Effects of packaging SrI₂(Eu) scintillator crystals

Journal Article · Sat Oct 23 00:00:00 EDT 2010 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

DOI:https://doi.org/10.1016/j.nima.2010.10.041· OSTI ID:1647912

Sturm, Benjamin W. ^[1]; Cherepy, Nerine J. ^[1]; Drury, Owen B. ^[1]; Thelin, Peter A. ^[1]; Fisher, Scott E. ^[1]; Payne, Stephen A. ^[1]; Burger, Arnold ^[2]; Boatner, Lynn A. ^[3]; Ramey, Joanne O. ^[3]; Shah, Kanai S. ^[4]; Hawrami, Rastgo ^[4]

---

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Fisk Univ., Nashville, TN (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
4. Radiation Monitoring Devices,Watertown,MA (United States)

Recent renewed emphasis placed on gamma-ray detectors for national security purposes has motivated researchers to identify and develop new scintillator materials capable of high energy resolution and growable to large sizes. We have discovered that SrI₂(Eu) has many desirable properties for gamma-ray detection and spectroscopy, including high light yield of ~90,000 photons/MeV and excellent light yield proportionality. We have measured <2.7% FWHM at 662 keV with small detectors (<1 cm³) in direct contact with a photomultiplier tube, and ~3% resolution at 662 keV is obtained for 1 in.³ crystals. Due to the hygroscopic nature of SrI₂(Eu), similar to NaI(Tl), proper packaging is required for field use. This work describes a systematic study performed to determine the key factors in the packaging process to optimize performance. These factors include proper polishing of the surface, the geometry of the crystal, reflector materials and windows. Further, a technique based on use of a collimated ¹³⁷Cs source was developed to examine light collection uniformity. Employing this technique, we found that when the crystal is packaged properly, the variation in the pulse height at 662 keV from events near the bottom of the crystal compared to those near the top of the crystal could be reduced to <1%. This paper describes the design and engineering of our detector package in order to improve energy resolution of 1 in.³-scale SrI₂(Eu) crystals.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1647912
• Report Number(s): LLNL-JRNL-436732; 405063; TRN: US2202801
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 652, Issue 1; ISSN 0168-9002
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Strontium iodide
Scintillators
Gamma rayspectrometers
Package