Re: [BLASTTALK] problem with TOF left 9 bottom

From: Adrian T Sindile (asindile@cisunix.unh.edu)
Date: Fri Nov 19 2004 - 20:48:57 EST


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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