Difference between revisions of "Compton Meeting, February 14, 2011"
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== Attendance == | == Attendance == | ||
| − | Kent, Amrendra, Mark, Vladas, Wouter (minutes), Dave (chair) | + | Kent, Dipangkar, Amrendra, Mark, Vladas, Wouter (minutes), Dave (chair) |
== Minutes == | == Minutes == | ||
| Line 16: | Line 16: | ||
* Electron detector | * Electron detector | ||
| − | ** presentation by Vladas | + | ** presentation by Vladas (elog 151) |
*** efficiency of ~8% for plane 1, ~2.5% for planes 2 and 3 | *** efficiency of ~8% for plane 1, ~2.5% for planes 2 and 3 | ||
*** efficiency-corrected population per strip looks reasonable | *** efficiency-corrected population per strip looks reasonable | ||
| Line 22: | Line 22: | ||
*** strip 0 is approximately half-way between rho = 0 and rho = 1 | *** strip 0 is approximately half-way between rho = 0 and rho = 1 | ||
*** now 3.6 mm away from beam?? should be 8.5 mm to strip 0, so maybe 7 mm, but then guard strips, and first 4 strips are connected to ground... so maybe 6 mm | *** now 3.6 mm away from beam?? should be 8.5 mm to strip 0, so maybe 7 mm, but then guard strips, and first 4 strips are connected to ground... so maybe 6 mm | ||
| − | ** | + | ** presentation by Amrendra (elog 150) |
| + | *** looks good | ||
| + | *** today will swap the cables | ||
| + | *** DD: different from Dec 10, now more hits on strips 0-32 | ||
| + | *** should figure out what to do on 0-32, then repeat efficiency studies on this run | ||
| + | *** background-subtracted and background on hclog 220185, odd channels lower due to being read out on one side, should be taken into account when efficiency is calculated on these runs | ||
| + | ** Amrendra: 4mm away from beam, is this safe? | ||
| + | *** in IR, no large excursions when looking at EPICS during beam recovery | ||
| + | *** it has survived beam trips already, so probably OK | ||
| + | *** should have taken out for Moller measurement today probably | ||
| + | *** general feeling that it should be safe unless wild things happen | ||
| + | *** harp scans upstream? no difference with being in garage... so also acceptable | ||
| + | ** if access, need 10 mins to push QWADs | ||
| + | |||
| + | * Laser | ||
| + | ** fine, apart for unhealthy CPslow | ||
| + | ** locking at 700W | ||
| + | ** time to go down? no, would need longer time | ||
| + | |||
| + | * Photon detector | ||
| + | ** signal path, see elog 56 | ||
| + | *** QDC is in data stream, only first QDC entry should correspond to the snapshot in the helicity event | ||
| + | *** threshold now 20mV for un-amplified signals coming up | ||
| + | ** shift of baseline | ||
| + | *** shifts in baseline from tunnel are large even in ms interval | ||
| + | *** pedestal shifts are not caused by the ADC itself, eliminated by Don's studies | ||
| + | *** phosphorescence in CsI(pure), see paper, evidence on 5-10s timescale | ||
| + | *** similar to what has been seen before at 20min timescale? | ||
| + | *** does correction as Don is doing right now taking care of this? | ||
| + | ** plans | ||
| + | *** Zener'ize the bases, characterize the tube, glue on to spare crystal | ||
| + | *** test: mini-megan, or detector group lab | ||
| + | *** build mini-megan into photon detector, Don has all the pieces | ||
| + | *** | ||
Revision as of 15:02, 14 February 2011
Agenda
Attendance
Kent, Dipangkar, Amrendra, Mark, Vladas, Wouter (minutes), Dave (chair)
Minutes
- Only last few days we had good beam
- before that, bad background, flucts in norm scint by factors
- since Friday/Saturday we have better conditions, S/N of 50%
- CPslow keeps locking up
- memory issue? need to run memtest on it at next access
- pictures of every lock-up would be useful
- hcreboot switch from GEM will be used for Compton
- Don set it up to reboot on exception error, not tested yet
- Electron detector
- presentation by Vladas (elog 151)
- efficiency of ~8% for plane 1, ~2.5% for planes 2 and 3
- efficiency-corrected population per strip looks reasonable
- Compton-edge at strip 48, or 1.74 cm (according to Mark & Jay's calculation)
- strip 0 is approximately half-way between rho = 0 and rho = 1
- now 3.6 mm away from beam?? should be 8.5 mm to strip 0, so maybe 7 mm, but then guard strips, and first 4 strips are connected to ground... so maybe 6 mm
- presentation by Amrendra (elog 150)
- looks good
- today will swap the cables
- DD: different from Dec 10, now more hits on strips 0-32
- should figure out what to do on 0-32, then repeat efficiency studies on this run
- background-subtracted and background on hclog 220185, odd channels lower due to being read out on one side, should be taken into account when efficiency is calculated on these runs
- Amrendra: 4mm away from beam, is this safe?
- in IR, no large excursions when looking at EPICS during beam recovery
- it has survived beam trips already, so probably OK
- should have taken out for Moller measurement today probably
- general feeling that it should be safe unless wild things happen
- harp scans upstream? no difference with being in garage... so also acceptable
- if access, need 10 mins to push QWADs
- presentation by Vladas (elog 151)
- Laser
- fine, apart for unhealthy CPslow
- locking at 700W
- time to go down? no, would need longer time
- Photon detector
- signal path, see elog 56
- QDC is in data stream, only first QDC entry should correspond to the snapshot in the helicity event
- threshold now 20mV for un-amplified signals coming up
- shift of baseline
- shifts in baseline from tunnel are large even in ms interval
- pedestal shifts are not caused by the ADC itself, eliminated by Don's studies
- phosphorescence in CsI(pure), see paper, evidence on 5-10s timescale
- similar to what has been seen before at 20min timescale?
- does correction as Don is doing right now taking care of this?
- plans
- Zener'ize the bases, characterize the tube, glue on to spare crystal
- test: mini-megan, or detector group lab
- build mini-megan into photon detector, Don has all the pieces
- signal path, see elog 56
