A. Kitagawa

Observation of spin polarization of projectile fragments from 106 A MeV 40Ca+Au collisions☆

Abstract Spin polarization of projectile fragments 37 K and 39 Ca has been observed in 106 A MeV 40 Ca+ 197 Au collisions n ear the grazing angle. The fragment polarization was determined to be positive for points on the high momentum side of the distribution and negative for points on the low momentum side. At the highest energy, the spin polarization follows the same systematics observed at much lower energies, where it is believed that very different reaction mechanisms dominate. A simple fragmentation model explained the observed momentum dependence of the polarization quite well.

Hyperfine interactions of beta emitter12B and12N in Mg crystal

Nuclear dipolar brondening in the NMR spectra of beta-emitting12B and12N implanted in single crystal Mg with h.c.p. structure was studied as function of orientation of the crystal axes relative to the external magnetic field. The implanted12N was located in interstitial trigonal site. The surrounding Mg atoms nearest to the12N were displaced from the regular lattice position, and lattice expansion δa/a=0.15 was determined.

A fragment separator at LBL for the beta-NMR experiment

Abstract The Beam 44 fragment separator was built at the Bevalac of LBL for NMR studies of beta emitting nuclei. 37K, 39Ca, and 43Ti fragments originating from 40Ca and 46Ti primary beams were separated by the separator for NMR studies on these nuclei. Nuclear spin polarization was created in 39 and 43Ti using the tilted foil technique (TFT), and the magnetic moment of 43Ti was deduced. Fragment polarization was measured for 37K and 39Ca emitted to finite deflection angles. The beam 44 fragment separator in combination with a proper polarization technique, such as TFT or fragment polarization, has been very effective for such NMR studies.

Quadrupole moment of the doubly-closed-shell-plus-one-nucleon nucleus 41Sc and its core deformation

The nuclear quadrupole moment of 41Sc(Iπ = 7−2, T12 = 0.596 s) has been measured to be |Q(41Sc; 7−2)| = 16.6 ± 0.8 fm2, by use of a modified β-NMR technique. Combining the value with its mirror quadrupole moment Q(41Ca; 7−2), it is shown that the valence proton in 41Sc carries more than 90% of the moment, and that of the remaining core carries about 10%. This is consistent with the picture that the core of 41Sc, 40Ca, is deformed by about e = −(0.44 ± 0.22)%.

Electric field gradient in Mg and Zn detected by β-emitters,8Li and12x0392;x0392;x0392;

The quadrupole coupling constants of8Li and12B in hcp Mg and Zn are determined by use of a newly developed nuclear quadrupole resonance technique (NNQR) as ¦eqQ(8Li in Mg)/h¦=3.0±0.3 kHz, ¦eqQ(8Li in Zn)/h¦=33.5±2 kHz, and ¦eqQ(12B in Mg)/h¦=47.0±0.1 kHz. Correspondingly, the electric field gradients at room temperature are deduced: ¦q(8Li in Mg)¦=(3.81±0.39)×1018, ¦q(8Li in Zn)¦=(4.25±0.27)×1019, and ¦q(12B in Mg)¦=(1.47±0.03)×1020, all in V/m2. The experiments are compared with the results of first-principles super-cell band structure calculations which can treat local lattice relaxations around the impurity nuclei. The calculations show that the most favorable location of these light interstitials in hcp Mg is not the octahedral-like sites which have the biggest interstitial volume, but the basal trigonal sites with a local lattice expansion of as big as 30%. Calculated electric field gradients at the impurity nuclei reproduce the experimental values fairly well.

Precise measurement of the magnetic moment of17F(I x =5/2+,T 1/2=64.5 s) and its hyperfine interactions in ionic crystals

Hyperfine interactions of β-emitting17F implanted in single crystals of NaF and CaF2 were studied. The nuclear magnetic moment of theTπ=5/2+ state was determined with an improved precision to be |μ(17F;π=5/2+,T1/2=64.5s|=4.72130±0.00025. nm. Isoscalar magnetic moments of the doubly closed shell ±1 nucleon nuclei around mass number 16 were derived and the effective nucleon mass in the nucleus was discussed.

Quadrupole moment of the doubly closed shell +1 nucleon nucleus41Sc(Iπ=7/2−)

The nuclear electric quadrupole moment of41Sc(Iπ=7/2−) was experimentally determined by use of the NMR detection in which the asymmetric β-ray distribution from spin polarized nuclei was monitored. The magnetic interaction of the state with high external magnetic field and the nuclear quadrupole interaction with the electric field gradient obtained in TiO2 crystal were studied. The field gradient seen to the implanted41Sc was measured independently by the high field NMR detection on the stable isotope45Sc located in the equivalent41Sc site with. |Q(41Sc;Iπ=7/2−)|=(0.120±0.006) b was determined.

Precise measurement of quadrupole moment of8B by use of a modified β-NMR

The nuclear quadrupole moment of8B(Iπ=2+,T1/2=769 ms) has been determined by use of a modified β-NMR detection as |Q(8B)|=68.3±2.1 mb. A field gradient was obtained in a single crystal Mg at room temperature.

Magnetic moment of beta-emitting41Sc(Iπ=7/2−) and knight shift in Pt metal

The nuclear magnetic moment of41Sc(Iπ=7/2−, Tl/2=0.59sec) was remeasured, and the precision of the value was improved about 10 times compared with the previously known one. The value was determined to be |μ(41Sc;Iπ=7/2)|=(5.4305±0.0018) nm. Comparing the value with the previously known NMR of the nuclei in Pt, the knight shift, K=−(0.4±5.3)·10−4 was determined.

Giant quadrupole moment andproton halo discovered in8B

The nuclear quadrupole moment of8B(Iπ=2+,T1/2=769 ms) has been determined by use of a modified β-NMR detection as |Q(8B)|=68.3±2.1 mb, which is twice the prediction of the Cohen-Kurath shell model calculation. The anomalous quadrupole moment which is carried mainly by the protons in the nucleus, has been accounted for by the proton halo effect.