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We report on our studies of possible configurations for the focal plane of the Constellation-X mission. Taking advantage of new developments in both SQUID multiplexing technology and position-sensitive detectors, we present a viable focal plane intrument design that would greatly enhance the reference Constellation-X configuration of a 32 × 32 array. An order of magnitude increase in the number of pixels of the focal plane array from the current 1024-pixel reference design is achievable.

Micro-X is a proposed sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. We describe the payload and the science targeted by this mission including the discussion of three possible Micro- X targets: the Puppis A supernova remnant, the Virgo Cluster, and Circinus X-1. For example, a Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plama diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. For clusters of galaxies, Micro-X can uniquely study turbulence and the temperature distribution function. For binaries, Micro-X's high resolution spectra will separate the different processes contributing to the Fe K lines at 6 keV and give a clear view of the geometry of the gas flows and circumstellar gas.

By implementing a large-area, gain-stabilized microcalorimeter array on an electron beam ion trap, the electron-impact excitation cross sections for the dominant x-ray lines in the Fe XVII spectrum have been measured as a function of electron energy establishing a benchmark for atomic calculations. The results show that the calculations consistently predict the cross section of the resonance line to be significantly larger than measured. The lower cross section accounts for several problems found when modeling solar and astrophysical Fe XVII spectra.

The mixing of atomic and macroscopic processes taking place in non‐terrestrial objects creates complex, dynamic, and intriguing environments. High resolution x‐ray spectra from these sources measured by satellites such as Chandra, XMM‐Newton, and the Solar Maximum Mission provide a means for understanding the physics governing these sources. Laboratory measurements of the atomic processes have proved crucial to the interpretation of these spectra. For example using the LLNL electron beam ion traps EBIT‐I & EBIT‐II a detailed study of the x‐ray spectrum of Fe XVII has been conducted addressing the large ratio predicted by theory compared to observations of considerably smaller values of the relative intensity of the 2p‐3d 1P1 resonant to the 3D1 intercombination line. The difference was often attributed to opacity effects. However, laboratory measurements in the optically thin limit agree with observations demonstrating that the prediction is too large and opacity need not be invoked. The laboratory result...

In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory.

We are developing a distributed-readout imaging spectrometer named Position-Sensitive Transition-Edge Sensor (PoST). A PoST is a microcalorimeter capagble of 1D imaging spectroscopy. It consists of two Transition-Edge Sensors (TESs) at each end of a long x-ray absorber. The position of an x-ray absorption event in the PoST is determined from the rise time and relative signal sizes in the two sensors. The energy of the absorbed photon is inferred from the sum of the two pulses. We discuss the modeling, operation, and readout of PoSTs and their application to the Constellation-X mission.

After the design of the calorimeter array for the high-resolution x-ray spectrometer (XRS) on the original Astro-E was frozen, new fabrication techniques became available and our understanding of these devices continually increased. We are now able to complete the optimization of this technology and, potentially, to increase the capability of new XRS instrument for Astro-E2, our on-going sounding recket experiments, and possible further applications. The most significant improvement comes from greatly reducing the excess noise of the ion-implanted thermistors by increasing the thickness of the implanted region.

Recent measurements of the K‐shell and L‐shell x‐ray spectra of highly charged helium‐like and neonlike ions are presented that were performed on the Livermore electron beam ion traps and the Princeton tokamaks. These measurements provide new insights into collisional and indirect line formation processes, identifications of forbidden lines, and a new plasma line diagnostic of magnetic field strength.

In the past year a spare NASA/GSFC Astro-E microcalorimeter has been installed, tested, and run successfully on the electron beam ions traps EBIT-I and EBIT-II at the Lawrence Livermore National Laboratory. The microcalorimeter complements crystal and grating spectrometers already part of the LLNL ebit program making it possible to measure a broad bandwidth (∼0.3–10 keV) with moderate resolution while simultaneously measuring a narrow bandwidth (∼0.7–1.3 keV) with high resolution. An overview of recent work is presented including measurements by the microcalorimeter of absolute excitation cross sections. These results continue our effort to provide atomic data of high quality to be used as benchmarks for theoretical calculations and to be included in atomic data bases employed by spectral fitting packages used to interpret spectra obtained by XMM-Newton and the Chandra X-Ray Observatory.

We have recently deployed an XRS (the X-ray Spectrometer on the Astro-E mission) engineering model microcalorimeter at the electron beam ion traps (EBIT I/II) at Lawrence Livermore National Laboratory. The EBIT I/II can produce well defined astrophysically interesting plasmas for a wide range of plasma conditions. The XRS engineering model was mated with a 32 element XRS 6×6 microcalorimeter array and integrated into a laboratory cryostat. The system was then transported to the EBIT I/II and operated over the last year. The microcalorimeter array has a composite resolution of 8 eV at 1 keV and 11 eV at 6 keV. During the campaign, we performed a number of high resolution, broad band observations including: K and L shell Fe with single ionization energies from 1–8 keV, Maxwellian distributions of Fe with 〈kT〉=0.5–3 keV, non-equilibrium states of Fe with very fine time resolution for η=109−1012 s cm−3. The total observation time for the campaign was over 10 Ms and the analysis is ongoing. We will present her...

The XRS instrument on Astro-E is a fully self-contained microcalorimeter x-ray instrument capable of acquiring optimally filtering, and characterizing events for 32 independent pixels. With the launch of the Astro-E spacecraft, a full flight spare detector system has been integrated into a laboratory cryostat for use on the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory. The detector system contains a microcalorimeter array with 32 instrumented pixels heat sunk to 60 mK using an adiabatic demagnetization refrio,erator. The instrument has a composite resolution of 8eV at 1 keV and 12eV at 6 keV with a minimum of 95% quantum efficiency. This will allow high spectral resolution, broadband observations of collisionally excited plasmas which are produced in the EBIT experiment. Unique to our instrument are exceptionally well characterized 1000 Angstrom thick aluminum on polyimide infrared blocking filters. The detailed transmission function including the edc,e fine structure of these filters has been measured in our laboratory using an erect field grating spectrometer. This will allow the instrument to perform the first broadband absolute flux measurements with the EBIT instrument. The instrument performance as well as the results of preliminary measurements will be discussed. Work performed under the auspices of the U.S. D.o.E. by Lawrence Livermore National Laboratory under contract W-7405-ENG-48 and was supported by the NASA High Energy Astrophysics Supporting Research and Technology Program.

We describe the transmission calibration of the Astro-E XRS blocking filters. The XRS instrument has five aluminized polymide blocking filters. These filters are located at thermal stages ranging from 200 K to 60 mK. They are each about 1000 angstrom thick. XRS will have high energy resolution which will enable it to see some of the extended fine structure around the oxygen and aluminum edges of these filters. Thus, we are conducting a high spectral resolution calibration of the filters near these energies to resolve out extended fine structure and absorption lines.

We describe the signal processing system of the Astro-E XRS instrument. The Calorimeter Analog Processor (CAP) provides bias and power for the detectors and amplifies the detector signals by a factor of 20,000. The Calorimeter Digital Processor (CDP) performs the digital processing of the calorimeter signals, detecting X-ray pulses and analyzing them by optimal filtering. We describe the operation of pulse detection, Pulse height analysis. and risetime determination. We also discuss performance, including the three event grades (hi-res mid-res, and low-res). anticoincidence detection, counting rate dependence, and noise rejection.

The Astro-E High Resolution X-ray Spectrometer (XRS) was developed jointly by the NASA/Goddard Space Flight Center and the Institute of Space and Astronomical Science in Japan. The instrument is based on a new approach to spectroscopy, the x-ray microcalorimeter. This device senses the energies of individual x-ray photons as heat with extreme precision. A 32 channel array of microcalorimeters is being employed, each with an energy resolution of about 12 eV at 6 keV. This will provide spectral resolving power 10 times higher than any other non-dispersive x-ray spectrometer. The instrument incorporates a three stage cooling system capable of operating the array at 60 mK for about two years in orbit. The array sits at the focus of a grazing incidence conical mirror. The quantum efficiency of the microcalorimeters and the reflectivity of the x-ray mirror system combine to give high throughput over the 0.3- 12 keV energy band. This new capability will enable the study of a wide range of high-energy astrophysical sources with unprecedented spectral sensitivity. This paper presents the basic design requirements and implementation of the XRS, and also describes the instrument parameters and performance.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

XRS is the microcalorimeter X-ray detector aboard the US-Japanese ASTRO-E observatory, which is scheduled to be launched in early 2000. XRS is a high resolution spectrometer- with less than 9 eV resolution at 3 keV and better than 14 eV resolution over its bandpass ranging from about 0.3 keV to 15 keV. Here we present the results of our first calibration of the XRS instrument. We describe the methods used to extract detailed information about the detection efficiency and spectral redistribution of the instrument. We also present comparisons of simulations and real data to test our detector models.

The XRS instrument has an array of 32 micro-calorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing x-ray absorbers. These devices have demonstrated a resolution of 9 eV at 3 keV and 11 eV at 6 keV. We will discuss the basic physical parameters of this array, including the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We will present representative performance data, though a more detailed presentation of the results of the instrument calibration is presented elsewhere in these proceedings. A silicon ionization detector is located behind the calorimeter array and serves to reject events due to cosmic rays. We will briefly describe this anti-coincidence detector and its performance in conjunction with the array.

The US-Japanese ASTRO-E observatory, is scheduled to be launched in early 2000. ASTRO-E carries four X-ray CCD detectors and a hard X-ray detector. The CCDs are located at the focus of grazing incidence X-ray mirrors and will primarily provide imaging over 0.4–12 keV bandpass. ASTRO-E also carries the XRS microcalorimeter X-ray detector. A platinum X-ray mirror will focus X-rays onto a 32-element array of microcalorimeter pixels for high-throughput, high-resolution spectroscopy with limited spatial resolution. The mean measured energy resolution of the XRS flight model detector is about 12 eV at 6 keV for the nominal operating temperature of 65 mK. We present results from our calibration of the XRS flight model detector. We describe the methods used to determine the spectral redistribution of the detector and the overall detection efficiency.

A concept for observation from space of the highest energy cosmic rays above 1020 eV with a satellite-borne observatory has been considered. A maximum-energy auger (air)-shower satellite (MASS) would use segmented lenses (and/or mirrors) and an array of imaging devices (about 106 pixels) to detect and record fluorescent light profiles of cosmic ray cascades in the atmosphere. The field-of-view of MASS could be extended to about (1000 km)2 so that more than 103 events per year could be observed above 1020 eV. From far above the atmosphere, MASS would be capable of observing events at all angles including near horizontal tracks, and would have considerable aperture for high energy photon and neutrino observation. With a large aperture and the spatial and temporal resolution, MASS could determine the energy spectrum, the mass composition, and arrival anisotropy of cosmic rays from 1020 eV to 1022 eV, a region hitherto not explored by ground-based detectors such as the fly's eye and air-shower arrays. MASS's ability to identify comic neutrinos and gamma rays may help providing evidence for the theory which attributes the above cut-off cosmic ray flux to the decay of topological defects.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We constructed a 24-pixel bolometer camera operating in the 350- and 450-μm atmospheric windows for the Caltech Submillimeter Observatory (CSO). This instrument uses a monolithic silicon bolometer array that is cooled to approximately 300 mK by a single-shot (3)He refrigerator. First-stage amplification is provided by field-effect transistors at approximately 130 K. The sky is imaged onto the bolometer array by means of several mirrors outside the Dewar and a cold off-axis elliptical mirror inside the cryostat. The beam is defined by cold aperture and field stops, which eliminates the need for any condensing horns. We describe the instrument, present measurements of the physical properties of the bolometer array, describe the performance of the electronics and the data-acquisition system, and demonstrate the sensitivity of the instrument operating at the observatory. Approximate detector noise at 350 μm is 5 × 10(-15) W/√Hz, referenced to the entrance of the Dewar, and the CSO system noise-equivalent flux density is approximately 4 Jy/√Hz. These values are within a factor of 2.5 of the background limit.

Semiconductor thermistors have been used for several years and their ideal behavior is well known both experimentally and theoretically. Their current performance is limited by non-ideal behaviors. These include 1/f noise and non-ohmic effects. We find that the 1/f noise appears to be a 2-D effect, and can be greatly reduced by fabricating thicker thermistors. Eliminating this noise could improve the intrinsic detector resolution as much as 40%. It also allows us to study other sources of excess noise in the thermometer. The non-ohmic behavior can be empirically explained using a hot-electron model. Although this model does not seem suitable for semiconductors in the variable range-hopping regime, where the electrons are localized, it fits the experimental data quite well. We measured an excess white noise at low frequencies consistent with the predicted thermodynamic fluctuations between electrons and phonons. We also measured a characteristic time of the non-ohmic behavior that is consistent with a C/G ...

Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom., X-IFU: et al., The X-ray Integral Field Unit (X-IFU) on board the Advanced Telescope for High-ENergy Astrophysics (Athena) 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 up to 7 keV. In this paper, we first review the core scientific objectives of Athena, driving the main performance parameters of the X-IFU, namely the spectral resolution, the field of view, the effective area, the count rate capabilities, the instrumental background. We also illustrate the breakthrough potential of the X-IFU for some observatory science goals. Then we brie y describe the X-IFU design as defined at the time of the mission consolidation review concluded in May 2016, and report on its predicted performance. Finally, we discuss some options to improve the instrument performance while not increasing its complexity and resource demands (e.g. count rate capability, spectral resolution)., We acknowledge support from the Athena Science Study Team, the Athena Working Group Chairs, the Athena Topical Panel Chairs and the Topical Panel members in strengthening the X-IFU top level performance requirements. Particular thanks go to: E. Rasia, V. Biffi, S. Borgani and K. Dolag for providing cosmological hydrodynamic simulations of a cluster used to produce simulation of X-IFU observation presented in Fig. 2; P.T. O'Brien for assistance with Sect. 2.2.1, A.C. Fabian and C. Pinto for providing inputs for Figure 1. We also thank the ESA project team, and in particular Mark Ayre and Ivo Ferreira, for their work on the assessment of the ToO efficiency requirement. The Italian contribution to X-IFU is supported through the ASI contract n. 2015-046-R.0. XB, MTC and BC acknowledge nancial support by MINECO through grant ESP2014-53672-C3-1-P. A.R., P.O, and A.J. were supported by Polish NSC grants: 2015/17/B/ST9/03422 and 2015/18/M/ST9/00541. GR, ER, YN, and PJ acknowledges support by FNRS and Prodex (Belspo). This work was supported by the French Space Agency (CNES).

We have characterized the 1/f noise in standard ion-implanted silicon thermistors, which are about 250 nm thick. We find that it is associated with the bulk of the implant, and is interpretable as a ∆R/R fluctuation that is independent of the bias and depends only on the doping density and resistivity, or electron temperature. This excess noise is large enough that it has a significant effect on the energy resolution or NEP of a detector using these thermistors. The very steep temperature dependence of the 1/f noise suggested that it might be related to the conduction becoming two- dimensional, and we have fabricated thicker detectors to test this hypothesis. Similar doped silicon thermistors that are 1500 nm thick show negligible 1/f noise, but otherwise behave identically to the thinner thermistors of the same volume. This simple change could provide a 40% improvement in resolution for some existing X-ray detectors.