The X-ray Integral Field Unit (X-IFU) of the Advanced Telescope for High-ENergy Astrophysics (Athena) large-scale mission of ESA will provide spatially resolved high-resolution X-ray spectroscopy ...from 0.2 to 12 keV, with 5
″
pixels over a field of view of 5 arc minute equivalent diameter and a spectral resolution of 2.5 eV (FWHM) up to 7 keV. The core scientific objectives of Athena drive the main performance parameters of the X-IFU. We present the current reference configuration of the X-IFU, and the key issues driving the design of the instrument.
ABSTRACT High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even ...with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field of view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates with an effective exposure of 106 s, obtaining a limit on the sterile neutrino mixing angle of at 95% CL for a 7 keV neutrino. Better sensitivity at the level of at 95% CL for a 7 keV neutrino is achievable with future 300-s observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.
Quantum electrodynamics in very strong Coulomb fields is one scope which has not yet been tested experimentally with sufficient accuracy to really determine whether the perturbative approach is ...valid. One sensitive test is the determination of the 1s Lamb shift in highly-charged very heavy ions. The 1s Lamb shift of hydrogen-like lead (Pb81+) and gold (Au78+) has been determined using the novel detector concept of silicon microcalorimeters for the detection of hard x-rays. The results of ( 260 53 ) eV for lead and ( 211 42 ) eV for gold are within the error bars in good agreement with theoretical predictions. To our knowledge, for hydrogen-like lead, this represents the most accurate determination of the 1s Lamb shift.
Low-temperature detectors often use mechanical coolers as part of the cooling chain in order to reach sub-Kelvin operating temperatures. The microphonic noise caused by the mechanical coolers is a ...general and inherent issue for these detectors. We have observed this effect in the ground test data obtained with the
Resolve
instrument to be flown on the XRISM satellite.
Resolve
is a cryogenic X-ray microcalorimeter spectrometer with a required energy resolution of 7 eV at 6 keV. Five mechanical coolers are used to cool from ambient temperature to
∼
4 K: four two-stage Stirling coolers (STC) driven nominally at 15 Hz and a Joule–Thomson cooler (JTC) driven nominally at 52 Hz. In 2019, we operated the flight-model instrument for two weeks, in which we also obtained accelerometer data inside the cryostat at a low-temperature stage (He tank). X-ray detector and accelerometer data were obtained continuously while changing the JTC drive frequency, which produced a unique data set for investigating how the vibration from the cryocoolers propagates to the detector. In the detector noise spectra, we observed harmonics of both STCs and JTC. More interestingly, we also observed the low (
<
20
Hz) frequency beat between the 4th JTC and 14th STC harmonics and the 7th JTC and the 23–24th STC harmonics. We present here a description and interpretation of these measurements.
ABSTRACT We have measured the energies of the strongest 1s-2 transitions in He- through Ne-like silicon and sulfur ions to an accuracy of using the Lawrence Livermore National Laboratory's electron ...beam ion traps, EBIT-I and SuperEBIT, and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify and measure the energies of 18 and 21 X-ray features from silicon and sulfur, respectively. The results are compared to new Flexible Atomic Code calculations and to semi-relativistic Hartree-Fock calculations by Palmeri et al. (2008). These results will be especially useful for wind diagnostics in high-mass X-ray binaries, such as Vela X-1 and Cygnus X-1, where high-resolution spectral measurements using Chandra's high-energy transmission grating has made it possible to measure Doppler shifts of . The accuracy of our measurements is consistent with that needed to analyze Chandra observations, exceeding Chandra's limit. Hence, the results presented here not only provide benchmarks for theory, but also accurate rest energies that can be used to determine the bulk motion of material in astrophysical sources. We show the usefulness of our results by applying them to redetermine Doppler shifts from Chandra observations of Vela X-1.
At NASA Goddard Space Flight Center, we have previously demonstrated a kilo-pixel array of transition-edge sensor (TES) microcalorimeters capable of meeting the energy resolution requirements of the ...future X-ray Integral Field Unit (X-IFU) instrument that is being developed for the Advanced Telescope for High ENergy Astrophysics (ATHENA) observatory satellite. The TES design in this array was a square device with side length of <inline-formula><tex-math notation="LaTeX">50 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula>. Here, we describe studies of TES designs with small variations of the dimensions, exploring lengths, parallel to the current direction, ranging from <inline-formula><tex-math notation="LaTeX">75 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">50 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula> and widths, perpendicular to the current direction, ranging from <inline-formula><tex-math notation="LaTeX">50 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">15 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula>. We describe how these changes impact transition properties, thermal conductance and magnetic field sensitivity. In particular, we show that using a TES with a length of <inline-formula><tex-math notation="LaTeX">50 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula> and width of <inline-formula><tex-math notation="LaTeX">30 \,\mathrm{\upmu }\mathrm{m}</tex-math></inline-formula> may be a promising route to reduce the maximum time-derivative of the TES current in an X-ray pulse and reduce the sensitivity of the TES to magnetic field.
We have developed fine-pitch, multilayer, superconducting wiring for routing around a ninety-degree corner terminated with wirebonding interfaces. The component-level testbed for the Advanced ...Telescope for High Energy Astrophysics (ATHENA) X-Ray Integral Field Unit (X-IFU) focal plane requires compact, high-density, low-crosstalk wiring fanout to connect the detectors in the focal plane array with NIST-fabricated SQUID time domain multiplexing (TDM) readout chips. The full assembly baselines two interface chips: a flexible interface chip bending around the corner and a planar silicon carrier chip. The TDM readout is indium bump-bonded to the silicon carrier and afterward the flexible chip is clipped in place and wirebonded to the detector and fanout wiring on the carrier. This assembly is repeated for each side of the hexagonal focal plane structure. As conventional commercial cables are not able to achieve the fine-pitch, low-crosstalk, superconducting wiring required, we fabricate these flexible interface chips in-house via lithographic patterning and etching of sputter deposited thin films to create broadside-coupled superconducting niobium microstrips. Within the chip, the wiring on the flexible polyimide region transitions to silicon substrate for the closely spaced wirebond pads. The Nb microstrip wiring climbing a thick polyimide sidewall presents a fabrication challenge which we shall discuss in this paper. We describe the function of these components to build an effective engineering testbed for the ATHENA X-IFU.
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