The levels in neutron-rich odd-A ^(107,109)Ru nuclei have been investigated by using γ -γ -and γ -γ -γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and t...The levels in neutron-rich odd-A ^(107,109)Ru nuclei have been investigated by using γ -γ -and γ -γ -γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from v(d_(5/2)+g_(7/2)) quasiparticle configurations and the negative parity bands are from vh_(11/2) orbital.展开更多
Levels in the neutron-rich ^(104)Mo nucleus have been investigated by observing promptγ-rays from the spontaneous fission of 252Cf with the Gammasphere detector array.The ground-state band,the one-phonon and the two-...Levels in the neutron-rich ^(104)Mo nucleus have been investigated by observing promptγ-rays from the spontaneous fission of 252Cf with the Gammasphere detector array.The ground-state band,the one-phonon and the two-phononγ-vibrational bands as well as a quasiparticle band have been confirmed and expanded with spin up to 14ħ.Other two side bands probably built on new quasiparticle states are identified.The possible configurations for the quasiparticle bands are discussed.Two of the quasiparticle bands show larger moments of inertia and may have pair-free characteristics.The levels of the ground-state band,the one-phononγ-band and the two-phononγ-band calculated from a general collective model are in close agreement with the experimental data.展开更多
Octupole deformation bands built onπh ll/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the promptγ-rays emitted from the 252Cf source.The alternating parity band structures and...Octupole deformation bands built onπh ll/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the promptγ-rays emitted from the 252Cf source.The alternating parity band structures and strong E1 transitions observed between negative-and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h ll/2 single proton coupling.According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.展开更多
High spin states in neutron-rich odd-N ^(145)Ba nucleus have been investigated from study of promptγ-rays in spontaneous fission of^(252)Cf.The alternating parity bands are identified indicating octupole deformation ...High spin states in neutron-rich odd-N ^(145)Ba nucleus have been investigated from study of promptγ-rays in spontaneous fission of^(252)Cf.The alternating parity bands are identified indicating octupole deformation with simplex quantum number s=-i.The ground state band shows signature splitting and inversion at low spin.These collective band structures exhibit the competition and co-existence between symmetric and asymmetric shapes.展开更多
Level schemes for the neutron-rich ^(140,143)Ba nuclei have been determined by study of promptγ-rays in spontaneous fission of ^(252)Cf.The level pattern and enhanced E1 transitions betweenπ=+andπ=-bands show refle...Level schemes for the neutron-rich ^(140,143)Ba nuclei have been determined by study of promptγ-rays in spontaneous fission of ^(252)Cf.The level pattern and enhanced E1 transitions betweenπ=+andπ=-bands show reflection asymmetric shapes with simplex quantum number s=+1 in ^(140)Ba and s=±i in ^(143)Ba,respectively.The octupole deformation stability with spin variation has been discussed.展开更多
We present long term optical variability studies of bright X-ray sources in four nearby elliptical galaxies with the Chandra Advanced CCD Imaging Spectrometer array （ACIS-S） and observations from the Hubble Space Te...We present long term optical variability studies of bright X-ray sources in four nearby elliptical galaxies with the Chandra Advanced CCD Imaging Spectrometer array （ACIS-S） and observations from the Hubble Space Telescope （HST） Advanced Camera for Surveys. Out of the 46 bright （X-ray counts 〉 60） sources that are in the common field of view of the Chandra and HST observations, 34 of them have potential optical counterparts, while the rest of them are optically dark. After taking into account systematic errors, estimated using optical sources in the field as a reference, we find that four of the X-ray sources （three in NGC 1399 and one in NGC 1427） have variable optical counterparts at a high level of significance. The X-ray luminosities of these sources are ～10^38 erg S^-1 and are also variable on similar time scales. The optical variability implies that the optical emission is asso- ciated with the X-ray source itself rather than being the integrated light from a host globular cluster. For one source, the change in optical magnitude is 〉 0.3, which is one of the highest reported for this class of X-ray sources and this suggests that the optical variability is induced by the X-ray activity. However, the optically variable sources in NGC 1399 have been reported to have blue colors （g - z 〉 1）. All four sources have been detected in the infrared （IR） by Spitzer as point sources, and their ratios of 5.8 to 3.6 μm flux are 〉 0.63, indicating that their IR spectra are like those of Active Galactic Nuclei （AGNs）. While spectroscopic confirmation is required, it is likely that all four sources are background AGNs. We find none of the X-ray sources having opticalfiR colors different from AGNs to be optically variable.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19775026the Science Foundation for Nuclear Industry of China under Grant No.Y7197AY509the U.S.Department of Energy under Grant Nos.DE-FG05-88ER40407 and DE-FG03-87ER40323.
文摘The levels in neutron-rich odd-A ^(107,109)Ru nuclei have been investigated by using γ -γ -and γ -γ -γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from v(d_(5/2)+g_(7/2)) quasiparticle configurations and the negative parity bands are from vh_(11/2) orbital.
基金Supported by the National Natural Science Foundation of China under Grant No.19975028the Science Foundation of China for Nuclear Industry under Grant No.Y7197AY509+1 种基金the Major State Basic Research Development Program of China under Contract No.G2000077400the U.S.Department of Energy under Grant No.DE-FG05-88ER40407.
文摘Levels in the neutron-rich ^(104)Mo nucleus have been investigated by observing promptγ-rays from the spontaneous fission of 252Cf with the Gammasphere detector array.The ground-state band,the one-phonon and the two-phononγ-vibrational bands as well as a quasiparticle band have been confirmed and expanded with spin up to 14ħ.Other two side bands probably built on new quasiparticle states are identified.The possible configurations for the quasiparticle bands are discussed.Two of the quasiparticle bands show larger moments of inertia and may have pair-free characteristics.The levels of the ground-state band,the one-phononγ-band and the two-phononγ-band calculated from a general collective model are in close agreement with the experimental data.
基金Supported by the National Natural Science Foundation of China under Grant No.19775026the Science Foundation for Nuclear Industry of China under Grant No.Y7197AY509the U.S.Department of Energy under Grant Nos.DE-FG05-88ER40407 and DE-FG03-87ER40323.
文摘Octupole deformation bands built onπh ll/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the promptγ-rays emitted from the 252Cf source.The alternating parity band structures and strong E1 transitions observed between negative-and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h ll/2 single proton coupling.According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.
基金Supported by the National Natural Science Foundation of China under Grant No.19775026the Science Foundation for Nuclear Industry of China under Grant No.Y7197AY509the U.S.Department of Energy under Grant Nos.DE-FG05-88ER0407 and DE-FG03-87ER40323.
文摘High spin states in neutron-rich odd-N ^(145)Ba nucleus have been investigated from study of promptγ-rays in spontaneous fission of^(252)Cf.The alternating parity bands are identified indicating octupole deformation with simplex quantum number s=-i.The ground state band shows signature splitting and inversion at low spin.These collective band structures exhibit the competition and co-existence between symmetric and asymmetric shapes.
基金Supported by the National Natural Science Foundation of China under Grant No.19375029the Science Foundation for Nuclear Industry,China under Grant No.J94AY5072the U.S.Department of Energy under Grant Nos.DE-FG05-88ER40407 and DE-FG03-87ER40323.
文摘Level schemes for the neutron-rich ^(140,143)Ba nuclei have been determined by study of promptγ-rays in spontaneous fission of ^(252)Cf.The level pattern and enhanced E1 transitions betweenπ=+andπ=-bands show reflection asymmetric shapes with simplex quantum number s=+1 in ^(140)Ba and s=±i in ^(143)Ba,respectively.The octupole deformation stability with spin variation has been discussed.
基金financial support from the Council of Scientific and Industrial Research(CSIR) through the SRF schemepartially funded from the ISRO-RESPOND program
文摘We present long term optical variability studies of bright X-ray sources in four nearby elliptical galaxies with the Chandra Advanced CCD Imaging Spectrometer array （ACIS-S） and observations from the Hubble Space Telescope （HST） Advanced Camera for Surveys. Out of the 46 bright （X-ray counts 〉 60） sources that are in the common field of view of the Chandra and HST observations, 34 of them have potential optical counterparts, while the rest of them are optically dark. After taking into account systematic errors, estimated using optical sources in the field as a reference, we find that four of the X-ray sources （three in NGC 1399 and one in NGC 1427） have variable optical counterparts at a high level of significance. The X-ray luminosities of these sources are ～10^38 erg S^-1 and are also variable on similar time scales. The optical variability implies that the optical emission is asso- ciated with the X-ray source itself rather than being the integrated light from a host globular cluster. For one source, the change in optical magnitude is 〉 0.3, which is one of the highest reported for this class of X-ray sources and this suggests that the optical variability is induced by the X-ray activity. However, the optically variable sources in NGC 1399 have been reported to have blue colors （g - z 〉 1）. All four sources have been detected in the infrared （IR） by Spitzer as point sources, and their ratios of 5.8 to 3.6 μm flux are 〉 0.63, indicating that their IR spectra are like those of Active Galactic Nuclei （AGNs）. While spectroscopic confirmation is required, it is likely that all four sources are background AGNs. We find none of the X-ray sources having opticalfiR colors different from AGNs to be optically variable.
