Progress in proton elastic scattering at intermediate energies to determine nuclear density distributions is reviewed. After challenges of about 15 years to explain proton elastic scattering and ...associated polarization phenomena at intermediate energies, we have reached to some conclusions regarding proton elastic scattering as a means of obtaining nuclear densities. During this same period, physics of unstable nuclei has become of interest, and the density distributions of protons and neutrons play more important roles in unstable nuclei, since the differences in proton and neutron numbers and densities are expected to be significant. As such, proton elastic scattering experiments at intermediate energies using the inverse kinematic method have started to determine density distributions of unstable nuclei. In the region of unstable nuclei, we are confronted with a new problem when attempting to find proton and neutron densities separately from elastic proton scattering data, since electron scattering data for unstable nuclei are not presently available. We introduce a new means of determining proton and neutron densities separately by double-energy proton elastic scattering at intermediate energies.
We study isoscalar (IS) and isovector (IV) densities in Ca40 in comparison with theoretical densities calculated by Skyrme Hatree-Fock (HF) models. The charge symmetry breaking and the charge ...independence breaking forces are introduced to study the effect on the IV density. The effect of isospin mixing in the ground-state density is examined by using the particle-vibration coupling model taking into account the collective IV giant monopole excitation. We show a clear correlations in the IV density and isospin impurity of Ca40 within the HF and the particle-vibration coupling model. We extract for the first time the experimental information of isospin impurity from the magnitude of IV density.
We searched for the 6α-condensed state in 24Mg by measuring the C12+12C scattering with the SAKRA Si detector array at Ecm=17.5–25.0 MeV. By using the invariant-mass method for the detected 3α ...particles, the inclusive cross sections for the C12+12C→12C(02+)+X and C12(31−)+X reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual C12 nucleus and the exclusive cross sections for the C12+12C→12C(02+)+12C(01+), C12(02+)+12C(21+), and C12(02+)+12C(02+) reactions. In both the inclusive C12(02+)+X channel and the exclusive C12(02+)+12C(01+) channel, the cross section peaked at Ecm=19.4 MeV, which correspond to the excitation energy of Ex=33.3 MeV in 24Mg. This 19.4-MeV state is a candidate for the 6α-condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive C12(02+)+12C(02+) channel, a broad state was observed at Ecm=22.5 MeV, which correspond to the excitation energy of Ex=36.4 MeV in 24Mg. From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be 4+. In addition, a 2+ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6α-condensed state, these states might be excited states of the 6α-condensed state such as the 22+ and 41+ states in C12.
We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient ^{14}O nucleus with large Fermi-surface asymmetry S_{n}-S_{p}=18.6 MeV at ∼100 ...MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the ^{13}N and ^{13}O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.
Mountable controller with parallelized VERSA Module Eurocard (VME) (MPV) is a VME-compatible system having a parallel readout architecture. This article presents the system architecture and its data ...acquisition performance. In this system, the readout sequence is implemented in a field-programmable gate array (FPGA) to achieve the ideal VME bus speed. Data from multiple VME slave modules are read out in parallel, merged, and sent to a server. Maximum data throughput of 400 Mbps was achieved. Thus, the MPV system can dramatically improve the performance of VME data acquisition systems.
Abstract
The matter radius of the doubly magic
$$^{56}$$
56
Ni was extracted from a measurement of the differential cross section by employing, for the first time, elastic proton scattering in ...inverse kinematics with a radioactive beam at
$$E_{kin}=390.2$$
E
kin
=
390.2
MeV/nucleon circulating in a storage ring and passing an internal hydrogen gas-jet target with a revolution frequency of around 2 MHz. The novel experimental scheme is based on UHV-compatible Si detectors operated as active vacuum windows, which were implemented in the ESR storage ring at GSI. A matter radius
$$<r_{m}^{2}>^{1/2}=3.74^{+0.03}_{-0.06}$$
<
r
m
2
>
1
/
2
=
3
.
74
-
0.06
+
0.03
fm was extracted for the doubly-magic self-conjugate nucleus
$$^{56}$$
56
Ni.
This work describes a silicon tracker system developed for experiments with proton-rich radioactive ion beams at the SAMURAI superconducting spectrometer of RIBF at RIKEN. The system is designed for ...accurate angular reconstruction and atomic number identification of relativistic heavy ions and protons which are simultaneously produced in reactions motivated by studies of proton capture reactions of interest for nuclear astrophysics. The technical characteristics of the tracking array are described in detail as are its performance in two pilot experiments. The physics justification for such a system is also presented.
The triple alpha reaction is one of the most important reactions in the nuclear astrophysics. However, its reaction rate in high temperature environments at T9> 2 was still uncertain. One of the ...major origins of the uncertainty was that the radiative-decay probability of the 31− state in 12C was unknown. In the present work, we have determined the radiative-decay probability of the 31− state to be 1.3−1.1+1.2×10−6 by measuring the 1H(12C,12Cp) reaction for the first time, and derived the triple alpha reaction rate in high temperature environments from the measured radiative-decay probability. The present result suggests that the 31− state noticeably enhances the triple alpha reaction rate although the contribution from the 31− state had been assumed to be small.
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