Fiber Tracker Meeting Minutes
December 02, 2003 - 10am, farside
- General current status : Borcherding
- two boards swapped this morning
- unsure if problem is VRB or AFE
- Jadzia claims there are 166 chips that are not getting bias (was 9 before shutdown)
- comments from George:
- 11 groups of 8 chips not working; strongly clustered at the end of the casette,
and at one end of a board
- majority of these things are in the east cryo
- noticed that Jadzia's list of dead VLPC's does not include those listed
as dead since January - need more history info on this
- CFT status : Warchol
- plots shown of low output channels
- unarchived slides shown with two plots on same page
- top is SVX thresh, bottom is disc.
- shows problems in both SVX and disc. (2 separate problems)
- unarchived slide with 6 plots on one page
- lower left: typical distribution
- upper left: very few entries, slightly skewed to low end
- upper middle: channel right next to left one - looks ok
- unarchived afe RMS plots
- increasing bias by one volt - some channels not affected
- talk slides
- 6B6 current vs. time (page 2):
- after Oct. 13 power outage, one board is suddenly lower
- this board swapped today
- 7A2 (page 3) - also swapped today
- 3A7 (page 4) - shows problem but not swapped
- list of unbiased channels (page 1)
- total: 480 VLPC pixels
- only 9A3 and 9A5 are in west cryostat; all others are in east
- other problems (page 5):
- 3 boards with readout errors; PDAQ examine does not show as a problem
so, id is getting sent but there is no data!
- could this be a bigger problem that we're just not seeing?
- want to pull these boards and see if it can be seen in test stand
- 2 need slightly higher thresholds
- George: do silicon people know about this? they should be told
- unbiased channels list (page 6)
- George: again notice most are in east cryo
- all problems seem to have shown up after the Oct 13 power outage
- dead cft channels (page 7)
- in August, 72 unbiased channels
- now about 170?
- Mike Matulik (sp?) says the problem is damage inside the cassette
- how hot did we get during the outage? need to find out
- CPS Status : Alton
- AFE II Status : Kotcher
- Boeriu/Jabeen: CFT light yield update
- light yield in MC Z->mumu
- slides
- pedestal mean used corresponds to 2pe
- mixing up threshold and pedestal again? MC does not have a pedestal (ped is zero)
- CFT occupancy : Lam
- CTT expert: Makoto
- many crate x13 problems
- swapped a board three times
- first board (which had been used before the shutdown) tested as bad
- second board tried was missing events
- third board was a spare seated in CFT x51 crate - it's kind of working
- this third board works fine for zero bias, but once in full operation
(9 VRBs in slot and 5 out of 9 VRBs in read out), crate x13 goes FEB
- currently using this third board, but only with 6 VRBs in the slot and
5 VRBs in the readout.
- plan is to get and test another VRBC