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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

LumaCam: a novel class of position-sensitive event mode particle detectors using scintillator screens

A new type of position-sensitive detectors is gaining attention in the neutron community. They are scintillator based detectors that detect the scintillation light on an individual photon basis via an image intensifier and a fast image sensor. Their readout operates in event mode i.e. it produces information about individual neutron interactions, reconstructed from the sensor data, thus enabling to achieve superior spatial and temporal resolutions compared to regular detectors. Although the development of current detectors is focused on neutrons, the concept is also applicable to the detection of other particles such as high-energy photons. This document provides a description on how these detectors are built, how they operate, and what their characteristics are. An example of a detector implementation based on a Timepix3 chip is described to illustrate the detector concept. This includes a detailed description of the algorithm that reconstructs the neutron interactions from the sensor data, one of the core components that sets it apart from established scintillator-based imaging detectors. Energy-resolved epithermal neutron radiography was performed at the ISIS EMMA beamline with this detector, illustrating some of the fundamental differences in the data that can be produced with the new type of detector compared to more established types of scintillator based neutron detectors. The term LumaCam is proposed to refer to this new class of position-sensitive event-mode detectors.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Algorithms for coordinate reconstruction in position-sensitive virtual Frisch-grid detectors

Arrays of position-sensitive virtual Frisch-grid (VFG) CdZnTe (CZT) detectors provide a cost-effective solution for integrating large-area arrays for gamma-ray imaging and spectroscopy. These detectors employ high-aspect ratio CZT crystals (bars) with thicknesses up to 50 mm and cross-sections of up to 10 × 10 mm 2 . Despite the long drift distances of charge carriers in such crystals, the detectors have demonstrated excellent performance, achieving energy resolutions better than 1 % full width at half maximum (FWHM) at 662 keV and 3D position resolutions finer than 1 mm. The high spatial resolution is a critical feature of these detectors, as it enables correction of response non-uniformities caused by crystal defects, which remain present even in the highest-quality CZT material. Dislocations and dislocation walls are the primary defects responsible for variations in charge carrier losses as they drift from the interaction points toward the charge-collecting electrodes. The mechanism by which these defects affect carrier transport is generally well understood. Dislocations and sub-grain boundaries act as sinks for carrier-trapping centers, primarily impurities and secondary phases such as tellurium inclusions and precipitates. Here, these regions exhibit significantly higher carrier-trapping rates, leading to variations in the μτ-products. Because the locations of these micron-sized regions are fixed within the detector volume, fluctuations in the total collected charge arise from the random distribution of interaction sites. This results in non-uniform detector responses and degradation of energy resolution. However, by measuring the interaction-site locations with sufficient precision, charge-loss variations can be accurately corrected, allowing recovery of nearly intrinsic energy resolution.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Laser beam pointing stabilization using analog position-sensitive diodes

Laser wire scanners have been used for ion beam profile and emittance measurements at the Spallation Neutron Source linear accelerator. Due to propagation distances exceeding 100 m, reliable measurements require laser beam stabilization, previously accomplished with a feedback control loop using a digital camera as a position sensor [Hardin et al., Opt. Express 19, 2874 (2011)]. Here, this paper presents an upgraded pointing stabilization system utilizing analog position-sensitive diodes (PSDs) as the position detector, optimized with an optical diffuser. The new system significantly surpasses the previous system by offering an order-of-magnitude improvement in radiation tolerance and a bandwidth limited only by the burst repetition rate of the laser beam. Operating with a 60-Hz burst mode laser, the new system effectively suppresses laser beam drifts up to 30 Hz, compared to the previous system’s 4 Hz limit. In addition, the amplitude of spectral components below 0.1 Hz was reduced by a factor of more than 100, which is over seven times greater than was achieved by the previous system.

Data acquisition↗
DOE OSTI2026

Improving Chirped Fiber Bragg Grating Resolution for Position-Sensitive Sensors in Shock- and Detonation-Driven Experiments

Chirped fiber Bragg gratings (CFBGs) are robust diagnostic sensors that are widely used to track detonation-driven and shock wave propagation. CFBGs are inscribed with a linearly chirped periodic index of refraction changes that alter the Bragg wavelength along the length of the probe. The light return of each individual Bragg element is captured by a detector at a unique time to map the full reflected spectrum. The CFBG spectrum is measured with a dispersive Fourier transform of the reflected light that temporally stretches the spectrum to increase spatial resolution and make a one-to-one map of the wavelength on a time axis. Here, we propose an improvement of CFBG temporal resolution by incorporating two co-linear laser pulses with orthogonal polarization states and a 5 ns time offset. The two separate signals were split and tracked by two separate detectors. An oscilloscope captured good separation in the signals, and two separate spectrograms were generated and interleaved in the post-processing of the data. This novel technique doubled the CFBG temporal resolution and led to a doubled location resolution. As a proof-of-concept of this technique, the resolution improvement was compared between standard CFBG measurements and the two polarization states method on a position-sensitive CFBG sensor. CFBG resolution doubling will advance sensor capabilities and will have a direct impact on improving capture and analysis in dynamic, high-explosive experiments.

42 ENGINEERING↗
NASA NTRS1973

A position-sensitive X-ray detector for the HEAO-A satellite.

A position-sensitive, low-energy proportional counter system is described which will be used on the High-Energy Astronomical Observatory, Mission A, spacecraft. The associated system incorporates the capability to employ pulse-shape discrimination for background rejection and interpolation circuitry to locate the centroid of an X-ray event with an accuracy of approximately one eighth the cathode-wire spacing.

Held, D.↗
DOE OSTI2025

Analysis of Radioactive Waste and Contamination using 3D Position-Sensitive CdZnTe Detectors

INTRODUCTION The US has surplus plutonium. This material will be diluted in gloveboxes at SRS [Ref 1 and 2]. This process will create holdup. Holdup is material in an unexpected or unwanted location. Because this holdup material is primarily PuO2, it must be accounted for (measured). This measurement is typically done using a liquid-nitrogen cooled, HPGe detector. To enable more rapid processing, advanced holdup technologies are being explored [Ref 3 and 4]. METHODS For the surplus plutonium dilute and dispose program, the traditional detector system could slow down the optimal operational tempo of the program. A multiple-detector system, providing complete glovebox coverage, based on CdZnTe crystals, 3D-positioning electronics, and a coded aperture mask, is in the process of being developed by ORNL and SRNL [Ref 4].

Whiteside, Tad [Savannah River National Laboratory↗
DOE OSTI2025

YSO implantation detector for beta-delayed neutron spectroscopy

A segmented-scintillator-based implantation detector was developed to study the energy distribution of β-delayed neutrons emitted from exotic isotopes. The detector comprises a 34 × 34 YSO scintillator coupled to an 8 × 8 anode Position-Sensitive Photo-Multiplier Tube (PSPMT) via a tapered light guide. The detector was used at RIBF, RIKEN for time-of-flight-based neutron spectroscopy measurement in the 78Ni region. The detector provides the position and timing resolution necessary for ion-beta correlations and time of flight measurements. The detector provides a high ~80% beta-detection efficiency and a sub-nanosecond timing resolution. This contribution discusses the details of the design, operation, implementation, and analysis developed to obtain neutron time-of-flight spectrum and the analysis methods in the context of neutron-rich nuclei in the 78Ni region.

Implantation detector↗
DOE OSTI2025

Performance characterization of 5×5×12 mm 3 virtual Frisch-grid TlBr detectors

Thallium bromide (TlBr) is a promising material for semiconductor gamma-ray detectors due to its high atomic number (Tl = 81, Br = 35), high density (7.56 g/cm 3 ), and relatively low melting point (460 °C). These properties give TlBr several competitive features, including high detection efficiency, good energy resolution, and lower fabrication costs, making it suitable for applications requiring compact, highly sensitive gamma-ray detection systems. Recent developments of TlBr detectors have progressed toward thicker crystals, up to 10–20 mm, configured as pixelated or virtual Frisch-grid (VFG) devices with volumes >1 cm 3 . Despite these advances, challenges remain in practical implementation, including material and fabrication issues that affect energy resolution, device stability, performance, and longevity. These challenges are similar to those faced by HgI 2 and lead-halide perovskite detectors. Here, this study presents results from characterizing over 100 position-sensitive 5×5×12 mm 3 virtual Frisch-grid detectors fabricated by Radiation Monitoring Devices Inc. For a prototype Radioisotope Identification Device (RIID). The work identified factors limiting the performance and longevity of TlBr detectors, including stochastic response variations that limit the energy resolution to 2–3 % (at 662 keV) for most devices, performance degradation associated with defect decoration, and contact delamination. Addressing these issues advances the use of TlBr and similar materials for reliable, high-resolution gamma-ray spectroscopy.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Thickness and uniformity mapping of thin foils using resistive silicon detectors

Alpha energy loss is a common tool used for measuring target thicknesses. However, these measurements are often made without position information, which either forfeits knowledge of material uniformity and local thickness or requires a prohibitive number of measurements per target to partially recover this information. In consideration of this, a method for measuring position-dependent thicknesses is described in this work; by using the position-sensitivity of the dual-axis duo-lateral (DADL) silicon detector, thicknesses across the entire face of the material can be measured to sub-mm precision with a single measurement. Several examples are presented using a number of targets with varying characteristics, which altogether demonstrate the precision, accuracy, and versatility of this technique.

Foil uniformity↗
DOE OSTI2026

Commissioning of an MPGD-based Drift Chamber for Heavy-ion Tracking in FRIB's Sweeper magnet system

A newly developed drift chamber equipped with an innovative hybrid Micro-Pattern Gaseous Detector based readout was commissioned at FRIB. The detector consists of a Multi-layer Thick Gas Electron Multiplier (M-THGEM) mounted over a high-granularity, position-sensitive readout board. Denoted as the Micro-Pattern Drift Chamber (MPDC), the new device is used to provide tracking capability as part of the detectors of the Sweeper magnet system for neutron-invariant-mass spectrometry at the Facility for Rare Isotope Beams (FRIB). The localization of impinging ions in a 30 × 30 cm 2 drift area is derived by processing the charge-avalanche distribution induced on the segmented readout board. The signals induced on the readout pads are processed by a compact, multi-channel Data Acquisition System (DAQ) based on the Scalable Readout System (SRS). To facilitate synchronization with other detector systems of the Sweeper magnet system, the SRS has been configured to accept an external trigger.

Gaseous detectors↗
DOE OSTI2026

Upgrades to the TRIUMF Fast Ion Counter, TRIFIC

TRIFIC, the TRIUMF Fast Ion Counter, is a downstream ionization chamber which provides beam composition monitoring and recoil tagging for in-beam reaction experiments. TRIFIC has been commissioned and deployed for use with radioactive isotope beams at the TRIUMF-ISAC facility. Recently, the detector has been upgraded to include an improved gas window that can accommodate higher beam rates and position-sensitive electrode grids for better position reconstruction.

Gaseous detectors↗
NASA NTRS1973

Solar aspect determination system

Sensor containing commercially available solid-state position-sensitive light detector provides complete space-vehicle sun or moon vector information.

Farthing, W. H.↗
NASA NTRS1974

Two high resolution velocity vector analyzers for cosmic dust particles

Methods are described to measure velocities and angles of incidence of charged cosmic dust particles with precisions of about 1 percent and 1 degree, respectively. Both methods employ four one-dimensional position-sensitive detectors in series. The first method utilizes a charge-dividing technique while the second utilizes a time-of-flight technique for determining the position of a particle inside the instrument. The velocity vectors are measured although mechanical interaction between the particle and the instrument is completely avoided. Applications to cosmic dust composition and collection experiments are discussed. The range of radii of measurable particles is from about 0.01 to 100 microns at velocities from 1 to 80 km/s.

Aver, S.↗
NASA NTRS1974

Separation of surface and bulk minority-carrier lifetimes in silicon

A photoexcitation technique is suggested which is direct and convenient, requiring little special equipment. No change in the dimensions of the crystal sample is necessary. Although related to the technique of interposing a filter between the light source and the sample, it differs in that the filter is part of the crystal itself. Basically, one of the electrodes is split into two electrodes, one collecting charge from carriers excited in the bulk. This phenomenon in which the carriers follow very closely the electric field lines has been used in position-sensitive semiconductor radiation detectors (Norbeck and Carlson, 1963) but has not been applied to lifetime measurements. In a sense, the split electrode creates a sample without a surface.

Carroll, K. A.↗
NASA NTRS1975

Two high resolution velocity vector analyzers for cosmic dust particles

Two new methods are described to measure velocities and angles of incidence of charged cosmic dust particles with precisions of about 1% and 1 deg, respectively. Both methods employ four one-dimensional position-sensitive detectors in series. The first method utilizes a charge-dividing technique while the second utilizes a time-of-flight technique for determining the position of a particle inside the instrument. The velocity vectors are measured although mechanical interaction between the particle and the instrument is completely avoided. Applications to cosmic dust composition and collection experiments are discussed. The range of radii of measurable particles is from about 0.01 to 100 microns at velocities from 1 to 80 km/sec.

Auer, S.↗
NASA NTRS1976

High-resolution imaging X-ray detector

The paper describes an X-ray detector using microchannel plates as a photocathode surface and imaging photoelectron multiplier, and a crossed wire grid as a two-dimensional position-sensitive detector. The position resolution is 10 microns. The crossed wire grid consists of 100-micron-diam wires on 200-micron centers. Position sensing is accomplished by electronic interpolation to 1/20 of the wire spacing. The quantum efficiency of the microchannel plates varies from 29% at 0.28 keV to 5% at 3 keV. This detector will provide second-of-arc X-ray imaging in the focal plane of the 342.9-cm focal length grazing-incidence telescope being prepared for the HEAO-B observatory. By addition of suitable photocathodes, it can be used for single-photon imaging light detection in the UV, visible, and near-IR-ranges. In all cases, it gives a very low dark counting rate, allows timing of individual events to 1 microsec or less, and can handle counting rates up to 10,000 per sec.

Kellogg, E.↗
NASA NTRS1976

Evaluation of clad scintillating light pipes

Arrays of fibers made of scintillating material were used as position-sensitive detectors or hodoscopes for beam-finding at ion accelerators. Experiments were made with alpha's from an Am241 source incident upon one end of the fiber, the other end being viewed with a photomultiplier tube. The scintillation light was not detected in any of the fibers tested beyond about 5 cm. The effective useful lengths for detection of relativistic heavy ions were given.

Source record↗
NASA NTRS1976

Quadrant anode image sensor

A position-sensitive event-counting electronic readout system for microchannel plates (MCPs) is described that offers the advantages of high spatial resolution and fast time resolution. The technique relies upon a four-quadrant electron-collecting anode located behind the output face of the microchannel plate, so that the electron cloud from each detected event is partly intercepted by each of the four quadrants. The relative amounts of charge collected by each quadrant depend on event position, permitting each event to be localized with two ratio circuits. A prototype quadrant anode system for ion, electron, and extreme ultraviolet imaging is described. The spatial resolution achieved, about 10 microns, allows individual MCP channels to be distinguished.

Lampton, M.↗