174 research outputs found
Spectroscopy of electron-induced fluorescence in organic liquidscintillators
Emission spectra of several organic liquid-scintillator mixtures which are relevant for the proposed LENA detector have been measured by exciting the medium with electrons of ∼10keV. The results are compared with spectra resulting from ultraviolet light excitation. Good agreement between spectra measured by both methods has been foun
Radon daughter removal from PTFE surfaces and its application in liquid xenon detectors
Long-lived radon daughters are a critical background source in experiments
searching for low-energy rare events. Originating from radon in ambient air,
radioactive polonium, bismuth and lead isotopes plate-out on materials that are
later employed in the experiment. In this paper, we examine cleaning procedures
for their capability to remove radon daughters from PTFE surfaces, a material
often used in liquid xenon TPCs. We found a large difference between the
removal efficiency obtained for the decay chains of Rn and Rn,
respectively. This indicates that the plate-out mechanism has an effect on the
cleaning success. While the long-lived Rn daughters could be reduced by
a factor of ~2, the removal of Rn daughters was up to 10 times more
efficient depending on the treatment. Furthermore, the impact of a nitric acid
based PTFE cleaning on the liquid xenon purity is investigated in a small-scale
liquid xenon TPC
Gator: a low-background counting facility at the Gran Sasso Underground Laboratory
A low-background germanium spectrometer has been installed and is being
operated in an ultra-low background shield (the Gator facility) at the Gran
Sasso underground laboratory in Italy (LNGS). With an integrated rate of ~0.16
events/min in the energy range between 100-2700 keV, the background is
comparable to those of the world's most sensitive germanium detectors. After a
detailed description of the facility, its background sources as well as the
calibration and efficiency measurements are introduced. Two independent
analysis methods are described and compared using examples from selected sample
measurements. The Gator facility is used to screen materials for XENON, GERDA,
and in the context of next-generation astroparticle physics facilities such as
DARWIN.Comment: 14 pages, 6 figures, published versio
Detection potential for the diffuse supernova neutrino background in the large liquid-scintillator detector LENA
The large-volume liquid-scintillator detector LENA (Low Energy Neutrino
Astronomy) will provide high-grade background discrimination and enable the
detection of diffuse supernova neutrinos (DSN) in an almost background-free
energy window from ~10 to 25 MeV. Within ten years of exposure, it will be
possible to derive significant constraints on both core-collapse supernova
models and the supernova rate in the near universe up to redshifts z<2.Comment: 11 pages, 8 figures. accepted for publication in Phys. Rev. D.
accepted for publication in Phys. Rev.
Low energy neutrino astronomy with the large liquid scintillation detector LENA
The detection of low energy neutrinos in a large scintillation detector may
provide further important information on astrophysical processes as supernova
physics, solar physics and elementary particle physics as well as geophysics.
In this contribution, a new project for Low Energy Neutrino Astronomy (LENA)
consisting of a 50kt scintillation detector is presented.Comment: Proccedings of the International School of Nuclear Physics, Neutrinos
in Cosmology, in Astro, Particle and Nuclear Physics, Erice (SICILY) 16 - 24
Sept. 200
Qualification Tests of the R11410-21 Photomultiplier Tubes for the XENON1T Detector
The Hamamatsu R11410-21 photomultiplier tube is the photodetector of choice for the XENON1T dual-phase time projection chamber. The device has been optimized for a very low intrinsic radioactivity, a high quantum efficiency and a high sensitivity to single photon detection. A total of 248 tubes are currently operated in XENON1T, selected out of 321 tested units. In this article the procedures implemented to evaluate the large number of tubes prior to their installation in XENON1T are described. The parameter distributions for all tested tubes are shown, with an emphasis on those selected for XENON1T, of which the impact on the detector performance is discussed. All photomultipliers have been tested in a nitrogen atmosphere at cryogenic temperatures, with a subset of the tubes being tested in gaseous and liquid xenon, simulating their operating conditions in the dark matter detector. The performance and evaluation of the tubes in the different environments is reported and the criteria for rejection of PMTs are outlined and quantified
Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors
For liquid-scintillator neutrino detectors of kiloton scale, the transparency
of the organic solvent is of central importance. The present paper reports on
laboratory measurements of the optical scattering lengths of the organic
solvents PXE, LAB, and Dodecane which are under discussion for next-generation
experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range
from 415 to 440nm. The contributions from Rayleigh and Mie scattering as well
as from absorption/re-emission processes are discussed. Based on the present
results, LAB seems to be the preferred solvent for a large-volume detector.Comment: 9 pages, 3 figures, accepted for publication by Rev. Scient. Instr
First Dark Matter Results from the XENON100 Experiment
The XENON100 experiment, in operation at the Laboratori Nazionali del Gran
Sasso in Italy, is designed to search for dark matter WIMPs scattering off 62
kg of liquid xenon in an ultra-low background dual-phase time projection
chamber. In this letter, we present first dark matter results from the analysis
of 11.17 live days of non-blind data, acquired in October and November 2009. In
the selected fiducial target of 40 kg, and within the pre-defined signal
region, we observe no events and hence exclude spin-independent WIMP-nucleon
elastic scattering cross-sections above 3.4 x 10^-44 cm^2 for 55 GeV/c^2 WIMPs
at 90% confidence level. Below 20 GeV/c^2, this result constrains the
interpretation of the CoGeNT and DAMA signals as being due to spin-independent,
elastic, light mass WIMP interactions.Comment: 5 pages, 5 figures. Matches published versio
Material screening and selection for XENON100
Results of the extensive radioactivity screening campaign to identify
materials for the construction of XENON100 are reported. This Dark Matter
search experiment is operated underground at Laboratori Nazionali del Gran
Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors
(HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been
applied for a few low mass plastic samples. Detailed tables with the
radioactive contaminations of all screened samples are presented, together with
the implications for XENON100.Comment: 8 pages, 1 figur
Implications on Inelastic Dark Matter from 100 Live Days of XENON100 Data
The XENON100 experiment has recently completed a dark matter run with 100.9
live-days of data, taken from January to June 2010. Events in a 48kg fiducial
volume in the energy range between 8.4 and 44.6 keVnr have been analyzed. A
total of three events have been found in the predefined signal region,
compatible with the background prediction of (1.8 \pm 0.6) events. Based on
this analysis we present limits on the WIMP-nucleon cross section for inelastic
dark matter. With the present data we are able to rule out the explanation for
the observed DAMA/LIBRA modulation as being due to inelastic dark matter
scattering off iodine at a 90% confidence level.Comment: 3 pages, 3 figure
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