- Slides: 5
Quality check & strip data base On line test of the production quality & strip db with cosmics set up and NIM/CAMAC electronics
Si. PM operation ~ 70 V 1 – 1. 5 V HV = HVbreak down + ΔHV v HVbreak down strongly depends on temperature: ~ 57 m. V/°C; v all important for us Si. PM characteristics (gain, efficiency, xtalk, noise) depends only on ΔHV – independently of temperature! choose working point: v efficiency < ~ saturation v noise (at 0. 5 p. e. ) < 1 MHz Si. PM noise (@ 8 p. e. threshold) < 1 k. Hz << neutron bg rate v xtalk < 20% To stay at the operation point it is sufficient to adjust HV to keep gain constant at chosen value to have maximum efficiency but staying in the linear region (robustness against temperature changes) ΔHV = 1. 4 V
Si. PM data base & distributions For 200 Si. PMs available at ITEP we measured main characteristics and put them to Si. PM db No big spread! Do we need calibration for the rest 18000 Si. PMs?
Cosmics tests the nearest m i d d l e f a to Si. PM o f r region s t r e n i p d v 10 strips of the same length: v 20 minutes cosmic run: 300 triggers at each point vlight yield statistical error ~ 2% vsystematic error: venvironment (temperature etc) after gain adjustment ~ 2% voptical connection ~ 6% Light yield: remove pedestal (due to non perfect trigger strips alignment) discard 10% low and 30% high (Landau tail); find average/gain Light yield then corrected for v non-perpendicular incidence: × 0. 86 v cross talk: × 1/(1+xtalk)
Data base Si. PMs: v temperature v HVbreak down v gain/ΔHV v noise (at working HV) v xtalk (at working HV) Strips: v production time v length v light yield at three points (two points for short strips < 1 m) + reference to test result n-tuple v # segment (filled during segment gluing) v # Si. PM (filled during assembly) Segments: v production time v type (1 -5) v #s of strips v # of the sector (filled during assembly) Sectors: v assembly time v #s of segments v cosmic run at KEK results reference to test result n-tuple v position (filled during installation)