I. Tanihata

Probing effect of tensor interactions in 16O via (p, d) reaction

Abstract We have measured the 16O(p,u2009d) reaction using 198-, 295- and 392-MeV proton beams to search for a direct evidence on an effect of the tensor interactions in light nucleus. Differential cross sections of the one-neutron transfer reaction populating the ground states and several low-lying excited states in 15O were measured. Comparing the ratios of the cross sections for each excited state to the one for the ground state over a wide range of momentum transfer, we found a marked enhancement of the ratio for the positive-parity state(s). The observation is consistent with large components of high-momentum neutrons in the initial ground-state configurations due to the tensor interactions.

Measurement of excitation spectra in the

Excitation spectra of ^{11}C are measured in the ^{12}C(p,d) reaction near the η^{} emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5xa0GeV impinges on a carbon target. The momenta of deuterons emitted at 0° are precisely measured with the fragment separator (FRS) operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound η^{}-mesic states in carbon nuclei, no distinct structures are observed associated with the formation of bound states. The spectra are analyzed to set stringent constraints on the formation cross section and on the hitherto barely known η^{}-nucleus interaction.

{}^{12}

We performed two search experiments for a Z=118 Superheavy nucleus in the reactions of 86Kr+208Pb and 84Kr+208Pb. We accumulated a dose of 2.1×1018 ions and 2×1018 ions, respectively. But we did not find any candidate of the evaporation residues with both experiments. A future plan proceeded by RIKEN Superheavy elements experimental group is also described.

C

Timing-pick up detectors with excellent timing resolutions are essential in many modern nuclear physics experiments. Aiming to develop a Time-Of-Flight system with precision down to about 10 ps, we have made a systematic study of the timing characteristic of TOF detectors, which consist of several combinations of plastic scintillators and photomultiplier tubes. With the conventional electronics, the best timing resolution of about 5.1 ps ({sigma}) has been achieved for detectors with an area size of 3x1 cm2. It is found that for data digitalization a combination of TAC and ADC can achieve a better time resolution than currently available TDC. Simultaneously measurements of both time and pulse height are very valuable for correction of time-walk effect.

(p,d)

The possible existence of η′-nucleus bound states has been put forward through theoretical and experimental studies. It is strongly related to the η′ mass at finite density, which is expected to be reduced because of the interplay between the UA(1) anomaly and partial restoration of chiral symmetry. The investigation of the C(p,d) reaction at GSI and FAIR, as well as an overview of the experimental program at GSI and future plans at FAIR are discussed.

reaction near the

Excitation-energy spectra of

η'

^{11}

emission threshold

C nuclei near the

Search for a Z=118 superheavy nucleus in the reaction of Kr beam with Pb target at RIKEN

eta^prime

Reaching time resolution of less than 10 ps with plastic scintillation detectors

-meson production threshold have been measured by missing-mass spectroscopy using the