24 research outputs found
Development of Dual-Gain SiPM Boards for Extending the Energy Dynamic Range
Astronomical observations with gamma rays in the range of several hundred keV
to hundreds of MeV currently represent the least explored energy range. To
address this so-called MeV gap, we designed and built a prototype CsI:Tl
calorimeter instrument using a commercial off-the-shelf (COTS) SiPMs and
front-ends which may serve as a subsystem for a larger gamma-ray mission
concept. During development, we observed significant non-linearity in the
energy response. Additionally, using the COTS readout, the calorimeter could
not cover the four orders of magnitude in energy range required for the
telescope. We, therefore, developed dual-gain silicon photomultiplier (SiPM)
boards that make use of two SiPM species that are read out separately to
increase the dynamic energy range of the readout. In this work, we investigate
the SiPM's response with regards to active area ( and
) and various microcell sizes (, , and ). We read out CsI:Tl chunks
using dual-gain SiPMs that utilize microcells for both
SiPM species and demonstrate the concept when tested with high-energy gamma-ray
and proton beams. We also studied the response of $17 \times 17 \times 100 \
\mathrm{mm}^30.25-400 \ \mathrm{MeV}2.5-30 \ \mathrm{MeV}$. This development aims to demonstrate
the concept for future scintillator-based high-energy calorimeters with
applications in gamma-ray astrophysics
A NuSTAR observation of the reflection spectrum of the low mass X-ray binary 4U 1728-34
We report on a simultaneous NuSTAR and Swift observation of the neutron star
low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray
bursts during the observation in order to study the persistent emission. The
continuum spectrum is hard and well described by a black body with 1.5
keV and a cutoff power law with 1.5 and a cutoff temperature of 25
keV. Residuals between 6 and 8 keV provide strong evidence of a broad Fe
K line. By modeling the spectrum with a relativistically blurred
reflection model, we find an upper limit for the inner disk radius of . Consequently we find that km,
assuming M=1.4{\mbox{\rm\,M_{\mathord\odot}}} and . We also find an
upper limit on the magnetic field of G.Comment: 9 pages, 8 figure
Development of a CsI Calorimeter for the Compton-Pair (ComPair) Balloon-Borne Gamma-Ray Telescope
There is a growing interest in astrophysics to fill in the observational
gamma-ray MeV gap. We, therefore, developed a CsI:Tl calorimeter prototype as a
subsystem to a balloon-based Compton and Pair-production telescope known as
ComPair. ComPair is a technology demonstrator for a gamma-ray telescope in the
MeV range that is comprised of 4 subsystems: the double-sided silicon detector,
virtual Frisch grid CdZnTe, CsI calorimeter, and a plastic-based
anti-coincidence detector. The prototype CsI calorimeter is composed of thirty
CsI logs, each with a geometry of .
The logs are arranged in a hodoscopic fashion with 6 in a row that alternate
directions in each layer. Each log has a resolution of around
full-width-at-half-maximum (FWHM) at with a dynamic energy
range of around . A array of
SensL J-series SiPMs read out each end of the log to estimate the depth of
interaction and energy deposition with signals read out with an IDEAS ROSSPAD.
We also utilize an Arduino to synchronize with the other ComPair subsystems
that comprise the full telescope. This work presents the development and
performance of the calorimeter, its testing in thermal and vacuum conditions,
and results from irradiation by monoenergetic gamma-ray
beams. The CsI calorimeter will fly onboard ComPair as a balloon experiment in
the summer of 2023
NuSTAR ground calibration: The Rainwater Memorial Calibration Facility (RaMCaF)
The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing hard X-ray (5-80 keV ) telescope to orbit. The ground calibration of the three flight optics was carried out at the Rainwater Memorial Calibration Facility (RaMCaF) built for this purpose. In this article we present the facility and its use for the ground calibration of the three optics
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.Comment: 23 pages, 16 figures, Published Journal of Astronomical Telescopes,
Instruments, and System
The cosipy library: COSI's high-level analysis software
The Compton Spectrometer and Imager (COSI) is a selected Small Explorer
(SMEX) mission launching in 2027. It consists of a large field-of-view Compton
telescope that will probe with increased sensitivity the under-explored MeV
gamma-ray sky (0.2-5 MeV). We will present the current status of cosipy, a
Python library that will perform spectral and polarization fits, image
deconvolution, and all high-level analysis tasks required by COSI's broad
science goals: uncovering the origin of the Galactic positrons, mapping the
sites of Galactic nucleosynthesis, improving our models of the jet and emission
mechanism of gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), and
detecting and localizing gravitational wave and neutrino sources. The cosipy
library builds on the experience gained during the COSI balloon campaigns and
will bring the analysis of data in the Compton regime to a modern open-source
likelihood-based code, capable of performing coherent joint fits with other
instruments using the Multi-Mission Maximum Likelihood framework (3ML). In this
contribution, we will also discuss our plans to receive feedback from the
community by having yearly software releases accompanied by publicly-available
data challenges