123884211
New half-life measurements of the most neutron-rich arsenic and germanium isotopes
The!-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of 86 Ge (226±21 ms) was determined for the first time, while those of 84,85 Ge and 84!87 As were remeasured. The results are compared to theoretical predictions of the gross theory of!decay, the finite-range droplet model, and the new calculations using the energy density functional DF3a with continuum quasiparticle random-phase approximation(CQRPA).Weconfirmtherobustnessandgoodpredictivepowerofthelattermodelfornucleinear closed shells. These DF3a+CQRPA calculations were used recently to analyzer-process isobaric abundances.
124889976
β -decay study of neutron-rich bromine and krypton isotopes
Short lived neutron rich nuclei including 93 Br, 93 Kr and 94 Kr were produced in proton induced fission of 238 U at the HRIBF in Oak Ridge. Their beta decay was studied by means of a high resolution on line mass separator and beta gamma spectroscopy methods. The half life of 93Br T1/2 = 152(8) ms and delayed branching ratio of Pn = 53-8+11 may be compared to the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half life of 94Kr T1/2 = 227(14) ms and B delayed branching ratio of Pn = 1.9+0.6 0.2 % of 93Kr are in very good agreement with literature values. The decay properties of 93Br include four new gamma transitions following beta delayed neutron emission.
122667645
First Observation of the Drip Line Nucleus 140Dy: Identification of a 7 Mu s K-isomer Populating the Ground State Band
A new $7 \ensuremath{\mu}\mathrm{s}$ isomer in the drip line nucleus ${}^{140}\mathrm{Dy}$ was selected from the products of the ${}^{54}\mathrm{Fe}$ $(315 \mathrm{MeV}{)+}^{92}\mathrm{Mo}$ reaction by a recoil mass spectrometer and studied with recoil-delayed $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences. Five cascading $\ensuremath{\gamma}$ transitions were interpreted as the decay of an ${I}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ ${\ensuremath{\nu}{9/2}^{\ensuremath{-}}[514]\ensuremath{\bigotimes}\ensuremath{\nu}{7/2}^{+}[404]}$ K isomer $({T}_{1/2}=7.0(5) \ensuremath{\mu}\mathrm{s})$ via the ground-state band. The probability of proton emission from ${}^{141}\mathrm{Ho}$ to the ${0}^{+}$ ground state and to the ${2}^{+}$ excited state in ${}^{140}\mathrm{Dy}$ is discussed.
3838065
Spectroscopy of element 115 decay chains.
A high-resolution α, x-ray, and γ-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum für Schwerionenforschung. Thirty correlated α-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z=115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z>112. Comprehensive Monte Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.
120523530
Neutron Single Particle Strengths from the (d,p) Reaction on 18F
The 19F nucleus has been studied extensively. However, there have been no comprehensive experimental studies of 18F+n single-particle components in 19F, and no measure of neutron vacancies in the 18F ground state, as such experiments require a (radioactive) 18F target or beam. We have used the 2H(18F,p)19F reaction to selectively populate states in 19F that are of 18F+n character. The 108.5-MeV radioactive 18F+9 beam was provided by the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Proton-recoil coincidence data were taken for both -decaying and particle-stable final states. Angular distributions and spectroscopic factors were measured for nine proton groups, corresponding to 13 states in 19F. The results are compared to shell model calculations.
121184959
Search for inverse fission of uranium
There is a long-term interest in running the fission reaction backward, i.e., studying the 'inverse fission' of uranium. The recent availability of beams of n-rich fission fragments has stimulated interest in this endeavor. The purpose is to search for inverse fission in the reactions {sup 124,132}Sn + {sup 100}Mo. In the {sup 124}Sn + {sup 100}Mo reaction, evaporation residues were searched for using in-beam detection of evaporation residues, in-beam {alpha} spectroscopy, and post-irradiation {alpha} spectroscopy, while in the {sup 132}Sn + {sup 100}Mo reaction, the evaporation residue {sup 230}U was searched for using post-irradiation {alpha} spectroscopy. No evidence for the occurrence of the inverse fission reactions was found. The upper-limit cross section for the latter reaction is {approx}550 {mu}b, while the experimental upper-limit cross section for the former reaction is about 21{sup -21}{sup +38} nb. The intensity of suitable radioactive beams is not high enough at present to detect inverse fission. For the {sup 124}Sn + {sup 100}Mo reaction, the observed upper limits are below the estimates of current models for these reactions, probably due to fusion hindrance.
122665147
De Sitter vacua and inflation in no-scale string models
This thesis studies the question of how de Sitter vacua and slow-roll inflation may be realized in string-motivated models. More specifically, we consider 4d N = 1 supergravity theories (without vector multiplets) with Kahler potentials which are ‘no-scale’ at leading order. Such theories frequently arise in the moduli sector of string compactifications. We discuss a condition on the scalar geometry (defined by the Kahler potential) and on the direction of supersymmetry breaking in the scalar manifold, which has to be met in order for the average of the masses of the sGoldstinos to be positive, and hence for metastable vacua to be possible. This condition also turns out to be necessary for the existence of trajectories admitting slow-roll inflation. Its implications for certain scalar manifolds which arise from Calabi-Yau string compactifications are discussed. In particular, for two-moduli models arising from compactifications of heteroticand type IIB string theory, a simple criterion on the intersection numbers needs to be satisfied for possible de Sitter phases to exist. In addition, we show that subleading corrections breaking the no-scale property may allow the condition on the scalar geometry to be fulfilled, even when it is violated at leading order. Finally, we develop a procedure to construct superpotentials for a given viable Kahler potential, such that the scalar potential has a realistic local minimum. We propose two-moduli models, with superpotentials which could arise from flux backgrounds and non-perturbative effects, which have a viable vacuum without employing subleading corrections or an uplifting sector.
118472215
Hybrid anomaly-gravity mediation with flavor
We study models with contributions of similar size to the soft masses from anomaly-and gravity mediation, thereby curing the tachyonic slepton problem of anomaly mediation. A possible origin of this hybrid setup in a 5-dimensional brane world is briefly discussed. The absence of excessive flavor violation is explained by alignment. The gravitino can be heavy enough so that the gravitino problem of supersymmetric theories with leptogenesis is avoided. The model has a characteristic signature: It predicts the distinctive gaugino mass pattern of anomaly mediation and, at the same time, (1) slepton mass splittings.
16376745
Einstein-Podolsky-Rosen correlations of ultracold atomic gases.
We demonstrate that collective continuous variables of two species of trapped ultracold bosonic gases can be Einstein-Podolsky-Rosen-correlated (entangled) via inherent interactions between the species. We propose two different schemes for creating these correlations--a dynamical scheme and a static scheme analogous to two-mode squeezing in quantum optics. We quantify the correlations by using known measures of entanglement and study the effect of finite temperature on these quantum correlations.
119272291
Flavorful hybrid anomaly-gravity mediation
We consider supersymmetric models where anomaly and gravity mediation give comparable contributions to the soft terms and discuss how this can be realized in a five-dimensional brane world. The gaugino mass pattern of anomaly mediation is preserved in such a hybrid setup. The flavorful gravity-mediated contribution cures the tachyonic slepton problem of anomaly mediation. The supersymmetric flavor puzzle is solved by alignment. We explicitly show how a working flavor-tachyon link can be realized with Abelian flavor symmetries and give the characteristic signatures of the framework, including O(1) slepton mass splittings between different generations and between doublets and singlets. This provides opportunities for same flavor dilepton edge measurements with missing energy at the Large Hadron Collider (LHC). Rare lepton decay rates could be close to their current experimental limit. Compared to pure gravity mediation, the hybrid model is advantageous because it features a heavy gravitino which can avoid the cosmological gravitino problem of gravity-mediated models combined with leptogenesis.
119253199
Inverse neutrino mass hierarchy in a flavour GUT model
Abstract We construct a supersymmetric SU ( 5 ) × A 4 flavour GUT model in which an inverse neutrino mass hierarchy is realised without fine-tuning of parameters. The model shares some properties with the normal hierarchy model which we presented in arXiv:1305.6612 – in particular the relation θ 13 PMNS ≃ θ C / 2 . Besides these shared features, there are also important differences, mainly due to the different neutrino sector. These differences not only change the predictions in the lepton sector, but also in the quark sector, and will allow to discriminate between the two models using the results of present and future experiments. From a Markov Chain Monte Carlo fit we find that the inverse hierarchy model is in excellent agreement with the present experimental data.