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We have measured the 3d→2p transition x rays of kaonic ^{3}He and ^{4}He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic ^{3}He and ^{4}He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.

International audience; The X-ray Integral Field Unit (X-IFU) of the Athena observatory, scheduled for launch in the mid 2030's, will provide X-ray spectroscopy data with unprecedented spectral and spatial resolution. This will be achieved with a 2 kilo-pixel array of transition-edge sensor (TES) microcalorimeters. The complete detection chain is under development by a large international collaboration. In order to perform an end-to-end demonstration of the X-IFU readout chain, a 50 mK test bench is being developed at IRAP in collaboration with CNES. The test bench uses a two-stage ADR cryostat from Entropy GmbH, a 1024-pixel array, and will initially be operated using a warm electronics chain from NIST and NASA Goddard Space Flight Center. We describe the complete system being installed in the cryostat and the current results obtained with these electronics. We also review the status of the integration of the digital readout electronics (DRE) prototype into the demonstration chain and the plan for integrating and testing the complete X-IFU readout chain.

The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the Cosmic Microwave Background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Taco in the Atacama Desert, at an altitude of 5190 meters. A six-met.er off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three WOO-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space mm-wave optics. Each frequency band has a field of view of approximately 22' x 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.

The Micro‐X Imaging X‐ray Spectrometer is a sounding rocket payload slated for launch in 2011. An array of Transition Edge Sensors, which is operated at a bath temperature of 50 mK, will be used to obtain a high resolution spectrum of the Puppis‐A supernova remnant. An Adiabatic Demagnetization Refrigerator (ADR) with a 75 gram Ferric Ammonium Alum (FAA) salt pill in the bore of a 4 T superconducting magnet provides a stable heat sink for the detector array only a few seconds after burnout of the rocket motors. This requires a cold stage design with very short thermal time constants. A suspension made from Kevlar strings holds the 255 gram cold stage in place. It is capable of withstanding loads in excess of 200 g. Stable operation of the TES array in proximity to the ADR magnet is ensured by a three‐stage magnetic shielding system which consists of a superconducting can, a high‐permeability shield and a bucking coil. The development and testing of the Micro‐X payload is well underway.

In typical algorithms for optimally filtering transition‐edge‐sensor‐microcalorimeter pulses, the average value of a filtered pulse is set to zero. The achieved energy resolution of the detector then depends strongly on the chosen length of the pulse record. We report experimental confirmation of this effect. We derive expressions for the dependence of energy resolution on record length, and apply them to a pair of detector models for the X‐ray Microcalorimeter Spectrometer instrument on NASA/ESA/JAXA’s proposed International X‐ray Observatory. Although the two models have identical pulse time‐constants, they differ by a factor of two in the record length required to achieve a given energy resolution. Finally, we derive an expression for the maximum output count rate at high energy resolution of a TES pixel.

We have measured the relation between sensor noise and the steepness (α = TR⋅ and β = IR⋅dRdI) of the superconducting transition for various superconducting transition edge sensors. The measurements are performed on square Mo/Cu bilayer thermistors of three sizes (125 μm, 250 μm and 400 μm), which are fabricated for X‐ray detection. We have identified the devices in two regimes: a) α>100 and b) α

Issues regarding the energy calibration of high dynamic range microcalorimeter detector arrays are presented with respect to new results from a minor actinide‐mixed oxide radioactive source. The need to move to larger arrays of such detectors necessitates the implementation of automated analysis procedures, which turn out to be nontrivial due to complex calibration shapes and pixel‐to‐pixel variability. Some possible avenues for improvement, including a more physics‐based calibration procedure, are suggested.

Over the last decade, the field of x‐ray calorimeters has matured to the point where calorimeter instruments are becoming more common, requiring the development of turnkey systems that are easy to use for non‐expert operators. In addition, the use of large arrays in spaceflight instruments requires a significant reduction in data density in order to remain compatible with highly restricted telemetry bandwidths. As calorimeter instruments mature and find wider use outside of the laboratory, the ability to perform signal analysis and data reduction on the raw data stream in real‐time has gone from a convenience to a necessity.We will report on the adaptation of the Digital Signal Processor (DSP) based analysis electronics originally developed for the 32 channel Astro‐E and Astro‐E2 satellite missions to a full software version implemented with off‐the‐shelf hardware. This implementation requires a minimum of human intervention and is capable of real‐time data analysis of x‐ray events on many channels simult...

The Micro‐X sounding rocket payload will be launched on January 18, 2011 to make the first observation of an astronomical target with Transition‐Edge Sensor (TES) X‐ray microcalorimeters. The 128 pixel TES array lies at the focus of a 2.165 m focal length conical imaging mirror with a 0.2–3.0 keV bandpass. The spectral resolution of the TES array will be between 2 and 4 eV at 1 keV. Our scientific program is focused on high‐spectral resolution observations of extended sources. For supernova remnants (SNRs) our scientific objectives are to map the velocity structure of the ejecta, and study both elemental abundances and the thermodynamic and ionization state of the plasma through plasma line diagnostics. For clusters of galaxies, Micro‐X can uniquely study turbulence, velocities, and the temperature phases of the plasma.For our initial flight, we have changed our target from the bright eastern knot to a recently discovered ejecta region in the Puppis A SNR. The target of the second flight in mid‐2012 is M87, the center of the Virgo Cluster. The third flight, in early 2014, will make an observation of the Cas A SNR. In this contribution we discuss the science objectives of our first flight.

The Micro‐X sounding rocket experiment will deploy an imaging transition‐edge‐sensor (TES) microcalorimeter spectrometer to observe astrophysical sources in the 0.2–3.0 keV band. The instrument has been designed at a systems level, and the first items of flight hardware are presently being built. In the first flight, planned for January 2011, the spectrometer will observe a recently discovered Silicon knot in the Puppis‐A supernova remnant. Here we describe the design of the Micro‐X science instrument, focusing on the instrument’s detector and detector assembly. The current design of the 2‐dimensional spectrometer array contains 128 close‐packed pixels with a pitch of 600 μm. The conically approximated Wolter‐1 mirror will map each of these pixels to a 0.95 arcmin region on the sky; the field of view will be 11.4 arcmin. Targeted energy resolution of the TESs is about 2 eV over the full observing band. A SQUID time‐division multiplexer (TDM) will read out the array. The detector time constants will be engineered to approximately 2 ms to match the TDM, which samples each pixel at 32.6 kHz, limited only by the telemetry system of the rocket. The detector array and two SQUID stages of the TDM readout system are accommodated in a lightweight Mg enclosure, which is mounted to the 50 mK stage of an adiabatic demagnetization refrigerator. A third SQUID amplification stage is located on the 1.6 K liquid He stage of the cryostat. An on‐board 55‐Fe source will fluoresce a Ca target, providing 3.69 and 4.01 keV calibration lines that will not interfere with the scientifically interesting energy band.

The International X-Ray Observatory (IXO) is under formulation by NASA, ESA and JAXA for deployment in 2022. IXO emerged over the last 18 months as the NASA Constellation-X and ESA/JAXA X-Ray Evolving Universe Spectrometer (XEUS) missions were combined. The driving performance requirements for the X-Ray Microcalorimeter Spectrometer (XMS) are a spectral resolution of 2.5 eV over the central 2'x2' in the 0.3-7.0 keV band, and 10 eV to the edge of the 5'x5' field of view (FOV). The XMS is now based on a microcalorimeter array of Transition-Edge Sensor (TES) thermometers with Au/Bi absorbers and a SQUID MUX readout. One of the concepts studied as part of the mission formulation has a core 40x40 array corresponding to a 2'x2' FOV with 3'' pixels surrounded by an outer, annular 52x52 array of 6'' pixels that extends the field of view to 5.4'x5.4' with better than 10 eV resolution. There are several options for implementing the readout and cooling system of the XMS under study in the US, Europe and Japan. The ADR system will have from two to five stages depending on the performance of the cryocooler. Mechanical coolers with sufficient cooling power at 4K are available now, and {approx}2K coolersmore » are under development. In this paper we give an overview of the XMS instrument, and some of the tradeoffs to be addressed for this observatory instrument.« less