1M. Ellis - Tracker PC - 7th March 2007 VLPC Cassette Characterisation Third application (as described in past tracker meeting and CM17) is now working and has been used on the data taken from cassettes 105 and 112. First look at cassette 105 data and compare set points determined by this application with those used at KEK. Then look at unknown cassette 112. Application attempts to categorise each channel as either: u Dead(no obvious light with the LED on) u Alive(good multi photon fit) u Break down(wide pedestal, no clear multi photon peaks) The application determines for each MCM which voltage produces the maximum number of alive channels with the highest number of photons seen (i.e. maximum QE). The gain is also returned for this optimum value.
2M. Ellis - Tracker PC - 7th March 2007 Cassette 105 Was used in KEK. Set points were taken from D0 values and then modified while at KEK to attempt to optimise the performance for the cosmic ray data taking (lower rate). This optimisation was done “by hand”, but serves as a resonable basis for comparison. Following plots show results of application. Three plots per MCM: 1. Shows the number of dead (red +), alive (green *) and broken down (blue o) channels as a function of the bias. 2. Shows the gain as a function of bias 3. Shows the number of photons as a function of bias.
3M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 1
4M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 2
5M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 3
6M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 4
7M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 5
8M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 6
9M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 7
10M. Ellis - Tracker PC - 7th March 2007 Cass 105 – MCM 8
11M. Ellis - Tracker PC - 7th March 2007 Cass 105 – Results AFE MCM Bias Alive Gain Num PE MCMKEK VCalib VGain# PE Voltages determined by application seem to be in reasonable agreement with values used in KEK run. Gains at these voltages are also similar. Mean number of PE is uniform ~ 10% over the cassette. No dead channels in cassette 105
12M. Ellis - Tracker PC - 7th March 2007 Cassette 112 New VLPCs with unknown performance. No prior experience (D0 or MICE) so no idea of correct bias, number of dead or noisy channels, gain, QE, etc... Application returned the following: A few channels are apparantly dead. Two MCMS have all channels good. Worst MCM has 5 dead channels. Overall: 495 out of 512 good channels
13M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 1
14M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 2
15M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 3
16M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 4
17M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 5
18M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 6
19M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 7
20M. Ellis - Tracker PC - 7th March 2007 Cass 112 – MCM 8
21M. Ellis - Tracker PC - 7th March 2007 Conclusions When I get a chance I want to tidy up the third application so that it is a little more user friendly, then it will go into CVS. I think the tools are working reasoanbly, although I suspect Alan and I need to spend some time together looking over the results to tweak a few things. We can get going with the VLPC characterisation (still need to sort out cryo set points for 9.5K though). It looks like Cassette 112 should be fine for QA work, but perhaps shouldn’t be used for a production cryostat.