Dear Bjorn and Christian,
thanks to Bjorn for committing the new
version of the ZDC Rdo module. I should explain what may be
causeing an offset. The cables from the ZDCs to the counting
room were very well matched in time. However in order to measure
the time we put the
signals into discriminators and send it off to the TDCs along
delay cables. These are not very well matched and indeed their
ordering was changed once during the run. This is presumably
the cause of the offset. However once the offset is cablirated it
should be relatively stable. The only variations should be due
to the differental effect of temperture variations. This can change
the delay of one cable versus another slightly. We have not
noticed this effect yet put it could be present.
Yours Michael
oting Bjorn H Samset <bjornhs@rcf.rhic.bnl.gov>:
>
> Howdy y'all. (Trying to sound like a Texan...)
>
> I've checked in a new and bigfixed version of BrRdoModuleZDC and
> BrRdoZDC
> in CVS. As before, this version has the slewing corrections done by
> Andrei
> Makeev (hardcoded for now), but it also has some important bugfixes and
> changes:
>
> 1) The "old" GetAdcTdc is back, in case someone wants to use older code
> (the new commands are also there of course)
> 2) The event bias introduced by the first module saturating is removed,
> i.e. statistics and event selection from the ZDC is now as before.
> 3) IMPORTANT --- vertex offset!!!
> The old modules have all had an offset of 107 cm hardcoded in them.
> This
> is now REMOVED, as it was an ah-hoc fix done last summer and never
> intended to be permanent. Instead, there is a function
> void SetPosOffset(const Float_t value)
> that can set an offset. An offset is still needed (I'm not sure
> why...),
> and the value I'm using is 26.5 cm. I.e. use teh command
> zdcRdoModule->SetPosOffset(26.5);
> This should make the ZDC's agree with both BB and TPM1.
>
> Please mail me any comments.
>
> ------------------------------------------------
> Bjorn H. Samset
> Master-student in Heavy Ion physics
> Mob: +47 92 05 19 98 Office: +47 22 85 77 62
> Adr: Kri 2A709 Sognsveien 218 0864 Oslo
>
>
Michael Murray, Cyclotron TAMU, 979 845 1411 x 273, Fax 1899
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