435 research outputs found
Energy resolution of alpha particles in a microbulk Micromegas detector at high pressure Argon and Xenon mixtures
The latest Micromesh Gas Amplification Structures (Micromegas) are achieving
outstanding energy resolution for low energy photons, with values as low as 11%
FWHM for the 5.9 keV line of Fe in argon/isobutane mixtures at
atmospheric pressure. At higher energies (MeV scale), these measurements are
more complicated due to the difficulty in confining the events in the chamber,
although there is no fundamental reason why resolutions of 1% FWHM or below
could not be reached. There is much motivation to demonstrate experimentally
this fact in Xe mixtures due to the possible application of Micromegas readouts
to the Double Beta Decay search of Xe, or in other experiments needing
calorimetry and topology in the same detector. In this paper, we report on
systematic measurements of energy resolution with state-of-the-art Micromegas
using a 5.5 MeV alpha source in high pressure Ar/isobutane mixtures. Values as
low as 1.8% FWHM have been obtained, with possible evidence that better
resolutions are achievable. Similar measurements in Xe, of which a preliminary
result is also shown here, are under progress.Comment: 16 pages, 19 figures, version after referees comments. Accepted for
publication in Nuclear Instruments and Methods
Solar Neutrinos as Background in Direct Dark Matter Searches
The coherent contribution of all neutrons in neutrino nucleus scattering due
to the neutral current is examined considering the boron solar neutrinos. These
neutrinos could potentially become a source of background in the future dark
matter searches aiming at nucleon cross sections in the region well below the
few events per ton per year.Comment: 6 pages, 5 figures, Submitted for the DSU proceedings to be published
by the American institute of Physics (AIP). References adde
Low energy recoil detection with a spherical proportional counter
We present low energy recoil detection results in the keV energy region, from
measurements performed with the Spherical Proportional Counter (SPC). An
fast neutron source is used in order to obtain
neutron-nucleus elastic scattering events inside the gaseous volume of the
detector. The detector performance in the energy region was resolved by
observing the line of a X-ray source, with energy
resolution of (). The toolkit GEANT4 was used to simulate the
irradiation of the detector by an source, while SRIM
was used to calculate the Ionization Quenching Factor (IQF). The GEANT4
simulated energy deposition spectrum in addition with the SRIM calculated
quenching factor provide valuable insight to the experimental results. The
performance of the SPC in low energy recoil detection makes the detector a good
candidate for a wide range of applications, including Supernova or reactor
neutrino detection and Dark Matter (WIMP) searches (via coherent elastic
scattering).Comment: 16 pages, 16 figures, preprin
Micromegas in a Bulk
In this paper we present a novel way to manufacture the bulk Micromegas
detector. A simple process based on the PCB (Printed Circuit Board) technology
is employed to produce the entire sensitive detector. Such fabrication process
could be extended to very large area detectors made by the industry. The low
cost fabrication together with the robustness of the electrode materials will
make it extremely attractive for several applications ranging from particle
physics and astrophysics to medicineComment: 6 pages, 4 figure
Coherent Neutral Current Neutrino-Nucleus Scattering at a Spallation Source; a Valuable Experimental Probe
The coherent contribution of all neutrons in neutrino nucleus scattering due
to the neutral current is examined considering the Spallation Neutron Source
(SNS) as a source of neutrinos. SNS is a prolific pulsed source of electron and
muon neutrinos as well as muon antineutrinos.Comment: 15 LaTex pages, 14 figures, 3 Table
Low-background applications of MICROMEGAS detector technology
The MICROMEGAS detector concept, generally optimized for use in accelerator experiments, displays a peculiar combination of features that can be advantageous in several astroparticle and neutrino physics applications. Their sub-keV ionization energy threshold, excellent energy and space resolution, and a simplicity of design that allows the use of radioclean materials in their construction are some of these characteristics. We envision tackling experimental challenges such as the measurement of neutral-current neutrino-nucleus coherent scattering or Weakly Interacting Massive Particle (WIMP) detectors with directional sensitivity. The large physics potential of a compact (total volume O(1)m), multi-purpose array of low-background MICROMEGAS is made evident
First tests of a Micromegas TPC in a magnetic field
Talk given by P. ColasSince the summer of 2003, a large Micromegas TPC prototype (1000 channels, 50 cm drift, 50 cm diameter) has been operated in a 2T superconducting magnet at Saclay. A description of this apparatus and first results from cosmic ray tests are presented. Additional measurements using simpler detectors with a laser source, an X-ray gun and radio-active sources are discussed. Drift velocity and gain measurements, electron attachment and aging studies for a Micromegas TPC are presented. In particular, using simulations and measurements, it is shown that an mixture is optimal for operation at a future Linear Collider
Progress on a spherical TPC for low energy neutrino detection
The new concept of the spherical TPC aims at relatively large target masses
with low threshold and background, keeping an extremely simple and robust
operation. Such a device would open the way to detect the neutrino-nucleus
interaction, which, although a standard process, remains undetected due to the
low energy of the neutrino-induced nuclear recoils. The progress in the
development of the fist 1 m prototype at Saclay is presented. Other physics
goals of such a device could include supernova detection, low energy neutrino
oscillations and study of non-standard properties of the neutrino, among
others.Comment: 3 pages, talk given at the 9th Workshop on Topics in Astroparticle
and Underground Physics, Zaragoza, September 10-1
Micromegas TPC studies at high magnetic fields using the charge dispersion signal
The International Linear Collider (ILC) Time Projection Chamber (TPC)
transverse space-point resolution goal is 100 microns for all tracks including
stiff 90 degree tracks with the full 2 meter drift. A Micro Pattern Gas
Detector (MPGD) readout TPC can achieve the target resolution with existing
techniques using 1 mm or narrower pads at the expense of increased detector
cost and complexity. The new MPGD readout technique of charge dispersion can
achieve good resolution without resorting to narrow pads. This has been
demonstrated previously for 2 mm x 6 mm pads with GEMs and Micromegas in cosmic
ray tests and in a KEK beam test in a 1 Tesla magnet. We have recently tested a
Micromegas-TPC using the charge dispersion readout concept in a high field
super-conducting magnet at DESY. The measured Micromegas gain was found to be
constant within 0.5% for magnetic fields up to 5 Tesla. With the strong
suppression of transverse diffusion at high magnetic fields, we measure a flat
50 micron resolution at 5 Tesla over the full 15 cm drift length of our
prototype TPC.Comment: 7 pages, 3 figure
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