arXiv subjects

Bernard Phlips

Publications and source records attributed to Bernard Phlips.

18 recordsLinked to original sources

arXiv2026

The iSTORM Instrument for Airborne Measurements of Gamma-Ray Emissions from Thunderstorms

The in-Situ Thunderstorm Observer for Radiation Mechanisms (iSTORM) is a gamma-ray spectrometer to study gamma-ray transients originating from thunderstorms, such as glows and terrestrial gamma-ray flashes (TGFs). It is designed and built by the U.S. Naval Research Laboratory for deployment aboard a NASA ER-2 aircraft. Using an array of 32 one-inch-diameter $\mathrm{CeBr}_3$ scintillators read out with silicon photomultipliers (SiPMs), the instrument achieves an energy range of $\sim 250 \ \mathrm{keV}$ to $5 \ \mathrm{MeV}$ under flight conditions, with a total geometrical area of $157 \ \mathrm{cm^2}$. One of two gamma-ray instruments in the ALOFT campaign, iSTORM recorded glows, terrestrial gamma-ray flashes (TGFs), and the newly discovered flickering gamma-ray flashes (FGFs).

physics.ao-ph↗

arXiv2025

Calibration of the ComPair Balloon Instrument

ComPair, the prototype of the All-sky Medium Energy Gamma-ray Observatory (AMEGO) mission concept, is a combined Compton imager and pair production telescope. It consists of four subsystems: a double-sided silicon strip detector (DSSD) Tracker, a virtual Frisch-grid cadmium zinc telluride (CZT) Low Energy Calorimeter, a cesium iodide (CsI) High Energy Calorimeter, and a plastic scintillator Anti-Coincidence Detector (ACD) to reject the charged particle background. These subsystems work together to reconstruct events, by tracking the locations and energies of gamma-ray scatters and pair production events. To quantify ComPair's scientific capabilities prior to a balloon launch in 2023, calibrations were performed to benchmark the instrument's performance in terms of angular resolution, energy resolution, and effective area. In this paper we provide an overview of the ComPair instrument and detail the calibration campaign. Finally, we compare our results to the expected performance based on simulations.

astro-ph.IM↗

arXiv2025

Background Measurements and Simulations of the ComPair Balloon Flight

ComPair, a prototype of the All-sky Medium Energy Gamma-ray Observatory (AMEGO), completed a short-duration high-altitude balloon campaign on August 27, 2023 from Fort Sumner, New Mexico, USA. The goal of the balloon flight was the demonstration of ComPair as both a Compton and Pair telescope in flight, rejection of the charged particle background, and measurement of the background $\gamma$-ray spectrum. This analysis compares measurements from the balloon flight with Monte Carlo simulations to benchmark the instrument. The comparison finds good agreement between the measurements and simulations and supports the conclusion that ComPair accomplished its goals for the balloon campaign. Additionally, two charged particle background rejection schemes are discussed: a soft ACD veto that records a higher charged particle event rate but with less risk of event loss, and a hard ACD veto that limits the charged particle event rate on board. There was little difference in the measured spectra from the soft and hard ACD veto schemes, indicating that the hard ACD veto could be used for future flights. The successes of ComPair's engineering flight will inform the development of the next generation of ComPair with upgraded detector technology and larger active area.

astro-ph.IM↗

arXiv2024

SIRI-2 Detection of the Gamma-ray Burst 221009A

SIRI-2 is a collection of Strontium Iodide gamma-ray detectors sensitive at approximately 400 keV to 10 MeV, launched on the Department of Defense's STPSat-6 to geosynchronous orbit. SIRI-2 detected the gamma-ray burst (GRB) 221009A and, unlike most GRB detectors, was not saturated and did not require any pulse pile-up corrections. The energetics of this burst as measured by SIRI-2 are consistent with those found by other instruments, and the Band function fits to the spectra are consistent with that from the unsaturated Insight and GECAM instruments, and similar to corrected spectra from the Fermi Gamma-ray Burst Monitor, but softer than those found by Konus-Wind when that instrument was saturated. The total fluence measured with SIRI-2 was measured to be 0.140 +/- 0.002 erg cm-2, lower than other instruments, likely due to the increasing background of SIRI-2 forcing the calculation to use a smaller time interval. An extrapolation of the distributions of fluences from GRBs to the fluence of 221009A measured with SIRI-2 indicates bursts brighter than this one should occur about once every 4,000 years.

astro-ph.HE↗

arXiv2024

ComPair-2: A Next Generation Medium Energy Gamma-ray Telescope Prototype

Many questions posed in the Astro2020 Decadal survey in both the New Messengers and New Physics and the Cosmic Ecosystems science themes require a gamma-ray mission with capabilities exceeding those of existing (e.g. Fermi, Swift) and planned (e.g. COSI) observatories. ComPair, the Compton Pair telescope, is a prototype of such a next-generation gamma-ray mission. It had its inaugural balloon flight from Ft. Sumner, New Mexico in August 2023. To continue the goals of the ComPair project to develop technologies that will enable a future gamma-ray mission, the next generation of ComPair (ComPair-2) will be upgraded to increase the sensitivity and low-energy transient capabilities of the instrument. These advancements are enabled by AstroPix, a silicon monolithic active pixel sensor, in the tracker and custom dual-gain silicon photomultipliers and front-end electronics in the calorimeter. This effort builds on design work for the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) concept that was submitted the 2021 MIDEX Announcement of Opportunity. Here we describe the ComPair-2 prototype design and integration and testing plans to advance the readiness level of these novel technologies.

astro-ph.IM↗

arXiv2024

The 2023 Balloon Flight of the ComPair Instrument

The ComPair balloon instrument is a prototype gamma-ray telescope that aims to further develop technology for observing the gamma-ray sky in the MeV regime. ComPair combines four detector subsystems to enable parallel Compton scattering and pair-production detection, critical for observing in this energy range. This includes a 10 layer double-sided silicon strip detector tracker, a virtual Frisch grid low energy CZT calorimeter, a high energy CsI calorimeter, and a plastic scintillator anti-coincidence detector. The inaugural balloon flight successfully launched from the Columbia Scientific Balloon Facility site in Fort Sumner, New Mexico, in late August 2023, lasting approximately 6.5 hours in duration. In this proceeding, we discuss the development of the ComPair Since balloon payload, the performance during flight, and early results.

astro-ph.IM↗

arXiv2024

Development of the cadmium zinc TElluride Radiation Imager (TERI)

The cadmium zinc TElluride Radiation Imager, or TERI, is an instrument to space qualify large-volume $4 \times 4 \times 1.5 \ \mathrm{cm}^3$ pixelated CdZnTe (CZT) detector technology. The CZT's anode is composed of a $22 \times 22$ array of pixels while the cathode is planar. TERI will contain four of those crystals with each pixel having an energy range of $40 \ \mathrm{keV}$ up to $3 \ \mathrm{MeV}$ with a resolution of $1.3 \%$ full-width-at-half maximum at $662 \ \mathrm{keV}$ all while operating in room temperature. As the detectors are 3D position sensitive, TERI can Compton image events. TERI is fitted with a coded-aperture mask which permits imaging low energy photons in the photoelectric regime. TERI's primary mission is to space-qualify large-volume CZT and measure its degradation due to radiation damage in a space environment. Its secondary mission includes detecting and localizing astrophysical gamma-ray transients. TERI is manifested on DoD's STP-H10 mission for launch to the International Space Station in early 2025.

astro-ph.IM↗

arXiv2024

Exploring Large-Volume GAGG Scintillators for use in MeV Gamma-Ray Astrophysics

Gamma-ray astrophysics in the MeV band is an exciting field in astronomy due to its potential for multi-messenger astrophysics. It has, however, remained under-explored when compared to other wavelengths. One reason for this observational gap is the difficulties with measuring these high-energy photons and the requirement of large amounts of detection material. In this work, we investigate the usage of large-volume GAGG scintillators for use as a calorimeter in future MeV telescopes. We developed a $5\times5$ array calorimeter utilizing $1\times1\times6 \ \mathrm{cm}^3$ GAGG crystals with onsemi C-series SiPM readout. We tested the calorimeter at the High Intensity Gamma-ray Facility (HIGS) with monoenergetic beams ranging from $2-25 \ \mathrm{MeV}$. Finally, we also investigate larger $1\times1\times8 \ \mathrm{cm}^3$ crystals and characterize their response across their depth when their surface treatment is either polished or frosted.

astro-ph.IM↗

arXiv2024

Results from the CsI Calorimeter onboard the 2023 ComPair Balloon Flight

The ComPair gamma-ray telescope is a technology demonstrator for a future gamma-ray telescope called the All-sky Medium Energy Gamma-ray Observatory (AMEGO). The instrument is composed of four subsystems, a double-sided silicon strip detector, a virtual Frisch grid CdZnTe calorimeter, a CsI:Tl based calorimeter, and an anti-coincidence detector (ACD). The CsI calorimeter's goal is to measure the position and energy deposited from high-energy events. To demonstrate the technological readiness, the calorimeter has flown onboard a NASA scientific balloon as part of the GRAPE-ComPair mission and accumulated around 3 hours of float time at an altitude of 40 km. During the flight, the CsI calorimeter observed background radiation, Regener-Pfotzer Maximum, and several gamma-ray activation lines originating from aluminum.

astro-ph.IM↗

arXiv2023

The Compton-Pair telescope: A prototype for a next-generation MeV $γ$-ray observatory

The Compton Pair (ComPair) telescope is a prototype that aims to develop the necessary technologies for future medium energy gamma-ray missions and to design, build, and test the prototype in a gamma-ray beam and balloon flight. The ComPair team has built an instrument that consists of 4 detector subsystems: a double-sided silicon strip detector Tracker, a novel high-resolution virtual Frisch-grid cadmium zinc telluride Calorimeter, and a high-energy hodoscopic cesium iodide Calorimeter, all of which are surrounded by a plastic scintillator anti-coincidence detector. These subsystems together detect and characterize photons via Compton scattering and pair production, enable a veto of cosmic rays, and are a proof-of-concept for a space telescope with the same architecture. A future medium-energy gamma-ray mission enabled through ComPair will address many questions posed in the Astro2020 Decadal survey in both the New Messengers and New Physics and the Cosmic Ecosystems themes. In this contribution, we will give an overview of the ComPair project and steps forward to the balloon flight.

astro-ph.IM↗

arXiv2023

Radiation Damage of $2 \times 2 \times 1 \ \mathrm{cm}^3$ Pixelated CdZnTe Due to High-Energy Protons

Pixelated CdZnTe detectors are a promising imaging-spectrometer for gamma-ray astrophysics due to their combination of relatively high energy resolution with room temperature operation negating the need for cryogenic cooling. This reduces the size, weight, and power requirements for telescope-based radiation detectors. Nevertheless, operating CdZnTe in orbit will expose it to the harsh radiation environment of space. This work, therefore, studies the effects of $61 \ \mathrm{MeV}$ protons on $2 \times 2 \times 1 \ \mathrm{cm}^3$ pixelated CdZnTe and quantifies proton-induced radiation damage of fluences up to $2.6 \times 10^8 \ \mathrm{p/cm^2}$. In addition, we studied the effects of irradiation on two separate instruments: one was biased and operational during irradiation while the other remained unbiased. Following final irradiation, the $662 \ \mathrm{keV}$ centroid and nominal $1\%$ resolution of the detectors were degraded to $642.7 \ \mathrm{keV}, 4.9 \% \ ( \mathrm{FWHM})$ and $653.8 \ \mathrm{keV}, 1.75 \% \ (\mathrm{FWHM})$ for the biased and unbiased systems respectively. We therefore observe a possible bias dependency on proton-induced radiation damage in CdZnTe. This work also reports on the resulting activation and recovery of the instrument following room temperature and $60^{\circ}\mathrm{C}$ annealing.

physics.ins-det↗

arXiv2022

The All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) Mission Concept

The All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) is designed to identify and characterize gamma rays from extreme explosions and accelerators. The main science themes include: supermassive black holes and their connections to neutrinos and cosmic rays; binary neutron star mergers and the relativistic jets they produce; cosmic ray particle acceleration sources including Galactic supernovae; and continuous monitoring of other astrophysical events and sources over the full sky in this important energy range. AMEGO-X will probe the medium energy gamma-ray band using a single instrument with sensitivity up to an order of magnitude greater than previous telescopes in the energy range 100 keV to 1 GeV that can be only realized in space. During its three-year baseline mission, AMEGO-X will observe nearly the entire sky every two orbits, building up a sensitive all-sky map of gamma-ray sources and emission. AMEGO-X was submitted in the recent 2021 NASA MIDEX Announcement of Opportunity.

astro-ph.IM↗

arXiv2022

Development of the ComPair gamma-ray telescope prototype

There is a growing interest in the science uniquely enabled by observations in the MeV range, particularly in light of multi-messenger astrophysics. The Compton Pair (ComPair) telescope, a prototype of the AMEGO Probe-class concept, consists of four subsystems that together detect and characterize gamma rays in the MeV regime. A double-sided strip silicon Tracker gives a precise measure of the first Compton scatter interaction and tracks pair-conversion products. A novel cadmium zinc telluride (CZT) detector with excellent position and energy resolution beneath the Tracker detects the Compton-scattered photons. A thick cesium iodide (CsI) calorimeter contains the high-energy Compton and pair events. The instrument is surrounded by a plastic anti-coincidence (ACD) detector to veto the cosmic-ray background. In this work, we will give an overview of the science motivation and a description of the prototype development and performance.

astro-ph.IM↗

arXiv2021

The Compton Spectrometer and Imager Project for MeV Astronomy

The Compton Spectrometer and Imager (COSI) is a 0.2-5 MeV Compton telescope capable of imaging, spectroscopy, and polarimetry of astrophysical sources. Such capabilities are made possible by COSI's germanium cross-strip detectors, which provide high efficiency, high resolution spectroscopy and precise 3D positioning of photon interactions. Science goals for COSI include studies of 0.511 MeV emission from antimatter annihilation in the Galaxy, mapping radioactive elements from nucleosynthesis, determining emission mechanisms and source geometries with polarization, and detecting and localizing multimessenger sources. The instantaneous field of view (FOV) for the germanium detectors is >25% of the sky, and they are surrounded on the sides and bottom by active shields, providing background rejection as well as allowing for detection of gamma-ray bursts or other gamma-ray flares over >50% of the sky. We have completed a Phase A concept study to consider COSI as a Small Explorer (SMEX) satellite mission, and here we discuss the advances COSI-SMEX provides for astrophysics in the MeV bandpass.

astro-ph.IM↗

arXiv2020

Radiation damage assessment of SensL SiPMs

Silicon Photomultipliers (SiPMs) are quickly replacing traditional photomultiplier tubes (PMTs) as the readout of choice for gamma-ray scintillation detectors in space. While they offer substantial size, weight and power saving, they have shown to be susceptible to radiation damage. SensL SiPMs with different cell sizes were irradiated with 64 MeV protons and 8 MeV electrons. In general, results show larger cell sizes are more susceptible to radiation damage with the largest 50 um SiPMs showing the greatest increase in current as a function of dose. Current increases were observed for doses as low at ~2 rad(Si) for protons and ~20 rad(Si) for electrons. The U.S. Naval Research Laboratory's (NRL) Strontium Iodide Radiation Instrument (SIRI-1) experienced a 528 uA increase in the bias current of the on-board 2x2 SensL J-series 60035 SiPM over its one-year mission in sun-synchronous orbit. The work here focuses on the increase in bulk current observed with increasing radiation damage and was performed to better quantify this effect as a function of dose for future mission. These include the future NRL mission SIRI-2, the follow on to SIRI-1, Glowbug and the GAGG Radiation Instrument (GARI).

physics.ins-det↗

arXiv2019

The Compton Spectrometer and Imager

In this Astro2020 APC White Paper, we describe a Small Explorer (SMEX) mission concept called the Compton Spectrometer and Imager. COSI is a Compton telescope that covers the bandpass often referred to as the "MeV Gap" because it is the least explored region of the whole electromagnetic spectrum. COSI provides a significant improvement in sensitivity along with high-resolution spectroscopy, enabling studies of 511 keV electron-positron annihilation emission and measurements of several radioactive elements that trace the Galactic history of supernovae. COSI also measures polarization of gamma-ray bursts (GRBs), accreting black holes, and pulsars as well as detecting and localizing multimessenger sources. In the following, we describe the COSI science, the instrument, and its capabilities. We highlight many Astro2020 science WPs that describe the COSI science in depth.

astro-ph.IM↗

arXiv2019

STROBE-X: X-ray Timing and Spectroscopy on Dynamical Timescales from Microseconds to Years

We present the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X), a probe-class mission concept selected for study by NASA. It combines huge collecting area, high throughput, broad energy coverage, and excellent spectral and temporal resolution in a single facility. STROBE-X offers an enormous increase in sensitivity for X-ray spectral timing, extending these techniques to extragalactic targets for the first time. It is also an agile mission capable of rapid response to transient events, making it an essential X-ray partner facility in the era of time-domain, multi-wavelength, and multi-messenger astronomy. Optimized for study of the most extreme conditions found in the Universe, its key science objectives include: (1) Robustly measuring mass and spin and mapping inner accretion flows across the black hole mass spectrum, from compact stars to intermediate-mass objects to active galactic nuclei. (2) Mapping out the full mass-radius relation of neutron stars using an ensemble of nearly two dozen rotation-powered pulsars and accreting neutron stars, and hence measuring the equation of state for ultradense matter over a much wider range of densities than explored by NICER. (3) Identifying and studying X-ray counterparts (in the post-Swift era) for multiwavelength and multi-messenger transients in the dynamic sky through cross-correlation with gravitational wave interferometers, neutrino observatories, and high-cadence time-domain surveys in other electromagnetic bands. (4) Continuously surveying the dynamic X-ray sky with a large duty cycle and high time resolution to characterize the behavior of X-ray sources over an unprecedentedly vast range of time scales. STROBE-X's formidable capabilities will also enable a broad portfolio of additional science.

astro-ph.IM↗

arXiv2006

The Advanced Compton Telescope Mission

The Advanced Compton Telescope (ACT), the next major step in gamma-ray astronomy, will probe the fires where chemical elements are formed by enabling high-resolution spectroscopy of nuclear emission from supernova explosions. During the past two years, our collaboration has been undertaking a NASA mission concept study for ACT. This study was designed to (1) transform the key scientific objectives into specific instrument requirements, (2) to identify the most promising technologies to meet those requirements, and (3) to design a viable mission concept for this instrument. We present the results of this study, including scientific goals and expected performance, mission design, and technology recommendations.

astro-ph↗