3,245 research outputs found
Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory
We have measured the muon flux and production rate of muon-induced neutrons
at a depth of 611 m water equivalent. Our apparatus comprises three layers of
crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray
muons and 760 L of gadolinium-doped liquid scintillator for producing and
detecting neutrons. The vertical muon intensity was measured to be cmssr. The yield of
muon-induced neutrons in the liquid scintillator was determined to be
neutrons/(gcm). A fit to the recently measured neutron
yields at different depths gave a mean muon energy dependence of for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table
Measurement of the Phase Difference Between eta00 and eta+- to a Precision of 1^0
We propose to add an additional regenerator to the E731 spectrometer in the MC beamline to enable us to measure the phase difference between the CP violation parameters {eta}{sub 00} and {eta}{sub +-} to an accuracy of 1{sup o}. Very general considerations indicate that CPT conservation requires the phase difference, {Delta}{phi} = Arg({eta}{sub 00}) - Arg({eta}{sub +-}), to be smaller than one degree. The current experimental value is {Delta}{phi} = (9.4 {+-} 5.1){sup o}
Long-lived neutral-kaon flux measurement for the KOTO experiment
The KOTO ( at Tokai) experiment aims to observe the CP-violating rare
decay by using a long-lived neutral-kaon
beam produced by the 30 GeV proton beam at the Japan Proton Accelerator
Research Complex. The flux is an essential parameter for the measurement
of the branching fraction. Three neutral decay modes, , , and were used to
measure the flux in the beam line in the 2013 KOTO engineering run. A
Monte Carlo simulation was used to estimate the detector acceptance for these
decays. Agreement was found between the simulation model and the experimental
data, and the remaining systematic uncertainty was estimated at the 1.4\%
level. The flux was measured as per protons on a
66-mm-long Au target.Comment: 27 pages, 16 figures. To be appeared in Progress of Theoretical and
Experimental Physic
Bremsstrahlung of a Quark Propagating through a Nucleus
The density of gluons produced in the central rapidity region of a heavy ion
collision is poorly known. We investigate the influence of the effects of
quantum coherence on the transverse momentum distribution of photons and gluons
radiated by a quark propagating through nuclear matter. We describe the case
that the radiation time substantially exceeds the nuclear radius (the relevant
case for RHIC and LHC energies), which is different from what is known as
Landau-Pomeranchuk-Migdal effect corresponding to an infinite medium. We find
suppression of the radiation spectrum at small transverse photon/gluon momentum
k_T, but enhancement for k_T>1GeV. Any nuclear effects vanish for k_T > 10GeV.
Our results allow also to calculate the k_T dependent nuclear effects in prompt
photon, light and heavy (Drell-Yan) dilepton and hadron production.Comment: Appendix A is extended compared to the version to be published in
Phys.Rev.
Search for the decay
We performed a search for the decay with the
E391a detector at KEK. In the data accumulated in 2005, no event was observed
in the signal region. Based on the assumption of
proceeding via parity-violation, we obtained the single event sensitivity to be
, and set an upper limit on the branching ratio to
be at the 90% confidence level. This is a factor of 3.2
improvement compared to the previous results. The results of proceeding via parity-conservation were also presented in this paper
Experimental study of the decay
The first dedicated search for the rare neutral-kaon decay
has been carried out in the E391a experiment at the
KEK 12-GeV proton synchrotron. The final upper limit of 2.6 at
the 90% confidence level was set on the branching ratio for the decay.Comment: 23 pages, 27 figures, accepted for publication as a regular article
in Physical Review
Acrylic Target Vessels for a High-Precision Measurement of theta13 with the Daya Bay Antineutrino Detectors
This paper describes in detail the acrylic target vessels used to encapsulate
the target and gamma catcher regions in the Daya Bay experiment's first pair of
antineutrino detectors. We give an overview of the design, fabrication,
shipping, and installation of the acrylic target vessels and their liquid
overflow tanks. The acrylic quality assurance program and vessel
characterization, which measures all geometric, optical, and material
properties relevant to {\nu}e detection at Daya Bay are summarized. This paper
is the technical reference for the Daya Bay acrylic vessels and can provide
guidance in the design and use of acrylic components in future neutrino or dark
matter experiments.Comment: 47 pages, 38 Figures, 14 Tables. Submitted to JINS
A side-by-side comparison of Daya Bay antineutrino detectors
The Daya Bay Reactor Neutrino Experiment is designed to determine precisely
the neutrino mixing angle with a sensitivity better than 0.01 in
the parameter sin at the 90% confidence level. To achieve this
goal, the collaboration will build eight functionally identical antineutrino
detectors. The first two detectors have been constructed, installed and
commissioned in Experimental Hall 1, with steady data-taking beginning
September 23, 2011. A comparison of the data collected over the subsequent
three months indicates that the detectors are functionally identical, and that
detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure
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