hi adrian,
TOF L9B is the only one with coplanarity/timing problems. L11 looks a
little bad in the efficiency plots, and L12 is a little lower in
ep-elastic yields but otherwise looks fine.
also, R8,15 have one tube that is counting just a few counts lower
than the coincidence, which might be a sign of something.
--thanks, chris
Adrian T Sindile wrote:
> Hi, Chris!
> It happens that I am on shift Saturday (tomorrow) so I will take care
> of this TOF then.
>
> There are a bunch of tubes that now seem to count lower on the scalers
> (it was not the case a few months ago). My crude "stability tests" did
> not show any problem for the last weeks - as you say, protons look
> fine and I usually test the flasher signal.
> Please let me know if you see any other tubes that have bad electron
> peaks. I will address those tomorrow as well.
>
> Thanks,
> Adrian
>
> On Fri, 19 Nov 2004, Chris Crawford wrote:
>
>> there is a problem with TTL9B, as can be seen in the above plot of
>> coplanarity peak versus timing peak for coincident events in L9,R9
>> (or R8 or R10). ideally this should be a point, since both variables
>> are peaks. however, if the bottom tof TDC has problems then it will
>> be a line of slope -1, and if the top tof TDC has problems it would
>> be a line of slope +1.
>> i looked at the length of the line as a function of TTL9B to see if
>> the problem could be calibrated away, and was able to decrease the
>> length from 35 channels to 25, by assuming fitting for the TDC
>> calibration of 31 ps/channel instead of the usual 50. but it is
>> still much worse than the width (7 channels). the timing resolution
>> is 3 times worse for this paddle.
>> therefore, i believe there is some problem with the discriminator.
>> you can also see that the problem only affects the electrons, because
>> the proton peaks look fine (they have higher adc's). so maybe the
>> problem can be fixed by raising the voltage to the phototube. this
>> problem goes way back to at least last december.
>> note: you can also see that tube counts much lower than the others:
>> 369 compared to 1514 on the top
>> --chris
>>
>> ltt ltb ltc rtt rtb rtc
>>
>> 0 3337, 3736, 2866, 5237, 3567, 3357
>> 1 4118, 3046, 2813, 3107, 3213, 2448
>> 2 2849, 2541, 2193, 3035, 2618, 2257
>> 3 2307, 2444, 1793, 1188, 1786, 1107
>> 4 2805, 3123, 2022, 3209, 2314, 1980
>> 5 2469, 564, 561, 1767, 1369, 1137
>> 6 1391, 2132, 1199, 1366, 2081, 1166
>> 7 1885, 1479, 1099, 1509, 1267, 972
>> 8 1391, 1800, 1039, 1671, 732, 695
>> 9>>> 1514, 369, 367, <<<< 1042, 980, 681
>> 10 1607, 1636, 974, 663, 975, 548
>> 11 2875, 3621, 1904, 1909, 3069, 1248
>> 12 1878, 2594, 1232, 987, 2706, 854
>> 13 1825, 1447, 867, 2141, 2002, 1045
>> 14 2426, 1721, 665, 1436, 2684, 1056
>> 15 2192, 2790, 1210, 2305, 563, 530
>>
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