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We are developing transition-edge sensor microcalorimeters for the X-ray integral field unit (X-IFU) on-board ESA's Athena space telescope. These detectors will be read out using time-domain multiplexing. Due to the limitations on bandwidth and dynamic range of the readout, the optimally filtered pulse heights of the measured X-ray signals suffer from a nonlinear variation with the exact photon arrival time relative to the sampling points. The shape and magnitude of this variation depend on the photon energy. We describe a method to characterize this energy-dependent variation with few parameters, which can then be interpolated to correct event energies across the whole spectrum. We implement our method on measurements from 200 pixels in a prototype X-IFU kilo-pixel array readout using 8-column × 32-row TDM. We show that the interpolation errors between calibration points, over the energy range 4–12 keV, can be made sufficiently small that they do not adversely impact the measured energy resolution across the full spectral range. [ABSTRACT FROM AUTHOR]

We are developing lab-based readout electronics for Transition-edge sensors (TES) using commercial-off-the-shelf (COTS) modules. These COTS modules are advantageous since they increase development speed and keep the cost low. We have developed these electronics to support both non-multiplexed and time-division multiplexing (TDM) readout systems. The system utilizes remote control via Ethernet, and the interface allows many types of measurements to be automated. With the TDM readout system, we have achieved 2.05 eV at 6 keV, 2.1 eV at 7 keV, 2.3 eV at 8 keV, and 2.8 eV at 12 keV with 2-column × 32-row multiplexing. We will be using this system in the characterization of detectors for the X-Ray Integral Field Unit (X-IFU) instrument on Athena. In this paper, we present an overview of the design and their performance. [ABSTRACT FROM AUTHOR]

In many superconducting transition-edge sensor (TES) microcalorimeters, the measured electrical noise exceeds theoretical estimates based on a thermal model of a single body thermally connected to a heat bath. Here, we report on noise and complex impedance measurements of a range of designs of TESs made with a Mo/Au bilayer. We have fitted the measured data using a two-body model, where the x-ray absorber and the TES are connected by an internal thermal conductance Gae. We find that the so-called excess noise measured in these devices is consistent with the noise generated from the internal thermal fluctuations between the x-ray absorber and the TES. Our fitted parameters are consistent with the origin of Gae being from the finite thermal conductance of the TES itself. These results suggest that even in these relatively low resistance Mo/Au TESs, the internal thermal conductance of the TES may add significant additional noise and could account for all the measured excess noise. Furthermore, we find that around regions of the superconducting transition with rapidly changing derivative of resistance with respect to temperature, an additional noise mechanism may dominate. These observations may lead to a greater understanding of TES devices and allow the design of TES microcalorimeters with improved performance. [ABSTRACT FROM AUTHOR]

We report the fabrication of superconducting nanowire single-photon detector (SNSPD, SSPD) based on molybdenum nitride (MoN) film with and without a cavity structure. Ultrathin polycrystalline γ-Mo2N films with a Tc about 6 K were obtained by reactive DC magnetron sputtering. The absorption efficiency of the device was calculated by the finite-difference time-domain (FDTD) method using the optical constants of MoN determined by ellipsometry measurements. The SNSPD with a meander of 150-nm-width and 7-nm-thick nanowire showed a long saturation plateau in the bias current dependence of the system detection efficiency (SDE) at visible wavelength. The SNSPD with a cavity structure showed an SDE of 37% and a timing jitter of 79 ps at a wavelength of 1560 nm. The results show that MoN is a promising alternative to amorphous superconductors for high-performance SNSPD. [ABSTRACT FROM AUTHOR]

The measured noise in Mo/Au transition-edge sensor (TES) microcalorimeters produced at NASA has recently been shown to be well described by a two-body electro-thermal model with a finite thermal conductance between the X-ray absorber and the TES. In this article, we present observations of a high-frequency peak in the measured current noise in some of these devices. The peak is associated with an oscillatory component of the TES response that is not predicted in a single-body model but can be qualitatively described by the two-body model. [ABSTRACT FROM AUTHOR]

In this paper, we report on X-ray transition-edge sensor (TES) microcalorimeters optimized to have the best possible energy resolution for a limited energy range for the incoming X-rays, such as an energy resolution of 0.3 eV full width half maximum (FWHM) for energies up to ≈ 0.8 keV as is desirable for one of the Lynx X-ray Microcalorimeter subarrays. The test array we have fabricated has 60 × 60 sensors on a pitch of 50 μ m , and has 46 × 46 μ m 2 absorbers that are one micrometer thick. We have measured a spectral energy resolution of the same device using 3 eV photons delivered through an optical fiber. For the one-photon 3 eV line, we have obtained an energy resolution of 0.25 eV FWHM, which is consistent with the estimated performance based on the signal size and noise. Further measurements will determine how the energy resolution degrades with energy. Based upon measurements of the TES transition characteristics, it appears that this level of energy resolution should be achievable up to 0.5 keV, and the performance will then gradually degrade to the measured energy resolution of around 2.3 eV at 1.5 keV. In this paper, we describe the full design and characterization of this detector, and discuss the performance limits of pixels designs like this. [ABSTRACT FROM AUTHOR]

We report on the development of multi-absorber transition-edge sensors (TESs), referred to as 'hydras'. A hydra consists of multiple X-ray absorbers each with a different thermal conductance to a TES. Position information is encoded in the pulse shape. With some trade-off in performance, hydras enable very large format arrays without the prohibitive increase in bias and readout components associated with arrays of individual TESs. Hydras are under development for the next generation of space telescope such as Lynx. Lynx is a NASA concept under study that will combine a < 1″ angular resolution optic with 100,000-pixel microcalorimeter array with energy resolution of ΔEFWHM ~ 3 eV in the soft X-ray energy range. We present first results from hydras with 25-pixels for Lynx. Designs with absorbers on a 25 μm and 50 μm pitch are studied. Arrays incorporate, for the first time, microstrip buried wiring layers of suitable pitch and density required to readout a full-scale Lynx array. The resolution from the coadded energy histogram including all 25-pixels was ΔEFWHM = 1.66 ± 0.02 eV and 3.34 ± 0.06 eV at an energy of 1.5 keV for the 25 μm and 50 μm absorber designs, respectively. Position discrimination is demonstrated from parameterization of the rise-time. [ABSTRACT FROM AUTHOR]

Presents information concerning the terahertz radiation with the use of the ultrafast photoconductive sampling detector. Information on pronounced coherent radiation; Indication of model calculations; What observation of the radiation on the IR-active coherent phonons provides.

A small animal PET scanner using 256-channel PS-PMTs has been designed, constructed, and evaluated. The scanner has twelve detector modules, each of which consists of a double-layer array of LYSO crystals and three PS-PMTs (Hama- matsu R8400-00-M256). In the LYSO crystal block, 32 times 53 crystal elements are optically coupled to 32 times 54 crystal elements with a shift of half the element pitch in the axial direction. The dimension of each crystal element is 1.275 times 2.675 mm2 in cross section and 7 mm in depth. The twelve detector modules are positioned on a 182 mm diameter ring to form 107 detector rings with 1.4 mm pitch. The transaxial FOV is 100 mm in diameter and the axial FOV is 151 mm, which is sufficient to cover the whole body of a mouse. In order to compensate for non-uniform outputs from the multi-anodes of the PS-PMTs, ASICs having 64-channel variable gain amplifiers and summing amplifiers are used in the front-end circuits. The preliminary experimental results are the transaxial resolution of 2.0 mm FWHM in the CFOV, and the axial resolution of 2.8 mm FWHM on the axis of the ring. The absolute coincidence sensitivity is 8.1% for a point source at the CFOV with setting an energy window of 350-750 keV and a timing window of 10 ns. The applicable imaging capability of the scanner was demonstrated by animal studies with a rat. [ABSTRACT FROM PUBLISHER]

We are developing a fiber type two-dimentional (2-D) position-sensitive detector having a spatial resolution less than 0.5 mm in order to use it in the time-of-flight (TOF) measurement. The detector performance was examined, and some experiments on the TOF radiography were performed using this detector. The results indicated that the detector could be applied successfully to the TOF measurement and that the TOF radiography was very useful since it gave more informative data than those obtained by the conventional radiography using a broad energy band. [ABSTRACT FROM AUTHOR]

For evaluating neutron optical devices, we have developed the two-dimensional position-sensitive neutron detectors (PSND) of the crossing fibre array type. In parallel, we have studied the PSNDs of the direct coupling type with flat panel photomultiplier tubes for responding to various spatial resolutions with high detection efficiency. This paper views and reports on the recent status of development of PSNDs based on neutron scintillators in neutron optics group. [Copyright &y& Elsevier]

Reports on the application of a scintillator-based area detector to the neutron time-of-flight method by developing an electronics system for the detector. Spatial resolution which was consistent with a fiber width of 0.4 millimeter; Detection efficiency for thermal neutrons.

A readout electronics system for linear position sensitive 3He gas detectors has been developed. It is widely used for neutron scattering instruments at KEK Neutron Science Laboratory (KENS). The basic structure of the system is quite versatile, and can be used for various imaging-systems. Several versatile readout systems have been developed at KENS. As one of such examples, a 2-dimensional imaging-system for a wavelength shifting fiber based scintillation counter system has been developed. [Copyright &y& Elsevier]