19,117 research outputs found
Performance of the AMS-02 Transition Radiation Detector
For cosmic particle spectroscopy on the International Space Station the AMS
experiment will be equipped with a Transition Radiation Detector (TRD) to
improve particle identification. The TRD has 20 layers of fleece radiator with
Xe/CO2 proportional mode straw tube chambers. They are supported in a conically
shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA
analog multiplexers are used as front-end readout. A 20 layer prototype built
from final design components has achieved proton rejections from 100 to 2000 at
90% electron efficiency for proton beam energies up to 250 GeV with cluster
counting, likelihood and neural net selection algorithms.Comment: 11 pages, 25 figures, espcrc2.sty (elsevier 2-column
New readout and data-acquisition system in an electron-tracking Compton camera for MeV gamma-ray astronomy (SMILE-II)
For MeV gamma-ray astronomy, we have developed an electron-tracking Compton
camera (ETCC) as a MeV gamma-ray telescope capable of rejecting the radiation
background and attaining the high sensitivity of near 1 mCrab in space. Our
ETCC comprises a gaseous time-projection chamber (TPC) with a micro pattern gas
detector for tracking recoil electrons and a position-sensitive scintillation
camera for detecting scattered gamma rays. After the success of a first balloon
experiment in 2006 with a small ETCC (using a 101015 cm
TPC) for measuring diffuse cosmic and atmospheric sub-MeV gamma rays (Sub-MeV
gamma-ray Imaging Loaded-on-balloon Experiment I; SMILE-I), a (30 cm)
medium-sized ETCC was developed to measure MeV gamma-ray spectra from celestial
sources, such as the Crab Nebula, with single-day balloon flights (SMILE-II).
To achieve this goal, a 100-times-larger detection area compared with that of
SMILE-I is required without changing the weight or power consumption of the
detector system. In addition, the event rate is also expected to dramatically
increase during observation. Here, we describe both the concept and the
performance of the new data-acquisition system with this (30 cm) ETCC to
manage 100 times more data while satisfying the severe restrictions regarding
the weight and power consumption imposed by a balloon-borne observation. In
particular, to improve the detection efficiency of the fine tracks in the TPC
from 10\% to 100\%, we introduce a new data-handling algorithm in
the TPC. Therefore, for efficient management of such large amounts of data, we
developed a data-acquisition system with parallel data flow.Comment: 11 pages, 24 figure
The COMPASS Experiment at CERN
The COMPASS experiment makes use of the CERN SPS high-intensitymuon and
hadron beams for the investigation of the nucleon spin structure and the
spectroscopy of hadrons. One or more outgoing particles are detected in
coincidence with the incoming muon or hadron. A large polarized target inside a
superconducting solenoid is used for the measurements with the muon beam.
Outgoing particles are detected by a two-stage, large angle and large momentum
range spectrometer. The setup is built using several types of tracking
detectors, according to the expected incident rate, required space resolution
and the solid angle to be covered. Particle identification is achieved using a
RICH counter and both hadron and electromagnetic calorimeters. The setup has
been successfully operated from 2002 onwards using a muon beam. Data with a
hadron beam were also collected in 2004. This article describes the main
features and performances of the spectrometer in 2004; a short summary of the
2006 upgrade is also given.Comment: 84 papes, 74 figure
The High-Acceptance Dielectron Spectrometer HADES
HADES is a versatile magnetic spectrometer aimed at studying dielectron
production in pion, proton and heavy-ion induced collisions. Its main features
include a ring imaging gas Cherenkov detector for electron-hadron
discrimination, a tracking system consisting of a set of 6 superconducting
coils producing a toroidal field and drift chambers and a multiplicity and
electron trigger array for additional electron-hadron discrimination and event
characterization. A two-stage trigger system enhances events containing
electrons. The physics program is focused on the investigation of hadron
properties in nuclei and in the hot and dense hadronic matter. The detector
system is characterized by an 85% azimuthal coverage over a polar angle
interval from 18 to 85 degree, a single electron efficiency of 50% and a vector
meson mass resolution of 2.5%. Identification of pions, kaons and protons is
achieved combining time-of-flight and energy loss measurements over a large
momentum range. This paper describes the main features and the performance of
the detector system
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