Scintillators are important materials for radiographic imaging and tomography (RadIT), when ionizing radiations are used to reveal internal structures of materials. Since its invention by Röntgen, RadIT now come in many modalities such as absorption-based X-ray radiography, phase contrast X-ray imaging, coherent X-ray diffractive imaging, high-energy X- and γ-ray radiography at above 1 MeV, X-ray computed tomography (CT), proton imaging and tomography (IT), neutron IT, positron emission tomography (PET), high-energy electron radiography, muon tomography, etc. Spatial, temporal resolution, sensitivity, and radiation hardness, among others, are common metrics for RadIT performance, which are enabled by, in addition to scintillators, advances in high-luminosity accelerators and high-power lasers, photodetectors especially CMOS pixelated sensor arrays, and lately data science. Medical imaging, nondestructive testing, nuclear safety and safeguards are traditional RadIT applications. Examples of growing or emerging applications include space, additive manufacturing, machine vision, and virtual reality or `metaverse'. Scintillator metrics such as light yield and decay time are correlated to RadIT metrics. More than 160 kinds of scintillators and applications are presented during the SCINT22 conference. New trends include inorganic and organic scintillator heterostructures, liquid phase synthesis of perovskites and μm-thick films, use of multiphysics models and data science to guide scintillator development, structural innovations such as photonic crystals, nanoscintillators enhanced by the Purcell effect, novel scintillator fibers, and multilayer configurations. Opportunities exist through optimization of RadIT with reduced radiation dose, data-driven measurements, photon/particle counting and tracking methods supplementing time-integrated measurements, and multimodal RadIT.

Material identification (ID) using radiography is a problem that has implicitly existed since the discovery of the X-ray. Since 9-11, this problem has received renewed attention for homeland security applications of the generic, “what is in the box?” type1. Examples of items potentially in the box include: roadside bombs, nuclear weapons, contraband shipments and the like. In these cases, the “what” can include: explosives, projectiles, fissile material, or drugs. Here we investigate the ability of 60Co gamma-rays, 14MeV neutrons, and their combination to tease apart information about density, thickness and atomic number of items in the box. That information subset can be combined with other types of independent information (e.g. neutron and gammaspectroscopy, intelligence, photographs etc.) to assert a more complete picture of what, exactly, is in the box? That more complete information set can form the basis for actions including: remote detonation, evacuations, disablement, detention, search, arrest etc.

discrepancy is most likely a USA instrumental effect which manifests itself as excess power in the frequency range of interest. Future work on correcting this problem should provide more accurate analyses that may yield a different result.

The numerous types of noise in a typical radiograph include: quantum noise, read noise, thermal noise, scatter, etc. The character of these noise sources can be non-stationary, non-linear, Gaussian, Poisson, white, pink, additive, multiplicative, point, random and/or systematic. Furthermore these noise sources impact radiographic factors including: conjugates, exposure duration, filtration, detector type, Swank & Fano factors, Bucky grids, energy, collection optics, charge leakage, digitizer type, dynamic range, detector temperature, pixel size, calibration technique, system stability etc. In short, the “noise” in a radiograph is a very complex subject with many real-world tradeoffs. We delineate the noise sources in a typical silicon detector (e.g. CCD, CMOS, or AmSi, TFT) to illustrate the character of those sources and statistics behind some of the choices required to readout and calibrate those detectors.

separate methods currently in use for deblurring radiographs. I begin by briefly describing the problems associated with image restoration, and outlining the three methods. Next, I illustrate how blurring affects the quantitative measurements using radiographs. I then present the results of the various deblur methods, evaluating each according to several criteria. After I have summarized the results of the evaluation, I give a detailed account of how the restoration process is actually implemented.

and detective quantum efficiency with increasing plate number, at the expense of resolution. Select detector geometries were tested by comparing simulation and experimental modulation transfer functions to validate the approach.

Monte Carlo transport codes have been used to model the detector blur and energy deposition in various detector geometries for applications in MeV radiography. Segmented scintillating detectors, where low Z scintillators combined with a high-Z metal matrix, can be designed in which the resolution increases with increasing metal fraction. The combination of various types of metal intensification screens and storage phosphor imaging plates has also been studied. A storage phosphor coated directly onto a metal intensification screen has superior performance over a commercial plate. Stacks of storage phosphor plates and tantalum intensification screens show an increase in energy deposited and detective quantum efficiency with increasing plate number, at the expense of resolution. Select detector geometries were tested by comparing simulation and experimental modulation transfer functions to validate the approach.

Los Alamos has used penetrating radiography extensively throughout its history dating back to the Manhattan Project where imaging dense, imploding objects was the subject of intense interest. This interest continues today as major facilities like DARHT1 have become the mainstay of the US Stockpile Stewardship Program2 and the cornerstone of nuclear weapons certification. Meanwhile, emerging threats to national security from cargo containers and improvised explosive devices (IEDs) have invigorated inspection efforts using muon tomography, and compact x-ray radiography. Additionally, unusual environmental threats, like those from underwater oil spills and nuclear power plant accidents, have caused renewed interest in fielding radiography in severe operating conditions. We review the history of penetrating radiography at Los Alamos and survey technologies as presently applied to these important problems.

We present a unique, lightweight, compact, low-cost, x-ray imager: MiniMAX (Miniature, Mobile, Agile, X-ray). This system, which exploits the best aspects of Computed Radiography (CR) and Digital Radiography (DR) technology, weighs less than 6lbs, fits into a 6 '' diameter x 16 '' long carbon-fiber tube, and is constructed almost entirely from off-the-shelf components. MiniMAX is suitable for use in weld inspection, archaeology, homeland security, and veterinary medicine. While quantum limited for MeV radiography, the quantum-efficiency is too low for routine medical use. Formats include: 4 '' x6 '', 8 '' x12 '', or 16 '' x24 '' and can be readily displayed on the camera back, using a pocket projector, or on a tablet computer. In contrast to a conventional, flying-spot scanner, MiniMAX records a photostimulated image from the entire phosphor at once using a bright, red LED flash filtered through an extremely efficient (OD>9) dichroic filter.

The Los Alamos National Laboratory's Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) generates flash radiographs of explosive experiments using two linear induction electron accelerators situated at right angles. The DARHT second axis accelerator generates an 18-MeV, 2 kA, 2 musec electron beam which is converted or ldquochoppedrdquo into four individual pulses ranging from 20 to 100 nsec in length at 2 MHz frequency. The individual electron beam pulses are down-converted by a segmented lutetium oxyorthosilicate scintillator, creating four visible light flashes, to image explosively driven events. To record these events, a high efficiency, high speed, imager has been fabricated which is capable of framing rates of 2 MHz. This device utilizes a 512 times 512 pixel charge coupled device (CCD) with a 25 cm 2 active area, and incorporates an electronic shutter technology designed for back-illuminated CCD's, making this the largest and fastest back-illuminated CCD in the world. Characterizing an imager capable of this frame rate presents unique challenges. High speed LED drivers and intense radioactive sources are needed to perform basic measurements. We investigate properties normally associated with single-frame CCD's such as read noise, gain, full-well capacity, detective quantum efficiency (DQE), sensitivity, and linearity. In addition, we investigate several properties associated with the imager's multi-frame operation such as transient frame response and frame-to-frame isolation while contrasting our measurement techniques and results with more conventional devices.

Massachusetts Institute of Technology, Lincoln Laboratory (MIT LL) has been developing both continuous and burst solid-state focal-plane-array technology for a variety of high-speed imaging applications. For continuous imaging, a 128 x 128-pixel charge coupled device (CCD) has been fabricated with multiple output ports for operating rates greater than 10,000 frames per second with readout noise of less than 10 e(-) rms. An electronic shutter has been integrated into the pixels of the back-illuminated (BI) CCD imagers that give snapshot exposure times of less than 10 ns.For burst imaging, a 5 cm x 5 cm, 512 x 512-element, multi-frame CCD imager that collects four sequential image frames at megahertz rates has been developed for the Los Alamos National Laboratory Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. To operate at fast frame rates with high sensitivity, the imager uses the same electronic shutter technology as the continuously framing 128 x 128 CCD imager. The design concept and test results are described for the burst-frame-rate imager.Also discussed is an evolving solid-state imager technology that has interesting characteristics for creating large-format x-ray detectors with ultra-short exposure times (100 to 300 ps). The detector will consist of CMOS readouts for high speed sampling (tens of picoseconds transistor switching times) that are bump bonded to deep-depletion silicon photodiodes. A 64 x 64-pixel CMOS test chip has been designed, fabricated and characterized to investigate the feasibility of making large-format detectors with short, simultaneous exposure times.

Despite a century-old patent, and wide application at lower energies, the fabrication of thick anti-scatter "Bucky" grids for application at megavolt energies has been an elusive goal. We discuss the design, fabrication and testing of a 45 cm-diameter grid with a focal length of 525 cm for use at the 20 MeV DARHT flash radiography facility. The predominant difficulties overcome were: (1) understanding the performance of such grids prior to fabrication, and (2) the precision fabrication itself. To understand the former, we employed a specially modified version of the MCNP Monte Carlo code run on the ASC blue-mountain supercomputer at Los Alamos to explore and optimize the parameter space. These calculations were benchmarked at the Los Alamos microtron facility using a small prototype grid. To have useful scatter rejection at megavolt energies, grid ratios of several hundred-to-one are required. State-of-the-art grids used in medical radiography have grid ratios of ten-to-one. We demonstrate a unique casting technology capable of accurately manufacturing large grids with very high grid ratios. Promising initial test results are also presented. It is our belief that similar grids will prove useful in a wide range of potential applications including: megavolt NDE radiography, Compton scatter radiography, balloon-born gamma-ray astronomy, medical therapy, and in the intended application of flash radiography at Los Alamos' DARHT facility

The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory's Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility (l). The first uses a CCD camera combined with high-brightness fluors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated Table 1. Common Spot Size Measurement Techniques modulation transfer function in real time for shot-to-shot comparison. After testing these methods and several others (using type AA radiographic film with l-mm lead screens), the large pin