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Trabajo presentado a la conferencia: "Space Telescopes and Instrumentation: Ultraviolet to Gamma Ray" celebrada en Amsterdam (Holanda) el 1 de julio de 2012.-- et al., One of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high-spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor (TES) and absorbers that consist of metal and semi-metal layers and a multiplexed SQUID readout. The array (32 x 32 pixels) provides an energy resolution of < 3 eV. Due to the large collection area of the Athena optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. Compared to the requirements for the same instrument on IXO, the performance requirements have been relaxed to fit into the much more restricted boundary conditions of Athena. In this paper we illustrate some of the science achievable with the instrument. We describe the results of design studies for the focal plane assembly and the cooling systems. Also, the system and its required spacecraft resources will be given. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

The technique which combines high resolution spectroscopy with imaging capability is a powerful tool to extract fundamental information in X-ray Astrophysics and Cosmology. TES (Transition Edge Sensors)-based microcalorimeters match at best the requirements for doing fine spectroscopy and imaging of both bright (high count rate) and faint (poor signal-to-noise ratio) sources. For this reason they are considered among the most promising detectors for the next high energy space missions and are being developed for use on the focal plane of the IXO (International X-ray Observatory) mission. In order to achieve the required signal-to-noise ratio for faint or diffuse sources it is necessary to reduce the particle-induced background by almost two orders of magnitude. This reduction can only be achieved by adopting an active anticoincidence technique. In this paper, we will present a novel anticoincidence detector based on a TES sensor developed for the IXO mission. The pulse duration and the large area of the IXO TESarray (XMS X-ray Microcalorimeter Spectrometer) require a proper design of the anticoincidence detector. It has to cover the full XMS area, yet delivering a fast response. We have therefore chosen to develop it in a four-pixel design. Experimental results from the large-area pixel prototypes will be discussed, also including design considerations.

One of the instruments on the International X-ray Observatory (IXO), under study with NASA, ESA and JAXA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor thermometers. The pixels have metallic X-ray absorbers and are read-out by multiplexed SQUID electronics. The requirements for this instrument are demanding. In the central array (40 x 40 pixels) an energy resolution of < 2.5 eV is required, whereas the energy resolution of the outer array is more relaxed (≈ 10 eV) but the detection elements have to be a factor 16 larger in order to keep the number of read-out channels acceptable for a cryogenic instrument. Due to the large collection area of the IXO optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. In this paper we will summarize the instrument status and performance. We will describe the results of design studies for the focal plane assembly and the cooling systems. Also the system and its required spacecraft resources will be given.

In this paper we present a spectrometer realized by bump-bonding a 300-μm-pitch, 32 × 32-pixel silicon X-ray detector chip to a 0.35-μm CMOS, 3-cm2 read-out chip. The selftriggered, mixed analog-digital read-out chip, with 1,024 channels, digitizes the X-ray photon energy with 10 bits of resolution, provides the coordinates of the triggered pixels and achieves 34 e- rms of input referred noise, ±3.3 LSB of INL and ±0.2 LSB of DNL, while consuming 555 mW from a 3.3-V supply. Preliminary experimental results on the complete spectrometer are reported.

The employment of large arrays of microcalorimeters in space missions (IXO, EDGE/XENIA)[1][2][3], requires the presence of an anticoincidence detector to remove the background due to the particles, with a rejection efficiency at least equal to Suzaku (98%) [1]. A new concept of anticoincidence is under development to match the very tight thermal requirements and to simplify the design of the electronic chain. The idea is to produce a Cryo-AntiCoincidence (Cryo-AC) based on a silicon absorber and read by a TES (Transition-Edge Sensor). This configuration would ensure very good performances in terms of efficiency, time response and signal to noise ratio. We present the results of estimations, simulations and preliminary measurement.

Recent progress in the CdZnTe (CZT) based detectors prototypes suggests the possibility of an efficient use as 3D detectors. In this paper we discuss how the z coordinate of the interacting photon can be obtained in thick pixellated CZT crystals with a spatial resolution equal to the linear dimension of the implemented pixel (mm). Two different approaches will be described. The first considers a fine segmentation of multi anode and cathode electrodes arranged in orthogonal strips and biased with an electric field transversal to the photons arrival line (PTF = Planar Transversal Field): this solution tends to simplify the readout electronics although at the expense of some complexity in detectors assembling. The second one is based on a more classical configuration, single cathode and multi electrodes anode (exploiting the small pixel effect) biased with a field parallel to the impinging photons direction (PPF = Parallel Transversal Field). This approach needs a more complex electronics to analyze the signal shape of each interaction in order to evaluate, among other parameters, the interaction depth. Conversely in this configuration the focal plane can be assembled with relative simplicity. Both the configurations can be disposed in a stack to improve the working energy range through an effective use of the Compton effect.

The instruments on board the latest gamma observatories (INTEGRAL, AGILE, GLAST) combines technologies based either on solid state or on scintillator detector, the first one being favorite when a low energy threshold and a good energy resolution is required, the latter being more convenient for large volume when worse performance are still acceptable. With the development of new scintillator materials and even more with new low-noise ligth readout devices the differences between the two techniques are narrowing and for some application the cheaper scintillator detector can compete with solid state devices. Furthermore both these detector concepts can be combined in a single compact device by means of the Pulse Shape Discrimination (PSD) technique that allows to discriminate direct interactions in silicon from scintillation events. Combined in arrays they can be the base for position senstive planes to be combined with coded mask in imaging instruments or the component of new generation Compton based telescopes. For this purpose two prototype systems have been designed and realized, both based on a 20 channels Silicon Drift Detectors (SDD) monolithic array coupled to individual 1 cm thick CsI(Tl) scintillator crystals. In the first system the detector readout is implemented with ASICs tailored specifically to the SDD readout, while in the second system the PSD readout of the array is implemented. The performance of these kind of detectors tested in the various prototypes as well as their applications in new generation space telescopes are discussed.

The instruments on board the latest gamma observatories (INTEGRAL, SWIFT, AGILE, GLAST) combines technologies based on solid state and on scintillator detector, the first one being favorite when a low energy threshold and a good energy resolution is required, the latter being more convenient for large volume when worse performance are still acceptable. With the developments achieved both with the new scintillator material and even more with new low-noise light readout devices the differences between the two techniques are narrowing and for some application the cheaper scintillator detector can compete with solid state devices. Starting from the techniques used in INTEGRAL-IBIS and AGILE a new generation position sensitive X and gamma ray detector based on scintillator with Silicon Drift Chamber readout has been developed and tested. The ASIC read-out electronics make it suitable for replication in a large scale when a great number of pixel is needed. The performance of the detector as well as its applications in new generation space telescopes are presented and discussed.

A Bismuth Germanate (BGO) 'veto' shield surrounds on five faces the detector planes of the IBIS instrument on-board the satellite INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory). The Veto System provides anti-coincidence signals to the two imager layers covering the energy range from 20 keV to 10 MeV. The area to be shielded is about 8000 cm2, and with a shield thickness of 20 mm, this leads to a total BGO crystal weight of about 115 kg. This paper describes the shield design, and how some scientific and engineering requirements are implemented. Also results from tests with the Engineering Model are presented. Particular emphasis is given to the electronic signal chain, and its response to overload particles, mainly high energy protons, expected in the INTEGRAL orbit (Elliptic Earth Orbit with 72 h period). The overload response has been studied in detail both with a built-in Light Emitting Diode (LED) in the laboratory, and at a proton beam facility. Based on the lab measurements the expected blinding of the shield in-orbit is around 1%. This is obtained with a simple, but optimized chain, consisting of a front-end amplifier and a bi-polar shaper, that provides input to the trigger generator. Results from beam tests with proton energies from 60 to 300 MeV are reported, and it is demonstrated that the proton pulses in terms of amplitude, shape and duration are very similar to the simulated ones, and thus confirm the expected system response.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

IBIS is a space-telescope designed to produce sky images in the 15 keV to 10 MeV energy range with an angular resolution of several arcminutes over a wide field of view. This is obtained by deconvolving the shadow gram projected by a coded mask onto two pixelated detector layers sensitive to the incident radiation interaction position. The upper layer, ISGRI, consists of 16384 CdTe elements operating in the low energy range, while the underlying layer, PICsIT, is made up of 8 identical modules housing altogether 4096 CsI(TI) scintillating crystals coupled to PIN photodiodes operating in the 0.15 to 10 MeV energy range. The expected performances of IBIS were described in a dedicated session of the SPIE Symposium in August 1996, while performances of the PICsIT single detection units have been presented at SPIE in July 1998.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.