333 research outputs found
A Noisy Monte Carlo Algorithm
We propose a Monte Carlo algorithm to promote Kennedy and Kuti's linear
accept/reject algorithm which accommodates unbiased stochastic estimates of the
probability to an exact one. This is achieved by adopting the Metropolis
accept/reject steps for both the dynamical and noise configurations. We test it
on the five state model and obtain desirable results even for the case with
large noise. We also discuss its application to lattice QCD with stochastically
estimated fermion determinants.Comment: 10 pages, 1 tabl
Mixed convection in a rotating porous cavity having local heater
Numerical simulation of convective heat transfer inside a rotating porous square cavity with local heater of constant temperature has been performed. Governing equations formulated on the basis of mass, momentum and energy conservation laws written using the dimensionless stream function, vorticity and temperature have been solved by the finite difference method. The effects of Rayleigh and Taylor numbers on periodic flow and heat transfer have been studied
Recent atmospheric neutrino results from Soudan 2
An updated measurement of the atmospheric nu_mu/nu_e ratio-of-ratios,
0.68+-0.11+-0.06, has been obtained using a 4.6-kty exposure of the Soudan-2
iron tracking calorimeter. The L/E distributions have been analyzed for effects
of nu_mu -> nu_x oscillations, and an allowed region in the Delta m^2 vs. sin^2
2 theta plane has been determined.Comment: 3 pages, 4 figures; presented at TAUP99, the 6th Int. Workshop on
Topics in Astroparticle and Underground Physics, Sept. 6-10, 1999, College de
France, Paris, Franc
A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector
Deep underground muon events recorded by the Soudan 2 detector, located at a
depth of 2100 meters of water equivalent, have been used to infer the nuclear
composition of cosmic rays in the "knee" region of the cosmic ray energy
spectrum. The observed muon multiplicity distribution favors a composition
model with a substantial proton content in the energy region 800,000 -
13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review
Exact Philosophy of Space-Time
Starting from Bunge's (1977) scientific ontology, we expose a materialistic
relational theory of space-time, that carries out the program initiated by
Leibniz, and provides a protophysical basis consistent with any rigorous
formulation of General Relativity. Space-time is constructed from general
concepts which are common to any consistent scientific theory and they are
interpreted as emergent properties of the greatest assembly of things, namely,
the world.Comment: 13 pages, 3 figures. Version compatible with the published one. arXiv
admin note: substantial text overlap with arXiv:gr-qc/971006
Testing Lorentz Invariance and CPT Conservation with NuMI Neutrinos in the MINOS Near Detector
A search for a sidereal modulation in the MINOS near detector neutrino data
was performed. If present, this signature could be a consequence of Lorentz and
CPT violation as predicted by a class of extensions to the Standard Model. No
evidence for a sidereal signal in the data set was found, implying that there
is no significant change in neutrino propagation that depends on the direction
of the neutrino beam in a sun-centered inertial frame. Upper limits on the
magnitudes of the Lorentz and CPT violating terms in these extensions to the
Standard Model lie between 0.01-1% of the maximum expected, assuming a
suppression of these signatures by factor of .
A Study of Muon Neutrino Disappearance Using the Fermilab Main Injector Neutrino Beam
We report the results of a search for muon-neutrino disappearance by the Main
Injector Neutrino Oscillation Search. The experiment uses two detectors
separated by 734 km to observe a beam of neutrinos created by the Neutrinos at
the Main Injector facility at Fermi National Accelerator Laboratory. The data
were collected in the first 282 days of beam operations and correspond to an
exposure of 1.27e20 protons on target. Based on measurements in the Near
Detector, in the absence of neutrino oscillations we expected 336 +/- 14
muon-neutrino charged-current interactions at the Far Detector but observed
215. This deficit of events corresponds to a significance of 5.2 standard
deviations. The deficit is energy dependent and is consistent with two-flavor
neutrino oscillations according to delta m-squared = 2.74e-3 +0.44/-0.26e-3
eV^2 and sin^2(2 theta) > 0.87 at 68% confidence level.Comment: In submission to Phys. Rev.
Search for the Proton Decay Mode proton to neutrino K+ in Soudan 2
We have searched for the proton decay mode proton to neutrino K+ using the
one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained
from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for
occurrence of a visible K+ track which decays at rest into mu+ nu or pi+ pi0.
We found one candidate event consistent with background, yielding a limit,
tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.Comment: 13 pages, Latex, 3 tables and 3 figures, Accepted by Physics Letters
Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS
The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray
muon data since the beginning of August, 2003 at a depth of 2070
meters-water-equivalent in the Soudan Underground Laboratory, Minnesota, USA.
The data with both forward and reversed magnetic field running configurations
were combined to minimize systematic errors in the determination of the
underground muon charge ratio. When averaged, two independent analyses find the
charge ratio underground to be 1.374 +/- 0.004 (stat.) +0.012 -0.010(sys.).
Using the map of the Soudan rock overburden, the muon momenta as measured
underground were projected to the corresponding values at the surface in the
energy range 1-7 TeV. Within this range of energies at the surface, the MINOS
data are consistent with the charge ratio being energy independent at the two
standard deviation level. When the MINOS results are compared with measurements
at lower energies, a clear rise in the charge ratio in the energy range 0.3 --
1.0 TeV is apparent. A qualitative model shows that the rise is consistent with
an increasing contribution of kaon decays to the muon charge ratio.Comment: 16 pages, 17 figure
- …