489 research outputs found
Identification problems of muon and electron events in the Super-Kamiokande detector
In the measurement of atmospheric nu_e and nu_mu fluxes, the calculations of
the Super Kamiokande group for the distinction between muon-like and
electronlike events observed in the water Cerenkov detector have initially
assumed a misidentification probability of less than 1 % and later 2 % for the
sub-GeV range. In the multi-GeV range, they compared only the observed
behaviors of ring patterns of muon and electron events, and claimed a 3 %
mis-identification. However, the expressions and the calculation method do not
include the fluctuation properties due to the stochastic nature of the
processes which determine the expected number of photoelectrons (p.e.) produced
by muons and electrons. Our full Monte Carlo (MC) simulations including the
fluctuations of photoelectron production show that the total mis-identification
rate for electrons and muons should be larger than or equal to 20 % for sub-GeV
region. Even in the multi-GeV region we expect a mis-identification rate of
several % based on our MC simulations taking into account the ring patterns.
The mis-identified events are mostly of muonic origin.Comment: 17 pages, 12 figure
Field-Induced Two-Step Phase Transitions in the Singlet Ground State Triangular Antiferromagnet CsFeBr
The ground state of the stacked triangular antiferromagnet CsFeBr is a
spin singlet due to the large single ion anisotropy . The
field-induced magnetic ordering in this compound was investigated by the
magnetic susceptibility, the magnetization process and specific heat
measurements for an external field parallel to the -axis. Unexpectedly, two
phase transitions were observed in the magnetic field higher than 3 T. The
phase diagram for temperature versus magnetic field was obtained. The mechanism
leading to the successive phase transitions is discussed.Comment: 8 pages, 9 figures, 10 eps files, jpsj styl
Solutions to the Wheeler-Dewitt Equation Inspired by the String Effective Action
The Wheeler-DeWitt equation is derived from the bosonic sector of the
heterotic string effective action assuming a toroidal compactification. The
spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology
is investigated and a suitable change of variables rewrites the equation in a
canonical form. Real- and imaginary-phase exact solutions are found and a
method of successive approximations is employed to find more general power
series solutions. The quantum cosmology of the Bianchi IX universe is also
investigated and a class of exact solutions is found.Comment: 21 pages of plain LaTeX, Fermilab-Pub-93/100-
Quantum and Thermal Phase Transitions of Halogen-Bridged Binuclear Transition-Metal Complexes
Aiming to settle the controversial observations for halogen-bridged binuclear
transition-metal (MMX) complexes, finite-temperature Hartree-Fock calculations
are performed for a relevant two-band Peierls-Hubbard model. Thermal, as well
as quantum, phase transitions are investigated with particular emphasis on the
competition between electron itinerancy, electron-phonon interaction and
electron-electron correlation. Recently observed distinct thermal behaviors of
two typical MMX compounds Pt_2(CH_3CS_2)_4I and
(NH_4)_4[Pt_2(P_2O_5H_2)_4I]2H_2O are supported and further tuning of their
electronic states is predicted.Comment: 5 pages, 3 figures embedded, to be published in J. Phys. Soc. Jpn.
Vol.70, No.5 (2001
Quantum Cosmology of Generalized Two--Dimensional Dilaton Gravity Models
The quantum cosmology of two-dimensional dilaton-gravity models is
investigated. A class of models is mapped onto the constrained
oscillator-ghost-oscillator model. A number of exact and approximate solutions
to the corresponding Wheeler-DeWitt equation are presented. A wider class of
minisuperspace models that can be solved in this fashion is identified.
Supersymmetric extensions to the induced gravity theory and the bosonic string
theory are then considered and closed-form solutions to the associated quantum
constraints are derived. The possibility of applying the third-quantization
procedure to two-dimensional dilaton-gravity is briefly discussed.Comment: 28 pages, late
Soliton excitations in halogen-bridged mixed-valence binuclear metal complexes
Motivated by recent stimulative observations in halogen (X)-bridged binuclear
transition-metal (M) complexes, which are referred to as MMX chains, we study
solitons in a one-dimensional three-quarter-filled charge-density-wave system
with both intrasite and intersite electron-lattice couplings. Two distinct
ground states of MMX chains are reproduced and the soliton excitations on them
are compared. In the weak-coupling region, all the solitons are degenerate to
each other and are uniquely scaled by the band gap, whereas in the
strong-coupling region, they behave differently deviating from the scenario in
the continuum limit. The soliton masses are calculated and compared with those
for conventional mononuclear MX chains.Comment: 9 pages, 10 figures embedded, to be published in J. Phys. Soc. Jpn.
71, No. 1 (2002
Effects of mandrel shape on deformation behavior for hot mandrel bending of elbows
Elbows of steel pipe joints are used in the industrial plants and are mainly manufactured by the hot mandrelbending from raw material of straight steel pipe. Elbows are generally manufactured at elevatedtemperature by means of pushing, expanding and bending of pipes simultaneously, using the innertool of mandrel. Characteristics of mandrel bending strongly depend on the integrated shape anddimensions of the mandrel. We investigate the effects of shape and dimension of mandrel on deformationbehaviors for hot mandrel bending of elbows, conducting experimental test and numerical analysis. Weclarify the effects of bending radius ratio Rout/Dout, expansion ratio Dout/Din, mandrel length ratio L/Doutand other items of mandrel shape. And optimum conditions of mandrel are estimated as conclusion
- …