Xu Guoji

Processes for the production of ultra-pure metals from oxide and their cold rolling to ultra-thin foils for use as targets and as reference materials

Abstract A wide variety of metals have been reduced from their oxides with high (>90%) yields using metallothermic reduction, hydrogen reduction or electrowinning. The high yields during metallothermic reduction were achieved by careful design of the collector and crucible orifice. Whilst each of the three techniques gave rise to reasonably (>99%) pure metals, subsequent carefully controlled vacuum distillation, using a system with especially designed crucible, baffle and collector systems, resulted in ultra-high-purity metals being produced. Using a stainless steel pack rolling technique, metals derived either directly from the reduction routes or following subsequent distillation could be rolled to foils thinner than previously reported in the literature in the majority of cases.

Preparation of targets on thin backings with a centrifugal precipitation method

The preparation of various powder-material targets in thicknesses of 0.1 to 15 mg/cm2 on backings of aluminium, gold, and carbon as thin as 0.2 μm using a centrifugal precipitation method is described. In this method, collodion in acetone is the suspension agent for the target materials. In most cases, the yield of the method is 80%. The amount of residual collodion in the target is about 5% and can be decreased to about 1% by heating.

Quadrupole moment and a proton halo structure in 17F (Iπ = 5/2+)

The quadrupole moment of light nuclei 17F in the ground state (Iπ = 5/2+) is measured by the β–NMR method. The effective charge of the last proton in a d5/2 orbit for 17F is extracted from the measured quadrupole moment Q(17F) divided by the quadrupole moment Qsp calculated with a single particle model. A proton effective charge of eeffp = 1.12 ± 0.07e is obtained, which is in agreement with that given by a particle–vibration coupling model calculation within the experimental error. The present value of the proton effective charge is strong evidence for the existence of a proton skin in 17F (Iπ = 5/2+).

Measurements of g-Factor of Rotational Levels in 83Y

The g-factors of the positive parity rotational levels up to spin I = 41/2+ in 83Y have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The experimentally measured g-factors show the g9/2 proton alignment followed by the g9/2 neutron alignment. The measured g-factors are in good agreement with the results calculated by an empirical formula based on the cranking shell model.

Rotational State g-Factors in 84Zr

The g-factors of the rotational states along the positive parity yrast band in even-even nuclei 84Zr were measured up to a spin I = 16+ by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model. A peak structure of the g-factors has been observed for the first time. The measured g-factors confirm the mixed configuration of proton and neutron alignments.

The g-factors and magnetic rotation in 82Rb

The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in 82Rb are measured for the first time by using a transient magnetic field-ion implantation perturbed angular distribution (TMF-IMPAD) method. The magnetic-rotational band in 82Rb is populated by the 60Ni(27Al,4pn)82Rb reaction, and the time-integral Larmor precessions are measured after recoil implantation into a polarized Fe foil. The calculation of g-factors is also carried out in terms of a semi-classical model of independent particle angular momentum coupling on the basis of the four-quasiparticle configuration π(g9/2)2 ⊗ π(p3/2, f5/2) ⊗ ν (g9/2). The measured and calculated g-factors are in good agreement with each other. The g-factors and deduced shear angles decrease with the increase of spin along the band. This clearly illustrates the shear effect of a step-by-step alignment of the valence protons and neutrons in magnetic rotation. The semi-classical calculation also shows that the alignment of the valence neutron angular momentum is faster than that of the valence protons, which results in a decrease of g-factors with increasing spin. The present results provide solid evidence of the shear mechanism of magnetic rotation.

Structure of β-emitting nuclei29P

The extoic structure of 29P was investigated by measuring its magnetic moment in the ground state with β-NMR method. We got the experimental value of 1.2346 μN after diamagnetism correction. It is very close to the calculated value of 1.1009 μN computed with shell model. The shell model calculation also gave a proton density distribution of 29P with a long tail. The present results show that 2s1/2 proton in the 29P may lead to the proton-skin structure.

Proton alignment in 82Sr investigated by g-factor measurements

The proton alignment in 82Sr has been investigated by the g-factor measurements of the ground state rotational band levels up to spin I = 8+. The g-factors were measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The obtained g-factors increase with the increasing of spin along the band and clearly show the g9/2 proton alignment that starts at I = 6+.

Measurements of g-Factor of Rotational Band States in 82Sr

The g-factors of the positive parity rotational states up to spin I = 8+ for the ground state band in even-even nuclei 82Sr have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The experimentally measured g-factors increase with the increasing spin along the band and show that the g9/2 proton aligns only and the alignment starts from I = 6+. The measured g-factors also indicate that the nuclei 82Sr gain their spins by the quasi-proton alignment at higher spin.

Dependence of Quasi-Particle Alignment on Proton Number in N = 44 Isotones 82Sr, 83Y, 84Zr and 85Nb

The g-factors of Ground Rotational Band states of N = 44 isotones 82Sr, 83Y, 84Zr and 85Nb have been measured by the transient-magnetic-field ion implantation perturbed angular distribution (TMF-IMPAD) method. The measured g-factors of 82Sr increase with the increase of spin I, indicating a proton alignment only. Positive peaks appear in the variation of g-factors with spin for 83Y and 84Zr at spin 21/2+ and 10+ respectively, indicating a proton alignment followed by a neutron alignment. A negative peak occurs for 85Nb at the spin 25/2+, indicating a neutron alignment followed by a proton alignment.