[Halld-online] [Revised Logentry] BCAL, CDC cosmic events

[davidl at jlab.org]

Logentry Text:
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A cosmic run was completed on June 18th that ran 3 DAQ systems fed simultaneously by the same cosmic trigger. The 3 DAQs read on the BCAL North side, BCAL South Side, and CDC crates. The files written were:

/gluonraid1/rawdata/active/RunPeriod000/BCAL/north4/bcal_n4_512.0
/gluonraid1/rawdata/active/RunPeriod000/BCAL/south/bcal_s4_3166.0.coda
/gluonraid1/Users/hdcdcops/run00091_00.evio

These were merged using the evio_merge_events tool in sim-recon (see src/programs/Utilities/evio_merge_events). The merged file can be found here:

~davidl/HallD/Studies/2014.06.23.bcal_cdc_cosmics/bcal_cdc_cosmics.evio

The file is 2.7GB and contains 1809 events. the large size is due to having read out a full window of samples for every channel for every event.

The events clearly show cosmics in coincidence between the BCAL and CDC. Here are a couple of screenshots of hdview2:

[figure:1]

[figure:2]

To produce these images, one needs to attach both the DAQ and TTab plugins to hdview2. One also needs to set a threshold on the amplitude value of CDC hits in order to cut away the noise. The exact command line is:

hdview2 -PPLUGINS=DAQ,TTab -PCDC:DIGI_THRESHOLD=500000 ~davidl/HallD/Studies/2014.06.23.bcal_cdc_cosmics/bcal_cdc_cosmics.evio

The CDC values are being converted from integrated fADC125 counts into "physical" units using a scaling factor of:  4.0E3/1.0E2. This was obtained empirically, but roughly estimating the size of "q" in the DCDCHit objects produced by simulation (i.e. in the HDDM file) and those of the integrated fADC125 values.

For both the BCAL and CDC hits, event-by-event measured pedestals were subtracted. The BCAL used a pedestal measured from the first 5 samples and the CDC used the first 20 samples.


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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3288617
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