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Advanced Materials for Gamma Spectrometry




OBJECTIVE: Develop innovative approaches to, and demonstrate the production of, an alternative gamma spectrometry material that simultaneously improves technical performance and lowers procurement costs. 


DESCRIPTION: Research, development, innovation, and demonstration of methods and processes are sought to reduce the costs of radioisotope identification detectors (RIIDs) materials while enhancing, or at a minimum, maintaining current commercial detection and identification performance. RIIDs need to be expeditious, reliable, and affordable while minimally impacting the Warfighter’s performance in concurrent missions. Other agencies such as DOE/NNSA and DTRA/J9 (R&D) develop new materials or new combinations of materials using methods such as co-doping or alternate dopants to get resolution down to 0.5%. While identification performance is enhanced, the associated increased costs are prohibitive in Acquisition. The type of instrument most commonly used for this mission is a hand-held gamma spectrometer referred to as a radiological isotope identification device (RIID) [1]. Their performance is determined by parameters such as the material system it uses for radiation detection, the electronics and software packages it uses for analysis, and its form factor. The material systems found in commercially-available RIIDs are either scintillators or semiconductors. The most prevalent material in DoD RIIDs is sodium iodide (NaI), a scintillator. It is prevalent because it is technologically mature – which enables the reliable production of high-quality crystals at reasonable cost and performance. The drawback of NaI is its energy resolution (~7%) which presents challenges when making identifications in complex environments. Cerium-doped lanthanum bromide (LaBr3:Ce) is a scintillator with better energy resolution (~4%) than NaI, but it costs twice as much[2]. The 'gold standard' for gamma spectrometry is high-purity germanium (HPGe), a semiconductor, due to its excellent energy resolution (<0.05%). But the benefit of improved technical performance is offset by much higher lifecycle costs for a system – the material is inherently expensive to produce at high quality and the small band gap of HPGe requires it to be kept at cryogenic temperatures (-180° C) during operation[3]. To provide the best combination of capability and cost, the Defense community has developed materials which fall somewhere in the middle – with technical performance approaching semiconductors (HPGe) at a price closer to scintillators (NaI, LaBr, CsI). The paragon of these efforts cadmium zinc telluride (CZT) – a semiconductor with energy resolution better than 3% (some results are approaching 1%) which is operable at room temperature. Continuous efforts to improve the quality of CZT have succeeded, but the cost to produce the material has remained sufficiently high that it has not been broadly incorporated into high-performing RIIDs at a cost comparable to scintillators. At the same time, the body of knowledge surrounding several other materials, for example [4, 5], is sufficient to acknowledge that they offer advantages to the Warfighter over current commercially-available materials. The maturity of the methods necessary to produce spectroscopic-grade specimens of these other materials and incorporate them into gamma spectroscopy systems at costs and scales advantageous to the Defense community remains low. Demonstrations of new and/or improved methods for producing these advanced non-CZT materials in large volumes, at consistently high quality, and acceptable growth rates are sought. If producibility hurdles can be overcome for new or emerging materials, they should yield radioisotope identification detectors (RIIDs) that affordably improve the performance of the warfighter. 


PHASE I: Identify and examine innovative approaches for producing a single specimen of a material suitable for gamma spectrometry in a hand-held sensor format. The approach/process should be able to produce material in sufficient volume and quality to yield a detector crystal whose utilization presents no inherent environmental, health, or safety hazard to the operator, a physical envelope comparable to commercially-available radiation detection materials, relative efficiency[6] that is at least 33%, energy resolution is below 3%, and production cost is comparable to commercially-available NaI. Responsive proposals should clearly describe the proposed approach to producing RIIDs material(s), describe and compare the advantages of the proposed approach and resultant material(s) including cost/benefit, address how the proposed material is superior to those currently used in commercially-available gamma spectrometers, include discussion of prior efforts producing the material(s), problems encountered in producing and integrating material into a gamma spectrometry system, and how the proposed approach could reliably overcome the difficulties, and a path to commercialization. Develop and demonstrate a process flow concept, produce a sample of the material that can be tested, produce supporting documentation with preliminary test data that establishes cost and performance baselines that will mitigate risk for a potential Phase II effort. 


PHASE II: Develop and validate the production process from Phase I to demonstrate yield of sufficient detector material at costs and sizes relevant to the Defense community such that the material could be incorporated into systems which are deployed in the field. Integrate the produced material into four (4) prototype RIID detectors for delivery to the Government. 


PHASE III: If Phase II were successful, the technology developed under this topic would be ready to enable the Warfighter to better accomplish their relevant missions. It would simultaneously allow the radiation detection needs for other groups beyond DoD, both public and private, to be met more affordably without requiring a decrease in performance. PHASE III DUAL USE APPLICATIONS: Dual-use markets are anticipated from Department of Homeland Defense, First Responders, Civil Support Teams, Customs and Border Patrol, and Industrial HAZMAT teams. 



1: (Ref. 1 was removed by TPOC on 9/22/17.)

2:  Brian D Milbrath, Bethany J Choate, Jim E Fast, Walter K Hensley, Richard T Kouzes, and John E Schweppe. 2007. "Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices." Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, 572(2):774-784 572 (2). United States. doi:10.1016/j.nima.2006.12.003.

3:  Sean Stave, Germanium Detectors in Homeland Security at PNNL. Journal of Physics: Conference Series 606 (2015)

4:  Henry Chen; Joo-Soo Kim; Proyanthi Amarasinghe; Withold Palosz;Feng Jin, et al. "Novel semiconductor radiation detector based on mercurous halides," Proc. SPIE 9593, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVII, 95930G (August 26, 2015);doi:10.1117/12.2188448;

5:  Utpal N. Roy, Aleksey E. Bolotnikov, Giuseppe S. Camarda, Yonggang Cui, Rubi Gul, Anwar Hossain, Ryan Tappero, Ge Yang, Ralph B. James, "Nuclear Weapons and Material Security (WMS) Team Program Review WMS2013 CdTeSe Crystals for Gamma-Ray Detectors."

6:  Hastings A. Smith Jr. and Marcia Lucas, "Chapter 3 - Gamma-Ray Detectors", NUREG/CR-5550 Passive Nondestructive Assay of Nuclear Materials, 1991.



KEYWORDS: Gamma, Spectrometry, Spectroscopy, Gamma Spec, Radiation Detection, Radiological Isotope Identification Device (RIID), Identification, Manufacturing Materials 


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