Fission of heavy Λ\Lambda hypernuclei with the Skyrme-Hartree-Fock approach

Fission-related phenomena of heavy $\Lambda$ hypernuclei are discussed with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a $\Lambda$ particle and a nucleon. Assuming that the $\Lambda$ particle adiabatically follows the fission motion, we discuss the fission barrier height of $^{239}_{\Lambda}$U. We find that the fission barrier height increases slightly when the $\Lambda$ particle occupies the lowest level. In this case, the $\Lambda$ particle is always attached to the heavier fission fragment. This indicates that one may produce heavy neutron-rich $\Lambda$ hypernuclei through fission, whose weak decay is helpful for the nuclear transmutation of long-lived fission products. We also discuss cases where the $\Lambda$ particle occupies a higher single-particle level.Comment: 20 pages, 18 figures, to be submitted to Nucl. Phys.

Prospects for the discovery of the next new element: Influence of projectiles with Z > 20

The possibility of forming new superheavy elements with projectiles having Z > 20 is discussed. Current research has focused on the fusion of 48Ca with actinides targets, but these reactions cannot be used for new element discoveries in the future due to a lack of available target material. The influence on reaction cross sections of projectiles with Z > 20 have been studied in so-called analog reactions, which utilize lanthanide targets carefully chosen to create compound nuclei with energetics similar to those found in superheavy element production. The reactions 48Ca, 45Sc, 50Ti, 54Cr + 159Tb, 162Dy have been studied at the Cyclotron Institute at Texas A&M University using the Momentum Achromat Recoil Spectrometer. The results of these experimental studies are discussed in terms of the influence of collective enhancements to level density for compound nuclei near closed shells, and the implications for the production of superheavy elements. We have observed no evidence to contradict theoretical predictions that the maximum cross section for the 249Cf(50Ti, 4n)295120 and 248Cm(54Cr, 4n)298120 reactions should be in the range of 10-100 fb.Comment: An invited talk given by Charles M. Folden III at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. Also contains information presented by Dmitriy A. Mayorov and Tyler A. Werke in separate contributions to the conference. This contribution will appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Mobility deficit – Rehabilitate, an opportunity for functionality

There are many pathological conditions that cause mobility deficits and that ultimately influence someone’s autonomy.Aims: to evaluate patients with mobility deficits functional status; to implement a Rehabilitation Nursing intervention plan; to monitor health gains through mobility deficits rehabilitation.Conclusion: Early intervention and the implementation of a nursing rehabilitation intervention plan results in health gains (direct or indirect), decreases the risk of developing Pressure Ulcers (PU) and the risk of developing a situation of immobility that affects patients’ autonomy and quality of life

Calculations of Branching Ratios for Radiative-Capture, One-Proton, and Two-Neutron Channels in the Fusion Reaction 209^{209}Bi+70^{70}Zn

We discuss the possibility of the non-one-neutron emission channels in the cold fusion reaction $^{70}$Zn + $^{209}$Bi to produce the element Z=113. For this purpose, we calculate the evaporation-residue cross sections of one-proton, radiative-capture, and two-neutron emissions relative to the one-neutron emission in the reaction $^{70}$Zn + $^{209}$Bi. To estimate the upper bounds of those quantities, we vary model parameters in the calculations, such as the level-density parameter and the height of the fission barrier. We conclude that the highest possibility is for the 2n reaction channel, and its upper bounds are 2.4$$ and at most less than 7.9% with unrealistic parameter values, under the actual experimental conditions of [J. Phys. Soc. Jpn. {\bf 73} (2004) 2593].Comment: 6 pages, 4 figure

Gas chemical investigation of hafnium and zirconium complexes with hexafluoroacetylacetone using preseparated short-lived radioisotopes

Volatile metal complexes of the group 4 elements Zr and Hf with hexafluoroacetylacetonate (hfa) have been studied using short-lived radioisotopes of the metals. The new technique of physical preseparation has been employed where reaction products from heavy-ion induced fusion reactions are isolated in a physical recoil separator - the Berkeley Gas-filled Separator in our work - and made available for chemistry experiments. Formation and decomposition of M(hfa)4 (M=Zr, Hf) has been observed and the interaction strength with a fluorinated ethylene propylene (FEP) Teflon surface has been studied. From the results of isothermal chromatography experiments, an adsorption enthalpy of -ΔHa=(57±3)kJ/mol was deduced. In optimization experiments, the time for formation of the complex and its transport to a counting setup installed outside of the irradiation cave was minimized and values of roughly one minute have been reached. The half-life of 165Hf, for which conflicting values appear in the literature, was measured to be (73.9±0.8)s. Provided that samples suitable for α-spectroscopy can be prepared, the investigation of rutherfordium (Rf), the transactinide member of group 4, appears possible. In the future, based on the studies presented here, it appears possible to investigate short-lived single atoms produced with low rates ( e.g. , transactinide isotopes) in completely new chemical systems, e.g. , as metal complexes with organic ligands as used here or as organometallic compound

Toward volatile metal complexes of rutherfordium - results of testexeriments with Zr and Hf

The chemical investigation of the transactinide elements (TAN, Z {ge}104) is a topic of great interest in recent nuclear chemistry research. The highly charged nucleus accelerates the innermost electrons to relativistic velocities thus causing contraction of spherical (s, p{sub 1/2}) orbitals and expansion of the others (p{sub 3/2}, d, and f), which directly affects the chemical behavior of these elements. Deviations from trends established in the periodic table may therefore occur due to these so-called relativistic effects [1,2]. In gas phase experiments, mostly volatile inorganic compounds (e.g., halides or oxides) of TAN were investigated. We refer to [3] for a recent review. For reasons such as low production cross-sections or short half-lives, but also technical challenges, more sophisticated chemical studies have not yet been possible. One restriction in present TAN research is the plasma behind the target caused by the intense heavy ion beam. ''Weak'' molecules (e.g., organic ligands) are immediately destroyed, thus limiting the possibilities of synthesizing chemical compounds directly behind the target to ''simple'' and robust inorganic compounds. It is highly desirable to expand the knowledge on the chemical behavior of the TAN to other compound classes, e.g., volatile metal complexes. The use of the Berkeley Gas-filled Separator (BGS) [4] as a physical preseparator makes such studies possible by separating the beam from the desired TAN isotopes

Particle-hole excited states in 133 Te

Excited states in neutron-rich ${}^{133}\mathrm{Te}$ have been identified with the Gamma sphere array by measuring three- and higher-fold prompt coincidence events following spontaneous fission of ${}^{252}\mathrm{Cf}.$ Four types of particle-hole bands built on the known 334.3 keV isomer in ${}^{133}\mathrm{Te}$ are identified. The yrast and near yrast particle-hole states observed up to 6.2 MeV in ${}^{133}\mathrm{Te}$ have characteristics quite similar to those in ${}^{134}\mathrm{Te}.$ These states are interpreted as a result of coupling a neutron \ensuremath{\nu}{h}_{11/2} hole to the ${}^{134}\mathrm{Te}$ core. The group of states observed above 5.214 MeV is the result of a neutron particle-hole excitation of the double magic core nucleus ${}^{132}\mathrm{Sn},$ and is a candidate for a tilted rotor band. Shell-model calculations considering ${}^{132}\mathrm{Sn}$ as a closed core have been performed and have provided guidance to the interpretation of the levels below 4.3 MeV. Very good agreement between theory and experiment is obtained for these states

Influence of projectile neutron number on cross section in cold fusion reactions

Elements 107-112 [1,2] have been discovered in reactions between {sup 208}Pb or {sup 209}Bi targets and projectiles ranging from {sup 54}Cr through {sup 70}Zn. In such reactions, the compound nucleus can be formed at excitation energies as low as {approx}12 MeV, thus this type of reaction has been referred to as 'cold fusion'. The study of cold fusion reactions is an indispensable approach to gaining a better understanding of heavy element formation and decay. A theoretical model that successfully predicts not only the magnitudes of cold fusion cross sections, but also the shapes of excitation functions and the cross section ratios between various reaction pairs was recently developed by Swiatecki, Siwek-Wilczynska, and Wilczynski [3,4]. This theoretical model, also referred to as Fusion by Diffusion, has been the guide in all of our cold fusion studies. One particularly interesting aspect of this model is the large predicted difference in cross sections between projectiles differing by two neutrons. The projectile pair where this difference is predicted to be largest is {sup 48}Ti and {sup 50}Ti. To test and extend this model, {sup 208}Pb({sup 48}Ti,n){sup 255}Rf and {sup 208}Pb({sup 50}Ti,n){sup 257}Rf excitation functions were recently measured at the Lawrence Berkeley National Laboratory's (LBNL) 88-Inch Cyclotron utilizing the Berkeley Gas-filled Separator (BGS). The {sup 50}Ti reaction was carried out with thin lead targets ({approx}100 {micro}g/cm{sup 2}), and the {sup 48}Ti reaction with both thin and thick targets ({approx}470 {micro}g/cm{sup 2}). In addition to this reaction pair, reactions with projectile pairs {sup 52}Cr and {sup 54}Cr [5], {sup 56}Fe and {sup 58}Fe [6], and {sup 62}Ni [7] and {sup 64}Ni [8] will be discussed and compared to the Fusion by Diffusion predictions. The model predictions show a very good agreement with the data

Entrance-channel effects in odd-Z tranactinide compound nucleus reactions

Swiatecki, Siwek-Wilczynska, and Wilczynski's 'Fusion By Diffusion' description [1] of transactinide (TAN) compound nucleus (CN) formation utilizes a three-step model. The first step is the 'sticking', or capture, which can be calculated relatively accurately. The second step is the probability for the formation of a CN by 'diffusion' analogous to that of Brownian motion. Lastly, there exists the probability of the CN 'surviving' deexcitation by neutron emission, which competes with fission and other de-excitation modes. This model predicts and reproduces cross sections typically within a factor of two. Producing the same CN with different projectile-target pairs is a very sensitive way to test entrance channel effects on heavy element production cross sections. If the same CN is produced at or near the same excitation energy the survival portion of the theory is nearly identical for the two reactions. This method can be used as a critical test of the novel 'diffusion' portion of the model. The reactions producing odd-Z TAN CN such as Db, Bh, Mt, and Rg (Z = 105, 107, 109, and 111, respectively) were first studied using even-Z projectiles on {sup 209}Bi targets (as opposed to odd-Z projectiles on {sup 208}Pb targets) because lower effective fissility [2] was expected to lead to larger cross sections. Many odd-Z projectile reactions producing odd-Z CN had not been studied in-depth until very recently. We have completed studies of these reaction pairs with the 88-Inch Cyclotron and the Berkeley Gas-Filled Separator (BGS) at the Lawrence Berkeley National Laboratory (LBNL), see Figure 1. Cross section ratios for several pairs of reactions will be presented and compared with theory