeeklyMeeting_06262013.pdf here]
| |
| − |
| |
| − | *Min
| |
| − | **Gave an update of LHRS optics calibration. She worked with Pengjia to get the bpm package with filter working <br>for ifarm replay (only LHRS for now, RHRS will be working soon). She used the updated bpm information to update <br>her results for straight-thru optics. She found that the results for theta were larger by a factor of ~3. She will try to <br>figure out if this is a result of the bpm filter or something else. She will also update her results to include cuts for <br>beam trips and beam moves. Her presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/06262013/062613_LHRS_revisit.pdf here]
| |
| − |
| |
| − | *Melissa
| |
| − | **Gave a followup on beam charge asymmetries. She updated her results to include beam trip cuts to compare with <br>Pengjia's results. The effect of adding the beam trip cuts is small (~ >0.05%), and Pengjia and Melissa's results agree <br>within ~1% or less. She also showed a comparison between results taken from ring buffer data and happex data. <br>There is a >1% difference between the two systems. Her slides can be seen [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/BeamCharge/BeamCharge_06_26.pdf here]
| |
| − |
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==6/19/2013==
| |
| − |
| |
| − | Present: Karl, JP, Vince, Jixie, Ellie, Kalyan, Chao, Jie, Min, Melissa <br>
| |
| − | By-Phone: Ryan, Toby, Pengjia, Alex <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Ryan
| |
| − | **Gave a recap of the y-target calibration for the LHRS. Last time he showed that he got strange results <br> during the optimization, specifically for the (0,0) and (-4,0) settings. By using a different run for <br>the (-4,0) setting he was able to improve the results. He then tried maximizing the event number per hole,<br> while still keeping the number of events approximately the same per hole. This improved the resolution of<br> the results. He also tried increasing the order of the optimization in the database. This also improved <br>the resolution, but may not be a reasonable solution since increasing the order can over constrain the matrix. <br>His presentation can be found [https://userweb.jlab.org/~rbziel/Weekly_Meetings/Optics_061913.pdf here].
| |
| − |
| |
| − | *Pengjia
| |
| − | **Gave an update on BPM analysis. He is currently rewriting the insert and calibration piece of the <br>beampackage to include the new filter method presented last time.
| |
| − | **Also working on a beam move check that uses rms detection for fast beam moves, looks at current trip<br> information, and splits events if the beam moves more than 0.3mm. He is still debugging this. He <br>also discussed pedestal subtraction for the bpm calibration. The pedestal shown was quite wide and had <br>multiple peaks. Pengjia will study this more to determine if this behavior is consistent through all runs,<br> or if this was a specific period when conditions were changing. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/06192013/bpm_status_20130619.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Worked with Josh and James to determine that there was in fact a bug in the online code to determine <br>target polarizations. This means the 2.5T polarization is actually ~50% of what was reported online. <br>This does not affect the 5T results.
| |
| − | **Showed details for his method of determining the TE points. He takes the time reported online for the <br>TE as the approximate start time, does a 0th order fit of the points and looks at the chi-squared value. <br>He then adds points until he finds the end point of the TE. Finally, he adds points at the beginning of <br>the TE to minimize the chi-squared value. The polarization is then averaged over each run. He questioned <br>how the polarization decay contributes to the uncertainty for each run, since the poarization is actually <br>decaying over each run. JP suggested using the average of the decay curve to determine this. Toby's <br>presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/06.19.13.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Has completed the efficiency study for multi-track events. This information will be in the mysql <br>database soon.
| |
| − | **Also working on data quality checks for optics variables. He looked at the t0 calibration first. One <br>concern is how "negative time" events are being dealt with. Jie will check that they aren't being cut out. <br>He also looked at the transport and rotated x,y,theta and phi variables. Within each kinematic settings, <br>these varibales look stable over all production runs. Jie will take a closer look the elastic settings next. <br>His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_06_18_optics_data_quality_check/data_quality_20130618.pdf here].
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==6/12/2013==
| |
| − |
| |
| − | Present: Karl, JP, Vince, Jixie, Chao, Jie, Min, Alexandre, Kalyan, Melissa <br>
| |
| − | By-Phone: Ellie, Toby, Ryan, Moshe, Pengjia <br>
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Chao
| |
| − | **Has fixed the bit-shift problem in the offline helicity decoder. The next round of farm replay will <br>have correct helicity information.
| |
| − |
| |
| − | *Melissa
| |
| − | **Showed a comparison between her and Pengjia's results for beam charge asymmetries. The results <br>show ~0.5% difference. It's possible that the beam trip cuts that Pengjia used is the reason for this <br>difference. Her presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/BeamCharge/BeamCharge_06_12.pdf here].
| |
| − |
| |
| − | *Min
| |
| − | **Showed an update of angle and vertex matrix calibration results using previous bpm calibrations. The results <br>are not better. She is still working on improving it by applying beam current cuts and beam position cuts.<br> She will also try using a different run to optimize that has the same conditions but a more stable current <br>She will check that the beam position is also stable during this run. Her slides can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/mhuang/06122013/061213_optics.pdf here]
| |
| − |
| |
| − |
| |
| − | ----
| |
| − |
| |
| − | ==6/5/2013==
| |
| − |
| |
| − | Present: Karl, Vince, Kalyan, Chao, Jie, Min, Melissa <br>
| |
| − | By-Phone: Ellie, Toby, Ryan, Moshe, Guy, Pengjia <br>
| |
| − |
| |
| − | '''General discussion:''' <br>
| |
| − | *There will be a practice talk for Min's Hall A Collaboration Meeting talk sometime soon (Friday or Monday?)
| |
| − |
| |
| − |
| |
| − | '''Feature presentations:'''
| |
| − | *Moshe
| |
| − | **Gave an update on the status of GEp analysis. He did a first round of analysis without calibrations, <br>to determine a general procedure for analysis. He showed preliminary results for elastic peak <br>identification, binning optimization, dilution factors and asymmetry extraction. He is also working <br>on writing a GEp event generator for HRSMC. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/melissac/Moshe/meeting_June0513_MF-1.pdf here].
| |
| − | **Details of status of GEp analysis can be found in [http://www.phys.huji.ac.il/~SimLiT/.gep/interim_analysis_report.pdf this document], written by Moshe.
| |
| − |
| |
| − | *Pengjia
| |
| − | **Working on improving BPM resolution. He added a low pass, software FIR filter when processing <br>the data, which seems to work very well. The previous results were 7-8X larger then the results that <br>have been processed with the filter. He is working on incorporating this into his beampackage code, <br>and will repeat his BPM noise study using the filter. Will also check if the central value changes at all <br>as a result of the filter. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/pzhu/06052013/bpm_resolution_improvement_20130605.pdf here].
| |
| − |
| |
| − | *Ryan
| |
| − | **Working on the LHRS Y-target calibration. He optimized 3 runs in the 2.2 GeV (0T, 6deg) setting <br>with different beam positions; (4,0), (0,0), (-4,0). The results seemed strange, specifically for the (0,0) <br>and (-4,0) settings. He first tried optimizing each run individually, which gives results that make sense. <br>He then tried optimizing them in pairs, and got reasonable results except for the combination of (0,0) <br>and (-4,0). Finally, he tried to check these results using other runs with the same beam positions, but <br>found that during these optics runs, the beam position was never moved back to (0,0). Vince pointed <br>out that the typical resolution for y-target is ~1mm, so these results may be ok. Ryan's presentation <br>can be found [https://userweb.jlab.org/~rbziel/Weekly_Meetings/Optics_060513.pdf here].
| |
| − |
| |
| − | *Toby
| |
| − | **Showed updated target polarization calibration constants. He decided to use a 3rd order polynomial <br>to fit the wings of the baseline-subtracted signal. It's possible that the discrepancy between using a <br>2nd and 3rd order polynomial could result from the signal "bleeding" into the wings. He described his <br>method for minimizing the reduced chi-squared to find the TE points. He starts with a set of 15 points <br>where the target is most thermalized, and adds points from the beginning/end of the TE to further reduce <br>the chi-squared.
| |
| − | **He also found that the 2.5T calibration constants found offline are ~50% smaller than what was determined <br>online. He will work closely with James/Josh to confirm that this really is a problem. His presentation can <br>be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/toby/g2p%20meetings/06.05.13.pdf here].
| |
| − |
| |
| − | *Jie
| |
| − | **Showed an updated version of multi-track efficiency analysis. He determined that his new method of <br>including background cuts is not as reliable as his previous method to determine uncertainty. By including <br>background cuts, the systematic uncertainty is decreased by about 20%, but it very position dependent, so <br>he suggests staying with his previous results. His presentation can be found [http://hallaweb.jlab.org/experiment/g2p/collaborators/jie/2013_06_04_multi_track_eff/Multitrack_20130604.pdf here].
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| Line 576: |
Line 50: |
| | [[Minutes_July2011_to_Dec_2011]] | | [[Minutes_July2011_to_Dec_2011]] |
| | ---- | | ---- |
| − | ==Jan-June 2012== | + | ==Jan-June 2011== |
| | [[Minutes_Jan2011_to_June_2011]] | | [[Minutes_Jan2011_to_June_2011]] |
| | ---- | | ---- |
