Search

Nuclear transmutation is emerging as a promising approach for reprocessing high-level waste, specifically treating long-lived nuclides like |$^{93}$| Zr 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 |$^{93}$| Zr 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 |$^{91-93}$| Nb, |$^{91,92}$| Zr, and |$^{88,89}$| Y. 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. [ABSTRACT FROM AUTHOR]

A strip-readout parallel-plate avalanche counter (SR-PPAC) has been developed with the aim of high-detection efficiency and good position resolution in high-intensity heavy-ion measurements. The performance was evaluated using 115 MeV u-1 132Xe, 300 MeV u-1 132Sn, and 300 MeV u-1 48Ca beams. A detection efficiency of greater than 99 percent for these beams is achieved even at an incident beam intensity of 0.7 million particles per second. The best position resolution achieved is 100 µm. [ABSTRACT FROM AUTHOR]

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 93Zr + 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, 93Zr 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 93Zr + d may feasibly transmute the waste into short-lived/stable nuclei. [ABSTRACT FROM AUTHOR]

We have measured the differential cross section and analyzing power for (p , 2 p) reactions that lead to discrete states of residual nuclei at an incident energy of 197 MeV for five kinds of target nuclei, 12C, 16O, 40,48Ca, and 90Zr. The data are compared with distorted-wave impulse approximation calculations using two kinds of global optical potentials. The spectroscopic factors obtained from these calculations agree with those determined in (e, e ′ p) studies within 20%, except for one orbital of the 90Zr nucleus where the distortion effect is much greater than that for the other orbitals of 90Zr and for other target nuclei. We also observed a clear and visibly distinct j -dependence in the analyzing power. [ABSTRACT FROM AUTHOR]

A prototype Dual Gain Multilayer Thick Gas Electron Multiplier (DG-M-THGEM) with an active area of 10 cm × 10 cm was manufactured aiming at the production of a large-volume active-target time projection chamber which can work under the condition of high-intensity heavy-ion beam injections. The DG-M-THGEM has an alternating structure of electrodes and insulators. Effective gas gains of two regions, which are called beam and recoil regions, are separately controlled. Performance of the prototype DG-M-THGEM in hydrogen gas at a pressure of 40 kPa was evaluated. Irradiating a 132Xe beam, an effective gas gain lower than 100 with a charge resolution of 3% was achieved in the beam region while an effective gas gain of 2000 was maintained in the recoil region. Position distributions of measured charges along the beam axis were investigated in order to evaluate gain uniformity in the high-intensity beam injection. The gain shift was estimated by simulations considering space charges in the drift region. The gain shift was suppressed within 3% even at the beam intensity of 2.5 × 106 particles per second. [ABSTRACT FROM AUTHOR]

We conduct an experimental project to make spectroscopy of deeply bound pionic atoms systematically over wide range of nuclei. We aim at studying the strong interaction in the low energy region, which has close connection to spontaneous chiral symmetry breaking and its partial restoration in nuclear matter. First experimental results show improved spectral resolution and much better statistical sensitivity than previous experiments. Present status of the experiment is reported.

A simulation method, which can predict the relation between the pulse shapes and the interaction points of incident [gamma]-rays, has been established for the entire effective volume of a segmented Ge detector with planar geometry, and the pulse shapes shows good agreement with the experimental observation. We are using pulse shape analysis to gain position information with a granularity finer than the segment size, and we will discuss the expected position resolution based on the simulation results. Index Terms--Planar, position sensitivity, pulse shape, segmented germanium detectors.

We performed a precision missing-mass spectroscopy experiment of the deeply bound pionic states in a 121Sn atom using the (d,3He) reaction near the π− emission threshold. The experiment serves as a pilot experiment for our new ‘pionic atom factory project’ at RIBF, which aims at precision spectroscopy of the energy spectrum of the pionic atom of isotopes and isotones. The result of the pilot experiment demonstrated the potentiality of BigRIPS and of the RIBF facilities for the project. The current status of the analysis is reported.

We have performed an inclusive spectroscopy of 122Sn(d, 3He) reaction near the pion emission threshold at an incident energy of Td = 250 MeV/nucleon. The first experiment aims as devloping the high precision spectroscopy of pionic atoms at the RI beam factory (RIBF) of RIKEN, which leads to a new project, pionic Atom Factory project (piAF) to measure pionic atoms for a wide range of elements. We report the analysis status of the pilot experiment.

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have measured the energy spectrum of pionic Sn atoms by missing-mass spectroscopy of the Sn( d, He) reaction near the π emission threshold. The measurement serves as a pilot experiment for high precision systematic spectroscopy of deeply bound pionic atoms in a new pionic Atom Factory project (piAF) at the RI beam factory (RIBF) of RIKEN. The status of the analysis is reported. [ABSTRACT FROM AUTHOR]

A rotational band with five cascade γ-ray transitions was newly found in 40Ar. The deduced transition quadrupole moment of $1.45_{-0.31}^{+0.49}\, {\rm eb}$ has demonstrated this band as having a superdeformed shape of β2 ~ 0.5. The structure of the band was discussed in the framework of cranked Hartree-Fock-Bogoliubov calculations and the assignment of multiparticle–multihole configuration has been made. [ABSTRACT FROM AUTHOR]

Lifetime measurement of the first excited 2+ state in 18C was performed using an upgraded recoil shadow method to determine the electric quadrupole transition. The measured mean lifetime is 18.9 ± 0.9 (stat) ± 4.4 (syst) ps, which corresponds to a $B(E2;\;2_1^+ \to 0_{{\rm{gs}}}^+)$ value of 4.3 ± 0.2 ± 1.0 e2fm4, or about 1.5 Weisskopf units. The mean lifetime of the first 2+ state in 16C was remeasured to be about 18 ps, about four times shorter than the value reported previously. By incorporating the γ-ray angular distribution measured in this work into the previous measurement, this discrepancy has been explained. The observed transition strengths in 16,18C are hindered compared to the empirical transition strengths, indicating that the anomalous hindered E2 strength observed in 16C persists in 18C. [ABSTRACT FROM AUTHOR]

A simulation method, which can predict the relation between the pulse shapes and the interaction points of incident γ-rays, has been established for the entire effective volume of a segmented Ge detector with planar geometry, and the pulse shapes shows good agreement with the experimental observation. We are using pulse shape analysis to gain position information with a granularity finer than the segment size, and we will discuss the expected position resolution based on the simulation results. [ABSTRACT FROM AUTHOR]

The Optimized Energy Degrading Optics (OEDO) beamline is an upgrade of the High-resolution beamline at the RI Beam Factory at RIKEN. Its purpose is to measure nuclear reactions induced by radioactive ions at |$10$| – |$50$| MeV/u. The main components of the OEDO beamline are two superconducting quadrupole triplet magnets and one radio-frequency deflector, which were recently installed. This setup produces slowed-down, well-focused radioactive-isotope beams by using a degree of freedom in the longitudinal phase space of the beam. This paper describes the OEDO beamline in detail, discusses the unique concept of its ion optics, and demonstrates its feasibility by conducting measurements with medium-mass radioactive-isotope beams. [ABSTRACT FROM AUTHOR]

An angle-tunable wedge degrader system has been developed to be used as a monoenergetic degrader for a low-energy radioactive isotope (RI) beamline working with the slowing-down method. The system consists of a pair of aluminum degraders with quadratic cross sections, whose overlap works effectively as a wedge-type degrader; the wedge angle can be tuned by changing the relative position of the two aluminum degraders. This paper presents the operation principle, estimation of performance and application range by simulation, and the experimental validation. [ABSTRACT FROM AUTHOR]