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We have re-investigated the beta decay of the three isomers of $$^{116}$$Ag at the Holifield Radioactive Ion Beam Facility (HRIBF). Through the use of half-life information, we have been able to construct individual decay schemes for each isomer, and correct what was a puzzling inconsistency with the published data, namely the beta feeding of 2$^+$ states by a 5$^+$ isomer. Our results indicate that the feeding of these levels arises from a 3$^+$ isomer in $$^{116}$$Ag. A total of 271 gamma-ray transitions (159 new) were assigned to 148 levels (94 new) from the beta-decay of $$^{116m1,m2,gs}$$Ag. Significant deviations are observed from expected U(5) symmetry in the 0$^+$ and 2$^+$ members of the previously assigned three-phonon quintuplet. Candidate states for the quadrupole-octupole quintuplet states and $$\pi$$g$$_{9/2}-\pi$$p$$_{1/2}$$, $$\pi$$g$$_{9/2}-\pi$$p$$_{3/2}$$, $$\nu$$h$$_{11/2}-\nu$$s$$_{1/2}$$, $$\nu$$h$$_{11/2}-\nu$$d$$_{3/2}$$, and $$\nu$$h$$_{11/2}-\nu$$d$$_{5/2}$$ broken pair states are assigned.

High spin excited states in the neutron-rich nuclei $^{137}\mathrm{I}$ and $^{139}\mathrm{Cs}$ were investigated from a study of the prompt $\ensuremath{\gamma}$ rays emitted in the spontaneous fission of $^{252}\mathrm{Cf}$ with the Gammasphere detector array. Ten new excited levels with $18$ new deexciting transitions were observed in $^{139}\mathrm{Cs}$ and the level scheme of $^{139}\mathrm{Cs}$ was extended up to $4670$ keV. Spins and parities of levels in $^{139}\mathrm{Cs}$ were firmly assigned up to $25/{2}^{+}$. Three new levels were found in $^{137}\mathrm{I}$. Shell model calculations were performed to interpret the experimental results. A good agreement between theory and experiment in both nuclei was found.

The multipole mixing ratios of $\ensuremath{\Delta}I=1$ transitions between levels in rotational bands built on single-particle states in odd neutron nuclei are dependent on the configurations of the states. In particular, the mixing ratio can be used to distinguish between several possible single-particle configurations if interpreted with the particle-axial-rotor model. This work features the first determination of the ground-state configurations of $^{109,111}\mathrm{Ru}$. The single-particle structures of the ground states of $^{101}\mathrm{Zr}$ and $^{103,105,107}\mathrm{Mo}$ as well as excited states in $^{103,107}\mathrm{Mo}$ are also investigated, with a new result found in $^{107}\mathrm{Mo}$.

High spin states in {sup 134}I were identified for the first time based on measurements of prompt {gamma} rays from the spontaneous fission of {sup 252}Cf at Gammasphere. Five excited levels with five deexciting transitions were observed. The mass number was assigned based on the intensity of transitions in the complementary Rh fragments. Angular correlations for the first two transitions in {sup 134}I and for high spin states in {sup 133,135,136}I were performed, but were not sufficient to firmly assign the spins and parities in {sup 134}I.

The high spin states of neutron-rich {sup 106,107}Tc nuclei have been reinvestigated by observing prompt {gamma} rays from the spontaneous fission of {sup 252}Cf. In {sup 106}Tc, a previously known collective band is expanded, and a new collective band is identified. In {sup 107}Tc, a collective band based on the {pi}5/2{sup -}[303] orbital is confirmed and extended. Inconsistencies in the configuration assignments for positive parity bands in {sup 105,107}Tc in the previous reports are clarified. The spins and parities as well as the configurations for the two bands in {sup 106}Tc are assigned according to the angular momentum alignments and g-factor calculations. Other characteristics for the observed bands are discussed.

Using new techniques developed for measuring angular correlations with large detector arrays, the g factors of 2{sup +} states in {sup 140,142}Xe are measured for the first time by the method of correlation attenuation in randomly oriented magnetic fields. g factors in {sup 146}Ba and {sup 146,148}Ce are measured to establish the method by comparison with previous values. The results are discussed in terms of IBM-2 and rotation-vibration models.

In an experiment carried out at the 4π Ge detector facility Gammasphere the yields of ternary fission events of 252Cf accompanied by the emission of He, Be and C LCPs were measured. For the first time independent yields were measured for 59 pairs of secondary fragments of the He ternary fission and for many fission fragments detected together with the He, Be and C LCPs. With a reasonable assumption that the detected LCPs predominantly are 4He, 10Be and 14C their yields and the charge distributions of fission fragments were conjointly analyzed in terms of the “energy cost” concept first suggested by Halpern.

With our high statistics γ‐γ‐γ data set taken with Gammasphere, we have identified a variety of new phenomena in A = 100–112 nuclei. The one‐ and two‐ phonon γ bands in 104,106Mo have been extended and similar bands identified in 108Mo and for the first time in both an odd N nucleus, 105Mo and an odd Z nucleus, 103Nb. The one‐ and two‐ phonon γ band energy levels in 104,105,106,108Mo are remarkably similar with a trend toward lower energy as N increases. In 108,110,112Ru the one phonon γ bands show a completely different behavior from 104–108Mo with very large odd‐even spin level energy staggering in 112Ru. Our data indicate a maximum triaxiality around 112Ru. In 100Nb which lies between N = 58 and 60 where a sudden shift from spherical to superdeformed structures occurs in Sr and Zr nuclei, we have discovered a Kπ = 1+ deformed ground state band. In 108Tc, we found the first pseudospin partner bands with nearly degenerate energies in this mass region.

The conclusions obtained from an early simulation study of the primary event in the vision process are reexamined by simulating the dynamics of the primary photoisomerization reaction in bacteriorhodopsin using a detailed molecular model for the protein-chromophore complex. The calculated photoisomerization time is of the same order of magnitude as that predicted by the early simulation and found in recent experimental studies. Several simulations with different conditions indicate that the isomerization process involves an efficient transfer of energy from the reaction coordinate to other degrees of freedom and is better described by a damped-motion model than by an inertial model. The damped motion is expected to give a significant quantum yield for both the cis→trans and trans→cis cases only if the minimum of the excited state potential surface is located above the ground state maximum (unless the excited state surface is extremely shallow or if the inertial effects associated with the surface crossing process are very large). The present study suggests that the observed quantum yield should not be analyzed by one-dimensional models but by multidimensional microscopic simulations that consider the surface crossing process and the subsequent ground state relaxation processes.

High spin states in neutron-rich odd-N 145Ba nucleus have been investigated from study of prompt γ-rays in spontaneous fission of 252Cf. 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.

High-spin structures in the neutron-rich $^{108}\mathrm{Tc}$ nucleus have been reinvestigated by measuring the prompt $\ensuremath{\gamma}$-rays from spontaneous fission of $^{252}\mathrm{Cf}$. A previously known collective band has been extended up to higher spin states and a new side band has been identified. These doublet bands are proposed as pseudospin partner bands with configurations $\ensuremath{\pi}1/{2}^{+}[431]\ensuremath{\bigotimes}\ensuremath{\nu}[\stackrel{~}{312} 5/{2}^{+},3/{2}^{+}]$, which is a first identification in $A~100$ region. The particle-rotor model (PRM) was applied to calculate levels and $B(M1)/B(E2)$ ratios of the bands in $^{108}\mathrm{Tc}$. The calculated results are in good agreement with the experimental values.

The g-factor of the 4{sup +} state in {sup 134}Te has been measured for the first time by using a new technique developed for measuring angular correlations with Gammasphere. Also reported is the first measurement of the g-factor of the 15/2{sup +} state in {sup 135}I and the mixing ratios of several transitions. Furthermore, spins and parities are assigned to several levels in {sup 134}Te and {sup 135}I. The g-factor measurements are compared to shell model predictions and good agreement is found between experiment and theory.

The level scheme of {sup 102}Zr has been expanded by measuring high-fold prompt {gamma}-ray coincidence events in the spontaneous fission of {sup 252}Cf with the Gammasphere array. Previous identifications have been confirmed. A two-quasi-particle band with a band head energy of 2926.4 keV has been identified for the first time, as well as two rotational collective bands, with band head energies of 1386.3 and 1652.7 keV, respectively. Spins and parties are assigned based on level systematics and angular correlation measurements.

The higher spin levels in neutron-rich $^{104}\mathrm{Nb}$ have been investigated from a study of the prompt \ensuremath{\gamma} rays in spontaneous fission of $^{252}\mathrm{Cf}$ with the Gammasphere detector array. A new collective band has been identified for the first time. This band is proposed as a semidecoupled band based on the configuration $\ensuremath{\pi}5/{2}^{\ensuremath{-}}[303]\ensuremath{\bigotimes}\ensuremath{\nu}1/{2}^{\ensuremath{-}}[541]$. The other structural characteristics are discussed.

The high spin excited states of neutron-rich nuclei 159 Sm and 89,91 Kr are identified for the first time from the spontaneous fission of 252 Cf. Six excited states and six y transitions in 159 Sm are reported here for the first time. Five and two new y transitions are identified in 89 Kr and 91 Kr, respectively. Level schemes in 59,91 Kr are interpreted as the 2d 5/2 neutron hole configuration weakly coupled to the neighboring even-even Kr nuclei. A possible yrast spin sequence of 11/2 - -9/2 + -5/2 + is suggested in 89 Kr. A rotational band with the proposed configuration of v5/2[523] is observed in 159 Sm.

Neutron-rich nuclei of {sup 153,155}Nd were studied from the spontaneous fission of {sup 252}Cf. Eleven and nine new {gamma} transitions were identified in {sup 153}Nd and {sup 155}Nd, respectively. Rotational bands with the configurations of {nu}5/2[642] and {nu}3/2[521] were identified in {sup 153}Nd and {sup 155}Nd, respectively. Excited states and {gamma} transitions in {sup 155}Nd are reported for the first time here.

The high-spin spectroscopy of neutron-rich $^{109}\mathrm{Ru}$ is studied by measuring the prompt \ensuremath{\gamma} rays from the spontaneous fission fragments of $^{252}\mathrm{Cf}$ with 102 Compton-suppressed Ge detectors in the Gammasphere detector array. Previous band structures are confirmed and the ground state band is extended. A positive parity band based on a 332.5 keV level is newly identified. This band is proposed as a single-neutron excitation band built on the $7/{2}^{+}[404]$ Nilsson orbital. Some band structural characteristics are discussed.

Production of nuclei above $^{100}\mathrm{Sn}$ in fusion-evaporation reactions between $^{58}\mathrm{Ni}$ and $^{54}\mathrm{Fe}$ ions was studied at Oak Ridge National Laboratory by means of the recoil mass spectrometer and charged particle detection. The beam energy was varied to optimize the yields for the two-, three- and four-particle evaporation channels. Experimental results verified the predictions of the statistical model code HIVAP. The optimum energy for the $^{54}\mathrm{Fe}$($^{58}\mathrm{Ni}$,$4n$)$^{108}\mathrm{Xe}$ reaction channel that allows one to study the $^{108}\mathrm{Xe}$-$^{104}\mathrm{Te}$-$^{100}\mathrm{Sn}$ \ensuremath{\alpha} decay chain is deduced as 240 MeV.

Triple coincidences between prompt γ-rays emitted in the spontaneous fission of 252Cf were measured with Gammasphere. These data are used to measure the angular correlation of cascades of γ-rays from excited states of neutron rich fission fragments stopped in an unmagnetized iron foil. The hyperfine fields in the iron lattice cause attenuations of the angular correlations between γ-rays emitted from the excited states which have sufficiently long lifetimes. This attenuation is measured and used to calculate the g-factors of excited states in many neutron rich nuclei. © 2007 Elsevier B.V. All rights reserved.

The high-spin levels in the neutron-rich 143 La nucleus have been investigated from the study of prompt y rays in the spontaneous fission of 252 Cf with the Gammasphere detector array. A new level scheme with spin up to 27/2 h has been established, and the collective bands have been identified for the first time. A set of opposite-parity bands connected by ∇I = 1E1 crossing transitions gives evidence for octupole correlations. The results of B(E1)/B(E2) branching ratios indicate that the octupole correlations in 143 La are strong. The reflection-asymmetry shell model is applied to calculate the levels of the octupole bands of 143 La, and the calculated results are in good agreement with the experimental ones.

An alpha-decay branch of (1.4+/-0.4) x 10(-4) has been discovered in the decay of 109I, which predominantly decays via proton emission. The measured Q(alpha) value of 3918+/-21 keV allows the indirect determination of the Q value for proton emission from 105Sb of 356+/-22 keV, which is approximately of 130 keV more bound than previously reported. This result is relevant for the astrophysical rapid proton-capture process, which would terminate in the 105Sn(p,gamma)106Sb(p,gamma)107Te(alpha decay)103Sn cycle at the densities expected in explosive hydrogen burning scenarios, unless unusually strong pairing effects result in a 103Sn(p,gamma)104Sb(p,gamma)105Te(alpha decay)101Sn) cycle.

High spin states of $^{137,138}\mathrm{Cs}$ have been studied by measuring $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidences from the spontaneous fission of $^{252}\mathrm{Cf}$ with the LBNL Gammasphere detector array. The high spin level scheme of the $N=83$ neutron-rich Cs ($Z=55$) isotope, $^{138}\mathrm{Cs}$, built on the ${6}^{\ensuremath{-}}$ isomeric state, has been established for the first time up to a 4626 keV level, assigned (${16}^{+}$). The level scheme of $^{137}\mathrm{Cs}$ has been expanded up to a 5495 keV level, assigned ($31/{2}^{\ensuremath{-}}$). Spins, parities, and configurations are assigned based on the agreement between experimental level energies and shell model calculations and level systematics. Similarities are observed in the $N=82$ isotones, $^{137}\mathrm{Cs}$ and $^{135}\mathrm{I}$, up to $17/{2}^{+}$ as well as in the $N=83$ isotones, $^{138}\mathrm{Cs}$ and $^{136}\mathrm{I}$, up to ${12}^{\ensuremath{-}}$. The shell model calculations indicate the important role played by interactions between the excitation of the valence protons outside the $Z=50$ major shell and the ${f}_{7/2}$ valence neutron outside the $N=82$ major shell.

An alpha-decay branch of (1.4+/-0.4) x 10(-4) has been discovered in the decay of 109I, which predominantly decays via proton emission. The measured Q(alpha) value of 3918+/-21 keV allows the indirect determination of the Q value for proton emission from 105Sb of 356+/-22 keV, which is approximately of 130 keV more bound than previously reported. This result is relevant for the astrophysical rapid proton-capture process, which would terminate in the 105Sn(p,gamma)106Sb(p,gamma)107Te(alpha decay)103Sn cycle at the densities expected in explosive hydrogen burning scenarios, unless unusually strong pairing effects result in a 103Sn(p,gamma)104Sb(p,gamma)105Te(alpha decay)101Sn) cycle.

The alpha decay chain 109Xe→105Te→101Sn was first identified at the Holifield Radioactive Ion Beam Facility. Recent developments in digital electronics enabled the detection of both alpha decays despite the short half‐life of 105Te. The development of the software algorithm responsible for extracting the double‐alpha events from the experimental data is ongoing. The possibility of using the derivative of the double‐alpha pulse to selectively identify double alpha pulses shows promise and is being developed.

In an experiment at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility, the very small α‐decay branch of 109I, bα = (1.4±0.4)⋅10−4, has been measured. The Qα‐value for this transition allowed for the determination of Qp(105Sb) = 356±22 keV, about 130 keV lower than previously claimed. This difference increases the partial half‐life for proton decay by several orders of magnitude, making the probability of observing direct proton decay of 105Sb very small, much below any previous experimental limit. The results and consequences for the astrophysical rp‐process are discussed.

Production of nuclei above 100Sn in fusion‐evaporation reactions between 58Ni beam and 54Fe target was investigated. Reaction products were studied at Oak Ridge by means of the Recoil Mass Spectrometer and charged particle detection. The yields for the 2n, pn, 3n, p2n, 2pn, p3n and 2p2n fusion‐evaporation channels were measured. These experimental results were used to verify the predictions of the statistical model code HIVAP. The optimum energy for the 54Fe(58Ni,4n)108Xe reaction allowing detection of the 108Xe‐104Te‐100Sn alpha decay chain is deduced as 240 MeV.

High spin states of neutron-rich nuclei such as 133,134Te, 93Sr, 105Nb have been studied by measuring γ- γ- γ coincidences (cube), γ- γ- γ- γ coincidences (hypercube) and angular correlations from the spontaneous fission of 252Cf with the LBNL Gammasphere detector array. Four types of particle-hole bands built on the known 334.3 keV isomer in 133Te were identified. The level structure of 93Sr is interpreted, in part, as arising from the weak coupling of the 1d5/2 neutron hole to the yrast states of the 94Sr core. The g-factor of the 4+ state in 134Te was measured, for the first time, by using a new technique developed for measuring angular correlations with Gammasphere. A new level scheme of 105Nb was established. Three new collective bands were identified with a total of 14 new levels and 36 new γ transitions. In 117-122Cd, a shift to more slightly deformed structures was found where the excited levels do not fit the long held picture of one, two and three phonon bands.

From an experiment with Gammasphere and a ${}^{252}\mathrm{Cf}$ spontaneous fission source, a new negative-parity band in ${}^{154}\mathrm{Nd}$ and new negative-parity levels in ${}^{152}\mathrm{Nd}$ were identified and the yrast bands were extended to ${18}^{+}$ in ${}^{154}\mathrm{Nd}$ and ${20}^{+}$ in ${}^{152}\mathrm{Nd}$ in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode. There is a constant difference as a function of spin between the ${J}_{1}$ values for the negative-parity band in ${}^{152}\mathrm{Nd}$ and ${J}_{1}$ for the similar negative-parity band in ${}^{154}\mathrm{Nd},$ however, their ${J}_{2}$ values are essentially identical. These bands indicate a new kind of identical band.