1,139 research outputs found
Further developments and tests of microstrip gas counters with resistive electrodes
We present results from further tests of Microstrip Gas Counters (MSGCs) with
resistive electrodes. The maim advantage of this detector is that it is
spark-protected: in contrast to "classical" MSGCs with metallic electrodes,
sparks in this new detector do not destroy its electrodes. As a consequence the
MSGC with resistive electrodes is more reliable in operation which may open new
avenues in applications. One of them which is under investigation now is the
use of Resistive electrodes MSGC (R-MSGC) as photodetector in some particular
designs of noble liquid dark matter detectors.Comment: Presented at the RD-51 mini-week at CERN, January 17, 201
First Tests of Gaseous Detectors Made of a Resistive Mesh
We describe here various detectors designs: GEM type, MICROMEGAStype,
PPACtype as well as cascaded detectors made of a resistive mesh manufactured
from a resistive Kapton foil, (20 microns thick, resistivity a few MOhm per
square) by a laser drilling technique. As in any other micropattern detectors
the maximum achievable gas gain of these detectors is restricted by the Raether
limit, however, the resistive mesh makes them and the front end electronics
fully spark protected. This approach could be an alternative or complimentary
to the ongoing efforts in developing MICROMEGAS and GEMs with resistive anode
readout plates and can be especially beneficial in the case of micropattern
detectors combined with a micropixel-type integrated front end electronic
An improved design of spark-protected microstrip gas counters (R-MSGC)
We have developed microstrip gas counters manufactured on standard printed
circuit board and having the following features: resistive cathode strips, thin
(10 micron) metallic anode strips and electrodes protected against surface
discharges by a Coverlay layer at their edges. These features allow the
detector to operate at gas gains as high as can be achieve with the best
microstrip gas counters manufactured on glass substrates. We believe that after
further developments this type of detectors can compete in some applications
with other micropattern detectors, for example MICROMEGAS.Comment: Presented at the 7th RD51 Collaboration meeting, CERN, April 201
Constant-q data representation in Neutron Compton scattering on the VESUVIO spectrometer
Standard data analysis on the VESUVIO spectrometer at ISIS is carried
out within the Impulse Approximation framework, making use of the West
scaling variable y. The experiments are performed using the
time-of-flight technique with the detectors positioned at constant
scattering angles. Line shape analysis is routinely performed in the
y-scaling framework, using two different (and equivalent) approaches:
(I) fitting the parameters of the recoil peaks directly to fixed-angle
time-of-flight spectral (2) transforming the time-of-flight spectra into
fixed-angle y spectra, referred to as the Neutron Compton Profiles, and
then fitting the line shape parameters. The present work shows that
scattering signals from different fixed-angle detectors can be collected
and rebinned to obtain Neutron Compton Profiles at constant wave vector
transfer, q, allowing for a suitable interpretation of data in terms of
the dynamical structure factor, S(q, w). The current limits of
applicability of such a procedure are discussed in terms of the
available q-range and relative uncertainties for the VESUVIO
experimental set up and of the main approximations involved. (C) 2008
Elsevier B.V. All rights reserved
Demonstration of new possibilities of multilayer technology on resistive microstrip/ microdot detectors
The first successful attempts to optimize the electric field in Resistive
Microstrip Gas Chamber and resistive microdot detectors using additional field
shaping strips located inside the detector substrate are describedComment: Presented at the RD-51 mmini week, CERN, June 201
Compressive fluctuations in high-latitude solar wind
International audienceSolar wind compressive fluctuations at MHD scales have been extensively studied in the past using data from spacecraft on the ecliptic plane. In the present study, based on plasma and magnetic field measurements by Ulysses, a statistical analysis of the compressive fluctuations observed in the high-latitude solar wind is performed. Data are from the first out-of-ecliptic orbit of Ulysses, when the Sun's activity is low and the high-latitude heliosphere is characterized by the presence of a fast and relatively steady solar wind, the polar wind. Our analysis is based on the computation of hourly-scale correlation coefficients for several pairs of solar wind parameters such as velocity, density, temperature, magnetic field magnitude, and plasma pressures (thermal, magnetic, and total). The behaviour of the fluctuations in terms of their amplitude has been examined, too, and comparisons with the predictions of existing models have been performed. The results support the view that the compressive fluctuations in the polar solar wind are mainly a superposition of MHD compressive modes and of pressure-balanced structures. Nearly-incompressible effects do not seem to play a relevant role. In conclusion, our results about compressive fluctuations in the polar wind do not appear as a break with respect to previous low-latitude observations. However, our study clearly indicates that in a homogeneous environment, as the polar wind, the pressure-balanced fluctuations tend to play a major role. Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma) ? Space plasma physics (turbulence
First tests of "bulk" MICROMEGAS with resistive cathode mesh
We present the first results from tests of a MICROMEGAS detector manufactured
using the so-called "bulk" technology and having a resistive cathode mesh
instead of the conventional metallic one. This detector operates as usual
MICROMEGAS, but in the case of sparks, which may appear at high gas gains, the
resistive mesh reduces their current and makes the sparks harmless. This
approach could be complementary to the ongoing efforts of various groups to
develop spark-protected MICROMEGAS with resistive anode planes
First Tests of Thick GEMs with Electrodes Made of a Resistive Kapton
We have developed a new design of a GEM-like detector with single-layer electrodes made of a resistive kapton. This detector can operate at gains close to 10E5 even in pure Ar and Ne and if transited to discharges at higher gains they, due to the high resistivity of electrodes, do not damage either the detector or the front-end electronics. Gains ~ 106 can be achieved in a cascaded mode of the operation. The detector can operate without gain degradation at counting rates up to 10E4Hz/cm2 and thus it could be very useful in many applications which require safe high gain operation, for example in RICH, TPCs, calorimetric
Hybrid Superconducting Neutron Detectors
A new neutron detection concept is presented that is based on superconductive
niobium (Nb) strips coated by a boron (B) layer. The working principle of the
detector relies on the nuclear reaction 10B+n + 7Li ,
with and Li ions generating a hot spot on the current-biased Nb strip
which in turn induces a superconducting-normal state transition. The latter is
recognized as a voltage signal which is the evidence of the incident neutron.
The above described detection principle has been experimentally assessed and
verified by irradiating the samples with a pulsed neutron beam at the ISIS
spallation neutron source (UK). It is found that the boron coated
superconducting strips, kept at a temperature T = 8 K and current-biased below
the critical current Ic, are driven into the normal state upon thermal neutron
irradiation. As a result of the transition, voltage pulses in excess of 40 mV
are measured while the bias current can be properly modulated to bring the
strip back to the superconducting state, thus resetting the detector.
Measurements on the counting rate of the device are presented and the future
perspectives leading to neutron detectors with unprecedented spatial
resolutions and efficiency are highlighted.Comment: 8 pages 6 figure
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