350 research outputs found
Search for the Radiative Capture d+d->^4He+\gamma Reaction from the dd\mu Muonic Molecule State
A search for the muon catalyzed fusion reaction dd --> ^4He +\gamma in the
dd\mu muonic molecule was performed using the experimental \mu CF installation
TRITON and NaI(Tl) detectors for \gamma-quanta. The high pressure target filled
with deuterium at temperatures from 85 K to 800 K was exposed to the negative
muon beam of the JINR phasotron to detect \gamma-quanta with energy 23.8 MeV.
The first experimental estimation for the yield of the radiative deuteron
capture from the dd\mu state J=1 was obtained at the level n_{\gamma}\leq
2\times 10^{-5} per one fusion.Comment: 9 pages, 3 Postscript figures, submitted to Phys. At. Nuc
A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector
We describe a compact, ultra-clean device used to deploy radioactive sources
along the vertical axis of the KamLAND liquid-scintillator neutrino detector
for purposes of calibration. The device worked by paying out and reeling in
precise lengths of a hanging, small-gauge wire rope (cable); an assortment of
interchangeable radioactive sources could be attached to a weight at the end of
the cable. All components exposed to the radiopure liquid scintillator were
made of chemically compatible UHV-cleaned materials, primarily stainless steel,
in order to avoid contaminating or degrading the scintillator. To prevent radon
intrusion, the apparatus was enclosed in a hermetically sealed housing inside a
glove box, and both volumes were regularly flushed with purified nitrogen gas.
An infrared camera attached to the side of the housing permitted real-time
visual monitoring of the cable's motion, and the system was controlled via a
graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements
to text, and revised reference
7Be Solar Neutrino Measurement with KamLAND
We report a measurement of the neutrino-electron elastic scattering rate of
862 keV 7Be solar neutrinos based on a 165.4 kton-day exposure of KamLAND. The
observed rate is 582 +/- 90 (kton-day)^-1, which corresponds to a 862 keV 7Be
solar neutrino flux of (3.26 +/- 0.50) x 10^9 cm^-2s^-1, assuming a pure
electron flavor flux. Comparing this flux with the standard solar model
prediction and further assuming three flavor mixing, a nu_e survival
probability of 0.66 +/- 0.14 is determined from the KamLAND data. Utilizing a
global three flavor oscillation analysis, we obtain a total 7Be solar neutrino
flux of (5.82 +/- 0.98) x 10^9 cm^-2s^-1, which is consistent with the standard
solar model predictions.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
Search for extraterrestrial antineutrino sources with the KamLAND detector
We present the results of a search for extraterrestrial electron
antineutrinos ('s) in the energy range using the KamLAND detector. In an exposure of
4.53 kton-year, we identify 25 candidate events. All of the candidate events
can be attributed to background, most importantly neutral current atmospheric
neutrino interactions, setting an upper limit on the probability of B
solar 's converting into 's at
(90% C.L.), if we assume an undistorted shape. This limit
corresponds to a solar flux of or an event
rate of above the energy threshold
. The present data also allows us to set more
stringent limits on the diffuse supernova neutrino flux and on the annihilation
rates for light dark matter particles.Comment: 22 pages, 6 figure
Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector
We report a measurement of the neutrino-electron elastic scattering rate from
8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The
background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold
is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a
pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a
spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1.
The analysis threshold is driven by 208Tl present in the liquid scintillator,
and the main source of systematic uncertainty is due to background from
cosmogenic 11Be. The measured rate is consistent with existing measurements and
with Standard Solar Model predictions which include matter enhanced neutrino
oscillation.Comment: 6 pages, 3 figure
Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND
Radioactive isotopes produced through cosmic muon spallation are a background
for rare-event detection in detectors, double--decay experiments,
and dark-matter searches. Understanding the nature of cosmogenic backgrounds is
particularly important for future experiments aiming to determine the pep and
CNO solar neutrino fluxes, for which the background is dominated by the
spallation production of C. Data from the Kamioka liquid-scintillator
antineutrino detector (KamLAND) provides valuable information for better
understanding these backgrounds, especially in liquid scintillators, and for
checking estimates from current simulations based upon MUSIC, FLUKA, and
GEANT4. Using the time correlation between detected muons and neutron captures,
the neutron production yield in the KamLAND liquid scintillator is measured to
be . For other isotopes,
the production yield is determined from the observed time correlation related
to known isotope lifetimes. We find some yields are inconsistent with
extrapolations based on an accelerator muon beam experiment.Comment: 16 pages, 20 figure
The T2K Side Muon Range Detector
The T2K experiment is a long baseline neutrino oscillation experiment aiming
to observe the appearance of {\nu} e in a {\nu}{\mu} beam. The {\nu}{\mu} beam
is produced at the Japan Proton Accelerator Research Complex (J-PARC), observed
with the 295 km distant Super- Kamiokande Detector and monitored by a suite of
near detectors at 280m from the proton target. The near detectors include a
magnetized off-axis detector (ND280) which measures the un-oscillated neutrino
flux and neutrino cross sections. The present paper describes the outermost
component of ND280 which is a side muon range detector (SMRD) composed of
scintillation counters with embedded wavelength shifting fibers and Multi-Pixel
Photon Counter read-out. The components, performance and response of the SMRD
are presented.Comment: 13 pages, 19 figures v2: fixed several typos; fixed reference
Strangelet search at RHIC
Two position sensitive Shower Maximum Detector (SMDs) for Zero-Degree
Calorimeters (ZDCs) were installed by STAR before run 2004 at both upstream and
downstream from the interaction point along the beam axis where particles with
small rigidity are swept away by strong magnetic field. The ZDC-SMDs provides
information about neutral energy deposition as a function of transverse
position in ZDCs. We report the preliminary results of strangelet search from a
triggered data-set sampling 100 million Au+Au collisions at top RHIC energy.Comment: Strange Quark Matter 2004 conference proceedin
Correlations in STAR: interferometry and event structure
STAR observes a complex picture of RHIC collisions where correlation effects
of different origins -- initial state geometry, semi-hard scattering,
hadronization, as well as final state interactions such as quantum intensity
interference -- coexist. Presenting the measurements of flow, mini-jet
deformation, modified hadronization, and the Hanbury Brown and Twiss effect, we
trace the history of the system from the initial to the final state. The
resulting picture is discussed in the context of identifying the relevant
degrees of freedom and the likely equilibration mechanism.Comment: 8 pages, 6 figures, plenary talk at the 5th International Conference
on Physics and Astrophysics of Quark Gluon Plasma, to appear in Journal of
Physics G (http://www.iop.org
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