725 research outputs found
Drift field generation with Cockcroft-Walton voltage multiplier in xenon gas for AXEL 0vββ search detector
16th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2019) 9-13 September 2019, Toyama, JapanFor noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC
Design and performance of a high-pressure xenon gas TPC as a prototype for a large-scale neutrinoless double-beta decay search
A high-pressure xenon gas time projection chamber, with a unique cellular
readout structure based on electroluminescence, has been developed for a
large-scale neutrinoless double-beta decay search. In order to evaluate the
detector performance and validate its design, a 180~L size prototype is being
constructed and its commissioning with partial detector has been performed. The
obtained energy resolution at 4.0~bar is 1.73 0.07% (FWHM) at 511 keV.
The energy resolution at the Xe neutrinoless double-beta decay Q-value
is estimated to be between 0.79 and 1.52% (FWHM) by extrapolation.
Reconstructed event topologies show patterns peculiar to track end-point which
can be used to distinguish signals from gamma-ray backgrounds.Comment: 24 pages, 25 figures, 1 table. Preprint paper for PTE
Landau model for uniaxial systems with complex order parameter
We study the Landau model for uniaxial incommensurate-commensurate systems of
the I class by keeping Umklapp terms of third and fourth order in the expansion
of the free energy. It applies to systems in which the soft mode minimum lies
between the corresponding commensurate wave numbers. The minimization of the
Landau functional leads to the sine-Gordon equation with two nonlinear terms,
equivalent to the equation of motion for the well-known classical mechanical
problem of two mixing resonances. We calculate the average free energies for
periodic, quasiperiodic and chaotic solutions of this equation, and show that
in the regime of finite strengths of Umklapp terms only periodic solutions are
absolute minima of the free energy, so that the phase diagram contains only
commensurate configurations. The phase transitions between neighboring
configurations are of the first order, and the wave number of ordering goes
through harmless staircase with a finite number of steps. These results are the
basis for the interpretation of phase diagrams for some materials from the I
class of incommensurate-commensurate systems, in particular of those for
ABX and BCCD compounds. Also, we argue that chaotic barriers which
separate metastable periodic solutions represent an intrinsic mechanism for
observed memory effects and thermal hystereses.Comment: 12 pages, 14 figures, LaTeX, to be published in Phys. Rev.
The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines
The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of
kton liquid double phase TPC complemented by a magnetised iron
calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km
from CERN. The conventional neutrino beam is produced by 400 GeV protons
accelerated at the SPS accelerator delivering 700 kW of power. The long
baseline provides a unique opportunity to study neutrino flavour oscillations
over their 1st and 2nd oscillation maxima exploring the behaviour, and
distinguishing effects arising from and matter. In this paper we
show how this comprehensive physics case can be further enhanced and
complemented if a neutrino beam produced at the Protvino IHEP accelerator
complex, at a distance of 1160 km, and with modest power of 450 kW is aimed
towards the same far detectors. We show that the coupling of two independent
sub-MW conventional neutrino and antineutrino beams at different baselines from
CERN and Protvino will allow to measure CP violation in the leptonic sector at
a confidence level of at least for 50\% of the true values of
with a 20 kton detector. With a far detector of 70 kton, the
combination allows a sensitivity for 75\% of the true values of
after 10 years of running. Running two independent neutrino
beams, each at a power below 1 MW, is more within today's state of the art than
the long-term operation of a new single high-energy multi-MW facility, which
has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 figure
Evidence for the Appearance of Atmospheric Tau Neutrinos in Super-Kamiokande
Super-Kamiokande atmospheric neutrino data were fit with an unbinned maximum
likelihood method to search for the appearance of tau leptons resulting from
the interactions of oscillation-generated tau neutrinos in the detector.
Relative to the expectation of unity, the tau normalization is found to be
1.42 \pm 0.35 \ (stat) {\}^{+0.14}_{-0.12}\ (syst) excluding the
no-tau-appearance hypothesis, for which the normalization would be zero, at the
3.8 level. We estimate that 180.1 \pm 44.3\ (stat)
{\}^{+17.8}_{-15.2}\ (syst) tau leptons were produced in the 22.5 kton
fiducial volume of the detector by tau neutrinos during the 2806 day running
period. In future analyses, this large sample of selected tau events will allow
the study of charged current tau neutrino interaction physics with oscillation
produced tau neutrinos.Comment: 7 pages, 4 figures. This is the version as published in Physical
Review Letters including the supplemental figure. A typographical error in
the description of figure 3 is also correcte
Measurements of , , , and proton production in proton-carbon interactions at 31 GeV/ with the NA61/SHINE spectrometer at the CERN SPS
Measurements of hadron production in p+C interactions at 31 GeV/c are
performed using the NA61/ SHINE spectrometer at the CERN SPS. The analysis is
based on the full set of data collected in 2009 using a graphite target with a
thickness of 4% of a nuclear interaction length. Inelastic and production cross
sections as well as spectra of , , p, and are
measured with high precision. These measurements are essential for improved
calculations of the initial neutrino fluxes in the T2K long-baseline neutrino
oscillation experiment in Japan. A comparison of the NA61/SHINE measurements
with predictions of several hadroproduction models is presented.Comment: v1 corresponds to the preprint CERN-PH-EP-2015-278; v2 matches the
final published versio
Atmospheric neutrino oscillation analysis with sub-leading effects in Super-Kamiokande I, II, and III
We present a search for non-zero theta_{13} and deviations of sin^2
theta_{23} from 0.5 in the oscillations of atmospheric neutrino data from
Super-Kamiokande -I, -II, and -III. No distortions of the neutrino flux
consistent with non-zero theta_{13} are found and both neutrino mass hierarchy
hypotheses are in agreement with the data. The data are best fit at Delta m^2 =
2.1 x 10^-3 eV^2, sin^2 theta_{13} = 0.0, and sin^2 theta_{23} =0.5. In the
normal (inverted) hierarchy theta_{13} and Delta m^2 are constrained at the
one-dimensional 90% C.L. to sin^2 theta_{13} < 0.04 (0.09) and 1.9 (1.7) x
10^-3 < Delta m^2 < 2.6 (2.7) x 10^-3 eV^2. The atmospheric mixing angle is
within 0.407 <= sin^2 theta_{23} <= 0.583 at 90% C.L.Comment: 17 Pages, 14 figures. To be submitted to Phys. Rev. D Minor update to
text after referee comments. Figures modified for better grayscale printing
Quadrupole Anisotropy in Dihadron Azimuthal Correlations in Central Au Collisions at =200 GeV
The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC)
reports measurements of azimuthal dihadron correlations near midrapidity in
Au collisions at =200 GeV. These measurements
complement recent analyses by experiments at the Large Hadron Collider (LHC)
involving central Pb collisions at =5.02 TeV, which
have indicated strong anisotropic long-range correlations in angular
distributions of hadron pairs. The origin of these anisotropies is currently
unknown. Various competing explanations include parton saturation and
hydrodynamic flow. We observe qualitatively similar, but larger, anisotropies
in Au collisions compared to those seen in Pb collisions at the
LHC. The larger extracted values in Au collisions at RHIC are
consistent with expectations from hydrodynamic calculations owing to the larger
expected initial-state eccentricity compared with that from Pb
collisions. When both are divided by an estimate of the initial-state
eccentricity the scaled anisotropies follow a common trend with multiplicity
that may extend to heavy ion data at RHIC and the LHC, where the anisotropies
are widely thought to arise from hydrodynamic flow.Comment: 375 authors, 7 pages, 5 figures. Published in Phys. Rev. Lett. v2 has
minor changes to text and figures in response to PRL referee suggestions.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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