hi adrian and pete,
this improved LB9 a little, from sigma=35 -> sigma=27, but it should
be ~7 (tdc resolution in channels). is it possible to raise the voltage
any more, or maybe to lower the discriminator threshold (or switch to a
new channel), or look at the signal on the scope to make sure it looks ok?
if there are no improvements possible in hardware, then it could be
possible to use the wire chambers to determine where the hit occured in
the scintillator, and work backwards to adjust the timing based on the
top PMT only. still the resolution would be worse by a factor of sqrt(2).
the above reslution plot is generated with the commands:
root[] flr->Draw("(ptr+ptl)/.735:(ttr-ttl)","ntl==9&&ntr==9")
root[] flr->Draw("(ptr+ptl)/.735-(ttr-ttl)","ntl==9&&ntr==9&&ttr>ttl")
also you can check the tof efficiency for a set of runs (all events)
dbl=0 for all events, dbl=1 cut on additional cerenkov, nc, or lads
hits
$ root -l tof_eff.C dbl=1 ###-###
or, for example you can use elastic cuts:
$ root -l tof_eff.C -c Helastic ###-###
or stricter elastic cuts:
$ root -l gcuts.C tof_eff.C -c Hcbc ###-###
--thanks, chris
Electronic Log Book wrote:
>Operator: adrian
>
>Runs 12771-12777 taken and crunching.
>TOF voltage changed for LB9, R8B, R15B (following Chris' report)... added 50 volts on each after run 12776. HVGUI rebooted at that time (see elog).
>
>Phys0 was jumping around at some point (noticed during runs 12775 and 12776)... BPhys0 stable, which shows a likely flaky scaler cable. Phys0 is OK now.
>
>
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