Quick VPT Test Rig meeting - minutes

Date of meeting: 6 April 2000

Present: KWB, PSF, BWK, ALL, CAXP, MS, JHW

1.  Future meetings will be held weekly at 10am on Friday

2.  Status of test rig mechanics (ALL/JHW)

• Design of 48-cell test array finished
• Mechanics 90% in hand; only awaiting mounting plate
• Rail system - finalise design as test array is constructed

3.  HV (ALL)

• Component list finished
• Read relays ordered - delivery time is 2 months

4.  Electronics (MS)

• Component list under way
• Triggering & readout electronics mostly exists
• LED - use same type as at Brunel, with peak at 430nm: need 3 per channel for burn-in + 1 for pulsing, so 200 total.  KWB suggested using the OPAL 48-way LED driver.  Will need RS232-controllable 5V power supply for burn-in
• Preamps: Bristol have 30; Tony Lodge has 100, of which 40 are believed to have long time constants for Brunel.  Frank Jacob may also have some - MS will investigate when he is at CERN from 9 April
• Cabling - expect to use screened twisted pairs outside rig
• Preamp box: need 2 25-way boxes for compatibility with supercrystals.  Get advice from Tony Lodge on screening, isolation, connector type.

5.  Bar code reader - will need advice from CRISTAL experts on suitable readers.  Possible difficulty arises from curvature of VPTs if bar code is applied around circumference.

6.  Control system software.

• Stepper motor control finished
• Magnet control - Andrew L's program works
• HV control - ALL has just received new LabView driver.  CAXP to try this out as soon as possible.
• Likely that we will need more than 3 serial ports - ALL to look into multi-port units.  8-port units exist for about $450 which might be suitable.

7.  Monitoring.

• Use a standard VPT in each row to monitor LED output, cycling through 8 positions  - ie 42 new VPTs per run
• KWB - need to avoid repeated burn-in of standard VPTs; best method seems to be masking burn-in LEDs in cells containing standards
• Possibly use pin diode and separate LED to monitor output of pulse generator
• ADCs: choice of 2249A or 2249W - A needs gate width of less than 200ns, W less than 2 us.  With Stephenson preamp A will be suitable.

8.  DAQ and data storage

• MS and CAXP have successfully transferred data from single-VPT test rig to Excel for analysis.
• BWK at CERN last week - talked to E Auffray & G Chevenier (CRISTAL and LabView experts respectively).  Chevenier has provided a skeleton LabView application to communicate with CRISTAL.
• P Lecoq and J-M LeGoff will be in UK during the week of 17 April - BWK will meet them & Helen Heath to discuss setting up CRISTAL d/b at RAL.

Bruce Kennedy / 05 December 2003