480 research outputs found
A test of the Feynman scaling in the fragmentation region
The result of the direct measurement of the fragmentation region will be presented. The result will be obtained at the CERN proton-antiproton collider, being exposured the Silicon calorimeters inside beam pipe. This experiment clarifies a long riddle of cosmic ray physics, whether the Feynman scaling does villate at the fragmentation region or the Iron component is increasing at 10 to the 15th power eV
Compton Imaging of MeV Gamma-Rays with the Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT)
The Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT) is the first
realization of a liquid xenon time projection chamber for Compton imaging of
MeV gamma-ray sources in astrophysics. By measuring the energy deposit and the
three spatial coordinates of individual gamma-ray scattering points, the
location of the source in the sky is inferred with Compton kinematics
reconstruction. The angular resolution is determined by the detector's energy
and spatial resolutions, as well as by the separation in space between the
first and second scattering. The imaging response of LXeGRIT was established
with gamma-rays from radioactive sources, during calibration and integration at
the Columbia Astrophysics Laboratory, prior to the 2000 balloon flight mission.
In this paper we describe in detail the various steps involved in imaging
sources with LXeGRIT and present experimental results on angular resolution and
other parameters which characterize its performance as a Compton telescope.Comment: 22 pages, 20 figures, submitted to NIM
A liquid Xenon Positron Emission Tomograph for small animal imaging : first experimental results of a prototype cell
A detector using liquid Xenon (LXe) in the scintillation mode is studied for
Positron Emission Tomography (PET) of small animals. Its specific design aims
at taking full advantage of the Liquid Xenon scintillation properties. This
paper reports on energy, time and spatial resolution capabilities of the first
LXe prototype module equipped with a Position Sensitive Photo- Multiplier tube
(PSPMT) operating in the VUV range (178 nm) and at 165 K. The experimental
results show that such a LXe PET configuration might be a promising solution
insensitive to any parallax effect.Comment: 34 pages, 18 pages, to appear in NIM
Absorption of Scintillation Light in a 100 Liquid Xenon Ray Detector and Expected Detector Performance
An 800L liquid xenon scintillation ray detector is being developed
for the MEG experiment which will search for decay
at the Paul Scherrer Institut. Absorption of scintillation light of xenon by
impurities might possibly limit the performance of such a detector. We used a
100L prototype with an active volume of 372x372x496 mm to study the
scintillation light absorption. We have developed a method to evaluate the
light absorption, separately from elastic scattering of light, by measuring
cosmic rays and sources. By using a suitable purification technique,
an absorption length longer than 100 cm has been achieved. The effects of the
light absorption on the energy resolution are estimated by Monte Carlo
simulation.Comment: 18 pages, 10 figures (eps). Submitted to Nucl. Instr. and Meth.
Scintillation yield of liquid xenon at room temperature
The intensity of scintillation light emission from liquid xenon at room
temperature was measured. The scintillation light yield at 1 deg. was measured
to be 0.64 +/- 0.02 (stat.) +/- 0.06 (sys.) of that at -100 deg. Using the
reported light yield at -100 deg. (46 photons/keV), the measured light yield at
1 deg. corresponds to 29 photons/keV. This result shows that liquid xenon
scintillator gives high light yield even at room temperature.Comment: 16pages,12figure
On the Background Rate in the LXeGRIT Instrument during the 2000 Balloon Flight
LXeGRIT is the first prototype of a novel Compton telescope for MeV gamma-ray
astrophysics based on a Liquid Xenon Time Projection Chamber (LXeTPC),
sensitive in the energy band of 0.15-10 MeV. In this homogeneous, 3D position
sensitive detector, gamma rays with at least two interactions in the sensitive
volume of 2800 cm, are imaged as in a standard Compton telescope.
Gamma-rays with a single interaction cannot be imaged and constitute a
background which can be easily identified and rejected. Charged particles and
localized beta-particles background is also easily suppressed based on the TPC
localization capability with millimeter resolution. A measurement of the total
gamma-ray background rate in near space conditions and the background rejection
power of the LXeTPC was a primary goal of the LXeGRIT balloon flight program.
We present here a preliminary analysis addressing this question, based on
balloon flight data acquired during the Oct 4-5, 2000 LXeGRIT balloon flight
from Ft. Sumner, NM. In this long duration (27 hr) balloon experiment, the
LXeGRIT TPC was not surrounded by any gamma-ray or charged particle shield.
Single site events and charged particles were mostly rejected on-line at the
first and second trigger level. The remaining count rate of single-site \g-ray
events, at an average atmospheric depth of 3.2 g cm, is consistent with
that expected from atmospheric and diffuse gamma-ray background, taking into
account the instrument mass model and response.Comment: 13 pages, 12 figures, SPIE 2002 Proceedings, Conf. Vol. 4851 - 151;
corrected reference
Design and Performance of the XENON10 Dark Matter Experiment
XENON10 is the first two-phase xenon time projection chamber (TPC) developed
within the XENON dark matter search program. The TPC, with an active liquid
xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground
laboratory (LNGS) in Italy, and operated for more than one year, with excellent
stability and performance. Results from a dark matter search with XENON10 have
been published elsewhere. In this paper, we summarize the design and
performance of the detector and its subsystems, based on calibration data using
sources of gamma-rays and neutrons as well as background and Monte Carlo
simulations data. The results on the detector's energy threshold, energy and
position resolution, and overall efficiency show a performance that exceeds
design specifications, in view of the very low energy threshold achieved (<10
keVr) and the excellent energy resolution achieved by combining the ionization
and scintillation signals, detected simultaneously
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