414 research outputs found
The \gamma-ray production in neutral-current neutrino oxygen interaction in the energy range above 100 MeV
We calculate the cross section of the gamma-ray production from
neutral-current neutrino-oxygen quasi-elastic interaction, , or , in
which the residual nuclei (15N* or 15O*) lead to the gamma-ray emission with
gamma-ray energy >6 MeV at the branching ratio of 41%. Above 200 MeV, this
cross section dominates over that of gamma-ray production from the inelastic
reaction, . In the present calculation, spectral
function and the spectroscopic factors of
states are essential. The gamma-ray production is dominated by the deexcitation
of state of the residual nucleus
Superdeformation and clustering in Ca studied with Antisymmetrized Molecular Dynamics
Deformed states in Ca are investigated with a method of
antisymmetrized molecular dynamics. Above the spherical ground state,
rotational bands arise from a normal deformation and a superdeformation as well
as an oblate deformation. The calculated energy spectra and transition
strengths in the superdeformed band reasonably agree to the experimental data
of the superdeformed band starting from the state at 5.213 MeV. By the
analysis of single-particle orbits, it is found that the superdeformed state
has particle-hole nature of an - configuration. One of new findings is
parity asymmetric structure with C+Si-like clustering in the
superdeformed band. We predict that C+Si molecular bands may be
built above the superdeformed band due to the excitation of inter-cluster
motion. They are considered to be higher nodal states of the superdeformed
state. We also suggest negative-parity bands caused by the parity asymmetric
deformation.Comment: 13 figures, submitted to Phys. Rev.
Alpha clustering and weak coupling in the A=90 region
From the viewpoint of a unified description of cluster structure and
scattering in the
A=90 region, scattering from Y is investigated.
clustering and weak coupling in Nb is discussed.Comment: 8 pages, 4 figure
Nuclear corrections of parton distribution functions
We report global analysis results of experimental data for nuclear
structure-function ratios F_2^A/F_2^{A'} and proton-nucleus Drell-Yan
cross-section ratios sigma_{DY}^{pA}/sigma_{DY}^{pA'} in order to determine
optimum parton distribution functions (PDFs) in nuclei. An important point of
this analysis is to show uncertainties of the distributions by the Hessian
method. The results indicate that the uncertainties are large for gluon
distributions in the whole x region and for antiquark distributions at x>0.2.
We provide a code for calculating any nuclear PDFs at given x and Q^2 for
general users. They can be used for calculating high-energy nuclear reactions
including neutrino-nucleus interactions, which are discussed at this workshop.Comment: 1+6 pages, LaTeX, 10 eps files, espcrc2.sty, to be published in Nucl.
Phys. B Supplements, Proceedings of the Third International Workshop on
Neutrino-Nucleus Interactions in the Few GeV Region (NuInt04), Gran Sasso,
Italy, March 17-21, 2004. Nuclear PDF library is available at
http://hs.phys.saga-u.ac.jp/nuclp.htm
Deformed Base Antisymmetrized Molecular Dynamics and its Application to ^{20}Ne
A new theoretical framework named as deformed base antisymmetrized molecular
dynamics that uses the localized triaxially deformed Gaussian as the single
particle wave packet is presented. The model space enables us to describe
sufficiently well the deformed mean-field structure as well as the cluster
structure and their mixed structure within the same framework. The improvement
over the original version of the antisymmetrized molecular dynamics which uses
the spherical Gaussian is verified by the application to
nucleus. The almost pure cluster structure of the
= band, the distortion of the cluster structure in the
= band and the dominance of the deformed mean-field structure of
the = band are confirmed and their observed properties are
reproduced. Especially, the intra-band E2 transition probabilities in
= and bands are reproduced without any effective charge.
Since it has been long known that the pure
cluster model underestimates the intra-band transitions in the
= band by about 30%, we consider that this success is due to the
sufficient description of the deformed mean-field structure in addition to the
cluster structure by the present framework. From the successful description of
, we expect that the present framework presents us with a
powerful approach for the study of the coexistence and interplay of the
mean-field structure and the cluster structure
Measurement of tau polarization in e+ e- annihilation at sqrt{s}=58 GeV
The polarization of tau leptons in the reaction e+ e- --> tau+ tau- has been
measured using a e+e- collider, TRISTAN, at the center-of-mass energy of 58
GeV. From the kinematical distributions of daughter particles in tau --> e nu
nu-bar, mu nu nu-bar, rho nu or pi(K) nu decays, the average polarization of
tau- and its forward-backward asymmetry have been evaluated to be 0.012 +-
0.058 and 0.029 +- 0.057, respectively.Comment: 18 pages, 5 figure
Tracking Performance of the Scintillating Fiber Detector in the K2K Experiment
The K2K long-baseline neutrino oscillation experiment uses a Scintillating
Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino
interactions in the near detector. We describe the track reconstruction
algorithm and the performance of the SciFi after three years of operation.Comment: 24pages,18 figures, and 1 table. Preprint submitted to NI
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