Quick VPT Test Rig meeting - minutes

Date of meeting: 12 May 2000

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

 1.  Mechanics

• All components now in hand
• Assembly started; first bank of 8 VPT holders should be ready for testing with stepper motor under LabVIEW control by 19 May.

2.  LabVIEW

• Stepper motor control system is ready for tests next week.
• Can now control HV supply; cosmetic improvements (nice control panel etc) in next few days.
• Magnet control application exists; cannot test until magnet cooling water becomes available (about 2 weeks).

3.  HT

• ALL has started to build the leakage current box.

4.  Electronics, LEDs

• BWK received an email from David Cussans concerning Stephenson preamps.  Bristol are having a set of 5-channel boards made for the testbeam.   We will request a spare board for testing (available by 19 May), and a 6*5 channel system should be available in the first week in June.  Bristol will find a suitable box for the system; our only special requirement is that it should be non-magnetic.
• Preproduction VPTs will arrive from manufacturer with 10 hours burn-in.  Results obtained by MS indicate that a longer burn-in period is required to reach a steady operating state, so we must still make provision to burn-in the VPTs.   The lids for the VPT holders are already drilled with 4 holes.  [Note added later: the VPT specification agreed with the manufacturer relates only to the loss in output after 10 hours burn-in. ]
• Would be beneficial to use ultra-bright LEDs for pulsing, to avoid noise from the 60V avalanche pulse generator.  These LEDs are 5mm in diameter rather than 3mm, but should be usable.  A possible disadvantage is that their output peaks at 470nm rather than 430nm like the lower output (hyperbright) LEDs - some investigation is needed to check whether this has any significant effect.

5.   CRISTAL

• ALL purchased a 500MHz PC for the supercrystal testing programme.   It appears that this PC will be spare, so could be used as the CRISTAL db server.   Will need a memory upgrade from 128Mb to 512 Mb (about £200).
• CRISTAL experts recommend RAID disks for reliability.  Probably not necessary for VPT tests, as time lost to a hard disk failure would not be critical.   Need to consider needs of SC Regional Centre as well, where periods of down time would be more serious and a RAID array might be justified.
• A suitable location must be found for the CRISTAL server.

Bruce Kennedy / 05 December 2003