arXiv subjects

Joseph M. Colosimo

Publications and source records attributed to Joseph M. Colosimo.

7 recordsLinked to original sources

arXiv2026

Development of next-generation event-driven x-ray hybrid CMOS detectors

The Penn State University High Energy Astrophysics Detector and Instrumentation Lab, in collaboration with Teledyne Imaging Sensors, has developed a next-generation event-driven X-ray hybrid CMOS detector. This detector is an HCD with a 1,024x1,024 array of 21-micron pitch pixels, featuring a comparator in each pixel to enable event-driven readout. While the full frame operation of this detector can reach readout speeds of up to 150 Hz, this event-driven operation allows readout of only those pixels that surpass a user-set charge threshold, enabling effective rates of up to 10 kHz. Here we report on the past detector development efforts at Penn State and describe these new detectors and expected performance improvements.

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arXiv2026

High-Energy Shock Breakout from Supernovae and Gamma-ray Bursts

Cosmic explosions play a critical role in a broad range of astrophysical fields. Although considerable progress has been made to understand the explosive engines and their progenitors, many of the details are not well understood. One of the most powerful electromagnetic probes of the explosive mechanism and the stellar progenitor is the first burst of photons emitted from this blastwave as it exits the stellar photosphere, known as shock breakout (SBO). Our understanding of SBO has evolved considerably in the past decade. Shock heating as the blastwave propagates through the star and circumstellar material can drastically alter this emission producing a much broader range of potential SBO signals than that predicted by standard analytical approaches. Here we present a semi-analytic approach to model this diverse SBO emission, focused on thermal Bremsstrahlung radiation, which more accurately captures the complexities in Nature over previous treatments. We calculate a range of signals for a range of supernova and gamma-ray burst types. Our models demonstrate how we can use these signals to place constraints on the nature of the explosive engines and better understand the role SBO can play in prompt gamma-ray bursts. We study the implications of these results to historic observations, Einstein Probe transients, and in the context of proposed missions. We find that stripped envelope events can be detected serendipitously with survey telescopes, but type Ia and II SBO detections require fast-pointing X-ray observations in response to early warning alerts from gravitational wave or neutrino detectors.

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arXiv2025

Characterization of Random Telegraph Noise in an H2RG X-ray Hybrid CMOS Detector

Hybrid CMOS detectors (HCDs) have several excellent features as high-performance X-ray detectors, including rapid readout, deep-depletion silicon for high quantum efficiency, radiation hardness, and low power. Random telegraph noise (RTN) is a type of noise that can reduce the performance of HCDs and other CMOS sensors. After finding and quantifying RTN in the recently developed engineering grade Speedster-EXD550 HCDs, this form of noise has also been found in other X-ray HCDs. This paper aims to investigate its presence and characteristics in the relatively mature H2RG X-ray HCD and to compare it with that of the Speedster-EXD550. We use archival data taken with an H2RG X-ray HCD at two different temperatures to determine the percentage of pixels that are being impacted by RTN. We identify RTN in 0.42% of pixels when the detector is operated at 140 K, while we are only able to identify RTN in 0.060% of pixels when the detector is operated at 160 K. We characterize RTN in two Speedster-EXD550 detectors, identifying 5.1% of pixels with RTN in one detector and 7.1% in another, which is significantly more than the H2RG. These results verify the difference between two different HCDs and provide techniques that can be applied to future hybrid CMOS detectors.

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arXiv2024

Expected Gamma-Ray Burst Detection Rates and Redshift Distributions for the BlackCAT CubeSat Mission

We report the results of an extensive set of simulations exploring the sensitivity of the BlackCAT CubeSat to long-duration gamma-ray bursts (GRBs). BlackCAT is a NASA APRA-funded CubeSat mission for the detection and real-time sub-arcminute localization of high-redshift ($z\gtrsim 3.5$) GRBs. Thanks to their luminous and long-lived afterglow emissions, GRBs are uniquely valuable probes of high-redshift star-forming galaxies and the intergalactic medium. In addition, each detected GRB with a known redshift serves to localize a region of high-redshift star formation in three dimensions, enabling deep follow-on searches for host galaxies and associated local and large-scale structures. We explore two distinct models for the GRB redshift distribution and luminosity function, both consistent with Swift observations. We find that, for either model, BlackCAT is expected to detect a mean of 42 bursts per year on-orbit, with 6.7% to 10% of these at $z>3.5$. BlackCAT bursts will be localized to $r_{90} \lesssim 55^{\prime\prime}$ precision and reported to the community within seconds. Due to the mission orbit and pointing scheme, bursts will be located in the night sky and well-placed for deep multiwavelength follow-up observations. BlackCAT is on schedule to achieve launch readiness in 2025.

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arXiv2023

Initial Characterization of the First Speedster-EXD550 Event-Driven X-Ray Hybrid Complementary Metal-Oxide Semiconductor Detectors

Future x-ray observatories will require imaging detectors with fast readout speeds that simultaneously achieve or exceed the other high performance parameters of x-ray charge-coupled devices (CCDs) used in many missions over the past three decades. Fast readout will reduce the impact of pile-up in missions with large collecting areas while also improving performance in other respects like timing resolution. Event-driven readout, in which only pixels with charge from x-ray events are read out, can be used to achieve these faster operating speeds. Speedster-EXD550 detectors are hybrid complementary metal-oxide semiconductor (CMOS) detectors capable of event-driven readout, developed by Teledyne Imaging Sensors and Penn State University. We present initial results from measurements of the first of these detectors, demonstrating their capabilities and performance in both full-frame and event-driven readout modes. These include dark current, read noise, gain variation, and energy resolution measurements from the first two engineering-grade devices.

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arXiv2022

Measuring the Soft X-Ray Quantum Efficiency of a Hybrid CMOS Detector

Next-generation X-ray observatories, such as the Lynx X-ray Observatory Mission Concept or other similar concepts in the coming decade, will require detectors with high quantum efficiency (QE) across the soft X-ray band to observe the faint objects that drive their mission science objectives. Hybrid CMOS Detectors (HCDs), a form of active-pixel sensor, are promising candidates for use on these missions because of their fast read-out, low power consumption, and intrinsic radiation hardness. In this work, we present QE measurements of a Teledyne H2RG HCD, performed using a gas-flow proportional counter as a reference detector. We find that this detector achieves high QE across the soft X-ray band, with an effective QE of $94.6 \pm 1.1 \%$ at the Mn K$α$/K$β$ energies (5.90/6.49 keV), $98.3 \pm 1.9 \%$ at the Al K$α$ energy (1.49 keV), $85.6 \pm 2.8 \%$ at the O K$α$ energy (0.52 keV), and $61.3 \pm 1.1 \%$ at the C K$α$ energy (0.28 keV). These values are in good agreement with our model, based on the absorption of detector layers. We find similar results in a more restrictive analysis considering only high-quality events, with only somewhat reduced QE at lower energies.

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arXiv2021

Measuring the Quantum Efficiency of X-Ray Hybrid CMOS Detectors

Next-generation X-ray observatories, such as the Lynx X-ray Observatory Mission Concept, will require detectors with high quantum efficiency (QE) across the soft X-ray band to observe the faint objects that drive their mission science cases. Hybrid CMOS Detectors (HCDs), a form of active-pixel sensor, are promising candidates for use on these missions because of their faster read-out, lower power consumption, and greater radiation hardness than detectors used in the current generation of X-ray telescopes. In this work, we present QE measurements of a Teledyne H2RG HCD. These measurements were performed using a gas-flow proportional counter as a reference detector to measure the absolute flux incident on the HCD. We find an effective QE of $95.0 \pm 1.1\%$ at the Mn K$α$/K$β$ lines (at 5.9 and 6.5 keV), $98.5 \pm 1.8\%$ at the Al K$α$ line (1.5 keV), and $85.0 \pm 2.8\%$ at the O K$α$ line (0.52 keV).

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