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Ay 191 Experiment
Development of Hard X-ray Imaging Detectors
J. Hong, B. Allen and J. Grindlay
• Hard X-rays (~5-600 keV) are direct probes of black
holes: GRBs, AGNs, Stellar BHs, etc.
• Direct imaging using mirrors is possible only for narrow
FoV (<~1º) and low energies (<~100 keV) => codedaperture telescope
• Harvard balloon-borne telescope (ProtoEXIST) is a
coded-aperture telescope for wide-field (~10ºx10º)
hard X-ray imaging.
• ProtoEXIST is a prototype platform for development of
EXIST (Energetic X-ray Imaging Survey Telescope), to
probe the early Universe using high redshift GRBs and
survey BHs on all scale.
Coded-Aperture Hard X-ray Imaging Telescope
Decoding Shadowgram
allows for wide-field imaging
in hard X-ray band.
Position-sensitive hard X-ray
detectors needed:
Use Cd-Zn-Te (CZT) arrays.
Cd-Zn-Te (CZT) Hard X-ray Imaging Detector
CZT Detectors
8 x 8 pixels on each 20 x 20mm
CZT crystal (pixels on bottom)
Schematic CZT detector:
Electrons drift to anode
Under ~600V bias
ProtoEXIST1 Detector Module (2.5mm pixel)
ProtoEXIST
• Demonstrate the technology for large array CZT
detectors with small pixels covering 5 – 600 keV
ProtoEXIST1 = 512 cm2 (2.5 mm pixel)
ProtoEXIST2 & 3 = 512 cm2 (0.6 mm pixel)
EXIST ~ 4.5 m2 (0.6 mm pixel)
• Identify the optimal shielding configuration
• Demonstrate continuous scanning codedaperture imaging technique
Ay191 experiments
• Learn about
-Hard X-ray sources in the sky: Black holes …
-Hard X-ray Imaging: Coded-aperture telescopes
-Hard X-ray Detectors: CdZnTe detector
• Experiments to be conducted (at CfA ProtoEXIST lab, B-105):
-Calibrating new CZT imager with 60, 122, 356 keV sources
-Measuring spatial and spectral resolution over detector
-Sensitivity to multi-pixel (split) events
-Cooling test (to ~0 – 5°C) with CZT modules