Interaction cross sections σ I for 58–77 Ni on a carbon target at 280 MeV / nucleon were measured at the RIKEN Radioactive Isotope Beam Factory (RIBF) using the BigRIPS fragment separator. The aim of this work is to deduce matter radii from the measured values of σ I through Glauber-model analysis and, by combining them with the charge radii that have been precisely determined by the laser spectroscopy, to determine the neutron-skin thickness r np of Ni isotopes over a wide range of neutron excess δ = ( N Z )/ A from 0.03 to 0.27. The present data of σ I constitute the first systematic set along the isotopic chain in the Ni mass region, providing a consistent basis for investigating the evolution of nuclear size and neutron-skin with increasing neutron excess. The slope of the neutron-skin thickness r np as a function of the neutron excess δ is expected to provide an important constraint on the L parameter of the nuclear matter equation of state (EOS), which represents the first-order term in the density dependence of the symmetry energy in nuclear matter. The EOS is essential for understanding not only the structure of atomic nuclei but also the mechanisms of supernova explosions and the properties of neutron stars. The results of this study are therefore expected to provide valuable insights into the elucidation of the EOS.

The charge-changing cross sections σ_CC have emerged as a promising observable for deducing nuclear charge radii of unstable nuclei. In this study, we measured σ_CC for neutron-rich nickel isotopes ^58–77 Ni at 250 MeV/u. The experimental results were analyzed by using a Glauber model including charged-particle evaporation effects, and the consistency between the measured σ _CC and existing charge radii was investigated. The results demonstrate that the present approach provides a reliable description of σ _CC systematics in the Ni isotopic chain. These findings support the applicability of σ _CC measurements as an alternative probe of charge radii, particularly for nuclei where direct measurements are not available.

The FRS lon Catcher (FRS-IC) is located at the final focal plane of the Fragment Separator FRS at GSI. The FRS-IC setup is well known for high-precision experiments with stopped exotic nuclei produced by projectile fragmentation and fission. The facility consists of the cryogenic gas-filled stopping cell (CSC), an RFQ-based beamline (DISTRICT), and a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). This paper illustrates how alpha spectroscopy performed at this facility has emerged as a promising tool to unveil the nuclear structure of exotic nuclei, i.e., half- live and decay energy measurements. First studies of that kind were performed on the decay chains of 218Rn, 219Rn, 221 Ac, 220Fr, and 221.224 Th produced by projectile fragmentation of 238U. The a decay energy measurements performed and the deduced Q, values confirm the known maximum at N= 128 and the values of Q, at N= 132-133 follow the predicted increasing in Q values compared to the values for At isotopes at the same neutron number N. Further, the production rate ratio of the isomer to the ground state of 211 Po was measured. It allows an estimate of the angular momentum distribution of 211 Po fragments following fragmentation of 238 U in a "Be target at relativistic energies. In addition, the potential of mass-selected decay spectroscopy behind the MR-TOF-MS was demonstrated with short-lived 215 Po ions (11/2 = 1.78 ms). This demonstrates that the FRS-IC is a reliable setup for a spectroscopy studies and related nuclear structure studies.

We developed a redundant logic for predicting Vertical Displacement Events (VDEs) using only magnetic diagnostics with a Support Vector Machine (Inoue et al 2022 Nucl. Fusion 62 086007). This logic was experimentally validated in the integrated commissioning of JT-60SA. Triggering of VDEs results in significant asymmetric heat loads on first walls and electromagnetic loads on conducting materials. These concerns are mitigated by a newly proposed direction control for VDEs. We successfully detected VDEs in experiments and controlled their direction by setting the control voltage to zero upon detection, thus guiding VDEs in an intended direction and reducing the risk to the device from unmitigated VDEs in either direction, although completely avoiding VDEs remains the ideal. In the developed predictor, VDEs are predicted using proxies to monitor the controller’s performance with an adaptive voltage allocation scheme (Inoue et al 2021 Nucl. Fusion 61 096009). For future experiments, we plan to extend our approach to monitor more detailed information from the equilibrium controller, including control values of each PID component, which has been shown to enhance the prediction accuracy of VDEs.

The charge-changing cross sections σ _cc of ^10-13 B, ^11-13 C, and ^12,13 N nuclides on multiple targets were measured at the energy of about 170 MeV/nucleon. The point-proton radii of these nuclides were determined by comparing the experimental σ _cc with the Glauber model calculation considering the charged-particle evaporation effect. For ^12,13 B, the present results are consistent with the existing experimental data deduced by different methods.

We report on the observation of previously-unknown isotope ^21Al, the first unbound aluminum isotope located beyond the proton dripline. The ^21Al nucleus decays by one-proton (1p) emission, and its in-flight decays were detected by tracking trajectories of all decay products with micro-strip silicon detectors. The 1p-emission processes were studied by analyses of the measured angular correlations of decay products ^20Mg+p. The 1p-decay energies of ground and low-lying excited states of ^21Al, its mass excess and proton separation energy value S_p=-1.1(1) MeV were determined.

Superconducting (SC) tokamak JT-60SA plays an essential role in fusion research and development by supporting and complementing the ITER project, providing directions to the DEMO design activity and fostering next generation scientists and engineers. Since the short circuit incident at the terminal joints of equilibrium field coil #1 during the integrated commissioning (IC) in March 2021, both EU and JA implementing agencies (IAs) have examined how to ensure safe operation of JT-60SA by mitigating the risk of possible discharge occurrence inside the cryostat. Based on the experience of the global Paschen tests, the IAs have established a strategy of risk mitigation measures, which is a combination of (i) reinforcement of insulation, (ii) avoiding unnecessary voltage application to the coil systems and (iii) immediate de-energization of the coils when deteriorated vacuum conditions are detected. Thanks to the considerable efforts of the Integrated Project Team members, the IC restarted in May 2023. After confirmation of the SC state of the coil systems (TF, EF and CS), the coil energization test and the plasma operation phase 1 (OP-1) started. The first plasma was successfully achieved on 23 October 2023 with a limited value of voltage and current applied to the coils. The plasma configuration control was also confirmed with low plasma current and low auxiliary heating power conditions. Based on the IO-F4E-QST collaboration, activities of JT-60SA have been shared with the IO and provided an important lesson for ITER assembly and commissioning, and will provide an outstanding contribution to fusion research at large. After OP-1, maintenance & enhancement phase 1 (M/E-1) starts from January 2024, in which in-vessel components are installed, and heating and diagnostic systems are extensively upgraded to allow a high power heating experiment planned in OP-2. In order to make the best use of JT-60SA, a newly organized JT-60SA experiment team will refine the research plan for the future high heating power operation phase.

Nuclear transmutation is emerging as a promising approach for reprocessing high-level waste, specifically treating long-lived nuclides like Zr-93 from spent fuel. It is essential to accumulate reaction data for these nuclei to advance this prominent treatment and to build a comprehensive understanding of reaction mechanisms. In this study, the residual production cross-sections resulting from proton-induced reactions on Zr-93 were measured at 27 MeV/nucleon in inverse kinematics. At the RI Beam Factory (RIBF), the Optimized Energy Degrading Optics beamline was used to deduce production cross-sections for isotopes Nb91-93, Zr-91,Zr-92, and Y-88,Y-89. Comparing the results from this study and prior research with calculated excitation functions, a moderate agreement is found with theoretical predictions derived from TALYS and CCONE. The measured cross-sections offer valuable insights for future considerations in nuclear-waste treatment facilities. This is particularly relevant for facilities exploring innovative methods, such as accelerator-driven systems.

We report the charge-changing cross sections (σcc) of 24 p-shell nuclides on both hydrogen and carbon at about 900A MeV, of which 8,9Li, 10-12Be, 10,14,15B, 14,15,17-22N and 16O on hydrogen and 8,9Li on carbon are for the first time. Benefiting from the data set, we found a new and robust relationship between the scaling factor of the Glauber model calculations and the separation energies of the nuclei of interest on both targets. This allows us to deduce proton radii (Rp) for the first time from the cross sections on hydrogen. Nearly identical Rp values are deduced from both target data for the neutron-rich carbon isotopes; however, the Rp from the hydrogen target is systematically smaller in the neutron-rich nitrogen isotopes. This calls for further experimental and theoretical investigations.

Effects of the kinetic thermal ions (KTIs) on ideal infernal modes and resistive infernal modes have been investigated by using magnetohydrodynamic (MHD) simulation without KTIs and kinetic-MHD hybrid simulation with KTIs. For the ideal infernal modes, the pressure profile is significantly flattened at the saturated state for both the models with and without the KTIs. As the beta value decreases, the ideal infernal modes are stabilized while the resistive infernal modes are still unstable. For the resistive infernal modes, while the saturated pressure profile is significantly flattened in the MHD simulation without KTIs, the pressure profile is not flattened at the saturated state in the kinetic-MHD hybrid simulation with KTIs. The suppression of the saturation level by the effects of the KTIs results from the phase mismatch between the radial velocity and perturbed pressure mode structures. This indicates that KTIs play an essential role for the suppression of pressure profile flattening due to slowly growing resistive MHD instabilities.

Background: Very recently, the PREX and CREX collaborations presented skin values r208 skin(newPREX2) = 0.278 +/- 0.078 (exp) +/- 0.012 (theor.) fm and r48skin = 0.121 +/- 0.026 (exp) +/- 0.024 (model), respectively. We re-cently determined a neutron-skin value r208 skin = 0.278 +/- 0.035 fm from measured reaction cross sections aR(exp) of p + 208Pb scattering in a range of incident energies 10 <= Ein <= 100 MeV where the chiral (Kyushu) g-matrix folding model is reliable for 12C + 12C scattering. The data aR(exp) are available for proton scattering on 58Ni, 40,48Ca, and 12C targets.Purpose: Our first aim is to test the Kyushu g-matrix folding model for p + 208Pb scattering in 20 <= Ein <= 180 MeV. Our second aim is to determine skin values rskin and matter and neutron radii, rm and rn, for 208Pb, 58Ni, 40,48Ca, and 12C from the aR(exp).Methods: Our method is the Kyushu g-matrix folding model with the densities scaled from the D1S-GHFB+AMP densities, where D1S-GHFB+AMP stands for Gogny-D1S HFB (GHFB) with angular momentum projection (AMP).uResults: As for proton scattering, we find that our model is reliable in 20 <= Ein <= 180 MeV. For 208Pb, the skin value deduced from aR(exp) in 20 <= Ein <= 180 MeV is r208 skin(aR) = 0.299 +/- 0.020 fm. Our results on rskin are compared with the previous works. Conclusion: Our result r208 skin(aR) = 0.299 +/- 0.020 fm agrees with r208skin(PREX2) = 0.283 +/- 0.071 fm. In addi-tion, our result r48 skin = 0.103 +/- 0.022 fm is consistent with the CREX value.

The deuteron is a loosely bound system that can easily break up into its constituent proton and neutron whilst in the presence of Coulomb and nuclear fields. Previous experimental studies have shown that this breakup process has a significant impact on residual-nucleus production from deuteron bombardment in the high-energy range of 50-210 MeV/nucleon. However, there remains a lack of cross-section data at energies below 50 MeV/nucleon. The current study determined Zr-93 + d reaction cross sections under inverse kinematics at approximately 28 MeV/nucleon using the BigRIPS separator, OEDO beamline, and SHARAQ spectrometer. Cross sections from this research were compared with previous measurements and theoretical calculations. The experimental results show a large enhancement of the production cross sections of residual nuclei, especially those produced from a small number of particle emissions, compared to the proton-induced reaction data at similar bombarding energy. The DEURACS calculation, which quantitatively takes deuteron-breakup effects into account, reproduces the data well. As a long-lived fission product, Zr-93 remains a challenge for nuclear-waste disposal and treatment. This study's low-energy data may assist future consideration of nuclear-waste treatment facilities, where Zr-93 + d may feasibly transmute the waste into short-lived/stable nuclei.

Resistive wall mode control coils (RWMCs) will be installed in the vacuum vessel of JT-60SA. Since 200 °C baking of vacuum vessel on JT-60SA is performed to remove the impurity in the plasma facing components, in-vessel components must be made with heat-resistant materials such as metal and ceramic or must be cooled with water. We looked for the heat-resistant organic insulator for JT-60SA RWMC and performed the heat resistant test for several resins. However, no resin passed the test (Sukegawa et al., 2015). We again performed the heat resistant test of several organic insulator in the circumstances without air and finally found that the some Bismaleimide–Triazine (BT) resin has enough heat resistance without air. We designed the eight-turn RWMC with the BT resin. Based on this design, the specification of RWMC and power supply requirement are decided. For the design of RWMC, the finite element (FEM) analysis of electromagnetic force during disruption and thermal stress during baking and operation were performed. Manufacturing of the RWMC has already launched.

Received 16 January 2023DOI:https://doi.org/10.1103/PhysRevC.107.029901Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeam diagnosticsBinding energy & massesIsomer decaysLifetimes & widthsNuclear bindingNuclear fragmentationNuclear reactionsNuclear structure & decaysSecondary beamsShell modelAccelerators & BeamsNuclear Physics

Background: Very recently, the PREX and CREX collaborations presented skin values ${r}_{\mathrm{skin}}^{208}(\mathrm{newPREX}2)=0.278\ifmmode\pm\else\textpm\fi{}0.078\phantom{\rule{4pt}{0ex}}(\mathrm{exp})\ifmmode\pm\else\textpm\fi{}0.012\phantom{\rule{4pt}{0ex}}(\mathrm{theor}.)\phantom{\rule{0.16em}{0ex}}\mathrm{fm}$ and ${r}_{\mathrm{skin}}^{48}=0.121\ifmmode\pm\else\textpm\fi{}0.026\phantom{\rule{4pt}{0ex}}(\mathrm{exp})\ifmmode\pm\else\textpm\fi{}0.024\phantom{\rule{4pt}{0ex}}(\mathrm{model})$, respectively. We recently determined a neutron-skin value ${r}_{\mathrm{skin}}^{208}=0.278\ifmmode\pm\else\textpm\fi{}0.035\phantom{\rule{0.16em}{0ex}}\mathrm{fm}$ from measured reaction cross sections ${\ensuremath{\sigma}}_{\mathrm{R}}(\mathrm{exp})$ of $p+^{208}\mathrm{Pb}$ scattering in a range of incident energies $10\ensuremath{\lesssim}{E}_{\mathrm{in}}\ensuremath{\lesssim}100$ MeV where the chiral (Kyushu) $g$-matrix folding model is reliable for $^{12}\mathrm{C}+^{12}\mathrm{C}$ scattering. The data ${\ensuremath{\sigma}}_{\mathrm{R}}(\mathrm{exp})$ are available for proton scattering on $^{58}\mathrm{Ni}$, $^{40,48}\mathrm{Ca}$, and $^{12}\mathrm{C}$ targets.Purpose: Our first aim is to test the Kyushu $g$-matrix folding model for $p+^{208}\mathrm{Pb}$ scattering in $20\ensuremath{\lesssim}{E}_{\mathrm{in}}\ensuremath{\lesssim}180$ MeV. Our second aim is to determine skin values ${r}_{\mathrm{skin}}$ and matter and neutron radii, ${r}_{\mathrm{m}}$ and ${r}_{\mathrm{n}}$, for $^{208}\mathrm{Pb}$, $^{58}\mathrm{Ni}$, $^{40,48}\mathrm{Ca}$, and $^{12}\mathrm{C}$ from the ${\ensuremath{\sigma}}_{\mathrm{R}}(\mathrm{exp})$.Methods: Our method is the Kyushu $g$-matrix folding model with the densities scaled from the D1S-GHFB+AMP densities, where D1S-GHFB+AMP stands for Gogny-D1S HFB (GHFB) with angular momentum projection (AMP).Results: As for proton scattering, we find that our model is reliable in $20\ensuremath{\lesssim}{E}_{\mathrm{in}}\ensuremath{\lesssim}180$ MeV. For $^{208}\mathrm{Pb}$, the skin value deduced from ${\ensuremath{\sigma}}_{\mathrm{R}}(\mathrm{exp})$ in $20\ensuremath{\lesssim}{E}_{\mathrm{in}}\ensuremath{\lesssim}180$ MeV is ${r}_{\mathrm{skin}}^{208}({\ensuremath{\sigma}}_{\mathrm{R}})=0.299\ifmmode\pm\else\textpm\fi{}0.020$ fm. Our results on ${r}_{\mathrm{skin}}$ are compared with the previous works.Conclusion: Our result ${r}_{\mathrm{skin}}^{208}({\ensuremath{\sigma}}_{\mathrm{R}})=0.299\ifmmode\pm\else\textpm\fi{}0.020$ fm agrees with ${r}_{\mathrm{skin}}^{208}(\mathrm{PREX}2)=0.283\ifmmode\pm\else\textpm\fi{}0.071$ fm. In addition, our result ${r}_{\mathrm{skin}}^{48}=0.103\ifmmode\pm\else\textpm\fi{}0.022$ fm is consistent with the CREX value.

The JT-60 Super Advanced (JT-60SA) tokamak was constructed with very tight tolerances for assembly and handling of heavy components in an enclosed space. Millimetre-order precision was required for the tokamak assembly, not only to avoid mechanical interference, but also to obtain good plasma performance by keeping the magnetic error field low. This effort entailed the development of numerous unique procedures. This paper reports on these procedures, focusing on assembly and testing of the final sector of the vacuum vessel, the central solenoid, top parts of the tokamak, and the in-vessel components.

Tanihata et al. (1988) determined matter radii rm(σI)for 4,6,8He from interaction cross sections σIof 4,6,8He+12C scattering at 790 MeV per nucleon, using the optical limit of the Glauber model. Lu et al. (2013) determined proton radii rp(AIS)for 4,6,8He with the atomic isotope shifts (AIS). We investigate whether the Love-Franey t-matrix folding model is good for 4,6,8He+12C scattering at 790 MeV per nucleon.

The fragment separator FRS has been used for the first time to measure the (n, p)- and (p, n)-type isobaric charge-exchange cross sections of stable Sn-112,Sn-124 isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasielastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic contribution can be associated to the excitation of isobar Delta(1232) resonances and to the pion emission in s wave, in both the target and projectile nuclei, while the quasielastic contribution is associated with the nuclear spin-isospin response of nucleon-hole excitations. The data lead to interesting results, where we observe a clear quenching of the quasielastic component, and their comparisons to theoretical calculations demonstrate that the baryonic resonances can be excited in the target and projectile nuclei. To go further in this investigation, we propose to study the excitation of baryonic resonances, taking advantage of the combination of high-resolving power magnetic spectrometers with the Wide Angle Shower Apparatus (WASA) calorimeter. These new measurements will allow us to determine the momenta of the ejectiles and pions emitted in coincidence after the single isobaric charge-exchange collisions, providing us unique opportunities to study the evolution of the baryonic resonance dynamics with the neutron-proton asymmetry through the use of exotic radioactive ion beams.

DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter- I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high- Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L–H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼ 8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co- I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.

The root mean square radii of the proton density distribution in ^{16-24}O derived from measurements of charge changing cross sections with a carbon target at ∼900A  MeV together with the matter radii portray thick neutron skin for ^{22-24}O despite ^{22,24}O being doubly magic. Imprints of the shell closures at N=14 and 16 are reflected in local minima of their proton radii that provide evidence for the tensor interaction causing them. The radii agree with ab initio calculations employing the chiral NNLO_{sat} interaction, though skin thickness predictions are challenged. Shell model predictions agree well with the data.