Y. Nojiri

Electromagnetic moments of short lived beta emitters F-21, Mg-23, Si-27 and Ca-39

The β-NMR spectra of 21F, 23Mg, 27Si and 39Ca which were produced in heavy ion collisions and implanted in various crystals have been observed. The magnetic moments of 21F and 27Si were determined to be |μ(21F)| = 3.9194 ± 0.0012 μN and |μ(27Si)| = 0.8653 ± 0.0003 μN, respectively. The electric quadrupole coupling constants were determined for the first time to be |eqQ(21F in MgF2)/h|= 9.94 ± 0.09 MHz, |eqQ(23Mg in MgF2)/h|= 1.96 ± 0.06 MHz, |eqQ(27Si in Al2O3)/h|= 1.90 ± 0.12 MHz, |eqQ(39Ca in CaCO3)/h|= 0.60 ± 0.04 MHz. From the present eqQ/h, the Q moments were deduced as |Q(21F)|= 110 ± 22 mb, |Q(23Mg)|= 114 ± 3 mb, |Q(27Si)|= 60 ± 13 mb and |Q(39Ca)|= 36± 7 mb. The present data were compared with the theoretical values obtained by the OXBASH shell model code.

Electric quadrupole moment of 25Na

The electric quadrupole coupling constant eqQ/h of 25Na (Iπ = 5/2+, T1/2 = 59.6 s), implanted in a TiO2 single crystal, has been measured by use of the β-NMR technique, to determine the electric quadrupole moment Q. As a result, |eqQ/h| = (44 ± 16) kHz and |Q(25Na)| = (1.0 ± 0.4) mb were determined. From the NMR on 25Na in NaCl, the magnetic moment was determined as |µ| = (3.6832 ± 0.0003) µN

Precise magnetic moment of short-lived beta emitter 35Ar

Abstract The magnetic moment of the short-lived β emitter 35Ar ( I π =3/2 + , T 1/2 =1.77 xa0s) has been remeasured by means of the combined technique of polarized nuclear beams and β-NMR. The obtained magnetic moment is 0.6322(2) μN. This value is consistent with the old data, but is one order of more magnitude precise. The value is well reproduced by the shell model calculation.

Nuclear Spin Alignment of 12,13B Produced in Heavy Ion Collisions

The nuclear spin alignments of the β-emitting fragments 12B(Iπ=1+, T1/2=20.2 ms) and 13B(Iπ=3/2−, T1/2=17.4 ms) produced in the 100A-MeV 13C, 15N + 9Be collisions respectively have been observed for the first time detecting asymmetric β-ray emission from these nuclei. By means of the spin manipulation technique based on the hyperfine interaction of B isotopes in TiO2, both the polarization P and the alignment A were determined reliably. The obtained P and A were significantly smaller than the expectation from the kinematical model. From the fact that the quenching factors for P and A are almost the same, there may be some depolarization mechanism in the collision process itself.

Hyperfine interactions of 19O in TiO2 and quadrupole moments of 13,19O

The electric quadrupole interaction of 19O(Iπ=(5/2)+, T1/2=27.0 s) in TiO2 single crystal was studied in detail by means of the β-NQR to determine the electric quadrupole moments Q of short-lived β-emitting nuclei 19O and 13O(Iπ=(3/2)-, T1/2=8.6 ms). Two implantation sites were found for the implanted O nucleus and the quadrupole coupling constants of 19O at these sites were determined. We observed FT-NMR of the enriched stable isotope 17O in TiO2 and obtained the electric field gradient (EFG) at the oxygen substitutional site. With this knowledge, we have determined Q(13O)=11.0 ± 1.3 mb and Q(19O)=3.7 ± 0.4 mb. The present results are compared with the theoretical values calculated by the shell model code, OXBASH and by the Hartree–Fock calculation with the realistic potential.

Electromagnetic Moments of Proton-Rich {sup 28}P and Decomposition of Its Spin

The magnetic moment of 28P(Iπu2009=u20093+, T1/2u2009=u2009270.3u2009ms) has been measured precisely by means of β‐NMR technique. The obtained magnetic moment is |μ(28P)|u2009=u20090.3115u2009(34)u2009μN. Combined with the magnetic moment of its mirror partner 28Al, the nuclear spin Iu2009=u20093 is decomposed into its 4 components. The measurement of the Q moment has also been tried. From the preliminary NQR spectrum, it was found that the quadrupole coupling constant eqQ/h may be slightly larger than the prediction, which may show enhancement of the Q moment.

Highly charged ion beam applied to lithography technique.

In various fields of nanotechnology, the importance of nanoscale three-dimensional (3D) structures is increasing. In order to develop an efficient process to fabricate nanoscale 3D structures, we have applied highly charged ion (HCI) beams to the ion-beam lithography (IBL) technique. Ar-ion beams with various charge states (1+ to 9+) were applied to fabricate spin on glass (SOG) and Si by means of the IBL technique. The Ar ions were prepared by a facility built at Kochi University of Technology, which includes an electron cyclotron resonance ion source (NANOGAN, 10 GHz). IBL fabrication was performed as a function of not only the charge state but also the energy and the dose of Ar ions. The present results show that the application of an Ar(9+) beam reduces the etching time for SOG and enhances the etching depth compared with those observed with Ar ions in lower charged states. Considering the high-energy deposition of HCI at a surface, the former phenomena can be understood consistently. Also, the latter phenomena can be understood based on anomalously deep structural changes, which are remarkable for glasses. Furthermore, it has also been shown that the etching depth can be easily controlled with the kinetic energy of the Ar ions. These results show the possibilities of the IBL technique with HCI beams in the field of nanoscale 3D fabrication.

Polarization and momentum distribution of 23Ne and 25Al produced in one nucleon pickup reactions at 10A MeV

We measured the polarization of the β‐emitting 23Ne (Iπ = 5/2+, T1/2 = 37.24 s) and 25Al(Iπ = 5/2+, T1/2 = 7.18 s), produced through the one nucleon pickup reactions in the intermediate energy heavy ion collisions, and was compared with those from the projectile fragmentation process. The larger polarization which seems to persistently be positive throughout the momentum distribution, and sharper momentum distributions suggest nuclear friction mechanism to be responsible for the polarization phenomena. Using such a large polarization, magnetic moment of 23Ne and the quadrupole moment of 25Al were measured. The obtained values are |μ(23Ne)| = 1.0817(9) μN and |Q(25Al)| = (240 ± 20) mb.

Nuclear Structure Study through Nuclear Moments of Mirror Pairs

β‐NMR spectra have been observed for 33Cl, 23Al and 23Ne. As a result, the magnetic moment of 33Cl was determined as |μ(33Cl)| = 0.7549(3) μN. Combined with the known magnetic moment of 33S and the ft‐value of the 33Cl β decay, the orbital angular momenta and the intrinsic spins for proton and neutron groups, are deduced separately as 〈lp〉 = 1.3, 〈n〉 = 0.3, 〈Sp〉 = −0.12 and 〈Sn〉 = −0.02. The magnetic moment of 23Al, and that of 23Ne were determined as |μ(23Al)| = 3.89(22) μN and |μ(23Ne)| = 1.0817(9) μN, respectively. As a result, the orbital angular momentum 〈lz〉 and the intrinsic spin 〈Sz〉 were deduced to be 2.09(29) and 0.41(29), respectively. Combined with the ft‐value of the β transition from the ground state of 23Al to the excited state of 23Mg, proton and neutron contributions are separated. The obtained expectation values 〈lp〉, 〈ln〉, 〈Sp〉 and 〈Sn〉 are compared with the shell model predictions.

Magnetic moment of extremely proton-rich nucleus 23Al

The g-factor of the extremely proton-rich nucleus 23Al (T1/2 = 0.47 s) has been measured by means of the β-NMR method for the first time. The g-factor were determined as |g| = 1.557(88) from the obtained NMR spectra. From the comparison between the experimental value and the shell model calculation, the spin parity of the ground state of 23Al was determined as Iπ = 5/2+. Thus, the magnetic moment of 23Al was determined as |μ| = 3.89(22)μN.