CDC recent run drift times

Fitted drift time function to straws in run 2451, picked straws with tmax slope < 30, used same straws for subsequent runs. Used same hit thresholds & window for all runs.

The drift times are for a small group of straws. In the earlier runs the amplitude histograms are cut off at the lower end by the sparsification threshold. There are a few straws with noise (and threshold) low enough that the MPV is visible. The max amplitude histograms show entries below the sparsification threshold because I used a lower threshold for analysis, added to the pedestal just before the peak; sometimes there is a smaller peak before a larger one; sometimes the pedestal rises between the start of the data window and the peak.

1 Run 2451 - solenoid off
2 Run 2551 - solenoid off
3 Run 2560 - solenoid off
4 Run 2577 - solenoid off
5 Run 2616 - solenoid at 1200A
6 Run 2617 - solenoid at 1200A
7 Run 2619 - solenoid at 1200A
8 Runs 2616 to 2619 combined - solenoid at 1200A
9 Run 2642 - solenoid off
10 Run 2644 - solenoid off
11 Run 2649 - solenoid off
12 Run 2676 - solenoid off
13 Run 2688
14 Run 2692 - solenoid off

Run 2451 - solenoid off

7 Feb 2015. First run of 2015. Increased sparsification thresholds from 7sigma to 15sigma.
Garfield 0T 5475-4525 Ar-CO2 has tmax ~560ns

Hit thresholds 180-100-25, window 44-150
Drift time fit straws with param 6 < 30	drift time fit zoomed in	pedestal	max amplitude vs time	max amplitude - pedestal, time < 500, straw 1021	max amplitude - pedestal (all)

Run 2551 - solenoid off

2-3 March 2015. 3 weeks after disengaging the alcohol bubbler.
Compared with run 2451, drift velocity has increased and gain decreased (but cannot measure the gain decrease very well due to thresholds).
Garfield 0T 5600-4400 Ar-CO2 has tmax ~542ns

Hit thresholds 180-100-25, window 44-150
Drift time fit straws with param 6 < 30	zoomed in	pedestal	max amplitude vs time	max amplitude - pedestal, time < 500, straw 1021	max amplitude - pedestal (all) \|}

Run 2560 - solenoid off

8 March 2015. 5 days after changing the CO2 gas factor from 0.773 to 0.74 (should result in increase in CO2 %). The gas factor was changed before run 2552.
Comparing with run 2551, drift velocity and gain have both decreased slightly (consistent with more CO2).

Hit thresholds 180-100-25, window 44-150
Drift time fit straws with param 6 < 30	zoomed in	pedestal	max amplitude vs time	max amplitude - pedestal, time < 500, straw 1021	max amplitude - pedestal (all)

Run 2577 - solenoid off

10 March 2015. 1 day after changing the gas mixer MFCs from master/slave "blend" to independent "rate" mode (this change was made before run 2563). For this run the readout window is different from that in all the others.

Hit thresholds 180-100-25, window 64-170
Drift time fit straws with param 6 < 30	zoomed in	pedestal	max amplitude vs time	max amplitude - pedestal (all)

Run 2616 - solenoid at 1200A

11 March 2015. 2 days after changing the gas mixer MFCs from master/slave "blend" to independent "rate" mode. Garfield 1.75T 5600-4400 Ar-CO2 has tmax ~596ns
Drift times increased substantially due to the magnetic field. Amplitude not inconsistent with that from run 2560 (lower stats in this run).

Hit thresholds 180-100-25, window 44-150
Drift time fit straws with param 6 < 30	zoomed in	pedestal	max amplitude vs time	max amplitude - pedestal, time < 500, straw 1021	max amplitude - pedestal (all)