Share Email Print

Proceedings Paper

Absolute light and resolution measurements for sensitive CsI(Tl)/photodiode detectors
Author(s): Michael M. Meier
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

To conserve volume and power, photodiode/scintillator combinations are strong candidates for gamma-ray detection in space applications. High sensitivity to MeV gamma rays necessitates large-volume scintillators, which are most effectively read out with large-area photodiodes. However, because photodiodes have unity gain, the electronic noise limits resolution, and therefore small-area photodiodes that minimize capacitance are preferred. Thus, optimization of resolution involves maximizing light production and transport in the scintillator and light collection in the photodiode, while minimizing photodiode area. Measurements of performance are reported for 1×1×1cm3/10×10mm2, 80cm3/18×18mm2, and 85cm3/10×10mm2 CsI(Tl)/photodiode combinations. Each large scintillator was a single crystal, machined to a geometry that comprised a 40mm diameter × 50mm height cylindrical section that was extended through a 20°conical section to a square face that matched the respective photodiode sensitive surface. Absolute scales were estimated for the light output by measuring the photodiode responses to 241Am (59.54keV), 57Co (122.06 and 136.47keV), and 133Ba (80.99keV) and assuming a value of 3.67eV/electron-hole pair. The photodiode quantum efficiencies for the CsI(Tl) emission spectrum, corrected for Si reflection back into the scintillator, was taken to be 0.835. We obtained values of 58.2, 46.7, and 34.6 photons/keV for the combined light production and transport into the CsI for the 1cm3, ~80cm3, and ~85cm3 detectors, respectively. The best measured resolutions at 662keVfor the detectors were 5.9%, 7.2%, and 7.4% FWHM, respectively.

Paper Details

Date Published: 10 January 2003
PDF: 9 pages
Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); doi: 10.1117/12.450821
Show Author Affiliations
Michael M. Meier, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 4784:
X-Ray and Gamma-Ray Detectors and Applications IV
Ralph B. James; Larry A. Franks; Arnold Burger; Edwin M. Westbrook; Roger D. Durst; Edwin M. Westbrook; Roger D. Durst, Editor(s)

© SPIE. Terms of Use
Back to Top