Hi all,
I'm not quite sure this is the right list to send this mail to, so
please excuse me of my ignorance.
This has to do with the Silicon wafers of the multiplicity array. I
know not a whole lot of work has been put into this, so consider this
a request, rather than a bug report.
As far as I can tell from looking at the code of "BrRawDataInput", it
seems that only the ADC values are written to the "BrDigMultSi"
objects, and the information on which strip in what wafer is lost. Is
this true? If so, could it be modified, as to also include the
wafer/strip information?
The point is, that we (Erik and me, and in part Peter and Ian) would
like to do different cuts in psuedo rapidity in this detector, to
study event-by-event fluctuations in both central and perifial
events. For that, we need the information on what strip was hit, and
how much energy was deposited, hence my request for such info to be
present in the data.
On a similar note, I'd like to know the status of the
"BrDigitizeMultSi" class in BRAT. I know there isn't one at the
moment, but is anyone working on it? If not, it may be something for
us (that is Erik and I) to do. If this is alright with you, will need
some info on the Silicon wafers and strips:
* How is the silicon strips numbered in GBRAHMS?
As far ad I can tell, there are 7 tables ("STRA" ... "STRAG"),
corresponding to the 7 strips in each wafer.
In these tables, there are 24 sub-entries accesible via the
"BrGeantHit::Isub()" method, numbered from 1(!) to 24. I guess that
means, that these 24 sub detectors are distributed over all 4
ladders, and the 6 wafers.
If I'm right, then this would mean that "STRA" corresponds to the
first strip in each wafer, "STRB" to the second, and so on. But how
are the 24 sub entries distributed?
I created a ROOT TGeometry from a GEANT ZEBRA geometry file, using
g2root, and started to look at the structure in ROOT, using a
TBrowser. It seems that the first 6 sub-entries
("BrGeantHit::Isub()" == 0,1,...,6) corresponds to the top most
ladder, the 7th to the 12th to second ladder, and so on. I'm I
right?
Could someone please share the right mapping with us. If there's a
mapping for the raw data, that would be useful to know also.
* It seems that there is no "BrDetectorParamsSi" class in BRAHMS. I
guess it need to contain fAdcGain, fSigmaAdc, and fAdcOffset, but
what else? And what is reasonable values for these parameters?
* Also, the geometry information on MultSi doesn't seem to be written
to the geometry output file from GBRAHMS. Is this right, or have we
forgotten a flag or something when running GBRAHMS? Is the info
needed at all? It doesn't seem to used in "BrDigitizeMultTile",
other than the "Event" method fails if it isn't there. In fact,
there seems to be no entry in the GBRAHMS geometry file for detector
"MultTile", so I guess "BrDigitizeMultTile::Event" always fails!?
Again we've might have forgotton a flag or something, but I really
don't think so, since we had
geoini
set_tree cave afso
geodef
geofin
In our GBRAHMS KUMAC file. How should we deal with this?
If this is indeed the wrong list, I thank you for your patience, and
apologize. If anyone could answer some of these questions, we'd be
very thankful.
Cheers,
Christian -----------------------------------------------------------
Holm Christensen Phone: (+45) 35 35 96 91
Sankt Hansgade 23, 1. th. Office: (+45) 353 25 305
DK-2200 Copenhagen N Web: www.nbi.dk/~cholm
Denmark Email: cholm@nbi.dk
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