Karen Dow wrote:
> The wire chamber TDC does not have a user-settable gain; it is fixed at
>0.5ns per bin. So cutting on bins or time is equivalent for the raw
>WCh. If the offset correction is done in units of time, rather than TDC
>bins, then maybe you want to cut on corrected time.
>
> We CAN however change the maximum TDC bin (the full-scale time
>measurement); currently set to 4usec, or 8000 bins. Probably the only
>reason to change the max bin would be if the common stop (the event
>trigger) got drastically later.
>
> Karen
>Tancredi Botto wrote:
>
>
>>I think/suggest that also for the Wch the cut is done on channels, not
>>on converted time. In particular because we may change the range of the TDC
>>one day (we also may not) so that say 8191 channels would be 8 us, and
>>then it'd be hard to think again of this discussion.
>>
>>It's easy to do this right once and for all. The thing started since
>>we realize that a few CC-tdc comes relatively late in recent runs and
>>we may not recon a few events beyond channel 4090.
>>
>>-- t
>>________________________________________________________________________________
>>Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
>>research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
>>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>
>>On Thu, 5 Jun 2003, Douglas Hasell wrote:
>>
>>
>>
>>>Hi,
>>>
>>> I expect I am showing my ignorance here but the wire chamber TDC
>>>values range from 0 to 8191 which corresponds to 0 to 4095.5 ns. I assume
>>>your number corresponds to 4090 ns which is certainly a safe upper limit.
>>>
>>> However, the range of realistic drift times is between something
>>>like 2000 and 6500 tdc counts or 1000 and 3250 ns before subtracting from
>>>the T0 value which is around 6500 tdc counts or 3250 ns. One way to
>>>eliminate some of the noise would be to only consider TDC values in the
>>>range 2000 to 6500 which would remove about 45% of noise. This is
>>>relatively safe so long as the trigger timing and cabling doesn't change.
>>>
>>>--On Wednesday, June 4, 2003 11:39 PM -0400 zhangchi
>>><zhangchi@general.lns.mit.edu> wrote:
>>>
>>>
>>>
>>>>Hi, maximal tdc value cuts in outer detector reconstruction is raised
>>>>from 4000 channels to 4090 channels.
>>>>
>>>>The related line is in TBLDetHit.h: const int tdc_over = 4090;
>>>>
>>>>Chi
>>>>
>>>>
>>>>
>>>
>>> Cheers,
>>> Douglas
>>>
>>>26-415 M.I.T. Tel: +1 617 258 7199
>>>77 Massachusetts Avenue Fax: +1 617 258 5440
>>>Cambridge, MA 02139, USA E-mail: hasell@mit.edu
>>>
>>>
>>>
For wire chamber, I initially put the TDC cut at 2000 < tdc < 8192.
If you want (and feel confident), I will restrict the range even more.
-T
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