3 research outputs found
Design report of the KISS-II facility for exploring the origin of uranium
One of the critical longstanding issues in nuclear physics is the origin of
the heavy elements such as platinum and uranium. The r-process hypothesis is
generally supported as the process through which heavy elements are formed via
explosive rapid neutron capture. Many of the nuclei involved in heavy-element
synthesis are unidentified, short-lived, neutron-rich nuclei, and experimental
data on their masses, half-lives, excited states, decay modes, and reaction
rates with neutron etc., are incredibly scarce. The ultimate goal is to
understand the origin of uranium. The nuclei along the pathway to uranium in
the r-process are in "Terra Incognita". In principle, as many of these nuclides
have more neutrons than 238U, this region is inaccessible via the in-flight
fragmentation reactions and in-flight fission reactions used at the present
major facilities worldwide. Therefore, the multi-nucleon transfer (MNT)
reaction, which has been studied at the KEK Isotope Separation System (KISS),
is attracting attention. However, in contrast to in-flight fission and
fragmentation, the nuclei produced by the MNT reaction have characteristic
kinematics with broad angular distribution and relatively low energies which
makes them non-amenable to in-flight separation techniques. KISS-II would be
the first facility to effectively connect production, separation, and analysis
of nuclides along the r-process path leading to uranium. This will be
accomplished by the use of a large solenoid to collect MNT products while
rejecting the intense primary beam, a large helium gas catcher to thermalize
the MNT products, and an MRTOF mass spectrograph to perform mass analysis and
isobaric purification of subsequent spectroscopic studies. The facility will
finally allow us to explore the neutron-rich nuclides in this Terra Incognita.Comment: Editors: Yutaka Watanabe and Yoshikazu Hirayam
First direct mass measurement of superheavy nuclide via MRTOF mass spectrograph equipped with an α-TOF detector
Probing Optimal Reaction Energy for Synthesis of Element 119 from <sup>51</sup>V+<sup>248</sup>Cm Reaction with Quasielastic Barrier Distribution Measurement
International audienceThe quasielastic barrier distribution of 51V+248Cm was extracted by measuring the excitation function of quasielastic backscattering using a gas-filled recoil ion separator, GARIS-III. The obtained barrier distribution is well explained by the coupled-channels calculation, indicating a significant effect of the rotational excitation of deformed 248Cm. From the measured average Coulomb barrier height and deformation parameters of 248Cm, the side-collision energy leading to a compact configuration of colliding nuclei was obtained. The relation between the side collision energy and the excitation function of the evaporation-residue cross sections in the 48Ca+248Cm system was evaluated as a reference for the 51V+248Cm case. The optimal reaction energy to synthesize a new element 119 at the 51V+248Cm fusion reaction (3n and 4n channels) was estimated with an aid of these experimental data