16 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
3D Position Sensitive XeTPC for Dark Matter Search
The technique to realize 3D position sensitivity in a two-phase xenon time
projection chamber (XeTPC) for dark matter search is described. Results from a
prototype detector (XENON3) are presented.Comment: Presented at the 7th UCLA Symposium on "Sources and Detection of Dark
Matter and Dark Energy in the Universe
Constraints on inelastic dark matter from XENON10
It has been suggested that dark matter particles which scatter inelastically
from detector target nuclei could explain the apparent incompatibility of the
DAMA modulation signal (interpreted as evidence for particle dark matter) with
the null results from CDMS-II and XENON10. Among the predictions of
inelastically interacting dark matter are a suppression of low-energy events,
and a population of nuclear recoil events at higher nuclear recoil equivalent
energies. This is in stark contrast to the well-known expectation of a falling
exponential spectrum for the case of elastic interactions. We present a new
analysis of XENON10 dark matter search data extending to E keV
nuclear recoil equivalent energy. Our results exclude a significant region of
previously allowed parameter space in the model of inelastically interacting
dark matter. In particular, it is found that dark matter particle masses
GeV are disfavored.Comment: 8 pages, 4 figure
A search for light dark matter in XENON10 data
We report results of a search for light (<10 GeV) particle dark matter with
the XENON10 detector. The event trigger was sensitive to a single electron,
with the analysis threshold of 5 electrons corresponding to 1.4 keV nuclear
recoil energy. Considering spin-independent dark matter-nucleon scattering, we
exclude cross sections \sigma_n>3.5x10^{-42} cm^2, for a dark matter particle
mass m_{\chi}=8 GeV. We find that our data strongly constrain recent elastic
dark matter interpretations of excess low-energy events observed by CoGeNT and
CRESST-II, as well as the DAMA annual modulation signal.Comment: Manuscript identical to v2 (published version) but also contains
erratum. Note v3==v2 but without \linenumber
First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory
The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg
xenon dual phase time projection chamber (XeTPC) to search for dark matter
weakly interacting massive particles (WIMPs). The detector measures
simultaneously the scintillation and the ionization produced by radiation in
pure liquid xenon, to discriminate signal from background down to 4.5 keV
nuclear recoil energy. A blind analysis of 58.6 live days of data, acquired
between October 6, 2006 and February 14, 2007, and using a fiducial mass of 5.4
kg, excludes previously unexplored parameter space, setting a new 90% C.L.
upper limit for the WIMP-nucleon spin-independent cross-section of 8.8 x
10^{-44} cm^2 for a WIMP mass of 100 GeV/c^2, and 4.5 x 10^{-44} cm^2 for a
WIMP mass of 30 GeV/c^2. This result further constrains predictions of
supersymmetric models.Comment: accepted for publication in Phys. Rev. Let
The scintillation and ionization yield of liquid xenon for nuclear recoils
XENON10 is an experiment designed to directly detect particle dark matter. It
is a dual phase (liquid/gas) xenon time-projection chamber with 3D position
imaging. Particle interactions generate a primary scintillation signal (S1) and
ionization signal (S2), which are both functions of the deposited recoil energy
and the incident particle type. We present a new precision measurement of the
relative scintillation yield \leff and the absolute ionization yield Q_y, for
nuclear recoils in xenon. A dark matter particle is expected to deposit energy
by scattering from a xenon nucleus. Knowledge of \leff is therefore crucial for
establishing the energy threshold of the experiment; this in turn determines
the sensitivity to particle dark matter. Our \leff measurement is in agreement
with recent theoretical predictions above 15 keV nuclear recoil energy, and the
energy threshold of the measurement is 4 keV. A knowledge of the ionization
yield \Qy is necessary to establish the trigger threshold of the experiment.
The ionization yield \Qy is measured in two ways, both in agreement with
previous measurements and with a factor of 10 lower energy threshold.Comment: 8 pages, 9 figures. To be published in Nucl. Instrum. Methods
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
3D Position Sensitive XeTPC for Dark Matter Search
The technique to realize 3D position sensitivity in a two-phase xenon time projection chamber (XeTPC) is described. Results from a prototype detector (XENON3) are presented.http://www.sciencedirect.com/science/article/B6TVD-4R68DXJ-13/1/c7a25befd9bec275706d42709c6eb3c