Absolute light and resolution measurements for sensitive CsI(Tl)/photodiode detectors

Michael M. Meier

doi:10.1117/12.450821

10 January 2003 Absolute light and resolution measurements for sensitive CsI(Tl)/photodiode detectors

Michael M. Meier

Proceedings Volume 4784, X-Ray and Gamma-Ray Detectors and Applications IV; (2003) https://doi.org/10.1117/12.450821
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

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.

Citation Download Citation

Michael M. Meier "Absolute light and resolution measurements for sensitive CsI(Tl)/photodiode detectors", Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); https://doi.org/10.1117/12.450821

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available