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Kaon LT Meetings » ref_times_email_exchange.txt

Nathan Heinrich, 01/26/2023 05:00 PM

 
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Hello Mark and Carlos,
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   I submitted the pull request.  You can see the type of diagnostic histograms the code produces here:
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https://hallcweb.jlab.org/xem2/tmp/plot_tmp.htm
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The only thing I am not totally sure about is the COIN DAQ Reference times for pT2 and hT1
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If you load "coin_reftimes.root" in the link above (enter CUE username and password) and load you will see c6_pT and c6_hT.  
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For T.coin.pT2 tdcTimeRaw and T.coin.hT1 tdcTimeRaw I am drawing the refence time as t_coin_trig_tdcrefcut.  
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Do you know if that is the correct reftime cut for those channels in the COIN DAQ?  I haven't used it much. 
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Cheers,
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Casey Morean
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Casey,
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      Carlos can double check me, but the pT1 is the reference time for slot 19 tdc
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and the pT2 is for slot 20 tdc. The slot 20 has the channels like pTRIG1_ROC2 
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which are used for coincidence.
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      We should really define te HMS trig detector and the SHMS trig detector
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for coincidence instead of this joint COIN trig detector.
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Then we could set the reference time separate for the HMS channels and
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SHMS. But we have been only using the SHMS channels for the coincidence.
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Cheers,
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          Mark
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Hi Casey,
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I think pT1,pT2 (SHMS) and hT1,hT2 (HMS), are just copies we use of the reference time, but only one from each arm 
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in set as the reference time in HCANA
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Here is a link to a DEF-file for 50k replay I have for CaFe, were I added the reference times directly to the 50k replay ONLINE GUI
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so I could monitor the reference times directly.
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For SHMS:
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https://github.com/Yero1990/cafe_online_replay/blob/master/DEF-files/cafe_shms50k.def#L393
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For HMS:
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https://github.com/Yero1990/cafe_online_replay/blob/master/DEF-files/cafe_hms50k.def#L358
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I don't  remember which one is actually used, but pT1 and pT2 should not really be that different. You can plot both pT1,pT2
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and check.  Same for hT1 and hT2, for HMS hodoscope reference times
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** Something I noticed when plotting reference times in the online GUI is that in the 50k replay, if you have both singles and coin. triggers
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enabled in the DAQ, you actually will see the reference time repeated for both singles and coincidence, and shifted by a time deltaT. 
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Then you can put a cut to require the event type to be either only singles or a coin. event,  and that way you can figure out which one
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you should put in the tcoin.param. Anyways, I only tried this recently, so you can also check using recent pionLT data.
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Also, like Mark said, we have always been using the tcoin.param to set the t_coin_trig_tdcrefcut
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from ONLY pT1.  And we should really probably add a parameter like:  t_coin_hms_trig_tdcrefcut, t_coin_shms_trig_tdcrefcut
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to set an HMS and SHMS ref. time cut independently, rather than only setting.  But I wonder if that means we have to change
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something in HCANA to allow these separate reference times to be applied.
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Thanks,
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Carlos
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