COSI is a NASA Small Explorer (SMEX) satellite mission for launch in 2027. COSI is a wide-field gamma-ray telescope designed to survey the entire sky at 0.2-5 MeV. It provides imaging, spectroscopy, and polarimetry of astrophysical sources, and its germanium detectors provide excellent energy resolution for emission line measurements. I will overview the COSI mission including the science, technical design, and status. The heart of the COSI instrument is an array of high-resolution cross strip germanium sensors. I will focus deeper on germanium detector developments in support of the COSI mission and ongoing work to optimize the in-flight detector performance.

A large-area photon-counting X-ray flat-panel detector with 100-µm pixel pitch using CdTe has been developed, using 0.75-mm-thick diode-type CdTe, connected to an 80-µm square area ultra-low-power photon-charge counting readout circuit, and 96 × 96 pixels. The 12 x 12 modules (9.6 mm square) are tiled to realize a large-area FPD of approximately 4.5 inches. Using ultra-high-precision 3D-IC stacking technology, the readout LSI was made thinner to form TSVs for signal input/output, and on the opposite side, metal for bump connection was formed on a 100µm pitch connection pad to form silver-based bump material, and flip chip bonding was performed with CdTe that had also formed metal to form a 9.6mm square module was formed. This module was tiled on a substrate with extremely flat planarity. A tiling gap of 1 pixel and a physical distance of 40 µm between CdTe and CdTe were achieved. Signal and power lines are taken out and supplied by crossing 90°, and signals are output via a controller with FPGA and DPS. The DQE, MTF, and other characteristics of this CdTe-FPD will be discussed.

This study addresses the need for advanced nuclear waste management strategies, particularly the efficient handling of low-level radioactive waste. Traditional radiation measurement methods pose risks due to the necessity of close proximity to radioactive samples and/or high exposure times. A Compton scattering-based system as an alternative to traditional methods is proposed. The camera employs a 5mm thick CdTe sensor paired with a 55μm Timepix3 detector. The Timepix3's data-driven output allows high photon flux analysis, recording energy and time-of-arrival, vital for accurate source localization and spectrum reconstruction. The comprehensive characterization of this setup, including energy calibration, spatial resolution, and performance in radiation source detection and localization, is presented, alongside challenges and solutions during development. This innovation promises to enhance low-level radioactive waste management safety and efficiency by reducing measurement and personnel exposure time, marking a significant advancement for the nuclear industry and related fields.

Plastic scintillators are widely deployed in radiation detection applications due to their low-cost, high scalability and generally favorable mechanical properties. However, due to their relatively low atomic number, plastic scintillators generally have low absolute efficiency and offer limited energy information for detected gamma-rays. To overcome these challenges, metal-organics can be included in these scintillators, offering higher efficiencies and gamma spectroscopy in plastics. LLNL is pursuing bismuth loading in plastics utilizing both conventional fluors (Bi-PVT) and triplet harvesting fluors (Bismuth-Loaded Iridium-fluor Plastics, BLIP). Bi-PVT is being produced by Eljen in sizes up to 1.5” x 6” x 30” as a drop-in replacement for portal monitors and LLNL is developing a modular spectrometer utilizing BLIP offering high sensitivity per unit mass of detector material.

The future of scintillation materials research lies in a deep exploration of underlying mechanisms and fundamental physics. This entails a shift towards understanding scintillation processes at a microscopic level to inform rational material design. By unraveling these mechanisms, one can guide the development of tailored materials to meet diverse application requirements effectively. This abstract highlights the necessity of a paradigmatic shift towards a more fundamental understanding to propel advancements in scintillation technology.

Transparent ceramics formed from garnet and sesquioxide crystal structures are under development for gamma spectroscopy detectors, x-ray imaging screens, solid state lighting, and laser gain media. For lens-coupled radiographic imaging, thin transparent scintillators with low optical scatter are required. For gamma spectroscopy, intra-band gap trap state distribution is critical to achieve light yield proportionality, to modify the pulse duration and afterglow. Recent advances in fabrication and implementation into systems will be described.

We are reporting novel thin-film scintillators using nanomaterials of a transparent boron compound (10B enriched) embedded in an organic or inorganic phosphor matrix. In comparison to the 6LiF/ZnS and 6LiF/gadolinium oxysulfide scintillators, the new scintillator has a much higher neutron absorption cross-section and a much lower x-ray/gamma ray sensitivity. Moreover, the fluorescent decay constant of our organic phosphor (~ns) is much shorter than the commercial scintillators (~ µs) that can potentially benefit neutron multiplicity counting to detect and quantify nuclear materials in safeguards, arms control, and emergency response. Due to the reinforcement of the boron nanomaterials, the scintillator thin films with organic and inorganic phosphors are both mechanically robust and can be made ultra-thin and flexible. Those new properties will allow them to conformally adhere to irregularly shaped imaging objects, leading to an improved spatial resolution for future neutron radiography.

High-resolution gamma-ray spectroscopy is a powerful tool for measuring the elemental composition of planetary bodies. Our group has built, or is currently building, germanium-based gamma-ray spectrometers for four deep-space planetary missions, including NASA's MESSENGER mission to the planet Mercury, the Psyche mission to the asteroid belt, the Dragonfly mission to Titan, as well as JAXA's mission to the moons of Mars. This talk will cover the engineering challenges of deploying germanium spectrometers in space, as well as the interesting planetary science enabled by this technology.

Halide perovskites have garnered strong attention in R&D on ionizing-radiation detectors due to their tunable bandgap, efficient absorption coefficient, superior charge transport characteristics, versatile chemistry synthesis, and cost-effective manufacturing. Enhanced growth methods can yield perovskite materials with improved crystallinity, purity, and overall performance. In this work, we grew a series of lead-free halide perovskite materials, e.g., FA3Bi2I9 (FA=CH(NH2)2) and Cs3Bi2I9, using different growth techniques. Systematic microstructural-, electrical-, optical-, and mechanical- characterization results, together with radiation response testing, will be presented and discussed.

Nuclear voltaic batteries are not a new concept, yet their advancement is hindered by low power conversion efficiency and low power output. An alternative method to integrating a radioisotope with a semiconductor energy transducer for power generation involves capturing gamma rays with a bulk scintillator, which then converts the resulting visible light directly to electricity through commercially available solar cells. This approach is referred to as a nuclear photovoltaic battery which targets external radiation fields such as waste storage or areas close to high-intensity gamma-ray emitters. We explored this concept using a 2cm x 2cm x 1cm Gadolinium Aluminum Gallium Garnet (GAGG:Ce (HL)) scintillator, a polycrystalline CdTe solar cell with an Au contact size of 1.3cm x 1.3cm, and a high gamma field emitted by a Cs-137 (~1.5 kRad/hr) irradiator. The preliminary measurements yielded a maximum power output of ~ 280nW, with open circuit voltage (Voc) and short circuit current (Isc) of 0.34V and 1.98μA, respectively, resulting in a Fill Factor of 41.5%.

In this study, we introduce a novel spectroscopic CT scanning method using a 12x1 Timepix3 detector array with 1mm CdTe sensors in data-driven readout mode. It enables full-spectrum data acquisition and processing on standard laboratory computers, addressing challenges of varying absorption and data volume issues. Our approach involves an initial preclustering step, reducing data size with an efficient algorithm. We then employ dynamic pixel masking to limit photon collection, optimizing signal-to-noise ratios and reducing data load. This strategy enables comprehensive CT scans on standard computers, advancing spectroscopic CT imaging.

We present the results from testing over 100 5x5x12 mm3 TlBr detectors configured as 3D position-sensitive virtual Frisch-grid (VFG) detectors with platinum contacts. The primary objective was to comprehensively understand factors limiting performance and long-term response variations in these detectors. The incorporation of 3D position sensitivity allowed us to monitor internal changes in charge collection efficiency after applying voltage, and to correlate them with device performance changes. The biased detectors underwent defect distribution alterations due to electric field-enhanced ion migration. Our results are based on an extensive dataset obtained from TlBr crystals produced by Radiation Monitoring Devices (RMD). These measurements were part of our development of a handheld isotope identifier based on an array of position-sensitive TlBr detectors, supported by the Department of Homeland Security, Countering Weapons of Mass Destruction Office. The majority of the detectors exhibited a common trend of performance improvement within 1-2 weeks, stabilization for some period of time, then a slow degradation; however, some detectors deviated from this pattern.

Antineutrinos emitted from nuclear reactors are important for investigating neutrino physical properties and exploring physics beyond the Standard Model. The antineutrino flux can also serve as a tool for remote monitoring of nuclear reactors. Ongoing advancements in detection technologies aim to improve background rejection, efficiency, and precision. We will discuss novel scintillators and detector designs, highlighting recent developments in liquids and plastics. Additionally, we will present new techniques, including crystal color center detection of neutrino elastic scatterings.

CdTe is used as a compound semiconductor detector that operates at room temperature. Because CdTe has a thick crystal of approximately 1mm, it is necessary to apply a high voltage to extract the charge generated by incident x-rays. Although it is necessary to suppress the leakage current that increases when a high voltage is applied, this leakage current can be suppressed by using the rectification effect of the diode. A pn junction is used as the diode, which has a potential barrier formed inside the crystal and is considered to have high heat resistance and mechanical resistance. Therefore, we propose a doping method using thermal diffusion using an electron beam. In order to verify thermal diffusion doping using an electron beam, we fabricated a pn-type CdTe radiation detector using an EBAS (Electron Beam Assist Source) device, which is an electron beam annealing device.