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Minutes of the Background Remediation meeting Jan 8

1. Workshop information

The workshop schedule and schedule contents were presented. All the

information is available on the BR Web page. The off line sessions Friday

afternoon will probably be not filled by talks since not all groups have

new things to report since the PRS forum held Dec 15. This will leave

more time for discussions on how to proceed on that front.

2. Detector protection (Overflow from the Dec 18 session)

DCH : A. Roodman explained that the new guestimate of nominal background

10xTDR will produce a dose of 0.1 C/cm/year, unconfortably close to the

usual rule of thumb. Tests underway at Colorado have shown however no

damage for that dose and they will be pursued at larger doses.

The dose in the electronics needs to be reevaluated in the MC since TDR

was meaningless in that region. the question of protection of the DC

electronics during machine developpment time needs to further thoughts

Aaron pointed out that since it will take about 1 minute

to ramp the chamber up and down, frequent topoff operation must be

automated. It wil also lead to 10% time loss if we topoff every 10

minutes. Witold introduced the trickle mode where you constantly inject

small amount of charges. This mode needs to be validated by babar

subdetectors which in that case would stay on during these small


Another point mentioned in the discussion was the need for an hardware

INJECTABLE flag, an issue for the workshop.

SVT (C. Hast) The dose that can be supported by the SVT is

around 0.5 Mrad /year (if we want to keep it ~4 years). The PIN diodes

offer a good protection for the system. Damage can be monitored through

leakage current increase for the detector, and noise increase for the

electronics (less straightforward)

DRC The material is available on the BR web page but B. Wilson will

discuss it during the workshop.

3. Data taking issues

The data taking questionnaire is available ont he BR web page. the idea

was to provide numbers to the online group concerning data size and time

spent in the roms to give information to the online group in time for the

workshop. Because of the holydays and the of the proximity of the workshop

itself, not all groups were able to make a report in time. I strongly

encourage the contact persons from these groups to post this information

on the BR hypernews asap so our online colleagues have this information.

(or by email to me)

SVT : a very detailed report is availbale from Al Eisner on the web. C.

hast summarized it by saying that the system currently saturates at qan

occupancy of ~25%, which looks OK but further capacity could be added if

needed by including more ROMs and backplanes.

DRC A preliminary message from S. Telnov indicates that at the maximum

tolerable input rate of 300 kHz, the time spent in feature extraction

will limit the trigger rate of just less than 2 kHz the maximum rate. So

it looks OK since some optimisation in the ROM is foreseen.




Guy Wormser Tel 01 6446 8478 (from France) 33 1 6446 8478 (abroad)

LAL Orsay Fax 01 6907 2517 (From France) 33 1 6907 2517 (abroad)

91405 Orsay