[g13] Flux Studies

Tue Sep 1 23:00:38 EDT 2015

Correction: For the first tagger t-bin cut listed in 2.65, it should be Run 53742.  

 - Paul

On Sep 1, 2015, at 10:57 PM, Paul Mattione <pmatt at jlab.org> wrote:

> I have more or less finished the flux studies.  I have been unable to find the exact source of a few of the large shifts in the flux-normalized yields, so I’ve decided to cut these runs from my analysis.  However, I have solved the discrepancies between the tagging ratios.  
> 
> Plots to refresh your memory (red lines in the FNY plots indicate regions where the tagging ratios are applied):
> Tagging Ratios: https://clasweb.jlab.org/rungroups/g13/wiki_secure/images/e/e6/Mattione_TaggingRatios_New.png
> 1.99 FNY: https://clasweb.jlab.org/rungroups/g13/wiki_secure/images/0/0b/Mattione_TotalFNY_1990.png
> 2.65 FNY: https://clasweb.jlab.org/rungroups/g13/wiki_secure/images/7/71/Mattione_TotalFNY_2655.png
> 
> 
> /*********************************************** TAGGER T-BIN CUTS ***********************************************/
> 
> Cuts for removing miscalibrated tagger t-bins (determined by studying fraction of photons that survived tagger/TOF delta-t cut) (All run ranges here and below are THROUGH the beginning and the end):
> 
> 1.99 GeV Data:
> 1) 53357: All T-Bins
> 2) T-Bin 30: All Runs
> 
> 2.65 GeV Data:
> 1) Run 53472: All T-Bins
> 2) Run 53853: 8, 22, 24, 42, 54, 56, 60
> 3) Run >= 53815: T-Bin: 62, 92, 102
> 4) Runs 53860 - 53862: T-Bin 94 - 96
> 5) T-Bin 4: 53833, 53850 - 53853
> 6) T-Bin 18: 53832 - 53833, 53838, 53844, 53849 - 53853, 53860 
> 7) T-Bin 26: 53833, 53844, 53850 - 53853
> 8) T-Bin 28: 53815 - 53853
> 9) T-Bin 30: All Runs
> 10) T-Bin 34 & 36: Runs 53820 - 53823, 53828 - 53853, 53855 - 53862
> 11) T-Bin 46: Runs 53829 - 53833, 53838 - 53839, 53843 - 53844, 53846, 53848 - 53853, 53860
> 12) T-Bin 76 & 94: Runs 53815 - 53818, 53855, 53860, 53862
> 
> 
> /*********************************************** BAD FNY RUN CUTS ***********************************************/
> 
> Cuts for removing runs with bad flux:
> 
> 1.99 GeV:
> 53333 - 53342 // Cause unclear
> 53459 - 53532 // Several plateaus, first one is beam position shift by 2mm. For the latter two, there is an abnormal increase in tagger hits for these runs, indicating possible beam scraping or some other additional noise hits.  These hits inflate the calculated flux, reducing the FNY. 
> 
> 2.65 GeV:
> 53551 // This run only had ~410k events (others had ~35 million), and for 86% of the scalar intervals the beam had tripped
> 53651 - 53687 // Cause unclear
> 
> 
> /************************************************* TAGGING RATIOS *************************************************/
> 
> Tagging ratio discussion:
> 
> 1) Tagging ratios from 53389, 53589, and 53770 are good.  The g, d -> p, pi-, (p) cross section is consistent between these run ranges (with a spread of < 2%). 
> 
> 2) Tagging ratios from 53228 should be ignored: The run was well prior to data taking (100 runs), during commissioning.  For these runs use the 53389 (nearby) constants instead.  
> 
> 3) Tagging ratios from 53699 should be ignored: During this run, the beam tripped during ~79% of the scaler intervals (hence the lower statistics).  It’s unclear if the “good” trip regions can even be determined with this many trips.  During the accepted scaler intervals, it’s likely that the beam was still scraping something, resulting in a lower tagging ratio.  For this run region, split it up amongst the 53589 and 53770 tagging ratios, with the split between runs 53655, 53656 (in a gap).  
> 
> 4) The tagging ratios from 53530 are OK.  However, IMMEDIATELY before this run, they performed many harp scans, noticed that the x/y axes of the harp scans were backwards, and moved the collimator position.  This probably improved the tagging ratio, meaning it should only be applied for runs 53530 - 53532.  However, all of the runs this tagging ratio is being applied to are being cut anyway, so it doesn’t really matter.  
> 
> 5) Relevant log entries for above:
> Noticed harp scan mixed: http://clasweb.jlab.org/clasonline/servlet/newloginfo?action=logentry&entryId=22575
> 53529: Harp scans with moving collimator position: Log entries 22576 through 22584
> 53536 (Between 1.99 & 2.65): Harp scans with moving collimator position: Log entries 22620 through 22622
> Collimator moved log entry: http://clasweb.jlab.org/clasonline/servlet/newloginfo?action=logentry&entryId=22623
> 
> 6) Until I rerun gflux, you can use the code I have for correcting the tagging ratios.  It’s on ifarm65 at:
> 
> /work/clas/clasg13/pmatt/svnroot_clas6/13a_pass2v2_32bit_centos65/users/pmatt/fluxcounter_v2/FluxCounterV2.cc
> 
> You can’t use this program directly, but the code you need is in the Correct_Flux() function towards the bottom, and the global (I know, I know, I was in a hurry) “gTagRatio” arrays.  
> 
> Enjoy.  
> 
> - Paul
> 
> 
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