2,852 research outputs found
Range fluctuations of high energy muons passing through matter
The information about energy spectrum of sea level muons at high energies beyond magnetic spectrographs can be obtained from the underground intensity measurements if the fluctuations problems are solved. The correction factor R for the range fluctuations of high energy muons were calculated by analytical method of Zatsepin, where most probable energy loss parameter are used. It is shown that by using the R at great depth together with the slope, lambda, of the vertical depth-intensity (D-I) curve in the form of exp(-t/lambda), the spectral index, gamma, in the power law energy spectrum of muons at sea level can be obtained
Energy spectra of high energy atmospheric neutrinos
Focusing on high energy neutrinos ( or = 1 TeV), a new calculation of atmospheric neutrino intensities was carried out taking into account EMC effects observed in P-A collisions by accelerator, recent measurement of primary cosmic ray spectrum and results of cosmic ray muon spectrum and charge ratio. Other features of the present calculation are (1) taking into account kinematics of three body decays of kaons and charm particles in diffusion equations and (2) taking into account energy dependence of kaon production
New calculation of atmospheric neutrino fluxes
We have performed a one-dimensional Monte Carlo calculation of atmospheric neutrino fluxes in the energy range 0.05
GeV–20 GeV including muon polarization effects. It is shown that the calculated n m On e ratio does not appear
sufficient to explain the Kamiokande data from sub-GeV to multi-GeV energy region. It is suggested that neutrino oscillations would provide a solution to the anomalous n m On e ratio
Predicting morphotropic phase boundary locations and transition temperatures in Pb- and Bi-based perovskite solid solutions from crystal chemical data and first-principles calculations
Using data obtained from first-principles calculations, we show that the
position of the morphotropic phase boundary (MPB) and transition temperature at
MPB in ferroelectric perovskite solutions can be predicted with quantitative
accuracy from the properties of the constituent cations. We find that the mole
fraction of PbTiO at MPB in Pb(BB)O-PbTiO,
BiBO-PbTiO and Bi(BB)O-PbTiO exhibits a linear
dependence on the ionic size (tolerance factor) and the ionic displacements of
the B-cations as found by density functional theory calculations. This
dependence is due to competition between the local repulsion and A-cation
displacement alignment interactions. Inclusion of first-principles displacement
data also allows accurate prediction of transiton temperatures at the MPB. The
obtained structure-property correlations are used to predict morphotropic phase
boundaries and transition temperatures in as yet unsynthesized solid solutions.Comment: Accepted for publication in J. Appl. Phy
Wang-Landau molecular dynamics technique to search for low-energy conformational space of proteins
Multicanonical molecular dynamics (MD) is a powerful technique for sampling
conformations on rugged potential surfaces such as protein. However, it is
notoriously difficult to estimate the multicanonical temperature effectively.
Wang and Landau developed a convenient method for estimating the density of
states based on a multicanonical Monte Carlo method. In their method, the
density of states is calculated autonomously during a simulation. In this paper
we develop a set of techniques to effectively apply the Wang-Landau method to
MD simulations. In the multicanonical MD, the estimation of the derivative of
the density of states is critical. In order to estimate it accurately, we
devise two original improvements. First, the correction for the density of
states is made smooth by using the Gaussian distribution obtained by a short
canonical simulation. Second, an approximation is applied to the derivative,
which is based on the Gaussian distribution and the multiple weighted histogram
technique. A test of this method was performed with small polypeptides,
Met-enkephalin and Trp-cage, and it is demonstrated that Wang-Landau MD is
consistent with replica exchange MD but can sample much larger conformational
space.Comment: 8 pages, 7 figures, accepted for publication in Physical Review
Large-Area Scintillator Hodoscope with 50 ps Timing Resolution Onboard BESS
We describe the design and performance of a large-area scintillator hodoscope
onboard the BESS rigidity spectrometer; an instrument with an acceptance of 0.3
m^{2}sr.
The hodoscope is configured such that 10 and 12 counters are respectively
situated in upper and lower layers.
Each counter is viewed from its ends by 2.5 inch fine-mesh photomultiplier
tubes placed in a stray magnetic field of 0.2 Tesla.
Various beam-test data are presented.
Use of cosmic-ray muons at ground-level confirmed 50 ps timing resolution for
each layer, giving an overall time-of-flight resolution of 70 ps rms using a
pure Gaussian resolution function.
Comparison with previous measurements on a similar scintillator hodoscope
indicates good agreement with the scaling law that timing resolution is
proportional to 1/, where is the effective
number of photoelectrons.Comment: 16 pages, 14 figure
A new ultra high energy gamma ray telescope at Ohya mine
The search for ultra high energy gamma rays coming from point sources is one of the main experimental aims. A fast air shower timing system was constructed at ICRR for the study of the angular resolution of the system and operated approximately half a year. The characteristics of the surface array of Ohya air shower telescope is described
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