Odd Mass Research Articles

High spin structure ofNd139

High spin states up to spin $41/2\ensuremath{\hbar}$ were populated in $^{139}\mathrm{Nd}$ using the heavy ion fusion evaporation reaction. The low spin states below $19/{2}^{\ensuremath{-}}$ indicate a triaxial shape. Two dipole bands, one negative parity and the other positive parity, have been identified in the present work. The configurations of different high spin states are discussed from a systematic comparison with neighboring $N=79$ odd mass isotopes. The observed dipole bands are compared with the results of the tilted axis cranking calculations.

Erratum: Algebraic description of triaxially deformed rotational bands in odd mass nuclei [Phys. Rev. C73, 034305 (2006)

Erratum: Algebraic description of triaxially deformed rotational bands in odd mass nuclei [Phys. Rev. C73, 034305 (2006)

Statistical Treatment of Low-Energy Nuclear Level Schemes

The level density parameter and the back shift energy E1 aredetermined for nuclei with A-values across the whole periodictable from fits to complete level schemes at low excitation energynear the neutron binding energies. We find that the energyback shift E1 shows complicated behavior and depends on thetype of the nucleus, even-even, odd mass, and odd-odd. The spincut-off factor has also been investigated for nuclei mentionedabove. The results are compared with the previous results anddifferent experimental data on level densities.

Role of pairing interaction in neutron rich odd and even Zr nuclei

Neutron rich Zr nuclei with number of neutrons between $N=50$ and 82 are investigated in the relativistic mean field approach in coordinate space. The resonant levels in the positive energy continuum have been explicitly included in the calculation. Odd nuclei have been treated in the blocking approximation. Our calculation indicates that the dripline for odd mass isotopes is far away from that for the even mass ones. Pairing interaction plays a significant role in stabilizing the even isotopes, thus extending the dripline for them.

Top-on-top mechanism and the electromagnetic transitions for the triaxial strongly deformed bands in odd mass nuclei

We found a set of quantum numbers for the particle-rotor model with one nucleon coupled to a triaxially deformed core. These quantum numbers classify the rotational bands, and lead the selection rules for the electromagnetic intraband and interband transitions.

Positive parity low spin states of odd-mass tellurium isotopes

In this work, we analyse the positive parity of states of odd-mass nucleus within the framework of interacting boson fermion model. The result of an IBFM-1 multilevel calculation with the lg 9/2, 2d 5/2, 2d 3/2, 3s 1/2 and one level, 1h 11/2 with negative parity, single particle orbits is reported for the positive parity states of the odd mass nucleus 123–125Te. Also, an IBM-1 calculation is presented for the low-lying states in the even–even 124–126Te core nucleus. The energy levels and B (E2) transition probabilities were calculated and compared with the experimental data. It was found that the calculated positive parity low spin state energy spectra of the odd-mass 123–125Te isotopes agree quite well with the experimental data.

Sputtered gas-phase dianions detected by high-sensitivity mass spectrometry

The detection of small doubly-charged molecular anions by means of highly sensitive mass spectrometry is discussed. The production of these gas-phase dianions is accomplished by sputtering the specimen with Cs + ions with an energy of a few keV. It is demonstrated that dianions can be detected most easily when the molecular ion has an odd total mass; then, the dianions will show up at half-integral mass numbers in the mass spectrum. In addition, the agreement of the relative abundances of several isotopomers of a dianion with the nominal isotopic pattern corroborates the identification of a dianionic species in the mass spectrum. These features are exemplified by monitoring mixed silicon–oxygen dianions of the general form Si n O 2 n + 1 2 - (with 2 ⩽ n ⩽ 8) in a low-energy mass spectrometer. They were formed by sputtering a silicon wafer at an elevated oxygen partial pressure in the vicinity of the sample’s surface. The flight time through the mass spectrometer of ∼15–30 μs establishes a lower limit with respect to the intrinsic lifetimes of these dianions. Emission energy spectra of various singly- and doubly-charged ions illustrate the occurrence of fragmentation processes. The yields of the doubly- and singly-charged mixed silicon–oxygen anions increase with the ratio of the O 2 arrival rate to the Cs + flux density, but tend to saturate when this ratio approaches unity. The benefits of high-energy accelerator mass spectrometry in dianion detection are illustrated for LiF 3 2 - and CaF 4 2 - .

Self-consistent Dirac quasi-particle blocking approximation applied to the α-decay scheme of the superheavy element 287115

A Dirac–Hartree–Bogoliubov formalism for axially deformed nuclei is used to study the ground-state properties of odd–even and odd–odd mass nuclei. The effect of odd proton/neutron numbers is treated by using a self-consistent Dirac quasi-particle blocking method. The approach is tested by studying the ground-state properties of known medium-mass proton-rich odd–odd and even–odd nuclei. The method is applied to the 287115 and 288115 nuclei where the ground state and low-lying single-particle states and deformations are calculated. Results for the α energies and half-lives in the α-decay chain of 287115 are compared with experimental data and other calculations.

Algebraic description of triaxially deformed rotational bands in odd mass nuclei

An extensive application of the Holstein-Primakoff boson expansion to both single-particle angular momentum and total angular momentum provides an algebraic solution, which gives a good approximation to the exact results for the particle-rotor model with one high-j nucleon coupled to a triaxially deformed core. Two kinds of quantum numbers classify the rotational bands characteristic of the particle-rotor model and lead the selection rules for the interband and intraband transitions. The algebraic solution is compared with the experimental data for the odd mass isotopes $^{163,165,167}\mathrm{Lu}$ as testing grounds.

GSI EXPERIMENTS ON SYNTHESIS AND NUCLEAR STRUCTURE INVESTIGATIONS OF HEAVIEST NUCLEI

The method of 'cold' fusion reactions has been applied successfully to synthesize isotopes of elements up to Z =113. However, the cross sections were found to decrease nearly exponential with increasing atomic number. The production of isotopes up to Z =118 using 48 Ca - projectiles and actinide targets was claimed from experiments performed at the Dubna Gasfilled Separator (DGFRS). Attempts to confirm the results from one of the used reactions (48 Ca + 238 U ) have been performed at other laboratories. The results of the different experiments are compared. In order to increase our knowledge on the structure of heaviest nuclei an experimental program on α - γ - decay spectroscopy of transfermium isotopes was started at SHIP, GSI. Results on trends in single particle levels in odd mass einsteinium isotopes as well as on the identification of a (possible) K -isomer in 252 No will be presented.

Dark matter andBs→μ+μ−with minimal SO10soft SUSY breaking II

We update and extend to larger masses our previous analysis of the MSSM with minimal $SO_{10}$ [MSO$_{10}$SM] soft SUSY breaking boundary conditions. We find a well--defined, narrow region of parameter space which provides the observed relic density of dark matter, in a domain selected to fit precision electroweak data, including top, bottom and tau masses. The model is highly constrained which allows us to make several predictions. We find the light Higgs mass $m_h \leq 121 \pm 3$ GeV and also upper bounds on the mass of the gluino $\mgluino\lsim3.1$ TeV and lightest neutralino $\mchi\lsim450$ GeV. As the CP odd Higgs mass $m_A$ increases, the region of parameter space consistent with WMAP data is forced to larger values of $M_{1/2}$ and smaller values of $m_h$. Hence, we find an upper bound $m_A \lsim 1.3$ TeV. This in turn leads to lower bounds on ${\rm BR}(B_s\to \mu^+ \mu^-) > 10^{-8}$ (assuming minimal flavor violation) and on the dark matter spin independent detection cross section $\sigsip > 10^{-9}$ pb. Finally, we extend our previous analysis to include WIMP signals in indirect detection and find prospects for WIMP detection generally much less promising than in direct WIMP searches.

Quantum numbers for the triaxial strongly deformed bands in odd mass nuclei

A set of quantum numbers describing both precessions of total spin I⃗ and single particle spin j⃗ is defined by applying boson expansion method to the particle-rotor model with one nucleon coupled to a triaxially deformed core. The derived algebraic energy formula can be applied to classify the triaxial, strongly deformed (TSD) bands in Lu isotopes.

Scherk–Schwarz supersymmetry breaking with radion stabilization

We study the issue of radion stabilization within five-dimensional supersymmetric theories compactified on the orbifold S 1/ Z 2 . We break supersymmetry by the Scherk–Schwarz mechanism and explain its implementation in the off-shell formulation of five-dimensional supergravity in terms of the tensor and linear compensator multiplets. We show that radion stabilization may be achieved by radiative corrections in the presence of five-dimensional fields which are quasi-localized on the boundaries through the presence of Z 2 odd mass terms. For the mechanism to work the number of quasi-localized fields should be greater than 2+ N V − N h where N V and N h are the number of massless gauge- and hypermultiplets in the bulk. The radion is stabilized in a metastable Minkowski vacuum with a lifetime much larger than cosmological time-scales. The radion mass is in the meV range making it interesting for present and future measurements of deviations from the gravitational inverse-square law in the submillimeter range.

Supersymmetry breaking with quasi-localized fields in orbifold field theories

We study the Scherk–Schwarz supersymmetry breaking in five-dimensional orbifold theories with five-dimensional fields which are not strictly localized on the boundaries (quasi-localized fields). We show that the Scherk–Schwarz (SS) mechanism, besides the SS-parameter ω, depends upon new parameters, e.g., supersymmetric five-dimensional odd mass terms, governing the level of localization on the boundaries of the five-dimensional fields and study in detail such a dependence. Taking into account radiative corrections, the potential along the ω direction has a global minimum in the range 0<ω<1/2.

Relativistic mean field calculation for odd mass nuclei inA∼60–70region

Relativistic mean field calculation has been performed for odd mass nuclei with $A\ensuremath{\sim}60--70$. The mean field is assumed to be axially symmetric and time-reversal symmetric. Blocked BCS method is used to restore time-reversal symmetry. The total binding energy and the last nucleon binding energy are reproduced with reasonable accuracy. The static quadrupole moments of different nuclei in their ground states are calculated and compared with experiment. In many nuclei, a number of solutions with different shapes but comparable energy values are obtained by blocking different single particle levels. In a few nuclei, the ground state spin is not reproduced.

N–p Pairing—diagonal matrix elements: Wigner energy, symmetry energy and spectroscopy

The role of diagonal matrix elements in n–p pairing is investigated. It is found that diagonal matrix elements, calculated with reasonable two-body interactions, explain the Wigner energy and the symmetry energy in a transparent way. It is also found that the diagonal matrix elements explain most of the changes in level density near ground of N=Z odd–odd nuclei as compared to N=Z+2 odd–odd nuclei. In addition, it is found that diagonal matrix elements have a major effect on the excitation energies of particle states relative to hole states in odd–mass nuclides near the N=Z line.

Oblate–prolate transition in odd-mass light mercury isotopes

Anomalous isotope shifts in the chain of light Hg isotopes are investigated by using the Hartree–Fock–Bogoliubov method with the Skyrme SIII, SkI3 and SLy4 forces. The sharp increase in the mean-square radius of the odd mass 181–185Hg isotopes is well explained in terms of the transition from an oblate to a prolate shape in the ground state of these isotopes. We discuss the polarization energy of time-odd mean-field terms in relation to the blocked level by the odd neutron.

Anisotropicαdecay in Am, Es, and Fm isotopes

A microscopic analysis of the $\ensuremath{\alpha}$ decay from odd mass axially deformed nuclei is performed to predict the anisotropies for ${}^{241\ensuremath{-}243}\mathrm{Am},$ ${}^{253\ensuremath{-}255}\mathrm{Es},$ and ${}^{255\ensuremath{-}257}\mathrm{Fm}$ isotopes. Realistic mean field plus pairing residual interaction has been used, together with a single particle basis consisting of two different harmonic oscillator representations. A spherical $\ensuremath{\alpha}$ formation amplitude has been used, so that the predicted anisotropy has to be ascribed, within the presented model, only to the deformed barrier penetration. Any disagreement between the present, properly filtered, theoretical predictions and future experimental data will provide evidence of relevant nuclear structure details not accounted for by the $L=0$ part of the formation amplitude.

Structures and properties the lead-doped carbon clusters PbCn/PbCn+/PbCn− (n=1–10)

A systemic density functional theory study of the lead-doped carbon clusters PbCn/PbCn+/PbCn− (n=1–10) has been carried out using B3LYP method with both CEP-31G and TZP+ basis sets. For each species, the electronic states, relative energies and geometries of various isomers are reported. According to these calculations, the Pb-terminated linear or quasilinear isomer is the most stable structure for PbCn/PbCn+/PbCn− clusters except for PbC2/PbC2+ and PbC10/PbC10+. Both PbC2 and PbC2+ have bent ground state structure. For neutral PbC10, the global minimum possesses a Pb-containing 11-membered ring structure, while for cationic PbC10+, the Pb-side-on C10 monocyclic configuration has lowest energy. Except for the smallest PbC, PbC+, and PbC−, the electronic ground state is alternate between Σ3 (for n-odd member) and Σ1 (for the n-even member) for linear PbCn and invariably Π2 for linear PbCn+ and PbCn−. The incremental binding energy diagrams show that strong even–odd alternations in the cluster stability exist for both neutral PbCn and anionic PbCn−, with their n-even members being much more stable than the corresponding odd n−1 and n+1 ones, while for cationic PbCn+, the alternation effect is less pronounced. These parity effects also reflect in the ionization potential and electron affinity curves. The even–odd alternation predicted by theoretical studies for anionic PbCn− is in good agreement with the even–odd alternation mass distribution observed in the time-of-flight mass spectra. By comparing with the fragmentation energies accompanying various channels, the most favorable dissociation channel for each kind of the PbCn/PbCn+/PbCn− clusters are given.

The quantum numbers for the triaxial superdeformed bands in odd mass nuclei

The quantum numbers for the triaxial superdeformed bands in odd mass nuclei