53 research outputs found
Neutron-rich rare isotope production from projectile fission of heavy beams in the energy range of 20 MeV/nucleon
We investigate the possibilities of producing neutron-rich nuclides in
projectile fission of heavy beams in the energy range of 20 MeV/nucleon
expected from low-energy facilities. We report our efforts to theoretically
describe the reaction mechanism of projectile fission following a multinucleon
transfer collision at this energy range. Our calculations are mainly based on a
two-step approach: the dynamical stage of the collision is described with
either the phenomenological Deep-Inelastic Transfer model (DIT), or with the
microscopic Constrained Molecular Dynamics model (CoMD). The
deexcitation/fission of the hot heavy projectile fragments is performed with
the Statistical Mul- tifragmentation Model (SMM). We compared our model
calculations with our previous experimental projectile-fission data of 238U (20
MeV/nucleon)+208Pb and 197Au (20 MeV/nucleon)+197Au and found an overall
reasonable agreement. Our study suggests that projectile fission following
periph- eral heavy-ion collisions at this energy range offers an effective
route to access very neutron-rich rare isotopes toward and beyond the
astrophysical r-process path
One-neutron knockout reaction of 17C on a hydrogen target at 70 MeV/nucleon
First experimental evidence of the population of the first 2- state in 16C
above the neutron threshold is obtained by neutron knockout from 17C on a
hydrogen target. The invariant mass method combined with in-beam gamma-ray
detection is used to locate the state at 5.45(1) MeV. Comparison of its
populating cross section and parallel momentum distribution with a Glauber
model calculation utilizing the shell-model spectroscopic factor confirms the
core-neutron removal nature of this state. Additionally, a previously known
unbound state at 6.11 MeV and a new state at 6.28(2) MeV are observed. The
position of the first 2- state, which belongs to a member of the lowest-lying
p-sd cross shell transition, is reasonably well described by the shell-model
calculation using the WBT interaction.Comment: 15 pages, 3 figure
The N = 16 spherical shell closure in 24O
The unbound excited states of the neutron drip-line isotope 24O have been
investigated via the 24O(p,p')23O+n reaction in inverse kinematics at a beam
energy of 62 MeV/nucleon. The decay energy spectrum of 24O* was reconstructed
from the momenta of 23O and the neutron. The spin-parity of the first excited
state, observed at Ex = 4.65 +/- 0.14 MeV, was determined to be Jpi = 2+ from
the angular distribution of the cross section. Higher lying states were also
observed. The quadrupole transition parameter beta2 of the 2+ state was
deduced, for the first time, to be 0.15 +/- 0.04. The relatively high
excitation energy and small beta2 value are indicative of the N = 16 shell
closure in 24O.Comment: to be submitted to Physical Review Letter
Rare Isotope Production in peripheral heavy-ion collisions at beam energy of 15 MeV/nucleon
This paper presents our recent study on the production of neutron-rich rare isotopes with heavy-ion beams in the energy region of 15 MeV/nucleon. We present calculated production cross sections of neutron-rich nuclides from collisions of a 86Kr (15 MeV/nucleon) beam with 238U targets. Our calculations are based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Transfer model (DIT), or with the microscopic Constrained Molecular Dynamics model (CoMD). The de-excitation of the hot heavy projectile fragments is performed with the Statistical Multifragmentation Model (SMM). We also performed calculations with a radioactive beam of 92Kr (15 MeV/nucleon) with a target of 238U and observed that the multinucleon transfer mechanism leads to very neutron-rich nuclides toward and beyond the astrophysical r-process path. In the future, we plan to experimentally investigate such reactions in the KOBRA spectrometer at the RISP facility in Korea. We conclude that the reaction mechanism at beam energies below the Fermi energy involving periph- eral nucleon exchange, constitutes a novel and effective route to access extremely neutron-rich isotopes toward the r-process path and the neutron drip-line
Design study of 10 kW direct fission target for RISP project
We are developing Isotope Separation On-Line (ISOL) target system, which consists of 1.3 mm-thick uranium-carbide multi-disks and cylindrical tantalum heater, to be installed in new facility for Rare Isotope Science Project in Korea. The intense neutron-rich nuclei are produced via the fission process using the uranium carbide targets with a 70 MeV proton beam. The fission rate was estimated to be ∼1.5 × 1013/sec for 10 kW proton beam. The target system has been designed to be operated at a temperature of ∼2000 °C so as to improve the release effciency
KoBRA Wien filter for low-energy RI beam production and recoil separation
The Wien filter is one of the key components in ion optics to improve the mass separation performance. The KoBRA Wien filter will be installed at the low-energy beamline KoBRA of RAON in Korea. The specifications of the KoBRA Wien filter were determined based on the ion beams expected in the KoBRA beamline, especially, beam energies less than about 5 MeV/nucleon suitable for nuclear astrophysics experiments. The Wien filter is designed to have the maximum field intensities of 0.2 T for the magnetic field and 2.0 kV/mm for the electric field in the ±75(H)×±50(V)×2500(L)mm3 good-field region. Performance of the Wien filter was estimated by the ion optics calculations of the KoBRA beamline for 40Ar beams at 18.5 MeV/nucleon and 14O beams at 2.5 MeV/nucleon. The mass resolving powers are 42.65 and 517, respectively. Currently, the KoBRA Wien filter is being manufactured, and will perform a factory acceptance test. © 2023 Elsevier B.V.11Nsciescopu
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