A setup for soft proton irradiation of X-ray detectors for future astronomical space missions

Protons that are trapped in the Earth's magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of the Physikalisches Institut of the University of T\"ubingen. Key advantages are a high flux uniformity over a large area, to enable irradiations of large detectors, and a monitoring system for the applied fluence, the beam uniformity, and the spectrum, that allows testing of detector prototypes in early development phases, when readout electronics are not yet available. Two irradiation campaigns have been performed so far with this setup. The irradiated detectors are silicon drift detectors, designated for the use on-board the LOFT space mission. This paper gives a description of the experimental setup and the associated monitoring system.Comment: 20 pages, 10 figures, 4 table

PixDD: a multi-pixel silicon drift detector for high-throughput spectral-timing studies

The Pixelated silicon Drift Detector (PixDD) is a two-dimensional multi-pixel X-ray sensor based on the technology of Silicon Drift Detectors, designed to solve the dead time and pile-up issues of photon-integrating imaging detectors. Read out by a two-dimensional self-triggering Application-Specific Integrated Circuit named RIGEL, to which the sensor is bump-bonded, it operates in the 0:5 — 15 keV energy range and is designed to achieve single-photon sensitivity and good spectroscopic capabilities even at room temperature or with mild cooling (< 150 eV resolution at 6 keV at 0 °C). The paper reports on the design and performance tests of the 128-pixel prototype of the fully integrated system

First results of a novel Silicon Drift Detector array designed for low energy X-ray fluorescence spectroscopy

We developed a trapezoidal shaped matrix with 8 cells of Silicon Drift Detectors (SDD) featuring a very low leakage current (below 180 pA/cm2 at 20 \ub0C) and a shallow uniformly implanted p+ entrance window that enables sensitivity down to few hundreds of eV. The matrix consists of a completely depleted volume of silicon wafer subdivided into 4 square cells and 4 half-size triangular cells. The energy resolution of a single square cell, readout by the ultra-low noise SIRIO charge sensitive preamplifier, is 158 eV FWHM at 5.9 keV and 0 \ub0C. The total sensitive area of the matrix is 231 mm2 and the wafer thickness is 450\u3bcm. The detector was developed in the frame of the INFN R&D project ReDSoX in collaboration with FBK, Trento. Its trapezoidal shape was chosen in order to optimize the detection geometry for the experimental requirements of low energy X-ray fluorescence (LEXRF) spectroscopy, aiming at achieving a large detection angle. We plan to exploit the complete detector at the TwinMic spectromicroscopy beamline at the Elettra Synchrotron (Trieste, Italy). The complete system, composed of 4 matrices, increases the solid angle coverage of the isotropic photoemission hemisphere about 4 times over the present detector configuration. We report on the layout of the SDD matrix and of the experimental set-up, as well as the spectroscopic performance measured both in the laboratory and at the experimental beamline. \ua9 2015 Elsevier B.V

The large area detector onboard the eXTP mission

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we will provide an overview of the LAD instrument design, its current status of development and anticipated performance

Latest results from the Pamela experiment

In this paper we present the latest results of the Pamela satellite experiment, focusing in particular on the p/p and the e +/(e+ +e-) ratios

Tomographic Back-Projection Algorithm for "Incomplete" Compton X-rays Detectors

A "Compton" detector finds the direction of an X-ray by letting it interact with a gaseous, liquid or thin solid material (Tracker) and employing no collimators. This paper takes into account the case of an "incomplete" solid Tracker where the recoiling electron travels only a few dozen microns and cannot be followed. However, impact positions and incoming and outgoing energies are measured. In this situation, exploiting the Compton Scattering formula, one is only able to identify a cone whose surface the X-ray belongs to. On the other hand, Compton tomography luckily requires only a few views (for example rotating the apparatus in just four positions around the subject), as the "electronic collimation" that takes place in each position already extracts X-rays coming from many directions. A back-projection algorithm that combines the reconstructed "cones" in space, weighed according to the Klein-Nishina formula, has been applied to the special case of small animal SPECT (Single Photon Emission Computed Tomography). Here the source is close to the detector, every imaged point in space is calculated from many rays that are emitted at different angles, and the algorithm totally differs from that of the Compton imaging in Astronomy. Tomography reconstruction has been validated by employing simulated data, generated using GEANT4 that includes the Doppler Broadening in the energies of scattered photons, which is due to moving non-free electrons. Space resolution has been assessed

A programmable System-on-Chip based digital pulse processing for high resolution X-ray spectroscopy

none18noIt is described the global architecture of a digital pulse processing system for high resolution X-Ray spectroscopy based on single photon detection and photon energy measurement. The core of the system is implemented in a modern hybrid device (Xilinx Zynq) that integrates an FPGA fabric along with a dual core 32-bits processor (ARM Cortex). It is also described the adopted strategy to deal with high input photon rates while preserving a good energy resolution. The digital performance of the system is ultimate determined by few key functional blocks including two finite impulse response filters and an algorithmic state machine. It is presented a numerical procedure to optimize the digital filters according to different constrains and goals, and it is described the analysis of experimental data to obtain the necessary information for the optimization of the system.Cicuttin, Andres; Crespo, Maria Liz; Mannatunga, Kasun Sameera; Garcia, Victor Villaverde; Baldazzi, Giuseppe; Rignanese, Luigi Pio; Ahangarianabhari, Mahdi; Bertuccio, Giuseppe; Fabiani, Sergio; Rachevski, Alexander; Rashevskaya, Irina; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Bellutti, Pierluigi; Picciotto, Antonino; Piemonte, Claudio; Zorzi, NicolaCicuttin, Andres; Crespo, Maria Liz; Mannatunga, Kasun Sameera; Garcia, Victor Villaverde; Baldazzi, Giuseppe; Rignanese, Luigi Pio; Ahangarianabhari, Mahdi; Bertuccio, Giuseppe; Fabiani, Sergio; Rachevski, Alexander; Rashevskaya, Irina; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Bellutti, Pierluigi; Picciotto, Antonino; Piemonte, Claudio; Zorzi, Nicol

X Rays Compton Detectors for Biomedical Application

Collimators are usually needed to image sources emitting X-rays that cannot be focused. Alternately, one may employ a Compton Camera (CC) and measure the direction of the incident X-ray by letting it interact with a thin solid, liquid or gaseous material (Tracker) and determine the scattering angle. With respect to collimated cameras, CCs allow higher gamma-ray efficiency in spite of lighter geometry, and may feature comparable spatial resolution. CCs are better when the X-ray energy is high and small setups are required. We review current applications of CCs to Gamma Ray Astronomy and Biomedical systems stressing advantages and drawbacks. As an example, we focus on a particular CC we are developing, which is designed to image small animals administered with marked pharmaceuticals, and assess the bio-distribution and targeting capability of these latter. This camera has to address some requirements: relatively high activity of the imaged objects; detection of gamma-rays of different energies that may range from 140 keV (Tc99m) to 511 keV; presence of gamma and beta radiation with energies up to 2 MeV in case of 188Re. The camera consists of a thin position-sensitive Silicon Drift Detector as Tracker, and a further downstream position-sensitive system employing scintillating crystals and a multi-anode photo-multiplier (Calorimeter). The choice of crystal, pixel size, and detector geometry has been driven by measurements and simulations with the tracking code GEANT4. Spatial resolution, efficiency and scope are discussed