E. Takeshita

Isomeric 0+ state in 12Be

An isomeric 0+ state at E x = 2.24 MeV in 12Be was found in the projectile fragmentation of 18O at 100 A MeV on a Be target. The excitation energy and the spin assignment were deduced by the measurements of the energies and the angular correlation function of the coincident two γ-rays corresponding to the 0+ → 2+ → 0+ decay, respectively.

Anomalously hindered E2 strength B(E2;2+(1)-->0+) in 16C.

The electric quadrupole transition from the first 2(+) state to the ground 0(+) state in 16C is studied through measurement of the lifetime by a recoil shadow method applied to inelastically scattered radioactive 16C nuclei. The measured mean lifetime is 77+/-14(stat)+/-19(syst) ps. The central value of mean lifetime corresponds to a B(E2;2+(1)-->0(+)) value of 0.63e(2) fm(4), or 0.26 Weisskopf units. The transition strength is found to be anomalously small compared to the empirically predicted value.

Different mechanism of two-proton emission from proton-rich nuclei 23 Al and 22 Mg

Two-proton relative momentum (q(pp)) and opening angle (theta(pp)) distributions from the three-body decay of two excited proton-rich nuclei, namely Al-23 --> p + p + Na-21 and Mg-22 --> p + p + Ne-20, have been measured with the projectile fragment separator (RIPS) at the RIKEN RI Beam Factory. An evident peak at q(pp) similar to 20 MeV/c as well as a peak in theta(pp) around 30 degrees are seen in the two-proton break-up channel from a highly-excited Mg-22. In contrast, such peaks are absent for the Al-23 case. It is concluded that the two-proton emission mechanism of excited Mg-22 is quite different from the Al-23 case, with the former having a favorable diproton emission component at a highly excited state and the latter dominated by the sequential decay process

Fragmentation cross sections and binding energies of neutron-rich nuclei

An exponential dependence of the fragmentation cross section on the average binding energy is observed and reproduced with a statistical model. The observed functional dependence is robust and allows the extraction of binding energies from measured cross sections. From the systematics of Cu isotope cross sections, the binding energies of {sup 76,77,78,79}Cu have been extracted. They are 636.94{+-}0.4,647.1{+-}0.4,651.6{+-}0.4, and 657.8{+-}0.5 MeV, respectively. Specifically, the uncertainty of the binding energy of {sup 75}Cu is reduced from 980 keV, as listed in the 2003 mass table of Audi, Wapstra, and Thibault to 400 keV. The predicted cross sections of two near drip-line nuclei, {sup 39}Na and {sup 40}Mg from the fragmentation of {sup 48}Ca are discussed.

Proton-proton correlations in distinguishing the two-proton emission mechanism of 23Al and 22Mg

The proton-proton momentum correlation functions (

Search for low lying dipole strength in the neutron rich nucleus 26Ne

C_{pp}(q)

Inelastic Scattering of 12Be with 4He

) for kinematically complete decay channels of

Inelastic Scattering of32Mg at 190 MeV/Nucleon from a Thick Proton Target

^{23}

Low-lying proton intruder state in 13B

Al

Coulomb Excitation of 24Si

\rightarrow