Evaluation of the surface strength of glass plates shaped by hot slumping process

The Hot Slumping Technology is under development by several research groups in the world for the realization of grazing-incidence segmented mirrors for X-ray astronomy, based on thin glass plates shaped over a mould at temperatures above the transformation point. The performed thermal cycle and related operations might have effects on the strength characteristics of the glass, with consequences on the structural design of the elemental optical modules and consecutively on the entire X-ray optic for large astronomical missions like IXO and ATHENA. The mechanical strength of glass plates after they underwent the slumping process was tested through destructive double-ring tests in the context of a study performed by the Astronomical Observatory of Brera with the collaboration of Stazione Sperimentale del Vetro and BCV Progetti. The entire study has been realized on more than 200 D263 Schott borosilicate glass specimens of dimension 100 mm x 100 mm and thickness 0.4 mm, either flat or bent at a Radius of Curvature of 1000 mm through the particular pressure assisted hot slumping process developed by INAF-OAB. The collected experimental data have been compared to non-linear FEM analyses and treated with Weibull statistic to assess the current IXO glass X-ray telescope design, in terms of survival probability, when subject to static and acoustic loads characteristic of the launch phase. The paper describes the activities performed and presents the obtained results.Comment: Accepted for publication in Optical Enginnering (Jun 26, 2014

An extension of the SHARC survey

We report on our search for distant clusters of galaxies based on optical and X-ray follow up observations of X-ray candidates from the SHARC survey. Based on the assumption that the absence of bright optical or radio counterparts to possibly extended X-ray sources could be distant clusters. We have obtained deep optical images and redshifts for several of these objects and analyzed archive XMM-Newton or Chandra data where applicable. In our list of candidate clusters, two are probably galaxy structures at redshifts of z$\sim$0.51 and 0.28. Seven other structures are possibly galaxy clusters between z$\sim$0.3 and 1. Three sources are identified with QSOs and are thus likely to be X-ray point sources, and six more also probably fall in this category. One X-ray source is spurious or variable. For 17 other sources, the data are too sparse at this time to put forward any hypothesis on their nature. We also serendipitously detected a cluster at z=0.53 and another galaxy concentration which is probably a structure with a redshift in the [0.15-0.6] range. We discuss these results within the context of future space missions to demonstrate the necessity of a wide field of view telescope optimized for the 0.5-2 keV range.Comment: Accepted in A&

SIMBOL-X : a new generation hard X-ray telescope

SIMBOL-X is a hard X-ray mission, operating in the 0.5-70 keV range, which is proposed by a consortium of European laboratories for a launch around 2010. Relying on two spacecraft in a formation flying configuration, SIMBOL-X uses a 30 m focal length X-ray mirror to achieve an unprecedented angular resolution (30 arcsec HEW) and sensitivity (100 times better than INTEGRAL below 50 keV) in the hard X-ray range. SIMBOL-X will allow to elucidate fundamental questions in high energy astrophysics, such as the physics of accretion onto Black Holes, of acceleration in quasar jets and in supernovae remnants, or the nature of the hard X-ray diffuse emission. The scientific objectives and the baseline concepts of the mission and hardware design are presented.Comment: 12 pages, 16 fig., Proc. SPIE conf. 5168, San Diego, Aug. 200

The imaging properties of the Gas Pixel Detector as a focal plane polarimeter

X-rays are particularly suited to probe the physics of extreme objects. However, despite the enormous improvements of X-ray Astronomy in imaging, spectroscopy and timing, polarimetry remains largely unexplored. We propose the photoelectric polarimeter Gas Pixel Detector (GPD) as an instrument candidate to fill the gap of more than thirty years of lack of measurements. The GPD, in the focus of a telescope, will increase the sensitivity of orders of magnitude. Moreover, since it can measure the energy, the position, the arrival time and the polarization angle of every single photon, allows to perform polarimetry of subsets of data singled out from the spectrum, the light curve or the image of source. The GPD has an intrinsic very fine imaging capability and in this work we report on the calibration campaign carried out in 2012 at the PANTER X-ray test facility of the Max-Planck-Institut f\"ur extraterrestrische Physik of Garching (Germany) in which, for the first time, we coupled it to a JET-X optics module with a focal length of 3.5 m and an angular resolution of 18 arcsec at 4.5 keV. This configuration was proposed in 2012 aboard the X-ray Imaging Polarimetry Explorer (XIPE) in response to the ESA call for a small mission. We derived the imaging and polarimetric performance for extended sources like Pulsar Wind Nebulae and Supernova Remnants as case studies for the XIPE configuration, discussing also possible improvements by coupling the detector with advanced optics, having finer angular resolution and larger effective area, to study with more details extended objects.Comment: Accepted for publication in The Astrophysical Journal Supplemen

Detector Control System of the ATLAS Insertable B-Layer

soumis à publicationTo improve tracking robustness and precision of the ATLAS inner tracker an additional fourth pixel layer is foreseen, called Insertable B-Layer (IBL). It will be installed between the innermost present Pixel layer and a new smaller beam pipe and is presently under construction. As, once installed into the experiment, no access is available, a highly reliable control system is required. It has to supply the detector with all entities required for operation and protect it at all times. Design constraints are the high power density inside the detector volume, the sensitivity of the sensors against heatups, and the protection of the front end electronics against transients. We present the architecture of the control system with an emphasis on the CO2 cooling system, the power supply system and protection strategies. As we aim for a common operation of pixel and IBL detector, the integration of the IBL control system into the Pixel one will be discussed as well

Использование вейвлет-преобразования при локализации последовательностей символов

В статье предложен метод автоматического определения масштаба вейвлет-преобразования при локализации квазипериодических последовательностей (текстур, областей с символьной информацией и т.д.) путем анализа функции энергии коэффициентов вейвлет-преобразования. Реализация предложенного метода при разработке приложений, связанных с локализацией и распознаванием символьной информации, повысила универсальность таких систем за счет повышения точности локализации символьной информации путем автоматизации выбора масштаба вейвлет-преобразования.У статті запропоновано метод автоматичного визначення масштабу вейвлет-перетворення при локалізації квазіперіодичних послідовностей (текстур, областей з символьною інформацією (СІ) тощо) шляхом аналізу функції енергії коефіцієнтів вейвлет-перетворення. Реалізація методу при розробці додатків, які пов’язані з локалізацією та розпізнаванням символьної інформації, підвищила універсальність таких систем за рахунок збільшення точності локалізації СІ шляхом автоматизації вибору масштабу вейвлет-перетворення.Method of automatically determining wavelet transform scale on the base of analyzing the function of the energy wavelet transform coefficients is proposed. It is used for localization of quasiperiodic sequences (patterns, areas with character information, etc.). The proposed method is used in image processing systems related to the localization and recognition of the symbolic information. It is allowed to increase versatility of such systems by improving the accuracy localization of the symbolic information by automating choice of scale wavelet transform

Inclusive search for same-sign dilepton signatures in pp collisions at root s=7 TeV with the ATLAS detector

An inclusive search is presented for new physics in events with two isolated leptons (e or mu) having the same electric charge. The data are selected from events collected from p p collisions at root s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb(-1). The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, e mu and mu mu channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks