1 / 14

GLAST Large Area Telescope: TKR Efficiency Trending Hiro Tajima (SLAC) TKR

Gamma-ray Large Area Space Telescope. GLAST Large Area Telescope: TKR Efficiency Trending Hiro Tajima (SLAC) TKR htajima@slac.stanford.edu 650-926-3035. Efficiency Trending Result @ IA Workshop. Consistent downward trend observed. Inconsistent with stable bad strips.

ecornell
Télécharger la présentation

GLAST Large Area Telescope: TKR Efficiency Trending Hiro Tajima (SLAC) TKR

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope: TKR Efficiency Trending Hiro Tajima (SLAC) TKR htajima@slac.stanford.edu 650-926-3035

  2. Efficiency Trending Result @ IA Workshop • Consistent downward trend observed. • Inconsistent with stable bad strips. • Probably due to LAT configuration change. • Efficiency values depend on track quality and other factors. • Further improvement on track selections required to make it more stable.

  3. Improvement on Efficiency Calculation • Use only towers with 6 or more hit layers. • Much improved. Still more scatter than the statistical error. • FMA: lower efficiencies in 16-tower and first LICOS muon data. • FM4: lower efficiencies in PSR muon data. • Systematically lower efficiency at NRL. • So is trigger rate. (~500 Hz @SLAC ⇒ ~420 Hz @NRL)

  4. FM4 (Bay 13) Layer Efficiencies • Layer X13 (plane# 26) shows significant efficiency drop. Efficiency + LICOS runs + PSR runs Layer ID

  5. FM4 X13 Strip-Level Efficiencies • This is not exact strip efficiency due to accuracy of track extrapolation. • It gives crude association of efficiency with strip#. • Efficiency of strips 1024-1152 degraded significantly. • This region had lower efficiencies in previous runs. Efficiency Strip ID

  6. SSD Wafer Dependence? Wafer 3 Wafer 1 GTFE • Occupancy does not depend on SSD wafer in the ladder. • Efficiency loss is well correlated with GTFE boundaries. Ladders Wafer 2 Wafer 0 GTFE boundaries Occupancy (arbitrary unit) – Wafer 0 – Wafer 1 – Wafer 2 – Wafer 3 Strip ID Strip ID

  7. Root Cause of Efficiency Loss • New hot strip around 1141, 1143 (close to edge of the SSD)! • 1142 was masked in previous runs. • Hot strips is due to large leak current from junction break down. • Mechanism for efficiency loss in two GTFEs is not understood. • New hot strip schema files released to mask these hot strips. • Mainly to reduce trigger occupancy. • It may not fix the efficiency loss since we had some efficiency loss even when these strips were quite. Sugizaki LICOS runs PSR runs 1141, 1143 Occupancy (arbitrary unit) 1142 Strip ID Strip ID

  8. FMA (Bay 0) Layer Efficiencies • Slight efficiency loss in Y0, Y3, Y4. Efficiency + LICOS runs + PSR runs Layer ID

  9. FMA Y3, Y4 Strip-Level Efficiencies • No localized significant efficiency loss observed. • Some intermittent strips in green circles could be a cause. ladder disconnected strips and healthy strips are mixed and averaged out. ladder disconnected strips disconnected strips

  10. Automated Layer Efficiency Trending • Tower efficiency is not very sensitive to local efficiency loss. • Useful for overall efficiency trending. • Layer efficiency is more sensitive for local efficiency loss. • Too many layers to be trended by human eyes. • Automated outlier detection script developed. • Take out systematic effects that affect all layers in each tower. • Take truncated (remove highest and lowest 10% of efficiencies) and weighted average of all runs for each layer. • Tag instances of efficiencies if it is 5 away from the above average. • Produce efficiency strip profile plots of outliers in comparison with the reference and save them as GIF for human inspection.

  11. FMA (Bay 0) Layer X0, X2 • X0 and X2 do not have bad channels in these regions. • Shadow of bad strips in X1 (1270-1500). • Inefficient regions are slightly shifted. • Old efficiency calculation is more susceptible. Efficiency strip ID Efficiency Relative efficiency Old efficiency calculation X1 bad channel region strip ID run ID (-77000000)

  12. FM6 (Bay 12) Layer Y5 Sugizaki • Noise flare according to Mutsumi. Relative efficiency Efficiency run ID (-77000000) strip ID

  13. FM13 (Bay 7) Layer X15 Sugizaki • Another noise flare • Only 1st ladder is affected. • GTRC buffer limit is not cause of inefficiency. • Probably due to dead time of preamplifier. Relative efficiency Efficiency run ID (-77000000) strip ID

  14. FM14 (Bay 2) Layer Y0 • No noisy strip found. • Need further investigation. # of hits per strip strip ID Efficiency Relative efficiency run ID (-77000000) strip ID

More Related