From: Pawel Staszel (staszel@alf.nbi.dk)
Date: Sat Jan 18 2003 - 16:11:15 EST
Dear Flemming, Jens Jorgen, Roman etc., If the problem with T3 mapping still persist, it might be much more effective to increase the threshold voltage (on T3) rather then decrease the HV. We know from AuAu data that T3 had a lot of "low energy" noisy hits - cutting on these hits on the software level do not affect the tracking efficiency. If the actual threshold voltage on T3 is lower or equal the threshold we used for AuAu and pp running it can certainly be increased by 0.1-0.3V above the used value. Best regards Pawel. Apache wrote: > ------------------------------------------------------------ > Date: Sat Jan 18 08:13:40 2003, Shift: 00:00-08:00 > Supervisor: JIJ, with: > Log book#13 pages 84 - 85 > > Shift Summary: > ------------------------------------------------------------ > 1. > Beam all shift. Low background. (See numbers in scaler snapshots in the e-log.) Very stable conditions. I'll report this to MCR. > > 2. > 7444 - 299k tr. 3 and 304k tr. 6 NO DC DATA. > 7445 - 199k tr. 3 and 149k tr. 6 NO DC DATA. > 7458 - 408k tr. 3 and 160k tr. 6, NO T3 OR T4 > 7459 - 344k tr. 3 and 120k tr. 6, NO T3 OR T4 > 7460 - still running. > > 3. > DC low voltage and DAQ problem. The following is also written in the e-log: > > Run 7445 was started. After some time we (Hiro was here too at that point.) noticed in supermon that there was no data in the DCs. All anodes were on, confirmed both by BRAHVO and by logging into "tsir 3015". Also low voltages were on. > > However, recycling the low voltages resulted in data from T5 after one cycle and T3 after a couple of cycles. We did not succeed bringing back T4. Then, after restarting the DAQ again, T3 had a whole lot of mapping errors, eventually resulting in IOServer crash and then RunServer crash. > > Increasing scaledown factor on the MRS, ZDC, INEL and FS triggers in various combinations did not help. Also, we noticed that the T3 anodes were at 1200V and not the prescribed 1190V. Turning T3 anodes down to 1190V didn't help either. The only solution was to turn off T3 anodes. > > The mapping errors, however, did not disappear. I noticed that there was still some ~200V measured on the T3 anodes. Turning down cathode and field removed the 200V, and turning up again the field and cathode, left T3 anodes at just a few volts. Still, however, there were mapping errors from T3. It finally disappeared when I turned off the low voltage of T3. Runs 7446-7458 should all be considered DAQ/DC debugging runs. > > ------------------------------------------------------------ -- ---------------------------------------------------------------------- | Pawel Staszel | | Niels Bohr Institute Tb 8 email: staszel@nbi.dk | | Blegdamsvej 17 phone: (+45) 35 32 53 51 | | København Ø FAX: (+45) 35 32 50 16 | | Danmark | ----------------------------------------------------------------------
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