808 research outputs found
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
MicroPattern Gas Detectors with pixel read-out
MicroPattern Gas Detectors are position-sensitive proportional counters whose sense electrodes are constructed using microelectronics, thin-film or advanced PCB techniques. The feature size attainable using these methods is of the order of a few microns and the detectors show excellent spatial resolution and fast charge collection. The real challenge with this class of detectors is the design of the read-out system which should not spoil the intrinsic performance of the devices. The most promising approach is the coupling of a pixelized collection anode and read-out system to the gas amplifying stage. We will discuss this principle and we will show examples of practical implementations in the field of X-ray Astronomy and Plasma Imaging
The MicroGap Chamber: a new detector for the next generation of high energy, high rate experiments
Abstract The concept of MicroGap Chamber (MGC) is introduced. Results from a large MGC (10 × 10 cm2) with a small stereo angle read-out are presented. Both coordinates are read out from the same side of the detector substrate. Measurements of gain stability, fraction of induced charge on the back electrode, uniformity of response along the strip and rate capability have been performed in the laboratory, using X-ray sources. Detection efficiency, spatial resolution, charge and space correlation have been measured with minimum ionizing particle beams at CERN
Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors
Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
A MWPC with a cathode coupled delay line read-out as radioactivity detector for DNA repair studies
A non selective method for the isolation of DNA repair-deficient mutants in mammalian cells is discussed. The method requires radioactive labelling of the short DNA sequences synthesized during repair of damaged regions. Mutants should be recognized by the absence of radioactive incorporation into thier DNA. A multiwire proportional chamber (MWPC) is proposed as a suitable radioactivity detector. The performance of a MWPC prototype with a cathode coupled delay line read-out is described and is shown to be adequate for this application. The main avaantages of a MWPC are reviewed with respect to other methods used for β− radioactivity counting of biological samples, such as liquid scintillators or autoradiography: the proposed detection method is non destructive for the cells, which are being kept alive for further biological studies; furthermore many cell clones can be screened within a reasonable time
A microstrip gas avalanche chamber with two-dimensional readout
Abstract A microstrip gas avalanche chamber with a 200 μm anode pitch has been built and successfully tested in our laboratory. A gas gain of 104 and an energy resolution of 18% (FWHM) at 6 keV have been measured using a gas mixture of argon-CO2 at atmospheric pressure. A preliminary measurement of the positional sensitivity indicates that a spatial resolution of 50 μm can be obtained
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]
ELECTRONIC AUTORADIOGRAPHY OF LIVING HUMAN-CELLS WITH A MWPC
Abstract The use of multiwire proportional chamber (MWPC) for mapping the incorporation of a radioactive precursor of DNA biosynthesis by aggregates of cells is discussed. The resolving power, sensitivity and linearity of the developed system are shown, together with preliminary "electronic autoradiograms" of 14C-labelled cells
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