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At least 55 records · Page 3

Impact of light output on the timing resolution of organic glass scintillator bars in a dual-ended readout configuration

The effectiveness of detector system modeling and validation depends on the quality of characterization performed on the system. For nuclear nonproliferation applications, which require detectors to address complex and variable field conditions, access to accurate system models is essential. This study presents the timing characterization of organic glass scintillator bars used in an imaging system developed at the University of Michigan. 137 Cs and 60 Co gamma-ray sources were used to determine the coincidence time resolution as a function of measured light output for two Compton scatter events between two organic glass scintillator bars. Timing resolution for two events, each with light output ranging from 100 to 1100 keVee were characterized. The resulting data were fit to a parametric function that was validated to agree with experimental results within ±25 ps. Simulations were performed to establish appropriate calibration points for each organic scintillator, thereby ensuring accurate calibration of light output values during analysis. This work successfully characterized the light output dependence of the coincidence timing resolution of a pair of organic glass detectors for use in an imaging system. Depending on the amount of scintillation light output from the events, the full width at half maximum of the measured coincidence time resolution ranged from 653.2 ± 16.1 ps for low light yields, 100 keVee, to 121.0 ± 8.4 ps for higher yields at 1100 keVee. The insights obtained from the timing resolution behavior will allow for accurate simulation capabilities in future security and verification efforts using scatter-based imaging systems.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Near-Infrared Single-Photon-Counting Detectors for Laser Instrument Applications at NASA Goddard Space Flight Center

We discuss single-photon-counting detectors requirements for NASA remote sensing and communications systems. We present experimental measurements on several different near-infrared single-photon-counting detectors including InGaAs/InP and InGaAs/InAlAs avalanche photodiodes (APD), an InGaAsP photocathode hybrid photomultiplier (PMT) and an InGaAs photomultiplier. We present the experimental performance of prototype instruments for laser ranging, communication, and trace-gas detection that use these detectors.

Krainak, Michael A.↗

Temperature Stabilization Requirements for Unchopped Thermal Detectors

The temperature stabilization requirements of unchopped thermistor bolometers and thermopile detectors are analyzed. The detector temperature, on which the bolometer output signal depends, is quite sensitive to changes in instrument temperature but relatively insensitive to changes in scene temperature. In contrast, the difference in temperature between detector and substrate (instrument), on which the thermopile signal depends, is equally sensitive to changes in instrument and scene temperature. Expressions for these dependencies are derived based on a simplified instrument model. It is shown that for a typical uncooled thermal imager, the temperature stabilization requirements for a bolometer are two orders of magnitude more stringent than those for a thermopile detector. Keywords: thermistor, bolometer, thermopile, detector, IR, thermal, temperature stabilization

Foote, Marc C.↗

Images of the future - Two decades in astronomy

Future instruments for the 100-10,000 A UV-wavelength region will require detectors with greater quantum efficiency, smaller picture elements, a greater wavelength range, and greater active area than those currently available. After assessing the development status and performance characteristics of vidicons, image tubes, electronographic cameras, digicons, silicon arrays and microchannel plate intensifiers presently employed by astronomical spacecraft, attention is given to such next-generation detectors as the Mosaicked Optical Self-scanned Array Imaging Camera, which consists of a photocathode deposited on the input side of a microchannel plate intensifier. The problems posed by the signal processing and data analysis requirements of the devices foreseen for the 21st century are noted.

Weistrop, D.↗

Enhancement of High-Speed Infrared Array Electronics (Center Director's Discretionary Fund)

A state-of-the-art infrared detector was to be used as the sensor in a new spectrometer-camera for astronomical observations. The sensitivity of the detector required the use of low-noise, high-speed electronics in the system design. The key component in the electronic system was the pre-amplifier that amplified the low voltage signal coming from the detector. The system was designed based on the selection of the amplifier and that was driven by the maximum noise level, which would yield the desired sensitivity for the telescope system.

Sutherland, W. T.↗

Towards Reliable Evaluation of Anomaly-Based Intrusion Detection Performance

This report describes the results of research into the effects of environment-induced noise on the evaluation process for anomaly detectors in the cyber security domain. This research was conducted during a 10-week summer internship program from the 19th of August, 2012 to the 23rd of August, 2012 at the Jet Propulsion Laboratory in Pasadena, California. The research performed lies within the larger context of the Los Angeles Department of Water and Power (LADWP) Smart Grid cyber security project, a Department of Energy (DoE) funded effort involving the Jet Propulsion Laboratory, California Institute of Technology and the University of Southern California/ Information Sciences Institute. The results of the present effort constitute an important contribution towards building more rigorous evaluation paradigms for anomaly-based intrusion detectors in complex cyber physical systems such as the Smart Grid. Anomaly detection is a key strategy for cyber intrusion detection and operates by identifying deviations from profiles of nominal behavior and are thus conceptually appealing for detecting "novel" attacks. Evaluating the performance of such a detector requires assessing: (a) how well it captures the model of nominal behavior, and (b) how well it detects attacks (deviations from normality). Current evaluation methods produce results that give insufficient insight into the operation of a detector, inevitably resulting in a significantly poor characterization of a detectors performance. In this work, we first describe a preliminary taxonomy of key evaluation constructs that are necessary for establishing rigor in the evaluation regime of an anomaly detector. We then focus on clarifying the impact of the operational environment on the manifestation of attacks in monitored data. We show how dynamic and evolving environments can introduce high variability into the data stream perturbing detector performance. Prior research has focused on understanding the impact of this variability in training data for anomaly detectors, but has ignored variability in the attack signal that will necessarily affect the evaluation results for such detectors. We posit that current evaluation strategies implicitly assume that attacks always manifest in a stable manner; we show that this assumption is wrong. We describe a simple experiment to demonstrate the effects of environmental noise on the manifestation of attacks in data and introduce the notion of attack manifestation stability. Finally, we argue that conclusions about detector performance will be unreliable and incomplete if the stability of attack manifestation is not accounted for in the evaluation strategy.

cyber defense↗

Demonstrating imaging plate detector stacks for proton radiography using exploding pusher capsules

A new detector design has been fielded on the Omega-60 laser facility using a D 3 He backlighter capsule to radiograph a magnetized experiment. D 3 He capsules produce a low flux (~ 10 8 total yield in 4π) of protons requiring detectors with close-to single-particle sensitivity to be employed. The new detector stack consisted of both imaging plate (IP) and CR-39 to detect 14.7 MeV protons where, historically, only CR-39 has been used. IP is sensitive to significant contributions in signal from both x-rays and protons so additional filtering has to be added to attenuate the x-rays. Here, the signals and features observed from a single shot are detected by both IP and CR-39, giving confirmation that it is protons creating the signatures on the IP. Measurements of PSL/pixel are used to calculate approximate on-shot proton yields and agree with commonly measured yields. A second IP is used at the rear of the stack to measure, and subsequently remove, a background signal. The spatial resolution at the IP is limited, primarily, by a range of proton energies with varying deflections being recorded at the detector, causing potential ‘blurring’ of features. We find for this setup that the blurring effect is less than the smallest identifiable features observed at the detector, and therefore of minimal impact. A large benefit to this new stack design is that IP can be scanned and processed on much faster timescales than CR-39 allowing for prompt shot feedback. Future designs and modifications to the stack design fielded on this experiment could help improve the contrast of the radiograph on IP, as well as detecting protons produced at alternative energies.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Future Circular Collider Feasibility Study Report

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.

Benedikt, M. [European Organization for Nuclear Re↗

A New Plasma Radar Concept for Simultaneous Magnetic and Density Measurements

An innovative, compact 288GHz interferometer has been fabricated, tested, installed and successfully demonstrated on the LAPD-U magnetized plasma at UCLA. The system takes advantage of frequency modulated (FM) radar techniques to deliver a compact heterodyne system. In addition, the reflected power from the source is taken advantage of to eliminate the need for additional quasi-optical components. Electron density in LAPD-U plasma has recently been increased substantially thereby requiring a higher frequency/shorter wavelength interferometer to avoid deleterious refractive effects. This system satisfies those needs. The system uses a 96GHz varactor tuned Gunn oscillator which passes to a passive tripler. This tripler has ~3% conversion efficiency. The 288GHz radiation is then coupled to free space using a so-called dual-mode or Pickett horn. The output 288GHz beam is then coupled to an aspheric lens manufactured from low-loss, high-density polyethylene. This lens is employed to collimate the emerging beam. Small axial adjustment of the lens position can also be used to create a slowly focusing beam so as to optimize the measured signal. In addition, up-down or side-to-side adjustment of the lens can be utilized to steer the beam vertically or horizontally – again to optimize alignment. The propagating beam passes through a beam splitter and then through a water-free, bubble-free fused quartz window into the LAPD-U vacuum vessel. The beam-splitter is a thin sheet of G10 which reflects a small fraction of the incident power (~5 %) towards a zero-bias detector optimized for the frequency range from 220 to 300GHz. Note that waveguides at this frequency have dimensions of ~0.9mm x 0.45mm and so have very large conductive losses. This drives the use of quasi-optical propagation. The detector requires no DC bias and is very responsive (> 1V/mW into 1MΩ). Radiation is coupled to the detector via a similar lens-horn arrangement used for the launch. This reflected beam acts as the local oscillator or reference millimeter-wave beam for the detector. The remainder of the launched source beam then enters the LAPD-U vacuum vessel and passes through the plasma at the mid-plane until reaching the opposing port which is closed off with an aluminum flange. This flange is used as a mirror to retroreflect the incident 288GHz beam back along its path. The retroreflected beam exits the input port but does NOT couple directly into the zero-bias detector. Instead, the majority of the return power continues towards the 288GHz source. As mentioned above the transmitted beam enters the source a second time. This would appear undesirable. However, at these frequencies multipliers are highly non-linear elements which results in a significant portion of the return beam (~20%) re-emerging from the multiplier and horn and then coupling via the G10 beam-splitter to the zero-bias detector. This approach eliminated the need for a second quasi-optical beam-splitter. The system is extremely compact measuring approximately 28 inches x 20 inches. The above did not explain how heterodyne operation was achieved. As mentioned above the Gunn oscillator is able to be varactor tuned. This allows a low voltage to be applied to control the operating frequency of the Gunn oscillator. During heterodyne operation a sawtooth shaped voltage is applied to the varactor at 750kHz using an 80MHz Arbitrary Waveform Generator (AWG). This voltage changes the Gunn frequency linearly during the up-sweep which is then reset abruptly at the sawtooth crash to be immediately followed by another linear sweep. Passage through the 288GHz multiplier triples the frequency change experienced by the electromagnetic wave. These frequency changes are small – tens of megahertz. This FM radar approach results in the launched electromagnetic wave frequencies at the detector for the reference and plasma wave to be different. The approximately 10 ns delay propagation delay for the plasma beam results in the local oscillator and plasma beams NOT having an identical frequency – there is in fact a fixed difference frequency. The frequency tuning level of the Gunn oscillator is then adjusted so that there is ONE cycle of this difference frequency during each linear ramp. During the sawtooth crash or downward re-sweep this one cycle replays in reverse but on a very fast timescale. The process then repeats. Low-pass filtering eliminates the fast re-sweep to leave a pure sine wave heterodyne signal. When the plasma is present it introduces a phase delay in the sine wave (caused by the extremely small Doppler shift resulting from the optical path length change). Of course, to measure this phase change we need a reference. This is simply obtained from an arbitrary waveform generator which provides a synchronized output pulse train which again is low pass filtered to obtain a 750kHz sinusoidal voltage reference for the interferometer. The interferometer was installed on LAPD-U where it has worked reliably and has established that electron densities exceeding 1x10 13 cm -3 are routinely achieved. In addition, the system sensitivity was able to easily observe density fluctuation at frequencies up to 50kHz. FM Radar techniques have enabled a full demonstration of a compact, sensitive, high frequency (288GHz/1mm) heterodyne interferometer.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Smart pixel sensors: towards on-sensor filtering of pixel clusters with deep learning

Highly granular pixel detectors allow for increasingly precise measurements of charged particle tracks. Next-generation detectors require that pixel sizes will be further reduced, leading to unprecedented data rates exceeding those foreseen at the High- Luminosity Large Hadron Collider. Signal processing that handles data incoming at a rate of $\mathcal{O}$(40 MHz) and intelligently reduces the data within the pixelated region of the detector at rate will enhance physics performance at high luminosity and enable physics analyses that are not currently possible. Using the shape of charge clusters deposited in an array of small pixels, the physical properties of the traversing particle can be extracted with locally customized neural networks. In this first demonstration, we present a neural network that can be embedded into the on-sensor readout and filter out hits from low momentum tracks, reducing the detector's data volume by 57.1%–75.7%. The network is designed and simulated as a custom readout integrated circuit with 28 nm CMOS technology and is expected to operate at less than 300 μW with an area of less than 0.2 mm 2 . The temporal development of charge clusters is investigated to demonstrate possible future performance gains, and there is also a discussion of future algorithmic and technological improvements that could enhance efficiency, data reduction, and power per area.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Fine-Pitch CdTe Detector for Hard X-Ray Imaging and Spectroscopy of the Sun with the FOXSI Rocket Experiment

We have developed a fine-pitch hard X-ray (HXR) detector using a cadmium telluride (CdTe) semiconductor for imaging and spectroscopy for the second launch of the Focusing Optics Solar X-ray Imager (FOXSI). FOXSI is a rocket experiment to perform high sensitivity HXR observations from 4 to 15 keV using the new technique of HXR focusing optics. The focal plane detector requires less than 100 micrometers position resolution (to take advantage of the angular resolution of the optics) and approximately equals 1 keV energy resolution (full width at half maximum (FWHM)) for spectroscopy down to 4 keV, with moderate cooling (greater than -30 C). Double-sided silicon strip detectors were used for the first FOXSI flight in 2012 to meet these criteria. To improve the detectors' efficiency (66% at 15 keV for the silicon detectors) and position resolution of 75 micrometers for the second launch, we fabricated double-sided CdTe strip detectors with a position resolution of 60 micrometers and almost 100% efficiency for the FOXSI energy range. The sensitive area is 7.67 mm x 7.67 mm, corresponding to the field of view of 791'' x 791''. An energy resolution of 1 keV (FWHM) and low-energy threshold of approximately equals 4 keV were achieved in laboratory calibrations. The second launch of FOXSI was performed on 11 December 2014, and images from the Sun were successfully obtained with the CdTe detector. Therefore, we successfully demonstrated the detector concept and the usefulness of this technique for future HXR observations of the Sun.

Ishikawa, Shin-nosuke↗

Nonlinear light-output calibration of the oxygenated xylene scintillators used in OMEGA neutron time-of-flight spectrometers

Neutron time-of-flight (nTOF) spectrometers are essential instruments for measuring and evaluating the performance of inertial confinement fusion implosions. The neutron spectrometers utilized for the OMEGA laser include two liquid-based scintillators, each consisting of a large volume filled with xylene that is coupled to four photomultiplier tubes. Analysis of the signal from these detectors requires detailed knowledge of the scintillator’s light output, which is needed to fit the nTOF spectrum, from which the neutron energy spectrum is informed. The light output is nonlinearly proportional to the neutron energy, which, in turn, affects the interpretation of the neutron energy spectrum from a TOF signal. A recent campaign on OMEGA was performed to calibrate the xylene detectors and infer the shape of the light-output curve. The campaign utilized materials with increasing Z placed in the OMEGA target chamber to initiate scattering events with the 14 MeV fusion neutrons. This process leads to the production of backscatter neutrons of varying energies that appear as peaks in the nTOF data. Simulations using a neutron transport code were combined with the measured deuterium–tritium neutron yields to calculate the expected backscattered neutron yields from the well-known scattering cross sections of each material. Furthermore, the neutron-energy dependent light output of the scintillator inferred from the experiment is compared to the light-output curve simulated with a neutron transport code for the following neutron energies: 1.5, 2.5, 6, and 14 MeV.

47 OTHER INSTRUMENTATION↗

Use of Diffusion Bonded Cu Strap and Integrated MLI for Thermal Control of 100 K IR Detector on L’Ralph Instrument

Passive cooling of cryogenic instruments is one of the most challenging aspects of spaceflight thermal control systems. They are highly sensitive to parasitic heat leaks from their warmer environment, especially the spacecraft components. The L’Ralph instrument on the Lucy mission is an example of such a system, with its LEISA detector requiring passive cooling to temperatures below 112 K. MLI performance can be measured in terms of estar, and analysts apply bias between a high and low estar value. This approach works well for conventional MLI at room temperature, however, it can be dangerous when a mission goes through a wide range of temperatures during its lifetime, with estar values increasing exponentially as temperatures get colder. Various estar correlations are presented as well as how L’Ralph is approaching the MLI problem with the use of IMLI. IMLI uses discrete spacers to isolate each layer, and doesn’t require intermediate layers such as dacron netting. This results in estar performance that can be more precisely estimated, and yields valuesaround 0.004 at the 112K operating temperature. L’Ralph is using IMLI on the backside of the radiator, which permits a more effective use of increased radiator area, by minimizing the area dependent heat leak impact from the instrument backloading. The detector is thermally coupled to the radiator via a diffusion bonded Cu strap. The diffusion bonding process chemically bonds the Cu foil ends in order to maximize heat transfer effectiveness across the multiple foils used. Employing a pressure compensation design via the use of Ti blocks and a clamp at the strap ends ensures that as temperatures go colder, pre-load is maintained in order to minimize resistance at the strap ends. The use of both of these technologies, and how they work together are crucial to the success of the L’Ralph thermal control system.

Thermal↗

Novel 4x4 SiPM array readout with integrated preamplification stage, optimized for the PWO detectors of the EIC EEEMCal

Here we are reporting on a new readout circuit developed for the lead tungstate (PbWO4) scintillation detectors for the Electron Ion Collider (EIC) Electron Endcap Electromagnetic Calorimeter EEEMCal. The high magnetic field region precludes the use of photomultiplier tubes while the detector requirements specify good spectral resolution performance and fast pulse integration over a large dynamic range. We selected a silicon photomultiplier (SiPM) from Hamamatsu and produced a matrix of 4 x 4 sensors to cover the 20 mm x 20 mm scintillator coupling surface. Signal acquisition and amplification electronics boards were designed and integrated with the sensor board to produce a compact high performance readout package. A prototype detector was built and tested at Jefferson Lab with encouraging resolution and timing performance results.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Searching for cosmological stochastic backgrounds by notching out resolvable compact binary foregrounds with next-generation gravitational-wave detectors

Stochastic gravitational-wave backgrounds can be of either cosmological or astrophysical origin. The detection of an astrophysical stochastic gravitational-wave background with ground-based interferometers is expected in the near future. Perhaps even more excitingly, the detection of stochastic backgrounds of cosmological origin by future ground-based interferometers could reveal invaluable information about the early Universe. From this perspective, the astrophysical background is a foreground that can prevent the extraction of this information from the data. In this paper, we revisit a time-frequency domain notching procedure previously proposed to remove the astrophysical foreground in the context of next-generation ground-based detectors, but we consider the more realistic scenario where we remove individually detectable signals by taking into account the uncertainty in the estimation of their parameters. We find that time-frequency domain masks can still efficiently remove the astrophysical foreground and suppress it to about 5% of its original level. Further removal of the foreground formed by unresolvable events (in particular, unresolvable binary neutron stars), which is about 10 times larger than the residual foreground from realistic notching, would require detector sensitivity improvements. Therefore, the main limitation in the search for a cosmological background is the unresolvable foreground itself, and not the residual of the notching procedure.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Searching for cosmological stochastic backgrounds by notching out resolvable compact binary foregrounds with next-generation gravitational-wave detectors

Stochastic gravitational-wave backgrounds can be of either cosmological or astrophysical origin. The detection of an astrophysical stochastic gravitational-wave background with ground-based interferometers is expected in the near future. Perhaps even more excitingly, the detection of stochastic backgrounds of cosmological origin by future ground-based interferometers could reveal invaluable information about the early Universe. From this perspective, the astrophysical background is a {\it foreground} that can prevent the extraction of this information from the data. In this paper, we revisit a time-frequency domain notching procedure previously proposed to remove the astrophysical foreground in the context of next-generation ground-based detectors, but we consider the more realistic scenario where we remove individually detectable signals by taking into account the uncertainty in the estimation of their parameters. We find that time-frequency domain masks can still efficiently remove the astrophysical foreground and suppress it to about $5\%$ of its original level. Further removal of the foreground formed by unresolvable events (in particular, unresolvable binary neutron stars), which is about $10$ times larger than the residual foreground from realistic notching, would require detector sensitivity improvements. Therefore, the main limitation in the search for a cosmological background is the unresolvable foreground itself, and not the residual of the notching procedure.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

EPRI Demonstration of an Autonomous Site Characterization Vehicle - 20523

A substantial effort is applied in performing radiological characterization of structures and land areas during decommissioning of a nuclear facility. This includes multiple surveys of land areas and large structures to support eventual site release under the Multi Agency Survey and Site Investigation Manual (MARSSIM, Reference 1). These surveys are typically performed using manually delivered systems, which is time consuming and labor intensive. Radiological surveys intentionally follow a prescribed protocol with respect to areas covered, scan speeds, responses to elevated readings, required detector offsets, the need for repeat measurements, etc. Based on these attributes, combined with the repetitive effort of performing surveys over large areas, automation of radiological characterization techniques has a high potential to be successful and promises substantial benefit. EPRI has performed a project that resulted in the development and demonstration of an autonomous site characterization system. This EPRI project focused on building surfaces and the surfaces of large land areas as these configurations lend themselves more readily to automated survey. The project included: - Identification of the requirements for an autonomous site characterization system; - A survey of existing control systems that use automation to conduct characterization of structures and land areas. - As no fully adequate systems were identified, a complete system was developed that utilized commercially available detection and analysis systems and a self driving vehicle owned by EPRI. The system was demonstrated at the Kewaunee nuclear power plant site in the fall of 2019. The demonstration included: - Autonomous surveys of floor areas inside the Auxiliary Building at Kewaunee after manually controlled mapping of the survey areas. - For land areas, the vehicle autonomously surveyed areas using travel paths had been preprogrammed onto an internet available map of area. In this case, GPS coordinates from the preprogramming were used for navigation by the vehicles guidance system. This paper summarizes the characterization system development and system demonstration which will also be published in an EPRI report in the first half of 2020. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗