A focal plane detector design for a wide-band Laue-lens telescope

The energy range above 60 keV is important for the study of many open problems in high energy astrophysics such as the role of Inverse Compton with respect to synchrotron or thermal processes in GRBs, non thermal mechanisms in SNR, the study of the high energy cut-offs in AGN spectra, and the detection of nuclear and annihilation lines. Recently the development of high energy Laue lenses with broad energy bandpasses from 60 to 600 keV have been proposed for a Hard X ray focusing Telescope (HAXTEL) in order to study the X-ray continuum of celestial sources. The required focal plane detector should have high detection efficiency over the entire operative range, a spatial resolution of about 1 mm, an energy resolution of a few keV at 500 keV and a sensitivity to linear polarization. We describe a possible configuration of the focal plane detector based on several CdTe/CZT pixelated layers stacked together to achieve the required detection efficiency at high energy. Each layer can operate both as a separate position sensitive detector and polarimeter or work with other layers to increase the overall photopeak efficiency. Each layer has a hexagonal shape in order to minimize the detector surface required to cover the lens field of view. The pixels would have the same geometry so as to provide the best coupling with the lens point spread function and to increase the symmetry for polarimetric studies.Comment: 10 pages, 9 figure

Development status of the LAUE project

We present the status of LAUE, a project supported by the Italian Space Agency (ASI), and devoted to develop Laue lenses with long focal length (up to 100 meters), for hard X--/soft gamma--ray astronomy (80-600 keV). Thanks to their focusing capability, the design goal is to improve the sensitivity of the current instrumention in the above energy band by 2 orders of magnitude, down to a few times $10^{-8}$ photons/(cm$^2$ s keV).Comment: 9 pages, 9 figures, presented at the Space Telescopes and Instrumentation Symposium in Amsterdam, 2012: Ultraviolet to Gamma Ray Conference. Published in the Proceedings of the SPIE, Volume 8443, id. 84430B-84430B-9 (2012

Hard x-ray broad band Laue lenses (80 - 600 keV): building methods and performances

We present the status of the laue project devoted to develop a technology for building a 20 meter long focal length Laue lens for hard x-/soft gamma-ray astronomy (80 - 600 keV). The Laue lens is composed of bent crystals of Gallium Arsenide (GaAs, 220) and Germanium (Ge, 111), and, for the first time, the focusing property of bent crystals has been exploited for this field of applications. We show the preliminary results concerning the adhesive employed to fix the crystal tiles over the lens support, the positioning accuracy obtained and possible further improvements. The Laue lens petal that will be completed in a few months has a pass band of 80 - 300 keV and is a fraction of an entire Laue lens capable of focusing X-rays up to 600 keV, possibly extendable down to 20 - 30 keV with suitable low absorption crystal materials and focal length. The final goal is to develop a focusing optics that can improve the sensitivity over current telescopes in this energy band by 2 orders of magnitude

Development status of a Laue lens project for gamma-ray astronomy

We report the status of the HAXTEL project, devoted to perform a design study and the development of a Laue lens prototype. After a summary of the major results of the design study, the approach adopted to develop a Demonstration Model of a Laue lens is discussed, the set up described, and some results presented.Comment: 11 pages, 11 figures, 2007 SPIE Conference on Optics for EUV, X-Ray, and Gamma-Ray Astronomy II

The gamma-ray burst monitor for Lobster-ISS

Lobster-ISS is an X-ray all-sky monitor experiment selected by ESA two years ago for a Phase A study (now almost completed) for a future flight (2009) aboard the Columbus Exposed Payload Facility of the International Space Station. The main instrument, based on MCP optics with Lobster-eye geometry, has an energy passband from 0.1 to 3.5 keV, an unprecedented daily sensitivity of 2x10^{-12} erg cm^{-2}s$^{-1}, and it is capable to scan, during each orbit, the entire sky with an angular resolution of 4--6 arcmin. This X-ray telescope is flanked by a Gamma Ray Burst Monitor, with the minimum requirement of recognizing true GRBs from other transient events. In this paper we describe the GRBM. In addition to the minimum requirement, the instrument proposed is capable to roughly localize GRBs which occur in the Lobster FOV (162x22.5 degrees) and to significantly extend the scientific capabilities of the main instrument for the study of GRBs and X-ray transients. The combination of the two instruments will allow an unprecedented spectral coverage (from 0.1 up to 300/700 keV) for a sensitive study of the GRB prompt emission in the passband where GRBs and X-Ray Flashes emit most of their energy. The low-energy spectral band (0.1-10 keV) is of key importance for the study of the GRB environment and the search of transient absorption and emission features from GRBs, both goals being crucial for unveiling the GRB phenomenon. The entire energy band of Lobster-ISS is not covered by either the Swift satellite or other GRB missions foreseen in the next decade.Comment: 6 pages, 4 figures. Paper presented at the COSPAR 2004 General Assembly (Paris), accepted for publication in Advances in Space Research in June 2005 and available on-line at the Journal site (http://www.sciencedirect.com/science/journal/02731177), section "Articles in press

Systematic review: early infant feeding and the prevention of coeliac disease.

BACKGROUND: PREVENTCD, Prevent Coeliac Disease, is an international project investigating the hypothesis of possible induction of tolerance to gluten in genetically predisposed children through introducing small quantities of gluten during the period of breastfeeding. AIM: To summarise current knowledge on the possible relationship between early feeding practices and the risk of coeliac disease (CD). METHODS: The Cochrane Library, MEDLINE, and EMBASE databases were searched in May 2011, and the search was updated in January 2012, and again in July 2012. RESULTS: Breastfeeding (BF) and CD: some studies show a protective effect of BF, while others show no effect. No studies have shown a long-term preventive effect. BF at the time of gluten introduction and CD: Results from a meta-analysis of five observational case-control studies suggest that BF at gluten introduction is associated with a lower risk of CD compared with formula feeding. It is unclear whether BF provides a permanent protection or only delays the onset of CD. Timing of gluten introduction: The data suggest that both early (≤4 months) and late (≥7 months) introduction of gluten may increase the risk of CD. Amount of gluten at weaning (and later) and CD: One incident case-referent study documented that the introduction of gluten in large amounts compared with small or medium amounts increased the risk of CD. CONCLUSIONS: In the absence of clear evidence, in order to decrease the risk of later coeliac disease, it is reasonable to avoid both early (<4 months) and late (≥7 months) introduction of gluten, and to introduce gluten while the infant is still being breastfed. Future studies may clarify the remaining uncertainties

Prospective blinded evaluation of a novel sensing methodology designed to reduce inappropriate shocks by the subcutaneous implantable cardioverter-defibrillator

Background: Most inappropriate shocks from the subcutaneous implantable cardioverter-defibrillator (S-ICD) are caused by cardiac oversensing. A novel sensing methodology, SMART Pass (SP; Boston Scientific Corporation, Natick, MA), aims to reduce cardiac oversensing. Objective: The purpose of this study was to evaluate the effect of SP on shocks in ambulatory patients with S-ICD. Methods: Patients implanted in 2015–2016 and enrolled in a remote patient monitoring system were included and followed for 1 year. Shocks were adjudicated by 3 independent blinded reviewers as appropriate or inappropriate. Shock incidence was calculated for patients with SP programmed enabled or disabled at implantation, censoring patients when SP programming changed or at the last transmission. The SP setting (enabled vs disabled) was modeled as a time-dependent Cox regression variable. Results: The cohort consisted of 1984 patients, and a total of 880 shocks were adjudicated. At implantation, SP was enabled in 655 patients (33%) and disabled in 1329 patients (67%). SP reduced the risk for the first inappropriate shock by 50% (P <.001) and the risk for all inappropriate shocks by 68% (P <.001) in multivariate analysis adjusted for age and device programming. The incidence of inappropriate shocks was 4.3% in the SP enabled arm vs 9.7% in the SP disabled arm. The incidence of appropriate shocks was similar (5.2

Scientific prospects in soft gamma-ray astronomy enabled by the LAUE project

This paper summarizes the development of a successful project, LAUE, supported by the Italian Space Agency (ASI) and devoted to the development of long focal length (up to 100 m) Laue lenses for hard X--/soft gamma--ray astronomy (80-600 keV). The apparatus is ready and the assembling of a prototype lens petal is ongoing. The great achievement of this project is the use of bent crystals. From measurements obtained on single crystals and from simulations, we have estimated the expected Point Spread Function and thus the sensitivity of a lens made of petals. The expected sensitivity is a few $\times10^{-8}$ photons cm$^{-2}$ s$^{-1}$ keV$^{-1}$. We discuss a number of open astrophysical questions that can settled with such an instrument aboard a free-flying satellite.Comment: 17 pages, 18 figures, published in Proceedings of the SPIE, Volume 8861, id. 886106 17 pp. (2013

Research of the Additional Losses Occurring in Optical Fiber at its Multiple Bends in the Range Waves 1310nm, 1550nm and 1625nm Long

Article is devoted to research of the additional losses occurring in the optical fiber at its multiple bends in the range waves of 1310 nanometers, 1550 nanometers and 1625 nanometers long. Article is directed on creation of the external factors methods which allow to estimate and eliminate negative influence. The automated way of calculation of losses at a bend is developed. Results of scientific researches are used by engineers of "Kazaktelekom" AS for practical definition of losses service conditions. For modeling the Wolfram|Alpha environment - the knowledge base and a set of computing algorithms was chosen. The greatest losses are noted on wavelength 1310nm and 1625nm. All dependences are nonlinear. Losses with each following excess are multiplicative