CDC recent run drift times

From GlueXWiki
Jump to: navigation, search

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; often there is a smaller peak before a larger one; less often the pedestal rises between the start of the data window and the peak.

Summary up to run 2713

Removing alcohol decreased max drift time by 20ns and decreases gain by at least 20%.
Decreasing CO2 gas conversion factor from 0.773 to 0.74 increased max drift time by 8s and decreased gain slightly (difficult to quantify the gain decrease).
Moving the CO2 from controller CH2 to 4 and switching the mixer from rate to blend and back caused only very small changes, if any.
Changing the CO2 gas conversion factor from 0.74 to 1.0 decreased max drift time by 70ns and increased gain x 236%
Changing the CO2 gas conversion factor to 0.5 increased max drift time and decreased gain, now looks like between 58 and 59% CO2


Run 2451 - solenoid off

7 Feb 2015. First run of 2015. Increased sparsification thresholds from 7sigma to 15sigma.
Garfield 0T 55.78% Ar 43.82% CO2 0.4% 2-propanol (0.4% propanol added to mix of 56% Ar + 44% CO2) has t 561ns @ 0.76cm, tmax 577ns @ 0.77cm
Adding 0.5% 2-propanol to 56/44 Ar/CO2 gives Garfield t of 565ns @ 0.76cm and 1% 2-propanol gives Garfield t of 590ns @ 0.76cm
With a gas mix of 65/44, time < (550-t0) x 0.8ns = 66ns corresponds approximately to drift radius < 2.9mm

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 < 550, 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 56% Ar 44% CO2 has t ~543ns @ 0.76cm, 558ns @ 0.77cm
Garfield 0T 57% Ar 43% CO2 has tmax ~543ns @ 0.77cm

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 < 550, 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 < 550, 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.
Drift times increased substantially due to the magnetic field. Amplitude not inconsistent with that from run 2560 (lower stats in this run).
Garfield 1.75T 56% Ar 44% CO2 has t ~597ns @ 0.76cm, 613ns @ 0.77cm
Garfield 1.75T 57% Ar 43% CO2 has tmax 603ns @ 0.77cm
Garfield 1.75T 57.5% Ar 42.5% CO2 has tmax 596ns @ 0.77cm

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 2617 - solenoid at 1200A

11 March

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal (all)


Run 2619 - solenoid at 1200A

12 March

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal (all)


Runs 2616 to 2619 combined - solenoid at 1200A

11-12 March

Hit thresholds 180-100-25, window 44-150, time 570 is drift time 0.8*(570-510) ~ max drift time at 1.75T for 0.23cm (drift radius for time 550 in earlier runs)
max amplitude vs time
max amplitude - pedestal, time < 570, straw 1021


Run 2642 - solenoid off

14 March. After moving CO2 controller from ch2 to ch4 (on March 13) and decreasing sparsification thresholds to 8sigma

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal (all)


Run 2644 - solenoid off

16 March.

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal, time < 556, straw 1021
max amplitude - pedestal (all)

Run 2649 - solenoid off

17 March. 10 hours after returning CO2 controller from ch4 to ch2

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal, time < 556, straw 1021
max amplitude - pedestal (all)


Run 2676 - solenoid off

22 March.


Run 2688

26 March. switched gas mixer back from independent "rate" mode into "blend" mode


Run 2692 - solenoid off

27 March. 1 day after switching gas mixer back from independent "rate" mode into "blend" mode

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal, time < 550, straw 1021
max amplitude - pedestal (all)


Run 2713 - solenoid off

6 April. 1 day after changing the CO2 gas conversion factor from 0.74 to 1.0
Comparing tmax with Garfield, this looks like 61.5% Ar 38.5% CO2

Hit thresholds 180-100-25, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude vs time
max amplitude - pedestal, time < 556, straw 1021
max amplitude - pedestal (all)


Run 2839 - solenoid off

17 April. **With HV filters** ~ 7 days after changing the CO2 gas conversion factor to 0.5
Comparing the max drift time with Garfield, this looks like a little over 48% Ar.

Hit threshold too high: 180-100-25, window 44-150 (same as previous)
Drift time fit, threshold too high
zoomed in (threshold too high)
pedestal
max amplitude vs time
max amplitude - pedestal, straw 1021
max amplitude - pedestal
*** Hit threshold too low: 40-48-12 (to see where the noise is) ***, window 44-150
Drift time fit, threshold too low
zoomed in (threshold too low)
pedestal
max amplitude - pedestal
Hit threshold: 60-48-12, window 44-150
Drift time fit
zoomed in
pedestal
max amplitude - pedestal

Tightening the window to 45-145 did not change the max drift time estimate; increasing the thresholds from multiples of 12 to multiples of 13 added 2ns.


Hit threshold: 65-52-13, window 45-145
Drift time fit
zoomed in
pedestal
max amplitude - pedestal
Same thresholds as previous, plots for all straws, not just neatest time group, hit threshold: 65-52-13, window 45-145
pedestal vs straw #
time vs straw #
max amplitude - pedestal vs straw #
time vs straw #
max amplitude - pedestal vs straw #
max amplitude straw 255 from cdc algorithm
Max amplitude from fa250 emulation (without pedestal subtraction, to find out what the sparsification thresholds are)
max amplitude straw 255 from emulated fa250 algorithm
max amplitude from emulated fa250 algorithm vs straw number, first straws


Run 2881 - solenoid off - 2150V

From Garfield for 2150V, 0T, 296K, 760mmHg, 48% Ar and 52% CO2, expect max drift time 647ns

Hit threshold: 65-52-13, window 45-145
Drift time fit
zoomed in
pedestal
max amplitude - pedestal
max amplitude using lower threshold to look for noise
max amplitude without pedestal subtraction to check on sparsification thresholds


Run 3221 - solenoid off - 2130V

Atmospheric pressure is 758mmHg, would make max drift time ~ 2ns quicker than at 760mmHg. Downstream plenum temp mean at start of run is 296.1K

 Garfield max drift times:
==> /raid1/cdc/garfield/xt_halld/xt_cdc_296K/xt_cdc_8mm_2130-0T-296K-760mmHg-4650-5350-20um.asc <==
0.77 0.67619509

==> /raid1/cdc/garfield/xt_halld/xt_cdc_296K/xt_cdc_8mm_2130-0T-296K-760mmHg-4700-5300-20um.asc <==
0.77 0.66548866

==> /raid1/cdc/garfield/xt_halld/xt_cdc_296K/xt_cdc_8mm_2130-0T-296K-760mmHg-4750-5250-20um.asc <==
0.77 0.65825182

==> /raid1/cdc/garfield/xt_halld/xt_cdc_296K/xt_cdc_8mm_2130-0T-296K-760mmHg-4800-5200-20um.asc <==
0.77 0.65352875


Hit threshold: 65-52-13, window 24-124, reduced number of straws due to bunches of noisy straws
Drift time fit
zoomed in
pedestal
max amplitude - pedestal