T. Furukawa

Radiative cooling of C7

The spontaneous and photo-induced neutralization of C₇⁻ produced in a laser ablation source was measured in an electrostatic storage ring. The measurements provide three independent determinations of the radiative cooling of the ions, based on the short time spontaneous decay and on the integrated amplitude and the shape of the photo-induced neutralization signal. The amplitude of the photo-induced signal was measured between 0.5 ms and 35 ms and found to depend on photon wavelength and ion storage time. All three signals can be reproduced with identical thermal IR radiative cooling rates with oscillator strengths equal to theoretical predictions. In addition, the measurements provide the excitation energy distribution.

Radiative cooling of C{sub 7}{sup −}

The spontaneous and photo-induced neutralization of C₇⁻ produced in a laser ablation source was measured in an electrostatic storage ring. The measurements provide three independent determinations of the radiative cooling of the ions, based on the short time spontaneous decay and on the integrated amplitude and the shape of the photo-induced neutralization signal. The amplitude of the photo-induced signal was measured between 0.5 ms and 35 ms and found to depend on photon wavelength and ion storage time. All three signals can be reproduced with identical thermal IR radiative cooling rates with oscillator strengths equal to theoretical predictions. In addition, the measurements provide the excitation energy distribution.

Hindered proton collectivity in 16(28)S12: possible magic number at Z=16.

The reduced transition probability B(E2;0(gs)(+)→2(1)(+)) for (28)S was obtained experimentally using Coulomb excitation at 53 MeV/nucleon. The resultant B(E2) value 181(31) e(2)fm(4) is smaller than the expectation based on empirical B(E2) systematics. The double ratio |M(n)/M(p)|/(N/Z) of the 0(gs)(+)→2(1)(+) transition in (28)S was determined to be 1.9(2) by evaluating the M(n) value from the known B(E2) value of the mirror nucleus (28)Mg, showing the hindrance of proton collectivity relative to that of neutrons. These results indicate the emergence of the magic number Z=16 in the |T(z)|=2 nucleus (28)S.

Observation of recurrent fluorescence photons from small carbon cluster anions

We directly observed recurrent fluorescence from small carbon cluster anions C−6 stored in an electrostatic ion storage ring TMU E-ring. This process, caused by the electronic transitions via low-lying electronic excited states after the inverse internal conversion (IIC), has been recently reported as fast cooling. In the present study, we succeeded in detection of emitted fluorescence. The observed lifetime was consistent with the theoretically estimated lifetime.

Search for electric dipole moment in 129Xe atom using a nuclear spin oscillator

We aim to measure the electric dipole moment (EDM) of a diamagnetic atom 129Xe using an optical-detection nuclear spin maser technique. The relation of EDM in a diamagnetic atom to nuclear Schiff moment and fundamental sources generating it is discussed, and the present status for the development of our experimental setup is presented.

Development of co-located 129 Xe and 131 Xe nuclear spin masers with external feedback scheme

We report on the operation of co-located Xe and Xe nuclear spin masers with an external feedback scheme, and discuss the use of Xe as a comagnetometer in measurements of the Xe spin precession frequency. By applying a correction based on the observed change in the Xe frequency, the frequency instability due to magnetic field and cell temperature drifts are eliminated by two orders of magnitude. The frequency precision of 6.2 μHz is obtained for a 10 s averaging time, suggesting the possibility of future improvement to ≈ 1 nHz by improving the signal-to-noise ratio of the observation.

Cooling dynamics of carbon cluster anions

A series of ion storage experiments on small carbon cluster anions was conducted to understand size-dependent cooling processes. The laser-induced delayed electron detachment time profile show clear even/odd alternation due to the presence of the electronic cooling. The time evolution of the internal energy distribution was simulated for Cn- (n=4 to 7) with a common procedure taking vibrational and electronic cooling into account.

Radioactive ion beam transportation for the fundamental symmetry study with laser-trapped atoms

The search for the violation of the fundamental symmetry in a radioactive atom is the promising candidate for precision tests of the standard model and its possible extensions. The subtle signal arising from the symmetry violation is enhanced in heavy atoms, such as a francium (Fr). To realize high precision measurements, a large amount of radioactive isotopes is required. The Fr is produced via a nuclear fusion reaction using a melted gold target with a (18)O primary beam at Cyclotron and Radioisotope Center, Tohoku University. The maximum extraction efficiency of the Fr ion was achieved at approximately 35%. The beam line consists of an electrostatic deflector, three electrostatic quadrupole triplets to the measurement area at 10 m away from the reaction point, and several beam diagnosis systems. We optimized parameters of the beam line.

Laser Cooled Francium Factory for the Electron Electric Dipole Moment Search

Cyclotron and Radioisotope Center, Tohoku University, Sendai, Miyagi 980-8578, Japan aGraduate school of Arts and Sciences, University of Tokyo, Meguro 153-8902, Tokyo, Japan bDepartment of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 102-0397, Japan cDepartment of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan dResearch Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan eAdvanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1184, Japan fDepartment of Physics, Kyoto University, Kyoto, Kyoto 606-8502, Japan gIndian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India hDepartment of Physics, Tohoku University, Sendai, Miyagi 980-8578, Japan iDepartment of Physics, Kyushu University, Fukuoka, Fukuoka 812-8581, Japan

EXPERIMENTAL INVESTIGATION OF THE STELLAR REACTION 30S(p,γ)31Cl VIA COULOMB DISSOCIATION

The Coulomb dissociation of the proton-rich nuclei 31Cl was studied experimentally using 31Cl beams at 58 MeV/nucleon with a lead target. The relative energy between the reaction products, 30S and proton, was obtained. The first excited state in 31Cl was observed which is relevant to the resonant capture of stellar 30S(p,γ)31Cl reaction.