541 research outputs found
Compton scattering sequence reconstruction algorithm for the liquid xenon gamma-ray imaging telescope (LXeGRIT)
The Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT) is a balloon born
experiment sensitive to \g -rays in the energy band of 0.2-20 MeV. The main
detector is a time projection chamber filled with high purity liquid xenon
(LXeTPC), in which the three-dimensional location and energy deposit of
individual \g -ray interactions are accurately measured in one homogeneous
volume. To determine the \g -ray initial direction (Compton imaging), as well
as to reject background, the correct sequence of interactions has to be
determined. Here we report the development and optimization of an algorithm to
reconstruct the Compton scattering sequence and show its performance on Monte
Carlo events and LXeGRIT data.Comment: To appear in: Hard X-Ray, Gamma-Ray, and Neutron Detector Physics II,
2000; Proc. SPIE, vol. 4141; R.B. James & R.C. Schirato, ed
Spectroscopy and Imaging Performance of the Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT)
LXeGRIT is a balloon-borne Compton telescope based on a liquid xenon time
projection chamber (LXeTPC) for imaging cosmic \g-rays in the energy band of
0.2-20 MeV. The detector, with 400 cm area and 7 cm drift gap, is filled
with high purity LXe. Both ionization and scintillation light signals are
detected to measure the energy deposits and the three spatial coordinates of
individual \g -ray interactions within the sensitive volume. The TPC has been
characterized with repeated measurements of its spectral and Compton imaging
response to \g -rays from radioactive sources such as \na, \cs, \yt and Am-Be.
The detector shows a linear response to \g -rays in the energy range 511 keV
-4.4 MeV, with an energy resolution (FWHM) of \Delta E/E=8.8% \: \sqrt{1\MeV
/E}. Compton imaging of \yt \g -ray events with two detected interactions is
consistent with an angular resolution of 3 degrees (RMS) at 1.8 MeV.Comment: To appear in: Hard X-Ray, Gamma-Ray and Neutron Detector Physics XI,
2000; Proc. SPIE, vol. 4140; K.A. Flanagan & O.H. Siegmund, ed
Suitability of high-pressure xenon as scintillator for gamma ray spectroscopy
In this paper we report the experimental study of high-pressure xenon used as
a scintillator, in the context of developing a gamma ray detector. We measure a
light yield near 2 photoelectrons per keV for xenon at 40 bar. Together with
the light yield, we also measured an energy resolution of ~9% (FWHM) at 662
keV, dominated by the statistical fluctuations in the number of photoelectrons.Comment: 15 pages, 11 figure
Measurement of Atmospheric Neutrino Oscillations with a High-Density Detector
We propose an experiment to test the hypothesis that the reported anomaly on
atmospheric neutrino fluxes is due to nu_mu nu_x oscillations. It will rely
both on a disappearance technique, exploiting the method of the dependence of
the event rate on L/E, which was recently shown to be effective for detection
of neutrino oscillation and measurement of the oscillation parameters, and on
an appearance technique, looking for an excess of muon-less events at high
energy produced by upward-going tau neutrinos. The detector will consist of
iron planes interleaved by limited streamer tubes. The total mass will be about
30 kt. The possibility of recuperating most of the instrumentation from
existing detectors allows to avoid R&D phases and to reduce construction time.
In four years of data taking, this experiment will be sensitive to oscillations
nu_mu nu_x with Delta m^2 > 10^-4 eV^2 and a mixing near to maximal, and
answer the question whether nu_x is a sterile or a tau neutrino
First operation and performance of a 200 lt double phase LAr LEM-TPC with a 40x76 cm^2 readout
In this paper we describe the design, construction, and operation of a first
large area double-phase liquid argon Large Electron Multiplier Time Projection
Chamber (LAr LEM-TPC). The detector has a maximum drift length of 60 cm and the
readout consists of a cm LEM and 2D projective anode to
multiply and collect drifting charges. Scintillation light is detected by means
of cryogenic PMTs positioned below the cathode. To record both charge and light
signals, we have developed a compact acquisition system, which is scalable up
to ton-scale detectors with thousands of charge readout channels. The
acquisition system, as well as the design and the performance of custom-made
charge sensitive preamplifiers, are described. The complete experimental setup
has been operated for a first time during a period of four weeks at CERN in the
cryostat of the ArDM experiment, which was equipped with liquid and gas argon
purification systems. The detector, exposed to cosmic rays, recorded events
with a single-channel signal-to-noise ratio in excess of 30 for minimum
ionising particles. Cosmic muon tracks and their -rays were used to
assess the performance of the detector, and to estimate the liquid argon purity
and the gain at different amplification fields.Comment: 23 pages, 21 figure
Giant Liquid Argon Observatory for Proton Decay, Neutrino Astrophysics and CP-violation in the Lepton Sector (GLACIER)
GLACIER (Giant Liquid Argon Charge Imaging ExpeRiment) is a large underground
observatory for proton decay search, neutrino astrophysics and CP-violation
studies in the lepton sector. Possible underground sites are studied within the
FP7 LAGUNA project (Europe) and along the JPARC neutrino beam in collaboration
with KEK (Japan). The concept is scalable to very large masses.Comment: 4 pages, 1 figure, Contribution to the Workshop "European Strategy
for Future Neutrino Physics", CERN, Oct. 200
An Ontology of Soil Properties and Processes
Assessing the Underworld (ATU) is a large interdisciplinary UK research project, which addresses challenges in integrated inter-asset maintenance. As assets on the surface of the ground (e.g. roads or pave- ments) and those buried under it (e.g. pipes and cables) are supported by the ground, the properties and processes of soil a ect the performance of these assets to a signi cant degree. In order to make integrated deci- sions, it is necessary to combine the knowledge and expertise in multiple areas, such as roads, soil, buried assets, sensing, etc. This requires an underpinning knowledge model, in the form of an ontology. Within this context, we present a new ontology for describing soil properties (e.g. soil strength) and processes (e.g. soil compaction), as well as how they a ect each other. This ontology can be used to express how the ground a ects and is a ected by assets buried under the ground or on the ground surface. The ontology is written in OWL 2 and openly available from the University of Leeds data repository: http://doi.org/10.5518/54
Stable operation with gain of a double phase Liquid Argon LEM-TPC with a 1 mm thick segmented LEM
In this paper we present results from a test of a small Liquid Argon Large
Electron Multiplier Time Projection Chamber (LAr LEM-TPC). This detector
concept provides a 3D-tracking and calorimetric device capable of charge
amplification, suited for next-generation neutrino detectors and possibly
direct Dark Matter searches. During a test of a 3~lt chamber equipped with a
1010~cm readout, cosmic muon data was recorded during three weeks
of data taking. A maximum gain of 6.5 was achieved and the liquid argon was
kept pure enough to ensure 20~cm drift (O(ppb)~O equivalent).Comment: 7 pages, 6 figures, to appear in Proc. of 1st International Workshop
towards the Giant Liquid Argon Charge Imaging Experiment (GLA2010), Tsukuba
(Japan), March 201
First operation of a double phase LAr Large Electron Multiplier Time Projection Chamber with a two-dimensional projective readout anode
We have previously reported on the construction and successful operation of
the novel double phase Liquid Argon Large Electron Multiplier Time Projection
Chamber (LAr LEM-TPC). This detector concept provides a 3D-tracking and
calorimetric device capable of adjustable charge amplification, a promising
readout technology for next-generation neutrino detectors and direct Dark
Matter searches. In this paper, we report on the first operation of a LAr
LEM-TPC prototype - with an active area of 1010 cm and 21 cm drift
length - equipped with a single 1 mm thick LEM amplifying stage and a two
dimensional projective readout anode. Cosmic muon events were collected, fully
reconstructed and used to characterize the performance of the chamber. The
obtained signals provide images of very high quality and the energy loss
distributions of minimum ionizing tracks give a direct estimate of the
amplification. We find that a stable gain of 27 can be achieved with this
detector configuration corresponding to a signal-over-noise ratio larger than
200 for minimum ionizing tracks. The decoupling of the amplification stage and
the use of the 2D readout anode offer several advantages which are described in
the text.Comment: 25 pages, 17 figure
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