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Title: Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices

Abstract

Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution [<3 percent at 662 kilo-electron volt (keV)] relative to sodium iodide [NaI(Tl)] but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5 ´ 1.5 inch LaBr¬3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5 ´ 2.2 inch NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal activity due to 138La in the LaBr3:Ce detector exists and NaI(Tl) consistently outperformed LaBr3:Ce.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
900916
Report Number(s):
PNNL-SA-51879
400903010; TRN: US0702491
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, 572(2):774-784; Journal Volume: 572; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; LANTHANUM BROMIDES; PHOSPHORS; RADIOACTIVE MATERIALS; RESOLUTION; SODIUM IODIDES; NAI DETECTORS; SOLID SCINTILLATION DETECTORS; COMPARATIVE EVALUATIONS; lanthanum bromide; sodium iodide; scintillator; isotope identification

Citation Formats

Milbrath, Brian D, Choate, Bethany J, Fast, Jim E, Hensley, Walter K, Kouzes, Richard T, and Schweppe, John E. Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices. United States: N. p., 2007. Web. doi:10.1016/j.nima.2006.12.003.
Milbrath, Brian D, Choate, Bethany J, Fast, Jim E, Hensley, Walter K, Kouzes, Richard T, & Schweppe, John E. Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices. United States. doi:10.1016/j.nima.2006.12.003.
Milbrath, Brian D, Choate, Bethany J, Fast, Jim E, Hensley, Walter K, Kouzes, Richard T, and Schweppe, John E. Sun . "Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices". United States. doi:10.1016/j.nima.2006.12.003.
@article{osti_900916,
title = {Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices},
author = {Milbrath, Brian D and Choate, Bethany J and Fast, Jim E and Hensley, Walter K and Kouzes, Richard T and Schweppe, John E},
abstractNote = {Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution [<3 percent at 662 kilo-electron volt (keV)] relative to sodium iodide [NaI(Tl)] but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5 ´ 1.5 inch LaBr¬3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5 ´ 2.2 inch NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal activity due to 138La in the LaBr3:Ce detector exists and NaI(Tl) consistently outperformed LaBr3:Ce.},
doi = {10.1016/j.nima.2006.12.003},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, 572(2):774-784},
number = 2,
volume = 572,
place = {United States},
year = {Sun Mar 11 00:00:00 EST 2007},
month = {Sun Mar 11 00:00:00 EST 2007}
}
  • Lanthanum halide (LaBr3:Ce) scintillators offer significantly better resolution (<3 percent at 662 kilo-electron volt [keV]) relative to sodium iodide (NaI(Tl)) and have recently become commercially available in sizes large enough for the hand-held radio-isotope identification device (RIID) market. There are drawbacks to lanthanum halide detectors, however. These include internal radioactivity that contributes to spectral counts and a low-energy response that can cause detector resolution to be lower than that of NaI(Tl) below 100 keV. To study the potential of this new material for RIIDs, we performed a series of measurements comparing a 1.5?1.5 inch LaBr?3:Ce detector with an Exploranium GRmore » 135 RIID, which contains a 1.5-2.2 inch NaI(Tl) detector. Measurements were taken for short time frames, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. Some measurements were noncontact, involving short distances or cargo shielding scenarios. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision TM). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal contamination in the LaBr3:Ce detector exist. NaI(Tl) consistently outperformed LaBr3:Ce for this important isotope. LaBr3:Ce currently costs much more than NaI(Tl), though this cost-difference is expected to diminish (but not completely) with time. As is true of all detectors, LaBr3:Ce will need to be gain-stabilized for RIID applications. This could possibly be done using the internal contaminants themselves. It is the experience of the authors that peak finding software in RIIDs needs to be improved, regardless of the detector material.« less
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