Progress towards a Technological Prototype for a Semi-Digital Hadron Calorimeter based on Glass RPCs

The semi-digital Hadronic calorimeter using GRPC as sensitive medium is one of the two options the ILD collaboration is considering for the ILD detector final design. A prototype of 1m3 has been conceived within the CALICE collaboration in order to validate this option. The prototype is intended to be as close as possible to the one proposed in the ILD LOI. A first unit of 1m2 GRPC of 3 mm thickness and fully equipped with a semi-digital electronics readout and new gas distribution design was produced and successfully tested. In 2010 we intend to produce 40 similar units to be inserted in a self-supporting mechanical structure. The prototype will then be exposed to test beams at CERN or at Fermilab for final validation.Comment: Presented at the International Linear Collider Workshop, Beijing, March 26-30 201

Progress with micro-pattern gas detectors

Abstract Micro-pattern gas detectors are position-sensitive proportional counters whose sense electrodes are constructed using micro-electronics, thin-film or advanced PCB techniques. The feature size attainable using these methods is of the order of a few microns and the detectors demonstrate excellent spatial resolution and fast charge collection. We review recent progress on micro-pattern gas detectors for tracking and other cross-disciplinary applications, focussing on design principles, performance and limitations. A short list of interesting applications is discussed

Discovery of complex narrow X-ray absorption features from the low-mass X-ray binary GX13+1 with XMM-Newton

We report the detection of a complex of narrow X-ray absorption features from the low-mass X-ray binary GX13+1 during 3 XMM-Newton observations in 2000 March and April. The features are consistent with being due to resonant scattering of the K_alpha and K_beta lines of He- and H-like iron (Fe xxv and Fe xxvi) and H-like calcium (Ca xx) K_alpha. Only the Fe xxvi K_alpha line has been previously observed from GX13+1. Due to the closeness in energy the Fe xxv and Fe xxvi K_beta features may also be ascribed to Nixxvii and Nixxviii K_alpha, respectively. We also find evidence for the presence of a deep (tau~0.2) Fe xxv absorption edge at 8.83 keV. The equivalent widths of the lines do not show any obvious variation on a timescale of a few days suggesting that the absorbing material is a stable feature of the system and present during a range of orbital phases

Forward-Backward Differential Equations: Approximation of Small Solutions

Com o apoio RAADRI.In the context of physics, economic dynamics, nance, optimal control, biology and other applied sciences, many mathematical models contain mixed type functional differential equations (MTFDEs), equations with both delayed and advanced arguments. Knowing from the analysis of delay di erential equations (DDEs) that the evaluation of small solutions (that decay faster than any exponential) often leads to computational problems (degeneracy), we investigate this subject in the case of MTFDEs. Some computations have been carried out and are presented here, concerning the linear nonautonomous case. We continue this work and extend the investigation to other problems

Strongly absorbed quiescent X-ray emission from the X-ray transient XTE J0421+56 (CI Cam) observed with XMM-Newton

We have observed the X-ray transient XTE J0421+56 in quiescence with XMM-Newton. The observed spectrum is highly unusual being dominated by an emission feature at ~6.5 keV. The spectrum can be fit using a partially covered power-law and Gaussian line model, in which the emission is almost completely covered (covering fraction of 0.98_{-0.06}^{+0.02}) by neutral material and is strongly absorbed with an N_H of (5_{-2}^{+3}) x 10^{23} atom cm^{-2}. This absorption is local and not interstellar. The Gaussian has a centroid energy of 6.4 +/- 0.1 keV, a width < 0.28 keV and an equivalent width of 940 ^{+650}_{-460} eV. It can be interpreted as fluorescent emission line from iron. Using this model and assuming XTE J0421+56 is at a distance of 5 kpc, its 0.5-10 keV luminosity is 3.5 x 10^{33} erg s^{-1}. The Optical Monitor onboard XMM-Newton indicates a V magnitude of 11.86 +/- 0.03. The spectra of X-ray transients in quiescence are normally modeled using advection dominated accretion flows, power-laws, or by the thermal emission from a neutron star surface. The strongly locally absorbed X-ray emission from XTE J0421+56 is therefore highly unusual and could result from the compact object being embedded within a dense circumstellar wind emitted from the supergiant B[e] companion star. The uncovered and unabsorbed component observed below 5 keV could be due either to X-ray emission from the supergiant B[e] star itself, or to the scattering of high-energy X-ray photons in a wind or ionized corona, such as observed in some low-mass X-ray binary systems.Comment: 8 pages, 4 postscript figures, accepted for publication in Astronomy and Astrophysic

Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton

We report the discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 during an XMM-Newton observation in 2001 February. The features are identified with the K alpha absorption lines of Fe xxv and Fe xxvi and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV and equivalent widths (EWs) of -7.5 +1.7 -6.3 eV and -16.6 +1.9 -5.9 eV, respectively. The EWs show no obvious dependence on orbital phase, except during a dip, and correspond to a column of greater than 10^17.3 Fe atom /cm2. In addition, faint absorption features tentatively identified with Ni xxvii K alpha and Fe xxvi K beta may be present. A broad emission feature at 6.58 +0.07 -0.04 keV with an EW of 78 +19 -6 eV is also evident. This is probably the 6.4 keV feature reported by earlier missions since fitting a single Gaussian to the entire Fe-K region gives an energy of 6.39 +0.03 -0.04 keV. A deep absorption feature is present during the dip with an energy consistent with Fe xxv K alpha. This is the second dipping LMXRB source from which narrow Fe absorption features have been observed. Until recently the only X-ray binaries known to exhibit narrow X-ray absorption lines were two superluminal jet sources and it had been suggested that these features are related to the jet formation mechanism. It now appears likely that ionized absorption features may be common characteristics of accreting systems with accretion disks.Comment: 6 pages. To appear in A&