[Sbs_gems] [New Logentry] GEM summary with new gas

[hszumila at jlab.org]

Logentry Text:
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Our work is about complete for today on studying the GEM HV gain with the new gas. Our run listing is here:https://logbooks.jlab.org/entry/4294620

Our merits that we studied: comparisons of the ADC spectra and cluster size, induction currents as measured and compared both to BigBite and the currents measured during the scan on 21-Apr. We loosely observed the efficiencies in a general way, but we see that the statistics is rather low at the low rate run and the efficiency decreases with the high rate runs. 

We have essentially settled at 3625V for the back tracker which showed very good efficiency at the low current hydrogen running (80-90%). 

We backed off on the HV for the front tracker to 3600V which also still looks much improved, but it would be good to study the data and tune-up the analysis/alignment/tracking over the next few shifts before motivating any higher push in HV for the front tracker. 

I also suspect that the analysis will benefit now from a slightly higher threshold in the software with this higher gain. While we probably still have some headroom to go up another 1% safely on the gas mixture, I think we should really optimize where we are at for now before trying for that change as it would need more dedicated time to safely study the gain response. 

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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/4294788
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