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 $^{55}$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 $^{136}$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

Supernova Detection via a Network of Neutral Current Spherical TPC's

The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current offers a realistic prospect of detecting supernova neutrinos. For a typical supernova at 10 kpc, about 1000 events are expected using a spherical gaseous detector of radius 4 m and employing Xe gas at a pressure of 10 Atm. We propose a world wide network of several such simple, stable and low cost supernova detectors with a running time of a few centuries.Comment: 7 pages, 2 figures. Talk presented at the International Symposium on Origin of Matter and Evolution of Galaxies (OMEG05)- New Horizon of Nuclear Astrophysics and Cosmology November 8-11, 2005, University of Tokyo, Tokyo, Japa

The TESLA Time Projection Chamber

A large Time Projection Chamber is proposed as part of the tracking system for a detector at the TESLA electron positron linear collider. Different ongoing R&D studies are reviewed, stressing progress made on a new type readout technique based on Micro-Pattern Gas Detectors.Comment: 5 pages, 8 figures; Proceeding for the topical Seminar on Innovative Particle and Radiation Detectors Siena, 21-24 October 2002; to appear in Nucl.Phys. B (Proceedings Supplement

Nostos - Spherical TPCs

A new concept, the spherical TPC, presents unique advantages when low energy neutrinos are to be detected. Some of the applications are: a) observation of the e oscillation when emitted by a tritium source ( = 14 keV) in a 10 m radius sphere. This project, baptized NOSTOS, intends to give the mixing angle 13, the Weinberg angle and a much lower limit (< 10-12 ?B) of the neutrino magnetic moment, b) an array of small (radius 2-4 m), cheap spheres scattered around the world would be perfect to monitor extragalactic supernovae, c) detect the spectrum of low energy (pp - 7Be) solar neutrinos.Comment: XIII International Symposium on Very High Energy Cosmic Ray Interactions at the NESTOR Institute - Pylos, Grece, 6-12 Septembre 200

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

A Network of Neutral Current Spherical TPC's for Dedicated Supernova Detection

The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current offers a realistic prospect of detecting supernova neutrinos. As a matter of fact. for a typical supernova at 10 kpc, about 1000 events are expected usinga spherical gaseous detector of radius 4 m andemploying Xe gas at a pressure of 10 Atm. We propose a world wide network of several such simple, stable and low cost supernova detectors with a running time of a few centuries.Comment: 17 LaTex pages, 9 PostScript figure

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