45 research outputs found
A detector to monitor the neutrino beam asymmetry at the T2K 280m hall
We propose to build and operate a new detector for the T2K 280m hall with the purpose of measuring and monitoring the possible neutrino beam left-right asymmetry with respect to the beam axis. The measurement will be performed by means of two identical detectors (modules) made of a sandwich of iron plates and planes of scintillator bars read out by WLS fibers and multianode PMTs. The two modules could be swapped in their positions in order to minimize systematic errors. We show that an overall uncertainty of less than 5% in the measurement of the beam asymmetry could be reached within one year of running
Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus
A new measurement of the momentum spectra of both positive and negative muons
as function of atmospheric depth was made by the balloon-borne experiment
CAPRICE94. The data were collected during ground runs in Lynn Lake on the
19-20th of July 1994 and during the balloon flight on the 8-9th of August 1994.
We present results that cover the momentum intervals 0.3-40 GeV/c for negative
muons and 0.3-2 GeV/c for positive muons, for atmospheric depths from 3.3 to
1000 g/cm**2, respectively. Good agreement is found with previous measurements
for high momenta, while at momenta below 1 GeV/c we find latitude dependent
geomagnetic effects. These measurements are important cross-checks for the
simulations carried out to calculate the atmospheric neutrino fluxes and to
understand the observed atmospheric neutrino anomaly.Comment: 28 pages, 13 Postscript figures, uses revtex.sty, to appear in Phys.
Rev.
Tau Neutrinos Favored over Sterile Neutrinos in Atmospheric Muon Neutrino Oscillations
The previously published atmospheric neutrino data did not distinguish
whether muon neutrinos were oscillating into tau neutrinos or sterile
neutrinos, as both hypotheses fit the data. Using data recorded in 1100
live-days of the Super-Kamiokande detector, we use three complementary data
samples to study the difference in zenith angle distribution due to neutral
currents and matter effects. We find no evidence favoring sterile neutrinos,
and reject the hypothesis at the 99% confidence level. On the other hand, we
find that oscillation between muon and tau neutrinos suffices to explain all
the results in hand.Comment: 9 pages with 2 figures, submitted to PR
Constraints on Neutrino Oscillations Using 1258 Days of Super-Kamiokande Solar Neutrino Data
We report the result of a search for neutrino oscillations using precise
measurements of the recoil electron energy spectrum and zenith angle variations
of the solar neutrino flux from 1258 days of neutrino-electron scattering data
in Super-Kamiokande. The absence of significant zenith angle variation and
spectrum distortion places strong constraints on neutrino mixing and mass
difference in a flux-independent way. Using the Super-Kamiokande flux
measurement in addition, two allowed regions at large mixing are found.Comment: 6 pages, 4 figures, submitted to PR
Solar 8B and hep Neutrino Measurements from 1258 Days of Super-Kamiokande Data
Solar neutrino measurements from 1258 days of data from the Super-Kamiokande
detector are presented. The measurements are based on recoil electrons in the
energy range 5.0-20.0MeV. The measured solar neutrino flux is 2.32 +-
0.03(stat.) +0.08-0.07(sys.)*10^6cm^{-2}s^{-1}, which is
45.1+-0.5(stat.)+1.6-1.4(sys.)% of that predicted by the BP2000 SSM. The day vs
night flux asymmetry is 0.033+-0.022(stat.)+0.013-0.012(sys.). The recoil
electron energy spectrum is consistent with no spectral distortion
(\chi^2/d.o.f. = 19.0/18). The seasonal variation of the flux is consistent
with that expected from the eccentricity of the Earth's orbit (\chi^2/d.o.f. =
3.7/7). For the hep neutrino flux, we set a 90% C.L. upper limit of 40
*10^3cm^{-2}s^{-1}, which is 4.3 times the BP2000 SSM prediction.Comment: 7 pages, 5 figures, submitted to PRL (part of this paper
Experimental study of the atmospheric neutrino backgrounds for proton decay to positron and neutral pion searches in water Cherenkov detectors
The atmospheric neutrino background for proton decay to positron and neutral
pion in ring imaging water Cherenkov detectors is studied with an artificial
accelerator neutrino beam for the first time. In total, about 314,000 neutrino
events corresponding to about 10 megaton-years of atmospheric neutrino
interactions were collected by a 1,000 ton water Cherenkov detector (KT). The
KT charged-current single neutral pion production data are well reproduced by
simulation programs of neutrino and secondary hadronic interactions used in the
Super-Kamiokande (SK) proton decay search. The obtained proton to positron and
neutral pion background rate by the KT data for SK from the atmospheric
neutrinos whose energies are below 3 GeV is about two per megaton-year. This
result is also relevant to possible future, megaton-scale water Cherenkov
detectors.Comment: 13 pages, 16 figure
Evidence for muon neutrino oscillation in an accelerator-based experiment
We present results for muon neutrino oscillation in the KEK to Kamioka (K2K)
long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced
muon neutrino beam with a mean energy of 1.3 GeV directed at the
Super-Kamiokande detector. We observed the energy dependent disappearance of
muon neutrino, which we presume have oscillated to tau neutrino. The
probability that we would observe these results if there is no neutrino
oscillation is 0.0050% (4.0 sigma).Comment: 5 pages, 4 figure
Search for coherent charged pion production in neutrino-carbon interactions
We report the result from a search for charged-current coherent pion
production induced by muon neutrinos with a mean energy of 1.3 GeV. The data
are collected with a fully active scintillator detector in the K2K
long-baseline neutrino oscillation experiment. No evidence for coherent pion
production is observed and an upper limit of is set on
the cross section ratio of coherent pion production to the total
charged-current interaction at 90% confidence level. This is the first
experimental limit for coherent charged pion production in the energy region of
a few GeV.Comment: 5 pages, 4 figure
Measurement of single charged pion production in the charged-current interactions of neutrinos in a 1.3 GeV wide band beam
Single charged pion production in charged-current muon neutrino interactions
with carbon is studied using data collected in the K2K long-baseline neutrino
experiment. The mean energy of the incident muon neutrinos is 1.3 GeV. The data
used in this analysis are mainly from a fully active scintillator detector,
SciBar. The cross section for single production in the resonance
region ( GeV/) relative to the charged-current quasi-elastic cross
section is found to be 0.734 . The energy-dependent cross
section ratio is also measured. The results are consistent with a previous
experiment and the prediction of our model.Comment: 15 pages, 12 figures, 7 tables. Uses revtex4. Minor revisions to
match version accepted for publication in Physical Review
Literature Mining for the Discovery of Hidden Connections between Drugs, Genes and Diseases
The scientific literature represents a rich source for retrieval of knowledge on associations between biomedical concepts such as genes, diseases and cellular processes. A commonly used method to establish relationships between biomedical concepts from literature is co-occurrence. Apart from its use in knowledge retrieval, the co-occurrence method is also well-suited to discover new, hidden relationships between biomedical concepts following a simple ABC-principle, in which A and C have no direct relationship, but are connected via shared B-intermediates. In this paper we describe CoPub Discovery, a tool that mines the literature for new relationships between biomedical concepts. Statistical analysis using ROC curves showed that CoPub Discovery performed well over a wide range of settings and keyword thesauri. We subsequently used CoPub Discovery to search for new relationships between genes, drugs, pathways and diseases. Several of the newly found relationships were validated using independent literature sources. In addition, new predicted relationships between compounds and cell proliferation were validated and confirmed experimentally in an in vitro cell proliferation assay. The results show that CoPub Discovery is able to identify novel associations between genes, drugs, pathways and diseases that have a high probability of being biologically valid. This makes CoPub Discovery a useful tool to unravel the mechanisms behind disease, to find novel drug targets, or to find novel applications for existing drugs