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NASA NTRS1984

Test results and in-orbit operation of the Infrared Astronomical Satellite circumvention circuit

The IRAS circumvention circuit (CC) eliminates the unwanted charged-particle pulses from the IR signal. The operation of the CC along with preflight and in-orbit testing is described. Ground testing of the brassboard circuit using a simulated preamplifier output showed that the CC would perform the circumvention function as designed. When all flight detectors and preamplifiers became available, the CC was tested using a gamma source to simulate charged-particle sources; with the low energy deposited in the detectors (20 keV average) the noise was reduced by up to 5 times with the CC turned on. In-orbit results show that the CC decreases the unwanted charged-particle background noise by up to two orders of magnitude. The difference in the results with the CC on and off is so great that the science team has recommended that no data be taken with the CC off.

Long, E. C.↗

NASA NTRS2013

Analytic Perturbation Method for Estimating Ground Flash Fraction from Satellite Lightning Observations

An analytic perturbation method is introduced for estimating the lightning ground flash fraction in a set of N lightning flashes observed by a satellite lightning mapper. The value of N is large, typically in the thousands, and the observations consist of the maximum optical group area produced by each flash. The method is tested using simulated observations that are based on Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) data. National Lightning Detection NetworkTM (NLDN) data is used to determine the flash‐type (ground or cloud) of the satellite-observed flashes, and provides the ground flash fraction truth for the simulation runs. It is found that the mean ground flash fraction retrieval errors are below 0.04 across the full range 0‐1 under certain simulation conditions. In general, it is demonstrated that the retrieval errors depend on many factors (i.e., the number, N, of satellite observations, the magnitude of random and systematic measurement errors, and the number of samples used to form certain climate distributions employed in the model).

Koshak, William↗

DOE OSTI2026

Detector alignment for X-ray crystallography using Millepede-II

I describe a method for accurately refining the geometrical parameters of segmented X-ray area detectors on the basis of serial crystallography data, using 'Millepede' – an algorithm created for a very similar problem in high-energy physics. The Millepede method for serial crystallography builds on the approach of Brewster et al. [Acta Cryst. (2018), D74, 877–894], in which the detector parameters are refined simultaneously with the parameters for each individual crystal. This accounts for the mutual dependency between the parameters and thereby avoids the bias and slow convergence problems that have afflicted older approaches in which the deviations between observed and calculated Bragg peak positions were taken directly as the updates for the detector panel positions. The Millepede method uses the special structure of the least-squares normal equations to reduce them to a much smaller form that can be solved very quickly, even compared with the sparse matrix methods used previously. This makes it practical to refine the detector geometry frequently and thereby maintain accurate calibration without specialized alignment campaigns. Tilts of detector panels out of the plane can be reliably refined, as can the overall distance of the detector in the beam direction. With a simulated test case, the new method produced panel shifts within 7% of the correct values with only one iteration, and produced almost exactly correct shifts after a second iteration. A simulated out-of-plane panel rotation was correctly determined to within 0.001°. Applied to experimental data from an X-ray free-electron laser, the method increased the indexable fraction of frames from 30% to 91% in a single iteration, and to 96% after two further iterations. Computing the geometry updates on the basis of 2060 crystals took only 0.819 s on desktop computing hardware, including the time taken to read the required data from disk. The scaling was found to be very close to linear for up to 100 980 sets of crystal parameters, which took only 78.2 s to process under the same conditions. The method has been applied as part of a real-time feedback system at a synchrotron radiation beamline, in which an out-of-plane detector tilt of 0.04° was detected and corrected. Possible further applications are also described here.

Millepede-II↗

NASA NTRS2000

Simulations of a Thin Sampling Calorimeter with GEANT/FLUKA

The Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS) will investigate the origin, composition and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays up to 10(exp 15) eV. These measurements will be made with a thin ionization calorimeter and a transition radiation detector. This paper reports studies of a thin sampling calorimeter concept for the ACCESS thin ionization calorimeter. For the past year, a Monte Carlo simulation study of a Thin Sampling Calorimeter (TSC) design has been conducted to predict the detector performance and to design the system for achieving the ACCESS scientific objectives. Simulation results show that the detector energy resolution function resembles a Gaussian distribution and the energy resolution of TSC is about 40%. In addition, simulations of the detector's response to an assumed broken power law cosmic ray spectra in the region where the 'knee' of the cosmic ray spectrum occurs have been conducted and clearly show that a thin sampling calorimeter can provide sufficiently accurate estimates of the spectral parameters to meet the science requirements of ACCESS. n

Lee, Jeongin↗

NASA NTRS1988

Hard X-ray and low-energy gamma-ray spectrometers

Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resoluton for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.

Gehrels, N.↗

NASA NTRS2013

Parameter Estimation for Compact Binary Coalescence Signals with the First Generation Gravitational-Wave Detector Network

Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a blind injection where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1M25M and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors.

Aasi, J.↗

DOE OSTI2025

The CMS Phase-2 Fast Beam Condition Monitor prototype test with beam

The Fast Beam Condition Monitor (FBCM) is a standalone luminometer for the High Luminosity LHC (HL-LHC) program of the CMS Experiment at CERN. The detector is under development and features a new, radiation-hard, front-end application-specific integrated circuit (ASIC) designed for beam monitoring applications. The achieved timing resolution of a few nanoseconds enables the measurement of both the luminosity and the beam-induced background. The ASIC, called FBCM23, features six channels with adjustable shaping times, enabling in-field fine-tuning. Each ASIC channel outputs a single binary asynchronous signal encoding time-of-arrival and time-over-threshold information. The FBCM is based on silicon-pad sensors, with two sensor designs presently being considered. This paper presents the results of tests of the FBCM detector prototype using both types of silicon sensors with hadron, muon, and electron beams. Irradiated FBCM23 ASICs and silicon-pad sensors were also tested to simulate the expected conditions near the end of the detector's lifetime in the HL-LHC radiation environment. Based on test results, direct bonding between the sensor and ASIC was chosen, and an optimal bias voltage and ASIC threshold for FBCM operation were proposed. The current design of the front-end test board was validated following the beam test and is now being used for the first front-end module, which is expected to be produced in summer 2025. These results represent a major step forward in validating the FBCM concept, first version of the firmware and establishing a reliable design path for the final detector.

Beam-line instrumentation (beam position and profi↗

DOE OSTI2021

Validation of neutron-induced reactions on natural carbon using an active target at neutron energies up to 22 MeV at LANSCE

A single crystal chemical vapor deposited (sCVD) diamond detector is used as an active target to measure neutron-induced reactions on natural carbon using the neutrons produced by spallation, with a broad energy spectrum at LANSCE. Additionally, the neutron-induced reactions are detected in the diamond as low as E n = 400 keV and up to approximately 100 MeV. Relative cross sections for C 12 ( n , α 0 ) , C 12 ( n , p 0 ) , C 12 ( n , d 0 + p 1 ) , and C 13 ( n , α 0 ) are reported up to E n = 22 MeV and comparisons on detected pulse-height spectra and detector response of scattering reactions are made with GEANT4 simulations using the ENDF/B-VIII.0 evaluated nuclear data library up to 20 MeV. The results are compared with past experimental data, including other works that incorporate diamond detectors as an active carbon target. In addition, R-matrix calculations for the C 13 + n system are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2025

Flow and thermal modelling of the argon volume in the DarkSide-20k TPC

The DarkSide-20k dark matter experiment, currently under construction at LNGS, features a dual-phase time projection chamber (TPC) with a ∼ 50 t argon target from an underground well. At this scale, it is crucial to optimise the argon flow pattern for efficient target purification and for fast distribution of internal gaseous calibration sources with lifetimes of the order of hours. To this end, we have performed computational fluid dynamics simulations and heat transfer calculations. The residence time distribution shows that the detector is well-mixed on time-scales of the turnover time (∼ 40 d). Notably, simulations show that despite a two-order-of-magnitude difference between the turnover time and the half-life of 83m Kr of 1.83 h, source atoms have the highest probability to reach the centre of the TPC 13 min after their injection, allowing for a homogeneous distribution before undergoing radioactive decay. We further analyse the thermal aspects of dual-phase operation and define the requirements for the formation of a stable gas pocket on top of the liquid. We find a best-estimate value for the heat transfer rate at the liquid-gas interface of 62 W with an upper limit of 144 W and a minimum gas pocket inlet temperature of 89 K to avoid condensation on the acrylic anode. This study also informs the placement of liquid inlets and outlets in the TPC. The presented techniques are widely applicable to other large-scale, noble-liquid detectors.

47 OTHER INSTRUMENTATION↗

NASA NTRSDate not supplied

Simulating Weak Gravitational Lensing in the Roman Space Telescope Using JWST Observed Galaxies

Some of the most perplexing mysteries of our Universe are connected to the energy and mater we have been unable to physically observe. Making up about 95% of the Universe, dark energy and dark mater do not emit, absorb, nor reflect any portion of the electromagnetic spectrum, and their existence is only inferred through their effects on the visible mater. For example, gravitational lensing is a phenomenon that refers to the magnification and shearing induced on light from distant galaxies caused by the gravitational potential of foreground mater. The amount of lensing is directly related to the total amount of mater present, not just the mater that emits light. Weak gravitational lensing, when these distortions are not as noticeable, allows for the entirety of the “cosmic web”, or large-scale structure, to be probed during dark mater searches instead of just the areas we know are dense with mater i.e. galaxy clusters. In order to properly measure weak lensing effects, accurate galaxy shape measurements that can be calibrated with simulations are required. The Nancy Grace Roman Space Telescope is the next upcoming NASA flagship mission. One of its main goals is elucidating the nature of dark mater and dark energy via ultra-wide field UV-NIR imaging surveys. Roman’s view is 100 times that of the Hubble Space Telescope, and we will be primed to measure large-scale structure in the context of weak lensing studies. In this poster, I will present our efforts to simulate JWST observed galaxies through the eyes of Roman. I will detail how we remove the PSF from a JWST NIRCam imaged galaxy, and add Roman filters and detector effects. We report the comparison between JWST and simulated Roman imaging, and place our results in the context of future weak lensing searches with Roman.

Amethyst S. Barnes↗

DOE OSTI2023

Large-volume CdZnTe bar detectors characterized by laser-induced transient currents

In this work, we studied the free-carrier transport properties and space-charge formation/polarization in a CdZnTe bar-shaped radiation detector using the Laser-Induced Transient Current technique. We found out that a steady-state space charge ranging from 8 x 10 8 to 2.1 x 10 9 cm -3 is formed throughout the detector at about 0.5 s following biasing. The measured current waveforms were modeled by Monte Carlo simulations after taking into account the electric and weighting fields inside the detector and shielding box. Modeling of the unpolarized waveforms revealed an exceptionally high electron mobility-lifetime product μ e τ e ≥0.095cm 2 V -1 . The observed formation of positive space charge in the biased detector and linear scaling of the current waveform shapes on applied bias revealed that the detector polarization is attributed to carrier injection at the anode. In conclusion, measurements in pulsed and DC bias in modified electrode geometry proved the surface-charge formation.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

In situ X-ray area detector flat-field correction at an operating photon energy without flat illumination

Flat-field calibration of X-ray area detectors is a challenge due to the inability to generate an X-ray flat-field at the selected photon energy the beamline operates at, which has a strong influence on the measurement behavior of the detector. A method is presented in which a simulated flat-field correction is calculated without flat-field measurements. Instead, a series of quick scattering measurements from an amorphous scatterer is used to calculate a flat-field response. The ability to rapidly obtain a flat-field response allows for recalibration of an X-ray detector as needed without significant expenditure of either time or effort. Area detectors on the beamlines used, such as the Pilatus 2M CdTe, PE XRD1621 and Varex XRD 4343CT, were found to have detector responses that drift slightly over timescales of several weeks or after exposure to high photon flux, suggesting the need to more frequently recalibrate with a new flat-field correction map.

47 OTHER INSTRUMENTATION↗

NASA NTRS1987

Charge-coupled-device X-ray detector performance model

A model that predicts the performance characteristics of CCD detectors being developed for use in X-ray imaging is presented. The model accounts for the interactions of both X-rays and charged particles with the CCD and simulates the transport and loss of charge in the detector. Predicted performance parameters include detective and net quantum efficiencies, split-event probability, and a parameter characterizing the effective thickness presented by the detector to cosmic-ray protons. The predicted performance of two CCDs of different epitaxial layer thicknesses is compared. The model predicts that in each device incomplete recovery of the charge liberated by a photon of energy between 0.1 and 10 keV is very likely to be accompanied by charge splitting between adjacent pixels. The implications of the model predictions for CCD data processing algorithms are briefly discussed.

Bautz, M. W.↗

DOE OSTI2023

TRANSLATE - a Monte Carlo simulation of electron transport in liquid argon

Here, the microphysics of electron and photon propagation in liquid argon is a key component of detector design and calibrations needed to construct and perform measurements within a wide range of particle physics experiments. As experiments grow in scale and complexity, and as the precision of their intended measurements increases, the development of tools to investigate important microphysics effects impacting such detectors becomes necessary. In this paper we present a new time-domain Monte Carlo simulation of electron transport in liquid argon. The simulation models the TRANSport in Liquid Argon of near-Thermal Electrons (TRANSLATE) with the aim of providing a multi-purpose software package for the study and optimization of detector environments, with a particular focus on ongoing and next generation liquid argon neutrino experiments utilizing the time projection chamber technology. TRANSLATE builds on previous work of Wojcik and Tachiya, amongst others, introducing additional processes, including ionization, thus modeling the full range of drift electron scattering interactions. The simulation is validated by benchmarking its performance with swarm parameters from data collected in experimental setups operating in gas and liquid.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Modeling and Simulation of MC-Small Design

In order to design a lightweight, highly portable neutron multiplicity counter for use in higher risk regions by mobile field teams, a redesign of the MC-15 is being performed, with the goal of producing a detector below 30 lbs for ease of transport. To achieve this, multiple MCNP® simulations were run, evaluating the number and positioning of the He-3 tubes in the detector as well as the amount of high-density polyethylene (HDPE) surrounding the tubes. Based on these simulations, the proposed redesign of the MC-15 (aka MC-Small) possesses 11 tubes and is 13 in wide, 3.21 in thick and 13 in tall. Including the changes to the positioning of the tubes and the removal of HDPE from less sensitive regions of the detectors (i.e. bases of tubes, back of detector), this resulted in an efficiency of 0.56% when measuring a bare Cf-252 source 19.69 in away, only 28% less efficient (relatively) than the MC-15 while weighing 18 lbs, 12 lbs less than the weight of the MC-15.

42 ENGINEERING↗

DOE OSTI2025

Analysis and Validation of PMT s Waveforms in ICARUS LArTPC Using Monte Carlo Simulations

ICARUS (Imaging Cosmic and Rare Underground Signals) serves as the Far Detector in the Short Baseline Neutrino (SBN) program at Fermilab, playing a central role in investigating the potential existence of sterile neutrinos in the eV squared mass range. The detector consists of two large Liquid Argon Time Projection Chambers (LArTPCs) with a total capacity of 760 tons of liquid Argon. A key component of the system is its array of 360 Photo-Multiplier Tubes (PMTs), which detect the scintillation light produced by charged particles in liquid Argon; the fast scintillation signal enables accurate event timing, triggering, and reconstruction. Together with the TPC and CRT systems, the PMTs ensure precise interaction time measurements, which are crucial for distinguishing neutrino interactions from cosmic-ray backgrounds. ICARUS uses Hamamatsu R5912-MOD PMTs, optimized for cryogenic temperatures, with high quantum efficiency, excellent timing resolution, low dark current (around 10 nA at 1500 V), and broad spectral sensitivity (300–650 nm). These characteristics are crucial for the efficient detection of scintillation light. Analyzing the waveforms of PMT signals allows for a detailed comparison between experimental data and Monte Carlo simulations. This analysis is fundamental for improving the accuracy of neutrino event reconstruction, enhancing detector calibration, and optimizing the detector's performance for current and future operations.

Brio, V. [Catania U.] (ORCID:0009000088807391)↗

DOE OSTI2020

Angular distribution of neutron production by proton and carbon-ion therapeutic beams

Carbon-ion beams are increasingly used in the clinical practice for external radiotherapy treatments of deep-seated tumors. At therapeutic energies, carbon ions yield significant secondary products, including neutrons, which may be of concern for the radiation protection of the patient and personnel. We simulated the neutron yield produced by proton and carbon-ion pencil beams impinging on a clinical phantom at three different angles: 15°, 45° and 90°, with respect to the beam axis. We validated the simulated results using the measured response of organic scintillation detectors. We compared the results obtained with FLUKA 2011.2 and MCNPX 2.7.0 based on three different physics models: Bertini, Isabel, and CEM. Over the different ions, energies, and angles, the FLUKA simulation results agree better with the measured data, compared to the MCNPX results. Simulations of carbon ions at low angles exhibit both the highest deviation from measured data and inter-model discrepancy, which is probably due to the different treatment of the pre-equilibrium stage. The reported neutron yield results could help in the comparison of carbon-ion and proton treatments in terms of secondary neutron production for radiation protection applications.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

nEXO: neutrinoless double beta decay search beyond 10 28 year half-life sensitivity

The nEXO neutrinoless double beta (0νββ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon to search for the decay in 136 Xe. Progress in the detector design, paired with higher fidelity in its simulation and an advanced data analysis, based on the one used for the final results of EXO-200, produce a sensitivity prediction that exceeds the half-life of 10 28 years. Specifically, improvements have been made in the understanding of production of scintillation photons and charge as well as of their transport and reconstruction in the detector. The more detailed knowledge of the detector construction has been paired with more assays for trace radioactivity in different materials. In particular, the use of custom electroformed copper is now incorporated in the design, leading to a substantial reduction in backgrounds from the intrinsic radioactivity of detector materials. Furthermore, a number of assumptions from previous sensitivity projections have gained further support from interim work validating the nEXO experiment concept. Together these improvements and updates suggest that the nEXO experiment will reach a half-life sensitivity of 1.35 × 10 28 yr at 90% confidence level in 10 years of data taking, covering the parameter space associated with the inverted neutrino mass ordering, along with a significant portion of the parameter space for the normal ordering scenario, for almost all nuclear matrix elements. Furthermore, the effects of backgrounds deviating from the nominal values used for the projections are also illustrated, concluding that the nEXO design is robust against a number of imperfections of the model.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗