OUSD (R&E) MODERNIZATION PRIORITY: Nuclear TECHNOLOGY AREA(S): Sensors; Nuclear; Materials; Electronics OBJECTIVE: Develop a portable, handheld, high-resolution, low operating voltage, spectroscopic-capable radiation detector using direct semiconductor radiation sensing elements that are based on perovskites. The detector could be carried by the warfighter or easily integrated into light vehicles to enable the operator to identify radioisotopes present in the battlefield or operational environment. DESCRIPTION: Currently available radiation detection and imaging systems capable of high-resolution, spectroscopic operation necessary for radioisotope identification and positioning are either incapable of being deployed in handheld, portable systems (due to SWAP or the requirements for cryogenic operation) or are prohibitively expensive to deploy to the general warfighter. Perovskite materials, including organic-inorganic hybrid perovskites and inorganic perovskites, are high-quality semiconductor materials with a high absorption cross-section to ionizing radiation. Additionally, perovskite materials exhibit a long carrier lifetime, moderate mobility, and can be grown using scalable, inexpensive methods, including solution processing. The use of inexpensive, earth-abundant materials in perovskites shows promise to significantly reduce the cost of radiation detection and imaging systems, enabling wider deployment of these systems. Although perovskite materials have been demonstrated to have a good energy resolution (near 2% at 662 keV), they can suffer from bias-induced performance degradation, and the material uniformity, material yield, surface and contact engineering, and compatible readout electronics and imaging systems still need optimization to enable deployment to the warfighter. DTRA envisions the use of such systems in battlefield radioisotope monitoring and warning, and general imaging usage (i.e. non-destructive testing of DoD components). Specific requirements of these systems include: Energy resolution < 2% at 662 keV Energy resolution < 5% at 2 MeV Detection efficiency > 80% at 662 keV Detection efficiency > 50% at 2 MeV Operating bias < 300 V Capability for dual-mode (gamma and fast neutron) operation Detector material cost < $15 USD per cubic centimeter Radiation survivability up to 10,000 cGy Maximum degradation in energy resolution of 20% (in terms of the zero-dose energy resolution) at a TAD of 3,600 cGy of neutrons and gammas in any proportion Detector yield > 75 % Detector variability (in terms of energy resolution) < 10 % Angular resolution for imager < 3 degrees System mass for imagers (excluding power supply) < 20 kg. Additionally, DTRA seeks the following innovations during the SBIR project: Ability for computer-controlled growth and optimization of the perovskite material, with minimal user intervention. Optimization of contact materials, interfaces, passivation and deposition techniques to minimize damage to the perovskite material. Design and optimization of readout electronics tailored to the material capacitance and carrier mobility and lifetime of the perovskite material. PHASE I: Demonstrate the feasibility of low-cost, handheld, portable, high-resolution perovskite detection systems by demonstrating a single-pixel detector meeting the above requirements of: energy resolution, detector efficiency, operating bias, material cost, and radiation survivability. Deliverables will include: radiation response characterization (in the form of spectra from various detectors), perovskite crystal detectors, and material growth procedures and recipes. The design of a customized circuit to improve the detector performance, if needed for performance improvement, can be part of Phase I. The development of stable material performance under bias which can include optimal rectifying contacts and surface passivation and deposition strategies is a critical goal of Phase I. The Phase I effort will include prototype design plans to be developed under Phase II. PHASE II: Develop a prototype imager, with a minimum of 144 pixels, meeting all the above project requirements. The design of a GUI for the imager, and if applicable, a working, computer-controlled material growth system will be completed. Phase II will include the demonstration of the performance of the prototype system to imaging both gamma-rays and fast neutrons. This demonstration will include mature hardware designs and documentation and prototype testing. A prototype imager, which may include an off-board power supply and data processing, will be delivered to the Government for testing. PHASE III DUAL USE APPLICATIONS: Final prototype development, including on-boarding all components (including the power supply and data processing systems) will be completed, and designs and initial prototypes for larger (greater number of pixel) imaging systems will be completed. The imaging system will transition to manufacturing, with a focus on acquisition of such systems by the DoD. Handheld radiation imaging systems, of varying design, are needed across industry for both defense and commercial applications, the latter of which include: medical imaging, non-destructive testing, contraband interdiction, and nonproliferation compliance enforcement. REFERENCES: H. Wei and J. Huang, Halide Lead Perovskites for Ionizing Radiation Detection, Nat. Commun. 10, 1 (2019). S. Yakunin, M. Sytnyk, D. Kriegner, S. Shrestha, M. Richter, G. J. Matt, H. Azimi, C. J. Brabec, J. Stangl, M. V. Kovalenko, and W. Heiss, Detection of X-Ray Photons by Solution-Processed Lead Halide Perovskites, Nat. Photonics 9, 444 (2015). W. Wang, et al., Electronic-Grade High-Quality Perovskite Single Crystals by a Steady Self-Supply Solution Growth for High-Performance X-ray Detectors, Adv. Mater., 32, 2001540 (2020). W. Pan, H. Wei, and B. Yang, Development of Halide Perovskite Single Crystal for Radiation Detection Applications, Front. Chem. 8, 1 (2020). L. Xu, W. Jie, G. Zha, Y. Xu, X. Zhao, T. Feng, L. Luo, W. Zhang, R. Nan, and T. Wang, Radiation Damage on CdZnTe:In Crystals under High Dose 60Co -Rays, CrystEngComm 15, 10304 (2013). Y. He, L. Matei, H. J. Jung, K. M. McCall, M. Chen, C. C. Stoumpos, Z. Liu, J. A. Peters, D. Y. Chung, B. W. Wessels, M. R. Wasielewski, V. P. Dravid, A. Burger, and M. G. Kanatzidis, High Spectral Resolution of Gamma-Rays at Room Temperature by Perovskite CsPbBr3 Single Crystals, Nat. Commun. 9, 1 (2018). J. Res. Natl. Inst. Stand. Technol. 109, 451-456 (2004) T. Gozani et al., Passive Nondestructive Assay of Nuclear Materials, NUREG/CR-5550 (US Nuclear Regulatory Commission, Washington, DC, 1991) M. Liu, Z. Li, W. Zheng, L. Kong, and L. Li, Improving the Stability of CsPbBr3 Perovskite Nanocrystals by Peroxides Post-Treatment, Front. Mater. 6, 1 (2019). P. Zhang, G. Zhang, L. Liu, D. Ju, L. Zhang, K. Cheng, and X. Tao, Anisotropic Optoelectronic Properties of Melt-Grown Bulk CsPbBr3 Single Crystal, J. Phys. Chem. Lett. 9, 5040 (2018). KEYWORDS: radiation detection, radiation sensor, radiation imaging, perovskite, gamma, neutron
