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			| Question about emc crystal numbering [message #9080] | Tue, 28 July 2009 15:59  |  
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					|  Jens Sören Lange Messages: 193
 Registered: June 2005
 | first-grade participant | From: *physik.uni-giessen.de 
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	| Hi all, 
 2 questions concerning emc crystal numbering.
 
 Question #1:
 
 in trunk/emc/EmcData/PndEmcHit.h
 
 Short_t GetCrystal() const { return (fDetectorID%10000)        ;}
 
 the crystal is the smallest unit (and not e.g. the "module"),
 so is the factor 10000 really correct here?
 (or should it just return fDetectorID ?)
 
 in other words, like this it only returns 1-digit "1, 2, ..."
 for fired crystal numbers and not 5-digit numbers.
 
 Question #2:
 
 when investigating fDetectorID (e.g. for the E=1 GeV photons
 from sim_emc.C using hit_analys.C) it turns out that it has
 has positive and _negative_ 5-digit integer detector numbers.
 
 Any idea why negative?
 
 cheers, Soeren
 
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