472 research outputs found
Muon-induced neutron production and detection with GEANT4 and FLUKA
We report on a comparison study of the Monte Carlo packages GEANT4 and FLUKA
for simulating neutron production by muons penetrating deep underground. GEANT4
is found to generate fewer neutrons at muon energies above ~100 GeV, by at most
a factor of 2 in some materials, which we attribute mainly to lower neutron
production in hadronic cascades. As a practical case study, the muon-induced
neutron background expected in a 250 kg liquid-xenon WIMP dark matter detector
was calculated and good agreement was found for the recoil event rates. The
detailed model of neutron elastic scattering in GEANT4 was also shown to
influence the nuclear recoil spectrum observed in the target, which is
presently a shortcoming of FLUKA. We conclude that both packages are suited for
this type of simulation, although further improvements are desirable in both
cases.Comment: (23 pages, 14 figures) To appear in Nucl. Instrum. Meth. A v2:
Changes to format only; v3: Corrected typo in front matter; v4: Looked up
additional experimental data for comparison with simulation
Measurements of Scintillation Efficiency and Pulse-Shape for Low Energy Recoils in Liquid Xenon
Results of observations of low energy nuclear and electron recoil events in
liquid xenon scintillator detectors are given. The relative scintillation
efficiency for nuclear recoils is 0.22 +/- 0.01 in the recoil energy range 40
keV - 70 keV. Under the assumption of a single dominant decay component to the
scintillation pulse-shape the log-normal mean parameter T0 of the maximum
likelihood estimator of the decay time constant for 6 keV < Eee < 30 keV
nuclear recoil events is equal to 21.0 ns +/- 0.5 ns. It is observed that for
electron recoils T0 rises slowly with energy, having a value ~ 30 ns at Eee ~
15 keV. Electron and nuclear recoil pulse-shapes are found to be well fitted by
single exponential functions although some evidence is found for a double
exponential form for the nuclear recoil pulse-shape.Comment: 11 pages, including 5 encapsulated postscript figure
Neutron background in large-scale xenon detectors for dark matter searches
Simulations of the neutron background for future large-scale particle dark
matter detectors are presented. Neutrons were generated in rock and detector
elements via spontaneous fission and (alpha,n) reactions, and by cosmic-ray
muons. The simulation techniques and results are discussed in the context of
the expected sensitivity of a generic liquid xenon dark matter detector.
Methods of neutron background suppression are investigated. A sensitivity of
pb to WIMP-nucleon interactions can be achieved by a
tonne-scale detector.Comment: 35 pages, 13 figures, 2 tables, accepted for publication in
Astroparticle Physic
A two-phase argon avalanche detector operated in a single electron counting mode
The performance of a two-phase Ar avalanche detector in a single electron
counting mode was studied, with regard to potential application in coherent
neutrino-nucleus scattering and dark matter search experiments. The detector
comprised of a 1 cm thick liquid Ar layer and a triple-GEM multiplier operated
in the saturated vapour above the liquid phase. Successful operation of the
detector in single electron counting mode, in the gain range from 6000 to
40000, has for the first time been demonstrated.Comment: 9 pages, 9 figures. Submitted to JINS
Structural, mechanical, and electrochemical properties of Ceria doped Scandia stabilized Zirconia
The properties of Ceria doped Scandia Stabilized Zirconia (1Ce10ScSZ) nano-powder produced in Ukraine (Ukr, VMMP) are compared to the properties of commercial ones produced by Daiichi Kigenso Kagaku Kogyo (DKKK, Japan) and Praxair (USA). In comparison to DKKK and Praxair, the Ukr nano-powder demonstrated the smallest size of the particles ranging from 20 to 50 nm. The bending strength of the isostatically pressed samples made of Ukr powder was 100â120 MPa similar to that of Praxair. The bending strength of DKKK was lower (50â100 MPa) depending on the isostatic pressure. The biaxial strength of uniaxially pressed samples was the highest for DKKK (375 MPa) decreasing to 250 MPa for Ukr and 220 MPa for Praxair. Among three tested samples, the highest electric conductivity measured at 700 °C was found for Ukr electrolyte.ĐĐžĐČŃĐ”ĐœĐŸ Đč ĐżĐŸŃŃĐČĐœŃĐœĐŸ ĐČлаŃŃĐžĐČĐŸŃŃŃ ĐœĐ°ĐœĐŸĐżĐŸŃĐŸŃĐșŃĐČ ĐŽĐČĐŸĐŸĐșĐžŃŃ ŃĐžŃĐșĐŸĐœŃŃ, ŃŃабŃĐ»ŃĐ·ĐŸĐČĐ°ĐœĐŸĐłĐŸ ĐŽĐČĐŸĐŸĐșĐžŃĐ°ĐŒĐž ŃĐ”ŃŃŃ ŃĐ° ŃĐșĐ°ĐœĐŽŃŃ 1Ce10ScSZ, ŃĐșŃ ĐČĐžĐłĐŸŃĐŸĐČĐ»Đ”ĐœĐŸ ĐČ ĐŁĐșŃĐ°ŃĐœŃ ĐœĐ° ĐŃĐ»ŃĐœĐŸĐłŃŃŃŃĐșĐŸĐŒŃ ĐŽĐ”ŃжаĐČĐœĐŸĐŒŃ ĐłŃŃĐœĐžŃĐŸ-ĐŒĐ”ŃĐ°Đ»ŃŃĐłŃĐčĐœĐŸĐŒŃ ĐșĐŸĐŒĐ±ŃĐœĐ°ŃŃ (ĐĐĐĐĐ), ĐČ ĐŻĐżĐŸĐœŃŃ ĐșĐŸĐŒĐżĐ°ĐœŃŃŃ Â«Daiichi Kigenso Kagaku Kogyo» (DKKK) ŃĐ° ĐČ ĐĄĐšĐ ĐșĐŸĐŒĐżĐ°ĐœŃŃŃ Â«Praxair». ĐĐŸŃŃĐČĐœŃĐœĐŸ Đ· ĐżĐŸŃĐŸŃĐșĐ°ĐŒĐž ĐČĐžŃĐŸĐ±ĐœĐžŃŃĐČĐ° DKKK ŃĐ° «Praxair» ĐżĐŸŃĐŸŃĐŸĐș ĐČĐžŃĐŸĐ±ĐœĐžŃŃĐČĐ° ĐĐĐĐĐ (ĐżĐŸĐ·ĐœĐ°ŃĐ”ĐœĐŸ ŃĐș «Ukr») ĐŒĐ°Ń ĐœĐ°ĐčĐŒĐ”ĐœŃĐžĐč ŃĐŸĐ·ĐŒŃŃ ŃĐ°ŃŃĐžĐœĐŸĐș ĐČ ŃĐœŃĐ”ŃĐČĐ°Đ»Ń 20-50 ĐœĐŒ. ĐŃŃĐœŃŃŃŃ Đ·ŃĐ°Đ·ĐșŃĐČ, ĐČĐžĐłĐŸŃĐŸĐČĐ»Đ”ĐœĐžŃ
ŃĐ· ĐżĐŸŃĐŸŃĐșŃ Â«Ukr» ŃĐ· ĐČĐžĐșĐŸŃĐžŃŃĐ°ĐœĐœŃĐŒ ŃĐ·ĐŸŃŃĐ°ŃĐžŃĐœĐŸĐłĐŸ ĐżŃĐ”ŃŃĐČĐ°ĐœĐœŃ, ŃŃĐ°ĐœĐŸĐČĐžŃŃ 100-120 ĐĐĐ° ĐżŃĐž Đ·ĐłĐžĐœŃ ŃĐ° Ń ĐżĐŸĐŽŃĐ±ĐœĐŸŃ ĐŽĐŸ ĐŒŃŃĐœĐŸŃŃŃ ĐżĐŸŃĐŸŃĐșŃ ĐČĐžŃĐŸĐ±ĐœĐžŃŃĐČĐ° «Praxair». ĐŃŃĐœŃŃŃŃ Đ·ŃĐ°Đ·ĐșŃĐČ ĐČĐžŃĐŸĐ±ĐœĐžŃŃĐČĐ° DKKK ĐŒĐ”ĐœŃĐ° (50-100 ĐĐĐ°) Đč залДжОŃŃ ĐČŃĐŽ ŃĐ·ĐŸŃŃĐ°ŃĐžŃĐœĐŸĐłĐŸ ŃĐžŃĐșŃ. ĐŃŃĐœŃŃŃŃ ĐŸĐŽĐœĐŸĐČŃŃĐœĐŸ ĐżŃĐ”ŃĐŸĐČĐ°ĐœĐžŃ
Đ·ŃĐ°Đ·ĐșŃĐČ ĐœĐ°ĐčĐČĐžŃĐ° ĐČ ĐżĐŸŃĐŸŃĐșŃ DKKK (375 ĐĐĐ°), Ń Đ·ŃĐ°Đ·ĐșĐ°Ń
«Ukr» Ń Â«Praxair» ĐČĐŸĐœĐ° ŃŃĐ°ĐœĐŸĐČĐžŃŃ ĐČŃĐŽĐżĐŸĐČŃĐŽĐœĐŸ 250 ĐĐĐ° ŃĐ° 220 ĐĐĐ°. ĐĐ·-ĐżĐŸĐŒŃж ŃŃŃĐŸŃ
ĐŽĐŸŃĐ»ŃĐŽĐ¶Đ”ĐœĐžŃ
ŃĐ”ŃŃĐč Đ·ŃĐ°Đ·ĐșŃĐČ ĐœĐ°ĐčĐČĐžŃŃ Đ”Đ»Đ”ĐșŃŃĐžŃĐœŃ ĐżŃĐŸĐČŃĐŽĐœŃŃŃŃ ĐżŃĐž 700 °Х ĐŒĐ°Đ»Đž ДлДĐșŃŃĐŸĐ»ŃŃĐž, ĐČĐžĐłĐŸŃĐŸĐČĐ»Đ”ĐœŃ Đ· ĐżĐŸŃĐŸŃĐșŃ Â«Ukr».ĐŃлО ОзŃŃĐ”ĐœŃ Đž ŃŃĐ°ĐČĐœĐ”ĐœŃ ŃĐČĐŸĐčŃŃĐČĐ° ĐœĐ°ĐœĐŸĐżĐŸŃĐŸŃĐșĐŸĐČ ĐŽĐČŃĐŸĐșĐžŃĐž ŃĐžŃĐșĐŸĐœĐžŃ, ŃŃабОлОзОŃĐŸĐČĐ°ĐœĐœĐŸĐłĐŸ ĐŸĐșĐžŃĐ»Đ°ĐŒĐž ŃĐ”ŃĐžŃ Đž ŃĐșĐ°ĐœĐŽĐžŃ 1Ce10ScSZ, ĐșĐŸŃĐŸŃŃĐ” ĐżŃĐŸĐžĐ·ĐČĐ”ĐŽĐ”ĐœŃ ĐČ ĐŁĐșŃĐ°ĐžĐœĐ” ĐœĐ° ĐĐŸĐ»ŃĐœĐŸĐłĐŸŃŃĐșĐŸĐŒ ĐłĐŸŃŃĐŽĐ°ŃŃŃĐČĐ”ĐœĐœĐŸĐŒ ĐłĐŸŃĐœĐŸ-ĐŒĐ”ŃаллŃŃгОŃĐ”ŃĐșĐŸĐŒ ĐșĐŸĐŒĐ±ĐžĐœĐ°ŃĐ” (ĐĐĐĐĐ), ĐČ ĐŻĐżĐŸĐœĐžĐž ĐșĐŸĐŒĐżĐ°ĐœĐžĐ”Đč «Daiichi Kigenso Kagaku Kogyo» (DKKK) Đž ĐČ ĐĄĐšĐ ĐșĐŸĐŒĐżĐ°ĐœĐžĐ”Đč «Praxair». Đ ŃŃĐ°ĐČĐœĐ”ĐœĐžĐž Ń ĐżĐŸŃĐŸŃĐșĐ°ĐŒĐž ĐżŃĐŸĐžĐ·ĐČĐŸĐŽŃŃĐČĐ° DKKK Đž «Praxair» Ń ĐżĐŸŃĐŸŃĐșĐ° ĐżŃĐŸĐžĐ·ĐČĐŸĐŽŃŃĐČĐ° ĐĐĐĐĐ (ĐŸĐ±ĐŸĐ·ĐœĐ°ŃĐ”Đœ ĐșĐ°Đș «Ukr») ĐœĐ°ĐžĐŒĐ”ĐœŃŃĐžĐč ŃĐ°Đ·ĐŒĐ”Ń ŃĐ°ŃŃĐžŃ ĐČ ĐžĐœŃĐ”ŃĐČалД 20â50 ĐœĐŒ. ĐŃĐŸŃĐœĐŸŃŃŃ ĐŸĐ±ŃĐ°Đ·ŃĐŸĐČ, ĐžĐ·ĐłĐŸŃĐŸĐČĐ»Đ”ĐœĐœŃŃ
Оз ĐżĐŸŃĐŸŃĐșĐ° «Ukr» Ń ĐžŃĐżĐŸĐ»ŃĐ·ĐŸĐČĐ°ĐœĐžĐ”ĐŒ ĐžĐ·ĐŸŃŃĐ°ŃĐžŃĐ”ŃĐșĐŸĐłĐŸ ĐżŃĐ”ŃŃĐŸĐČĐ°ĐœĐžŃ, ŃĐŸŃŃĐ°ĐČĐ»ŃĐ”Ń 100â120 ĐĐĐ° ĐżŃĐž ОзгОбД Đž ĐżĐŸĐŽĐŸĐ±ĐœĐ° ĐżŃĐŸŃĐœĐŸŃŃĐž ĐŸĐ±ŃĐ°Đ·ŃĐŸĐČ ĐžĐ· ĐżĐŸŃĐŸŃĐșĐ° ĐżŃĐŸĐžĐ·ĐČĐŸĐŽŃŃĐČĐ° «Praxair». ĐŃĐŸŃĐœĐŸŃŃŃ ĐŸĐ±ŃĐ°Đ·ŃĐŸĐČ ĐžĐ· ĐżĐŸŃĐŸŃĐșĐ° DKKK ĐŒĐ”ĐœŃŃĐ” (50â100 ĐĐĐ°) Đž Đ·Đ°ĐČĐžŃĐžŃ ĐŸŃ ĐŽĐ°ĐČĐ»Đ”ĐœĐžŃ ĐžĐ·ĐŸŃŃĐ°ŃĐžŃĐ”ŃĐșĐŸĐłĐŸ ĐżŃĐ”ŃŃĐŸĐČĐ°ĐœĐžŃ. ĐŃĐŸŃĐœĐŸŃŃŃ ĐŸĐŽĐœĐŸĐŸŃĐœĐŸ ĐżŃĐ”ŃŃĐŸĐČĐ°ĐœĐœŃŃ
ĐŸĐ±ŃĐ°Đ·ŃĐŸĐČ ĐœĐ°ĐžĐ±ĐŸĐ»Đ”Đ” ĐČŃŃĐŸĐșĐ° (375 ĐĐĐ°) Ń ĐżĐŸŃĐŸŃĐșĐ° DKKK, ĐČ ĐŸĐ±ŃĐ°Đ·ŃĐ°Ń
«Ukr» Đž «Praxair» ĐŸĐœĐ° ŃĐŸŃŃĐ°ĐČĐ»ŃĐ”Ń ŃĐŸĐŸŃĐČĐ”ŃŃŃĐČĐ”ĐœĐœĐŸ 250 ĐĐĐ° Đž 220 ĐĐĐ°. ĐĐ· ŃŃĐ”Ń
ĐžŃĐżŃŃĐ°ĐœĐœŃŃ
ŃĐ”ŃĐžĐč ĐŸĐ±ŃĐ°Đ·ŃĐŸĐČ ŃĐ°ĐŒĐ°Ń ĐČŃŃĐŸĐșĐ°Ń ŃлДĐșŃŃĐŸĐżŃĐŸĐČĐŸĐŽĐœĐŸŃŃŃ ĐżŃĐž 700 °Х бŃла Ń ŃлДĐșŃŃĐŸĐ»ĐžŃĐŸĐČ, ĐžĐ·ĐłĐŸŃĐŸĐČĐ»Đ”ĐœĐœŃŃ
Оз ĐżĐŸŃĐŸŃĐșĐ° «Ukr»
The ZEPLIN-III dark matter detector: performance study using an end-to-end simulation tool
We present results from a GEANT4-based Monte Carlo tool for end-to-end
simulations of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase
detector which measures both the scintillation light and the ionisation charge
generated in liquid xenon by interacting particles and radiation. The software
models the instrument response to radioactive backgrounds and calibration
sources, including the generation, ray-tracing and detection of the primary and
secondary scintillations in liquid and gaseous xenon, and subsequent processing
by data acquisition electronics. A flexible user interface allows easy
modification of detector parameters at run time. Realistic datasets can be
produced to help with data analysis, an example of which is the position
reconstruction algorithm developed from simulated data. We present a range of
simulation results confirming the original design sensitivity of a few times
pb to the WIMP-nucleon cross-section.Comment: Submitted to Astroparticle Physic
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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