GERB Detector Calibration Facility Status GERB 4 Detector

GERB Detector & Calibration Facility Status GERB 4 Detector & Calibration Facility Status N. Nelms GIST 23 DWD, Germany 27 April 2005

GERB Detector & Calibration Facility Status Goldblack Pre-black Goldblack qualification and acceptance review complete - deposition using slit mask - reticulation using laser Post-black Post-laser 27 April 2005

GERB Detector & Calibration Facility Status Detector Status Initial flight detectors completed early January - problem discovered with all devices - traced to combination of detector over-etch and use of new, higher frequency wire-bonder - new detectors processed, blacked, lasered and mounted - stage 1 wire-bonding due to take place tomorrow - Focal plane build completion due end May 27 April 2005

GERB Detector & Calibration Facility Status Detector Calibration Facility • Picture goes here FILTER WHEEL & CHOPPER DETECTORS SHUTTER XY TRANSLATION STAGE SOURCES MONOCHROMATOR 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues 1. Chopper timing issues This caused a problem on previous calibrations with incorrect data from the GERB detector being collected and stored. Extensive investigations revealed the causes of this problem – insufficient time allowed for data processing and collection resulting in the chopper shifting out of phase with data collection over the 40 ms period. The timing, operation and monitoring procedure of the chopper system has been altered to prevent this situation recurring. 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues 2. Detector position within beam profile Shows wavelength dependence 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues Can be explained by non-vertical detector alignment Beam start position Detector Beam final position 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues Solution adopted for GERB-4 calibration The cross-section of the beam profile will be measured using a pixel near the top and the bottom of the GERB array – detector vertical alignment can be determined. The position of the GERB detector will then be adjusted during calibration to compensate. 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues 3. Intra-pixel patch wavelength dependence 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues Solution adopted for GERB-4 calibration The beam profile will be measured (once at each wavelength) using a single GERB pixel. The fractional radiant power in any particular location within the beam can then be found compared to the integrated whole. Combined with the alignment operation from issue 2, the same area of the beam can then be used for individual (or small group) measurements. 27 April 2005

GERB Detector & Calibration Facility Status Previous calibration issues Profile measurements 27 April 2005

GERB Detector & Calibration Facility Status Summary Focal plane production continuing with new detectors (and old wirebonder) – due end May. Calibration facility Test Readiness Review complete – action items being incorporated into calibration plan – calibration due to finish mid July. 27 April 2005