PulsarSpectrum: simulating gamma-ray pulsars for the GLAST mission

We present here an overview of PulsarSpectrum, a program that simulates the gamma ray emission from pulsars. This simulator reproduces not only the basic features of the observed gamma ray pulsars, but it can also simulate more detailed effects related to pulsar timing. It is a very useful tool to understand the GLAST capabilities in the pulsar science.Comment: 6 pages, 3 figures, contribution for "Third Workshop on Science with the New Generation of High Energy Gamma-ray Experiments", May 2005, Cividale del Friuli (UD), Ital

Quality of reporting on the vegetative state in Italian newspapers. The case of Eluana Englaro.

Background: Media coverage of the vegetative state (VS) includes refutations of the VS diagnosis and describes behaviors inconsistent with VS. We used a quality score to assess the reporting in articles describing the medical characteristics of VS in Italian newspapers. Methodology/Principal Findings: Our search covered a 7-month period from July 1, 2008, to February 28, 2009, using the online searchable databases of four major Italian newspapers: Corriere della Sera, La Repubblica, La Stampa, and Avvenire. Medical reporting was judged as complete if three core VS characteristics were described: patient unawareness of self and the environment, preserved wakefulness (eyes open), and spontaneous respiration (artificial ventilator not needed). We retrieved 2,099 articles, and 967 were dedicated to VS. Of these, 853 (88.2%) were non-medical and mainly focused on describing the political, legal, and ethical aspects of VS. Of the 114 (11.8%) medical articles, 53 (5.5%) discussed other medical problems such as death by dehydration, artificial nutrition, neuroimaging, brain death, or uterine hemorrhage, and 61 (6.3%) described VS. Of these 61, only 18 (1.9%) reported all three CORE characteristics and were judged complete. We found no differences among the four investigated newspapers (Fisher’s exact = 0.798), and incomplete articles were equally distributed between journalistic pieces and expert opinions (x2 = 1.8854, P = 0.170). Incorrect descriptions of VS were significantly more common among incomplete articles (13 of 43 vs. 1 of 18; Fisher’s exact P = 0.047). Conclusions/Significance: Core VS characteristics are rarely reported in Italian newspaper articles, which can alter adequate comprehension of new developments and (mis)inform political, legal, and ethical decisions

Reading a GEM with a VLSI pixel ASIC used as a direct charge collecting anode

In MicroPattern Gas Detectors (MPGD) when the pixel size is below 100 micron and the number of pixels is large (above 1000) it is virtually impossible to use the conventional PCB read-out approach to bring the signal charge from the individual pixel to the external electronics chain. For this reason a custom CMOS array of 2101 active pixels with 80 micron pitch, directly used as the charge collecting anode of a GEM amplifying structure, has been developed and built. Each charge collecting pad, hexagonally shaped, realized using the top metal layer of a deep submicron VLSI technology is individually connected to a full electronics chain (pre-amplifier, shaping-amplifier, sample and hold, multiplexer) which is built immediately below it by using the remaining five active layers. The GEM and the drift electrode window are assembled directly over the chip so the ASIC itself becomes the pixelized anode of a MicroPattern Gas Detector. With this approach, for the first time, gas detectors have reached the level of integration and resolution typical of solid state pixel detectors. Results from the first tests of this new read-out concept are presented. An Astronomical X-Ray Polarimetry application is also discussed.Comment: 11 pages, 14 figures, presented at the Xth Vienna Conference on Instrumentation (Vienna, February 16-21 2004). For a higher resolution paper contact [email protected]

Spectral and polarimetric characterization of the Gas Pixel Detector filled with dimethyl ether

The Gas Pixel Detector belongs to the very limited class of gas detectors optimized for the measurement of X-ray polarization in the emission of astrophysical sources. The choice of the mixture in which X-ray photons are absorbed and photoelectrons propagate, deeply affects both the energy range of the instrument and its performance in terms of gain, track dimension and ultimately, polarimetric sensitivity. Here we present the characterization of the Gas Pixel Detector with a 1 cm thick cell filled with dimethyl ether (DME) at 0.79 atm, selected among other mixtures for the very low diffusion coefficient. Almost completely polarized and monochromatic photons were produced at the calibration facility built at INAF/IASF-Rome exploiting Bragg diffraction at nearly 45 degrees. For the first time ever, we measured the modulation factor and the spectral capabilities of the instrument at energies as low as 2.0 keV, but also at 2.6 keV, 3.7 keV, 4.0 keV, 5.2 keV and 7.8 keV. These measurements cover almost completely the energy range of the instrument and allows to compare the sensitivity achieved with that of the standard mixture, composed of helium and DME.Comment: 20 pages, 11 figures, 5 tables. Accepted for publication by NIM

Studies of cosmic ray electrons with the Fermi-LAT

The Fermi Large Area Telescope measures the cosmic-ray electron spectrum from 7GeV up to 1TeV, covering a broad range of approximately 2.5 decades with unprecedented accuracy. This result is based on an analysis of about 8 million electron candidates detected in the first 12 months of operations of the satellite. It extends our previously published measurement down to 7GeV, and confirms a spectrum harder than expected and with no prominent spectral features. In this paper we describe key points of the analysis and of its validations, as well as a cross-check measurement of the spectrum via a subset of events selected for the best energy resolution. Possible interpretations of the result and prospects for future Fermi measurements are briefly discussed at the end

The Micro-Groove Detector

We introduce the Micro-Groove Detector (MGD), a new type of position-sensitive gas proportional counter produced using advanced printed circuit board (PCB) technology. The MGD is based on a thin kapt on foil, clad with gold-plated copper on both sides. An array of micro-strips at a typical pitch of 200um is defined on the top metal layer. Using as a protection mask the metal left after the patter ning, charge amplifying micro-grooves are etched into the kapton layer. These end on a second micro-strip pattern which is defined on the bottom metal plane. The two arrays of micro-strips can have a n arbitrary relative orientation and so can be used for read-out to obtain 2-D positional information. First results from our systematic assessment of this device are reported: gas gain > 15000, rat e capability above 10^6mm-2s-1, energy resolution 22% at 5.4 keV, no significant charging or aging effects up to 5mC/cm, full primary charge collection efficiency even at high drift fields

The WELL Detector

We introduce the WELL detector, a new type of position-sensitive gas proportional counter produced using advanced printed circuit board (PCB) technology. The WELL is based on a thin kapton foil, copp erclad on both sides. Charge amplifying micro-wells are etched into the first metal and kapton layers. These end on a micro-strip pattern which is defined on the second metal plane. The array of micr o-strips is used for read-out to obtain 1-D positional information. First results from our systematic assessment of this device are reported