M. Wakasugi

Changes of the Nuclear Charge Distribution of Nd, Sm, Gd and Dy from Optical Isotope Shifts

Isotope shifts and hyperfine structures in 28 optical transitions for 28 stable isotopes of Nd, Sm, Gd and Dy were measured by means of the atomic-beam laser-spectroscopy. The nuclear parameter λ was obtained from the isotope shift measurement for all the stable nuclei with the improved accuracy. The λ values were analyzed by using the Fermi distribution for the nuclear charge density. As a result, the diffuseness at the nuclear surface or the hollow depth near the center of nucleus in the charge distribution depends on the neutron number. The values of δ and also δ were determined. It is shown that λ is a good probe into the systematic change of the nuclear charge distribution.

HYPERFINE STRUCTURE AND ISOTOPE SHIFT IN ER I BY THE ATOMIC-BEAM LASER SPECTROSCOPY

Isotope shifts of 5 transitions from the 3 H 6 and 3 F 4 levels of the ground configuration 4 f 12 6 s 2 in Er I were measured for the stable isotopes with A =162-170 by the atomic-beam laser spectroscopy. Hyperfine constants A and B of 7 atomic levels were determined. Changes of mean square nuclear charge radii δ and mean square nuclear deformation parameters δ were deduced. The deformations of 164-170 Er were found to be mainly quadrupole and contributions of higher order deformation parameters for 162 Er were estimated. J -dependence of isotope shifts in the (6, 1) term of 4 f 12 6 s 6 p was found. It is concluded that the J -dependence was caused by the crossed-second-order effect in which the field shift has dominant contribution.

Atomic Beam Diode-Laser Spectroscopy

Combined with a collimated atomic beam source, diode laser without external cavity has been used as a spectroscopic light source to study atomic hyperfine structures and isotope shifts of Ba i. Spectroscopic measurements of the 6s21S0 – 6s6p3P1 transition of Ba i have been carried out. All hyperfine peaks of 135,137Ba have been clearly seen and resolution of 50 MHz has been attained. Hyperfine constants A and B of the 3P1 state of 135,137Ba have been determined. Isotope shifts of stable Ba isotopes have also been measured. From the measured isotope shifts, the 6s electron density at the nucleus has been deduced to be 76.4(53) a.u. and discussed in terms of the Hartree-Fock approximation.

Population of the Metastable State of Yb I by an Electric Discharge

An atomic beam oven of a discharge type is constructed and the performance in populating a metastable state of Yb I is examined. The relative populations of the ground state 4f146s21S0 and the metastable state 4f135d6s2 (7/2, 3/2)5 of Yb I are measured for the first time by the laser-induced fluorescence method. It is found that the population of the metastable state increases with the discharge current and that of the ground state decreases to 30%. The method is also applicable for other elements.

Measurement of Hyperfine Structure of the 4f35d 5G-4f36p 5H in PrII by Collinear Laser-Ion-Beam Spectroscopy

The hyperfine structure of the transitions 4 f 3 ( 4 I o )5 d 5 G 2 o -4 f 3 ( 4 I o )6 p 5 H 3 (λ=601.94 nm) and 4 f 3 ( 4 I o )5 d 5 G 3 o -4 f 3 (^4I^o)6 p ^5H_3 (λ=604.83 n m ) o f P r I I h a s b e e n m e a s u r e d b y c o l l i n e a r l a s e r - i o n - b e a m s p e c t r o s c o p y . T h e m a g n e t i c - d i p o l e c o n s t a n t A a n d t h e e l e c t r i c - q u a d r u p o l e c o n s t a n t B o f t h e l e v e l s i n v o l v e d h a v e b e e n d e t e r m i n e d t o b e : A ( M H z ) B ( M H z ) 4f^3(^4I^o)5 d ^5G_2^o 1703.2±0.8 -14.1±5.8 4f^3(^4I^o)5 d ^5G_3^o 932.8±2.2 -15.1±6.6 4f^3(^4I^o)6 p ^5H_3 1028.7±1.0 -14.3±2.5.

The SCRIT electron scattering facility project at RIKEN RI beam factory

The self-confining RI target (SCRIT) electron scattering facility has been constructed at RIKEN RI Beam Factory. The commissioning experiment was performed, and the luminosity was achieved to around 1027 cm−2 s−1 with stable ions at a 250 mA electron beam current. For the electron scattering with short-lived unstable nuclei, the radioactive isotope production was started at electron-beam-driven RI separator for SCRIT. Furthermore, new devices, the electron spectrometer window frame spectrometer for electron scattering and the cooler buncher system were constructed. After the setup of new devices, a first electron scattering experiment with short-lived nuclei will be performed soon.

Fast-kicker system for rare-RI ring

We are developing a new fast-kicker system for rare-RI ring at RIKEN RI beam factory. New fast-kicker system enables us to inject a rare particle into the ring individually, and also to extract the rare particle from the ring quickly. It consists of a kicker power supply, which has a fast-response mechanism and a hybrid charging system, and a large acceptance kicker magnet. Propagation time from a trigger signal input to the power supply until the flat-top center of the kicker magnetic field is approximately 465 ns, the result is sufficient to achieve an individual injection with an energy of 200 MeV/nucleon. Reliable operation of the hybrid charging system makes it possible to extract a particle from the ring in 700 μs by using the same kicker magnet. A waveform of the magnetic field is under investigation by using a prototype kicker magnet.

The Scrit Electron Scattering Facility At Riken RI Beam Factory

The SCRIT (Self-Confining Radioactive-Isotope Ion Target) electron scattering facility has been constructed at the RIKEN RI Beam Factory. In the commissioning experiment, the ion-trapping properties of the SCRIT system were studied using stable ions. By using an electron spectrometer, the momentum transfer distribution of the electron elastic scattering of

A resonant Schottky pick-up for Rare-RI Ring at RIKEN

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Isochronous field study of the Rare-RI Ring

Xe was measured at 150, 200, and 300~MeV, and the charge density distribution was deduced. During the measurements, a luminosity of