46 research outputs found
Production Spectra of He(, ) Reactions with Continuum Discretized Coupled Channels
We investigate theoretically production spectra of He(,
) reactions at 1.05--1.20 GeV/ in the distorted-wave impulse
approximation, using the continuum-discretized coupled-channel method. The
production cross section of a H(1/2) ground state is also
discussed.Comment: 8 pages, 4 figures; contribution to the Proceedings of the 8th
International Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba,
November 13-17, 201
Repulsion and absorption of the -nucleus potential for -He in the Li(, ) reaction
We study phenomenologically inclusive spectra of the Li(, )
reaction at 1.2 GeV/ within a distorted-wave impulse approximation with the
optimal Fermi-averaging matrix. We attempt to
clarify the property of a -nucleus potential for -He by
comparing the calculated spectra with the data of the J-PARC E10 experiment.
The result shows that the repulsive and absorptive components of the
-He potential provide the ability to explain the data of the
continuum spectra in and regions; the strengths of +30 MeV and 26 MeV are favored within the
Woods-Saxon potential, consistent with analyses for heavier nuclei. Effects of
the size and potential range for -He in the neutron excess of
0.2 are also discussed.Comment: 35 pages, 11 figure
Discrimination of -nucleus potentials in the angular distribution of elastic scattering of hyperons from nuclei
We theoretically investigate the elastic scattering of 50-MeV
hyperons from Si and Pb in order to clarify the radial
distribution of -nucleus (optical) potentials. The angular
distributions of differential cross sections are calculated using several
potentials that can explain experimental data of the atomic X-ray
and (, ) reaction spectra simultaneously. The magnitude and
oscillation pattern of the angular distributions are understood by the use of
nearside/farside decompositions of their scattering amplitudes. It is shown
that the resultant angular distributions can considerably discriminate among
the radial distributions of the potentials that have a repulsion inside the
nuclear surface and an attraction outside the nucleus with a sizable
absorption
Medium effects on production in the nuclear (, ) reaction
We study theoretically medium effects on production in the (,
) reaction, using the optimal Fermi-averaging procedure which describes
the Fermi motion of a nucleon on the on-energy-shell
reaction condition in nuclei. The result shows the strong energy and angular
dependence of the in-medium cross section,which affects
significantly the shape and magnitude of the production spectrum for
hypernuclear states in the (, ) reaction on a nuclear target.The
application to the quasi-free production via the (, )
reaction on a C target is also discussed in a Fermi gas model.Comment: 18 pages, 5 figure
Coulomb-assisted -nucleus bound states in the (, ) reaction
We study a production of Coulomb-assisted -nucleus bound states by
nuclear (, ) reactions within a distorted-wave impulse
approximation, so as to examine several types of the -nucleus
potentials that are consistent with the available atomic X-ray data
and nuclear (, ) data. We theoretically demonstrate the inclusive
(, ) spectra of the unstable bound states on Si,
Ni, and Pb targets at incident lab momenta MeV/c. The results show that the near-recoilless (,
) reaction on the Ni target gives a clear candidate to confirm
properties of the -nucleus potentials having a repulsion inside the
nuclear surface and an attraction outside the nucleus with a sizable
absorption, whereas details of the repulsion of the potential at the nuclear
center cannot be determined by the inclusive spectra. This is a promising
attempt to extract properties of the -nucleus potential in the nucleus
at forthcoming J-PARC experiments, as a full complement to the analyses of the
atomic and (, ) data
Production of doubly strange hypernuclei via {\Xi}- doorways in the 16O(K-, K+) reaction at 1.8 GeV/c
We examine theoretically production of doubly strange hypernuclei, 16 {\Xi}-C
and 16 {\Lambda}{\Lambda}C, in doublecharge exchange 16O(K-, K+) reactions
using a distorted-wave impulse approximation. The inclusive K+ spectrum at the
incident momentum pK- = 1.8 GeV/c and scattering angle {\theta}lab = 0^{\circ}
is estimated in a one-step mechanism, K-p \to K+{\Xi}- via {\Xi}- doorways
caused by a {\Xi}-p-{\Lambda}{\Lambda} coupling. The calculated spectrum in the
{\Xi}- bound region indicates that the integrated cross sections are on the
order of 7-12 nb/sr for significant 1- excited states with 14C(0+, 2+) \otimes
s{\Lambda}p{\Lambda} configurations in 16 {\Lambda}{\Lambda}C via the doorway
states of the spin-stretched 15N(1/2-, 3/2-) \otimes s{\Xi}- in 16 {\Xi}-C due
to a high momentum transfer q{\Xi}- \approx 400 MeV/c. The {\Xi}- admixture
probabilities of these states are on the order of 5-9%. However, populations of
the 0+ ground state with 14C(0+) \otimes s2{\Lambda} and the 2+ excited state
with 14C(2+) \otimes s2 {\Lambda} are very small. The sensitivity of the
spectrum on the {\Xi}N-{\Lambda}{\Lambda} coupling strength enables us to
extract the nature of {\Xi}N-{\Lambda}{\Lambda} dynamics in nuclei, and the
nuclear (K-, K+) reaction can extend our knowledge of the S = -2 world.Comment: 10 pages, 3 figure
The Japanese space gravitational wave antenna; DECIGO
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future
Japanese space gravitational wave antenna. DECIGO is expected to open a new window of
observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing
various mysteries of the universe such as dark energy, formation mechanism of supermassive
black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of
three drag-free spacecraft, whose relative displacements are measured by a differential Fabry–
Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-
DECIGO first and finally DECIGO in 2024
DECIGO pathfinder
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article
The status of DECIGO
DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present