60 research outputs found
A GEANT-based study of atmospheric neutrino oscillation parameters at INO
We have studied the dependence of the allowed space of the atmospheric
neutrino oscillation parameters on the time of exposure for a magnetized Iron
CALorimeter (ICAL) detector at the India-based Neutrino Observatory (INO). We
have performed a Monte Carlo simulation for a 50 kTon ICAL detector generating
events by the neutrino generator NUANCE and simulating the detector response by
GEANT. A chi-square analysis for the ratio of the up-going and down-going
neutrinos as a function of is performed and the allowed regions at 90%
and 99% CL are displayed. These results are found to be better than the current
experimental results of MINOS and Super-K. The possibilities of further
improvement have also been discussed.Comment: 8 pages, 13 figures, a new figure added, version accepted in IJMP
Oscillation Effects On Neutrinos From The Early Phase Of a Nearby Supernova
Neutrinos emitted during stellar core collapse leading to a supernova are
primarily of the electron neutrino type at source which may undergo oscillation
between flavor eigenstates during propagation to an earth-bound detector.
Although the number of neutrinos emitted during the pre-bounce collapse phase
is much smaller than that emitted in the post-bounce phase (in which all
flavors of neutrinos are emitted), a nearby supernova event may nevertheless
register a substantial number of detections from the pre-bounce phase at
SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). The
calorimetric measurement of the supernova neutrino fluence from this stage via
the charge current and neutral current detection channels in SNO and the
corresponding distortion of detected spectrum in SK over the no-oscillation
spectrum, can probe information about neutrino mass difference and mixing which
are illustrated here in terms of two- and three-flavor oscillation models
Solar Neutrino Rates, Spectrum, and its Moments : an MSW Analysis in the Light of Super-Kamiokande Results
We re-examine MSW solutions of the solar neutrino problem in a two flavor
scenario taking (a) the results on total rates and the electron energy spectrum
from the 1117-day SuperKamiokande (SK) data and (b) those on total rates from
the Chlorine and Gallium experiments. We find that the SMA solution gives the
best fit to the total rates data from the different experiments. One new
feature of our analysis is the use of the moments of the SK electron spectrum
in a analysis. The best-fit to the moments is broadly in agreement
with that obtained from a direct fit to the spectrum data and prefers a comparable to the SMA fit to the rates but the required mixing angle is
larger. In the combined rate and spectrum analysis, apart from varying the
normalization of the B flux as a free parameter and determining its
best-fit value we also obtain the best-fit parameters when correlations between
the rates and the spectrum data are included and the normalization of the B
flux held fixed at its SSM value. We observe that the correlations between the
rates and spectrum data are important and the goodness of fit worsens when
these are included. In either case, the best-fit lies in the LMA region.Comment: 17 pages, 4 figure
Discussion on a possible neutrino detector located in India
We have identified some important and worthwhile physics opportunitites with
a possible neutrino detector located in India. Particular emphasis is placed on
the geographical advantage with a stress on the complimentary aspects with
respect to other neutrino detectors already in operation.Comment: 9 pages; arXiv copy of published proceedings contributio
Violation of the Equivalence Principle in the light of the SNO and SK solar neutrino results
The SNO result on charged current deuteron disintegration, the
SuperKamiokande 1258-day data on electron scattering, and other solar neutrino
results are used to revisit the model of neutrino oscillations driven by a
violation of the equivalence principle. We use a chisq minimization technique
to examine oscillation between the nu(e) and another active neutrino, both
massless, and find that within the Standard Solar Model the fit to the SNO and
SuperKamiokande spectra are moderately good while a very good fit is obtained
when the absolute normalizations of the 8B and hep neutrino fluxes are allowed
to vary. The best fit prefers large, but not maximal, mixing, essentially no
hep neutrinos, and a 40% reduction in the 8B neutrino flux. The fit to the
total rates from the different experiments is not encouraging but when the
rates and spectra are considerd together the situation is much improved. We
remark on the expectations of the VEP model for the neutral current
measurements at SNO.Comment: Latex, 11 pages (incl. 1 postscript figure
Development of a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport
Monte Carlo simulation is the most accurate method for absorbed dose
calculations in radiotherapy. Its efficiency still requires improvement for
routine clinical applications, especially for online adaptive radiotherapy. In
this paper, we report our recent development on a GPU-based Monte Carlo dose
calculation code for coupled electron-photon transport. We have implemented the
Dose Planning Method (DPM) Monte Carlo dose calculation package (Sempau et al,
Phys. Med. Biol., 45(2000)2263-2291) on GPU architecture under CUDA platform.
The implementation has been tested with respect to the original sequential DPM
code on CPU in phantoms with water-lung-water or water-bone-water slab
geometry. A 20 MeV mono-energetic electron point source or a 6 MV photon point
source is used in our validation. The results demonstrate adequate accuracy of
our GPU implementation for both electron and photon beams in radiotherapy
energy range. Speed up factors of about 5.0 ~ 6.6 times have been observed,
using an NVIDIA Tesla C1060 GPU card against a 2.27GHz Intel Xeon CPU
processor.Comment: 13 pages, 3 figures, and 1 table. Paper revised. Figures update
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