The dependences of radiation induced defects on irradiation temperature up to 700℃ at 15 dpa and on irradiation dose up to 85 dpa at room temperature have been investigated by the heavy ion irradiation and the positr...The dependences of radiation induced defects on irradiation temperature up to 700℃ at 15 dpa and on irradiation dose up to 85 dpa at room temperature have been investigated by the heavy ion irradiation and the positron annihilation lifetime spectroscopy for the CLAM. A void size peak is observed at -500℃ where the vacancy cluster contains 9 vacancies and has an average diameter of 0.59 nm. The size of the vacancy clusters increases with the increase of irradiation dose at room temperature, and the vacancy cluster at 85 dpa consists of 9 vacancies and reaches a size of 0.60 nm in diameter. The absolute values of the void size at the peak and the increase of void size with dose in the CLAM steel are negligible compared to those of the normal stainless steels, indicating that the CLAM steel has good radiation resistant property.展开更多
Magnetic moments of the A=12 unstable mirror pair nuclides 12B and 12N have been measured by the β-NMR technique. The experimentally measured magnetic moments are μ（12B）=1.001（17）μN and μ（12N）=0.4571（1）μN...Magnetic moments of the A=12 unstable mirror pair nuclides 12B and 12N have been measured by the β-NMR technique. The experimentally measured magnetic moments are μ（12B）=1.001（17）μN and μ（12N）=0.4571（1）μN. The improved shell model using an SFO Hamiltonian with enhanced spin-isospin monopole proton-neutron interaction and modified single-particle energies is employed to calculate the magnetic moments of 12B and 12N. The calculation yields μ （12B）=0.929μN and μ（12N）=0.452μN and has produced a new magic number 6 for the short-lived unstable mirror pair nuclides 12B and 12N.展开更多
The La-dopping effect on the piezoelectricity in the K0.5Na0.5NbO3 （KNN） crystal with a tetragonal phase is investigated for the first time using the first-principle calculation based on density functional theory. T...The La-dopping effect on the piezoelectricity in the K0.5Na0.5NbO3 （KNN） crystal with a tetragonal phase is investigated for the first time using the first-principle calculation based on density functional theory. The full potentiallinearized augumented plane wave plus local orbitals （APW-LO） method and the supercell method are used in the calculation for the KNN crystal with and without the La doping. The results show that the piezoelectricity originates from the strong hybridization between the Nb atom and the O atom, and the substitution of the K or Na atom by the La impurity atom introduces the anisotropic relaxation and enhances the piezoelectricity at first and then restrains the hybridization of the Nb-O atoms when the La doping content further increases.展开更多
The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb are measured for the first time by using a transient magnetic field-ion implantation perturbed angular ...The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb 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（27A1,4pn）^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（99/2）^2 Оπ（p3/2, f5/2） О v （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.展开更多
Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β^＋-decay half-life of ^22Na implanted into the metal host of palladium. It i...Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β^＋-decay half-life of ^22Na implanted into the metal host of palladium. It is found that the β^＋-decay half-life of ^22Na in the metal Pd cooled to T = 15 K is shorter by 0.46（14）% than that at room temperature. The result is consistent in sign with, but dearly smaller than, the estimated one by the Debye model.展开更多
The g-factors of Ground Rotational Band states of N = 44 isotones 82^Sr, 83^Y, 84^Zr and 85^Nb have been measured by the transient-magnetic-field ion implantation perturbed angular distribution （TMF-IMPAD） method. T...The g-factors of Ground Rotational Band states of N = 44 isotones 82^Sr, 83^Y, 84^Zr and 85^Nb have been measured by the transient-magnetic-field ion implantation perturbed angular distribution （TMF-IMPAD） method. The measured g-factors of 82^Sr increase with the increase of spin I, indicating a proton alignment only. Positive peaks appear in the variation of g-factors with spin for 83^Y and 84^Zzr at spin 21/2^＋ and 10^＋ respectively, indicating a proton alignment followed by a neutron alignment. A negative peak occurs for SSNb at the spin 25/2^＋, indicating a neutron alignment followed by a proton alignment.展开更多
An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augme...An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augmented plane wave plus local orbital method(LAPW+lo)in the frame of density functional theory.The atomic lattice relaxations caused by the implanted impurities were calculated for two different charged states to well describe the electronic structure of the doped system.The EFG at the site of the phosphorous impurity in the charged supercell calculated with the exchange-correlation potential of the Wu-Cohen generalized gradient approximation(WC-GGA)is 0.573×10^(21) V/m^(2).Then,the nuclear quadrupole moment of the I=3 state in ^(28)P is deduced to be 137 mb from the quadrupole interaction frequency of 190 kHz measured recently by theβ-NQR method.展开更多
基金supported by the State Major Basic Research Development Program in China(No.2009GB109000)National Science Foundation of China(No.11005158)
文摘The dependences of radiation induced defects on irradiation temperature up to 700℃ at 15 dpa and on irradiation dose up to 85 dpa at room temperature have been investigated by the heavy ion irradiation and the positron annihilation lifetime spectroscopy for the CLAM. A void size peak is observed at -500℃ where the vacancy cluster contains 9 vacancies and has an average diameter of 0.59 nm. The size of the vacancy clusters increases with the increase of irradiation dose at room temperature, and the vacancy cluster at 85 dpa consists of 9 vacancies and reaches a size of 0.60 nm in diameter. The absolute values of the void size at the peak and the increase of void size with dose in the CLAM steel are negligible compared to those of the normal stainless steels, indicating that the CLAM steel has good radiation resistant property.
基金Supported by the National Natural Science Foundation of China under Grant No 10435010.
文摘Magnetic moments of the A=12 unstable mirror pair nuclides 12B and 12N have been measured by the β-NMR technique. The experimentally measured magnetic moments are μ（12B）=1.001（17）μN and μ（12N）=0.4571（1）μN. The improved shell model using an SFO Hamiltonian with enhanced spin-isospin monopole proton-neutron interaction and modified single-particle energies is employed to calculate the magnetic moments of 12B and 12N. The calculation yields μ （12B）=0.929μN and μ（12N）=0.452μN and has produced a new magic number 6 for the short-lived unstable mirror pair nuclides 12B and 12N.
基金supported by National Nature Science Foundation of China (No.11075110)
文摘The La-dopping effect on the piezoelectricity in the K0.5Na0.5NbO3 （KNN） crystal with a tetragonal phase is investigated for the first time using the first-principle calculation based on density functional theory. The full potentiallinearized augumented plane wave plus local orbitals （APW-LO） method and the supercell method are used in the calculation for the KNN crystal with and without the La doping. The results show that the piezoelectricity originates from the strong hybridization between the Nb atom and the O atom, and the substitution of the K or Na atom by the La impurity atom introduces the anisotropic relaxation and enhances the piezoelectricity at first and then restrains the hybridization of the Nb-O atoms when the La doping content further increases.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10435010 and 10375093)
文摘The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb 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（27A1,4pn）^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（99/2）^2 Оπ（p3/2, f5/2） О v （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.
基金Supported by the National Natural Science Foundation of China under Grant No 10605039, and the Major State Basic Research Programme of China under Grant No 2007CB815003. The the Pd tandem authors thank Professor Xu Guoji for rolling foil and thank the staff at the CIAE HI-13 accelerator
文摘Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β^＋-decay half-life of ^22Na implanted into the metal host of palladium. It is found that the β^＋-decay half-life of ^22Na in the metal Pd cooled to T = 15 K is shorter by 0.46（14）% than that at room temperature. The result is consistent in sign with, but dearly smaller than, the estimated one by the Debye model.
基金supported by National Science Foundation of China (Nos.10435010,109751891)
文摘The g-factors of Ground Rotational Band states of N = 44 isotones 82^Sr, 83^Y, 84^Zr and 85^Nb have been measured by the transient-magnetic-field ion implantation perturbed angular distribution （TMF-IMPAD） method. The measured g-factors of 82^Sr increase with the increase of spin I, indicating a proton alignment only. Positive peaks appear in the variation of g-factors with spin for 83^Y and 84^Zzr at spin 21/2^＋ and 10^＋ respectively, indicating a proton alignment followed by a neutron alignment. A negative peak occurs for SSNb at the spin 25/2^＋, indicating a neutron alignment followed by a proton alignment.
基金Supported by National Natural Science Foundation of China under Grant Nos 10975189 and 91126002.
文摘An ab initio calculation of the electric-field gradient(EFG)at the site of a phosphorous impurity substituting an Al atom in α-Al_(3)O_(2) is carried out using the WIEN2k code with the full-potential linearized augmented plane wave plus local orbital method(LAPW+lo)in the frame of density functional theory.The atomic lattice relaxations caused by the implanted impurities were calculated for two different charged states to well describe the electronic structure of the doped system.The EFG at the site of the phosphorous impurity in the charged supercell calculated with the exchange-correlation potential of the Wu-Cohen generalized gradient approximation(WC-GGA)is 0.573×10^(21) V/m^(2).Then,the nuclear quadrupole moment of the I=3 state in ^(28)P is deduced to be 137 mb from the quadrupole interaction frequency of 190 kHz measured recently by theβ-NQR method.
