GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 1 GLAST Large Area Telescope: TKR Bad strips analysis update Hiro Tajima (SLAC) TKR Gamma-ray Large Area Space Telescope

GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 2 New TKR Recon Side Effects Shadow of dead strips. –Tracking stops when no hit can be associated. Inclusion of dead strips to recon clusters. –Some dead strips appears alive. This is a feature of recon. –Not all dead strips are affected. (not understood) Digi clusters Recon clusters strip Id

GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 3 Cluster from Digi hits Form clusters from digi hits. Collect all clusters consistent with recon track. –Multiple clusters per layers allowed. –Requires geometry information. Tower center and layer z position can be obtained from recon clusters. Ladder gap and strip pitch is hard coded. –These parameters are very likely to be invariant. Cluster – track (mm)

GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 4 Result of digi clusters Digi clusters fix both problems. strip Id

GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 5 Utilization of Track Position Use track position “occupancy” as a reference to calculate Poisson probability for each strip. –Useful to get shape, not absolute rate. Track position Strip occupancy strip Id

GLAST LAT Project Instrument Analysis Meeting– May 27, 2005 Hiro Tajima, TKR Bad Strips 6 Layer Occupancies Under study Track position Digi clusters Recon clusters Accepted Digi clusters Plane Id