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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 OSTI2020

2D microspatial distribution uniformity of photon detection efficiency and crosstalk probability of multi-pixel photon counters

Two-dimensional (2D) microspatial distribution uniformity of photon detection efficiency (PDE) and optical crosstalk probability P{sub ct} of multi-pixel photon counters (MPPCs) is studied. The experimental results show that the 2D spatial distribution of P{sub ct} is obviously uneven, i.e. P{sub ct} is larger at the corners and edges of a single pixel in MPPCs, which suggest a higher electrical field in the depletion region of the pixel at the corners and edges. The nonuniformity of the 2D spatial distribution of PDE also become evident when the size of the pixels of MPPCs is small, which signifies higher nonuniformity of the electric field distribution in MPPCs with small pixel size. A method is proposed for characterization of the 2D electrical field spatial distribution uniformity in a single pixel of MPPCs, which can be used for guiding the optimisation of the fabrication process of MPPCs and their properties. This promising method can naturally be extended to any Geiger avalanche photodiodes (G-APDs) and their arrays. (laser applications and other topics in quantum electronics)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2024

Rapid Variability of Mrk 421 During Extreme Flaring as Seen Through the Eyes of XMM-Newton

By studying the variability of blazars across the electromagnetic spectrum, it is possible to resolve the underlying processes responsible for rapid flux increases, so-called flares. We report on an extremely bright X-ray flare in the high-peaked BL Lacertae object Markarian 421 (Mrk 421) that occurred simultaneously with enhanced γ-ray activity detected at very high energies by First G-APD Cherenkov Telescope on 2019 June 9. We triggered an observation with XMM–Newton, which observed the source quasi-continuously for 25 h. We find that the source was in the brightest state ever observed using XMM–Newton, reaching a flux of 2.8 × 10 −9 erg cm -2 s -1 over an energy range of 0.3–10 keV. We perform a spectral and timing analysis to reveal the mechanisms of particle acceleration and to search for the shortest source-intrinsic time-scales. Mrk 421 exhibits the typical harder-when-brighter behaviour throughout the observation and shows a clock-wise hysteresis pattern, which indicates that the cooling dominates over the acceleration process. While the X-ray emission in different sub-bands is highly correlated, we can exclude large time lags as the computed z-transformed discrete correlation functions are consistent with a zero lag. We find rapid variability on time-scales of 1 ks for the 0.3–10 keV band and down to 300 s in the hard X-ray band (4–10 keV). Taking these time-scales into account, we discuss different models to explain the observed X-ray flare, and find that a plasmoid-dominated magnetic reconnection process is able to describe our observation best.

acceleration of particles↗
DOE OSTI2024

Batch VUV4 characterization for the SBC-LAr10 scintillating bubble chamber

The Scintillating Bubble Chamber (SBC) collaboration purchased 32 Hamamatsu VUV4 silicon photomultipliers (SiPMs) for use in SBC-LAr10, a bubble chamber containing 10 kg of liquid argon. A dark-count characterization technique, which avoids the use of a single-photon source, was used at two temperatures to measure the VUV4 SiPMs breakdown voltage (V BD ), the SiPM gain (g SiPM ), the rate of change of g SiPM with respect to voltage (m), the dark count rate (DCR), and the probability of a correlated avalanche (P CA ) as well as the temperature coefficients of these parameters. A Peltier-based chilled vacuum chamber was developed at Queen's University to cool down the Quads to 233.15 ± 0.2 K and 255.15 ± 0.2 K with average stability of ±20 mK. An analysis framework was developed to estimate V BD to tens of mV precision and DCR close to Poissonian error. The temperature dependence of V BD was found to be 56 ± 2 mV K -1 , and m on average across all Quads was found to be (459 ± 3(stat.)±23(sys.))× 10 3 e- PE -1 V -1 . The average DCR temperature coefficient was estimated to be 0.099 ± 0.008 K -1 corresponding to a reduction factor of 7 for every 20 K drop in temperature. The average temperature dependence of P CA was estimated to be 4000 ± 1000 ppm K -1 . P CA estimated from the average across all SiPMs is a better estimator than the P CA calculated from individual SiPMs, for all of the other parameters, the opposite is true. All the estimated parameters were measured to the precision required for SBC-LAr10, and the Quads will be used in conditions to optimize the signal-to-noise ratio.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatory

Here, AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m 2 detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), is proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98% efficiency for the highest tested overvoltage, combined with a low probability of accidental counting (~2%), show a promising performance for this new system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

An automated system to measure the quantum efficiency of CCDs for astronomy

We describe a system to measure the Quantum Efficiency in the wavelength range of 300 nm to 1100 nm of 40 × 40 mm n-channel CCD sensors for the construction of the 3.2 gigapixel LSST focal plane. The technique uses a series of instrument to create a very uniform flux of photons of controllable intensity in the wavelength range of interest across the face the sensor. This allows the absolute Quantum Efficiency to be measured with an accuracy in the 1% range. Finally, this system will be part of a production facility at Brookhaven National Lab for the basic component of the LSST camera.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Status of the CCD development for the Dark Energy Spectroscopic Instrument

We describe improvements in CCD performance that have been achieved on 4k×4k, (15 μm)(2)-pixel, fully depleted CCDs for the Dark Energy Spectroscopic Instrument (DESI) [1]. With respect to our previous work on CCDs for the Dark Energy Camera and the Baryon Oscillation Spectroscopic Survey, our goals for the DESI CCD development were to improve read noise and quantum efficiency, improve the astrometric precision, and decrease pixel-size variations. We report experimental results on recently fabricated CCDs to be used in DESI.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Fringing in MonoCam Y4 filter images

Here, we study the fringing patterns observed in MonoCam, a camera with a single Large Synoptic Survey Telescope (LSST) CCD sensor. Images were taken at the U.S. Naval Observatory in Flagstaff, Arizona (NOFS) employing its 1.3 m telescope and an LSST y4 filter. Fringing occurs due to the reflection of infrared light (700 nm or larger) from the bottom surface of the CCD which constructively or destructively interferes with the incident light to produce a net "fringe" pattern which is superimposed on all images taken. Emission lines from the atmosphere, dominated by hydroxyl (OH) spectra, can change in their relative intensities as the night goes on, producing different fringe patterns in the images taken. We found through several methods that the general shape of the fringe patterns remained constant, though with slight changes in the amplitude and phase of the fringes. Lastly, we also found that a superposition of fringes from two monochromatic lines taken in the lab offered a reasonable description of the sky data.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Study of silicon photomultiplier performance in external electric fields

In this paper, we report on the performance of silicon photomultiplier (SiPM) light sensors operating in electric field strength up to 30 kV/cm and at a temperature of 149 K, relative to their performance in the absence of an external electric field. The SiPM devices used in this study show stable gain, photon detection efficiency, and rates of correlated pulses, when exposed to external fields, within the estimated uncertainties. No visible damage to the surface of the devices was caused by the exposure.

Noble liquid detectors (scintillation, ionization,↗
DOE OSTI2018

Silicon photomultipliers radiation damage and recovery via high temperature annealing

The performance of Silicon Photomultipliers (SiPMs) from several vendors are characterized before and after exposure of up to 10 10 neutron/cm 2 dosage. Collectively, we firmly established that the typical orders of magnitude increase in dark current upon neutron irradiation can be lowered substantially after processing them with a thermal annealing procedure, and single-photon detection are to some extent recovered at room temperature. Furthermore, we found no significant difference on neutron damaged behavior when SiPMs are irradiated at room temperature or in liquid nitrogen.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

The BDX detector prototype for dark matter searches in a Beam Dump eXperiment at JLAB

The Beam Dump eXperiment (BDX) is an electron-beam thick-target experiment aimed to investigate the existence of light dark matter particles in the MeV-GeV mass range at Jefferson Lab. A small-scale prototype (BDX-Proto) of the BDX detector has been constructed in order to validate the proposed design and to demonstrate with real measurements the capability to efficiently reject the cosmogenic backgrounds. Here we report the peformance of BDX-Proto extracted from a long campaign of cosmic ray measurements performed at INFN, Sez. Catania and INFN, LNS.

calorimeters↗
DOE OSTI2020

A measurement of absolute efficiency of the ARAPUCA photon detector in liquid argon

In the Fall of 2017, two photon detector designs for the Deep Underground Neutrino Experiment (DUNE) Far Detector were installed and tested in the TallBo liquid argon (LAr) cryostat at the Proton Assembly (PAB) facility, Fermilab. The designs include two light bars developed at Indiana University and a photon detector based on the ARAPUCA light trap engineered by Colorado State University and Fermilab. The performance of these devices is determined by analyzing 8 weeks of cosmic ray data. The current paper focuses solely on the ARAPUCA device as the performance of the light bars will be reported separately. The article briefly describes the ARAPUCA concept, the TallBo setup, and focuses on data analysis and results.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Design, upgrade and characterization of the silicon photomultiplier front-end for the AMIGA detector at the Pierre Auger Observatory

AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to complement the study of ultra-high-energy cosmic rays (UHECR) by measuring the muon content of extensive air showers (EAS). It consists of an array of 61 water Cherenkov detectors on a denser spacing in combination with underground scintillation detectors used for muon density measurement. Each detector is composed of three scintillation modules, with 10 m 2 detection area per module, buried at 2.3 m depth, resulting in a total detection area of 30 m 2 . Silicon photomultiplier sensors (SiPM) measure the amount of scintillation light generated by charged particles traversing the modules. In this paper, the design of the front-end electronics to process the signals of those SiPMs and test results from the laboratory and from the Pierre Auger Observatory are described. Compared to our previous prototype, the new electronics shows a higher performance, higher efficiency and lower power consumption, and it has a new acquisition system with increased dynamic range that allows measurements closer to the shower core. The new acquisition system is based on the measurement of the total charge signal that the muonic component of the cosmic ray shower generates in the detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Calibration of the underground muon detector of the Pierre Auger Observatory

To obtain direct measurements of the muon content of extensive air showers with energy above 10 16.5 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m 2 -modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m 2 close to the intersection of the shower axis with the ground to much less than one per m 2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Reflectivity of VUV-sensitive silicon photomultipliers in liquid Xenon

Silicon photomultipliers are regarded as a very promising technology for next-generation, cutting-edge detectors for low-background experiments in particle physics. This work presents systematic reflectivity studies of Silicon Photomultipliers (SiPM) and other samples in liquid xenon at vacuum ultraviolet (VUV) wavelengths. A dedicated setup at the University of Münster has been used that allows to acquire angle-resolved reflection measurements of various samples immersed in liquid xenon with 0.45° angular resolution. Four samples are investigated in this work: one Hamamatsu VUV4 SiPM, one FBK VUV-HD SiPM, one FBK wafer sample and one Large-Area Avalanche Photodiode (LA-APD) from EXO-200. Here, the reflectivity is determined to be 25–36 % at an angle of incidence of 20° for the four samples and increases to up to 65 % at 70° for the LA-APD and the FBK samples. The Hamamatsu VUV4 SiPM shows a decline with increasing angle of incidence. The reflectivity results will be incorporated in upcoming light response simulations of the nEXO detector.

(pin diodes, APDs, SiPMs, G-APDs, CCDs, EBCCDs, EM↗
DOE OSTI2023

Studies in pulse shape discrimination for an optimized ASIC design

The continued advancements of Silicon Photomultipliers (SiPMs) have made them viable photosensors for low recoil energy Pulse Shape Discrimination (PSD) between fast neutron and gamma interactions when coupled to an appropriate scintillator. At the same time, the large number of channels in a typical array calls for the development of low-cost and low-power electronics. A custom integrated circuit (ASIC) is an ideal solution for this purpose. To assess the requirements for such an ASIC, studies were performed using two scintillators, Stilbene and EJ-276, coupled to a 6 x 6 mm SiPM from Onsemi. We demonstrate that both scintillators are viable for performing PSD for interaction energies from 100 keV to several MeV while optimizing the integration periods used in the PSD metric. These measurements inform the design parameters of the ASIC under development.

Si-PMTs↗
DOE OSTI2023

Skipper-CCD sensors for the Oscura experiment: requirements and preliminary tests

Oscura is a proposed multi-kg skipper-CCD experiment designed for a dark matter (DM) direct detection search that will reach unprecedented sensitivity to sub-GeV DM-electron interactions with its 10 kg detector array. Oscura is planning to operate at SNOLAB with 2070 m overburden, and aims to reach a background goal of less than one event in each electron bin in the 2–10 electron ionization-signal region for the full 30 kg-year exposure, with a radiation background rate of 0.01 dru.[1 dru (differential rate unit) corresponds to 1 event/kg/day/keV.] In order to achieve this goal, Oscura must address each potential source of background events, including instrumental backgrounds. In this work, we discuss the main instrumental background sources and the strategy to control them, establishing a set of constraints on the sensors' performance parameters. We present results from the tests of the first fabricated Oscura prototype sensors, evaluate their performance in the context of the established constraints and estimate the Oscura instrumental background based on these results.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Investigating resource-efficient neutron/gamma classification ML models targeting eFPGAs

There has been considerable interest and resulting progress in implementing machine learning (ML) models in hardware over the last several years from the particle and nuclear physics communities. A big driver has been the release of the Python package, hls4ml, which has enabled porting models specified and trained using Python ML libraries to register transfer level (RTL) code. So far, the primary end targets have been commercial field-programmable gate arrays (FPGAs) or synthesized custom blocks on application specific integrated circuits (ASICs). However, recent developments in open-source embedded FPGA (eFPGA) frameworks now provide an alternate, more flexible pathway for implementing ML models in hardware. These customized eFPGA fabrics can be integrated as part of an overall chip design. In general, the decision between a fully custom, eFPGA, or commercial FPGA ML implementation will depend on the details of the end-use application. In this work, we explored the parameter space for eFPGA implementations of fully-connected neural network (fcNN) and boosted decision tree (BDT) models using the task of neutron/gamma classification with a specific focus on resource efficiency. We used data collected using an AmBe sealed source incident on Stilbene, which was optically coupled to an OnSemi J-series silicon photomultiplier (SiPM) to generate training and test data for this study. We investigated relevant input features and the effects of bit-resolution and sampling rate as well as trade-offs in hyperparameters for both ML architectures while tracking total resource usage. The performance metric used to track model performance was the calculated neutron efficiency at a gamma leakage of 10 -3 . The results of the study will be used to aid the specification of an eFPGA fabric, which will be integrated as part of a test chip.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Doping liquid argon with xenon in ProtoDUNE Single-Phase: effects on scintillation light

Doping of liquid argon TPCs (LArTPCs) with a small concentration of xenon is a technique for light-shifting and facilitates the detection of the liquid argon scintillation light. In this paper, we present the results of the first doping test ever performed in a kiloton-scale LArTPC. From February to May 2020, we carried out this special run in the single-phase DUNE Far Detector prototype (ProtoDUNE-SP) at CERN, featuring 720 t of total liquid argon mass with 410 t of fiducial mass. A 5.4 ppm nitrogen contamination was present during the xenon doping campaign. The goal of the run was to measure the light and charge response of the detector to the addition of xenon, up to a concentration of 18.8 ppm. The main purpose was to test the possibility for reduction of non-uniformities in light collection, caused by deployment of photon detectors only within the anode planes. Light collection was analysed as a function of the xenon concentration, by using the pre-existing photon detection system (PDS) of ProtoDUNE-SP and an additional smaller set-up installed specifically for this run. In this paper we first summarize our current understanding of the argon-xenon energy transfer process and the impact of the presence of nitrogen in argon with and without xenon dopant. We then describe the key elements of ProtoDUNE-SP and the injection method deployed. Two dedicated photon detectors were able to collect the light produced by xenon and the total light. The ratio of these components was measured to be about 0.65 as 18.8 ppm of xenon were injected. We performed studies of the collection efficiency as a function of the distance between tracks and light detectors, demonstrating enhanced uniformity of response for the anode-mounted PDS. We also show that xenon doping can substantially recover light losses due to contamination of the liquid argon by nitrogen.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗