698 research outputs found
Hydrogen targets for exotic-nuclei studies developed over the past 10 years
Hydrogen-induced reactions provide essential information on nuclear
structure, complementary to other experimental probes. For studies at both low
and relativistic incident energy, developments in hydrogen targets have been
performed over the past 10 years in parallel with the development of new
radioactive beams. We present a review of all major hydrogen target
developments related to the study of exotic nuclei with direct reactions in
inverse kinematics. Both polarized and non-polarized systems are presented.Comment: 24 pages, 27 figures, review articl
Thermal Conductivity of the Quasi One-Dimensional Spin System Sr_2_V_3_O_9_
We have measured the thermal conductivity along the [101] direction,
kappa_[101]_, along the [10-1] direction, kappa_[10-1]_, and along the b-axis,
kappa_b_, of the quasi one-dimensional S=1/2 spin system Sr_2_V_3_O_9_ in
magnetic fields up to 14 T, in order to find the thermal conductivity due to
spinons and to clarify whether the spin-chains run along the [101] or [10-1]
direction. It has been found that both kappa_[101]_, kappa_[10-1]_ and kappa_b_
show one peak around 10 K in zero field and that the magnitude of kappa_[10-1]_
is larger than those of kappa_[101]_ and kappa_b_. By the application of
magnetic field along the heat current, the peak of kappa_[10-1]_ is markedly
suppressed, while the peaks of kappa_[101]_ and kappa_b_ little change. These
results indicate that there is a large contribution of spinons to kappa_[10-1]_
and suggest that the spin-chains run along the [10-1] direction.Comment: 3 pages, 4 figure
Electron wave functions in beta-decay formulas revisited (II): Completion including recoil-order and induced currents
We present complete formulas of the allowed and first-forbidden transitions
of the nuclear beta decay taking into account the recoil-order and induced
currents up to the next-to-leading order (NLO). The longitudinal part of the
vector current is cleared away by the use of the conservation of the vector
current for the multipole operators of the natural-parity transitions, which
makes the effect of the meson exchange current for the vector current as small
as possible. The formula is transparent enough to be applied to various
beta-decay processes. As a numerical demonstration, we apply our formulas to
the beta decay of a neutron-rich nucleus Sn. We find that the NLO
corrections amount to 10--20\% of the total decay rate, whereas the induced
currents alter the rate at most 5\%.Comment: 25 pages, 2 figure
Total reaction cross section on a deuteron target and the eclipse effect of the constituent neutron and proton
Background: Eclipse effect of the neutron and proton in a deuteron target is
essential to correctly describe high-energy deuteron scattering. The
nucleus-deuteron scattering needs information not only on the nucleus-proton
but also the nucleus-neutron interaction, for which no direct measurement of
the nucleus-neutron cross sections is available for unstable nuclei.
Purpose: We systematically evaluated the total reaction cross sections by a
deuteron target to explore the feasibility of extracting the nucleus-neutron
interaction from measurable cross sections.
Methods: High-energy nucleus-deuteron collision is described by the Glauber
model, in which the proton and neutron configuration of the deuteron is
explicitly taken into account.
Results: Our calculation reproduces available experimental total reaction
cross section data on the nucleus-deuteron scattering. The possibility of
extracting the nucleus-neutron total reaction cross section from
nucleus-deuteron and nucleus-proton total reaction cross sections is explored.
The total reaction cross sections of a nucleus by proton, neutron, and deuteron
targets can be expressed, to good accuracy, in terms of the nuclear matter
radius and neutron skin thickness. Incident-energy dependence of the total
reaction cross sections is examined.
Conclusions: The total reaction cross section on a deuteron target includes
information on both the nucleus-neutron and nucleus-proton profile functions.
Measuring the cross sections by deuteron and proton targets is a promising tool
to extract the nuclear size properties.Comment: 9 pages, 5 figures, to appear in Phys. Rev.
Thermal Conductivity in the Bose-Einstein Condensed State of Triplons in the Bond-Alternating Spin-Chain System Pb2V3O9
In order to clarify the origin of the enhancement of the thermal conductivity
in the Bose-Einstein Condensed (BEC) state of field-induced triplons, we have
measured the thermal conductivity along the [101] direction parallel to
spin-chains, , and perpendicular to spin-chains,
, of the S=1/2 bond-alternating spin-chain system Pb2V3O9
in magnetic fields up to 14 T. With increasing field at 3 K, it has been found
that both and are suppressed in the
gapped normal state in low fields. In the BEC state of field-induced triplons
in high fields, on the other hand, is enhanced with
increasing field, while is suppressed. That is, the
thermal conductivity along the direction, where the magnetic interaction is
strong, is markedly enhanced in the BEC state. Accordingly, our results suggest
that the enhancement of in the BEC state is caused by the
enhancement of the thermal conductivity due to triplons on the basis of the
two-fluid model, as in the case of the superfluid state of liquid 4He.Comment: 5 pages, 3 figure
Measurement of Single and Double Spin-Flip Probabilities in Inelastic Deuteron Scattering on 12C at 270 MeV
The deuteron single and double spin-flip probabilities, S1 and S2, have been
measured for the 12C(pol{d},pol{d}') reaction at Ed = 270 MeV for an excitation
energy range between 4 and 24 MeV and a scattering angular range between
Theta_lab = 2.5 and 7.5 deg. The extracted S1 exhibits characteristic values
depending on the structure of the excited state. The S2 is close to zero over
the measured excitation energy range. The SFP angular distribution data for the
2+ (4.44 MeV) and 1+ (12.71 MeV) states are well described by the microscopic
DWIA calculations
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