Preparation and characterisation of isotopically enriched Ta2O5 targets for nuclear astrophysics studies

Level energies in two-quasiparticle (2qp) structures in ¹⁵⁶ ₆₁Pm₉₅ are evaluated using the phenomenological rotor-particle model for odd-odd deformed nuclei with the inclusion of the residual p-n interaction contribution. Using these results as location guides, the experimental data from a recent ¹⁵⁶Nd decay study are used to construct a level scheme for ¹⁵⁶Pm with excitation energies upto 550 keV, wherein 26 (out of 30) ????s reported in ¹⁵⁶Nd decay are incorporated. Spin-parities and configuration assignments are suggested for 15 levels, in addition to the two isomers, in this energy domain. These investigations point to the need for information on higher-energy ????s and on ??-?? and ??-?? coincidence data from ¹⁵⁶Nd ??-decay to confirm these assignments.     

The reaction 48Ca + 248Cm → 296116* studied at the GSI-SHIP

The synthesis of element 116 in fusion-evaporation reactions of a ⁴⁸Ca beam with radioactive ²⁴⁸Cm targets was studied at the velocity filter SHIP of GSI in Darmstadt. At excitation energies of the compound nuclei of 40.9MeV, four decay chains were measured, which were assigned to the isotope ²⁹²116, and one chain, which was assigned to ²⁹³116. Measured cross-sections of (3.4 _?1.6 ^+2.7 ) pb and (0.9 _?0.7 ^+2.1 ), respectively, and decay data of the chains agree with data measured previously at the Flerov Laboratory of Nuclear Reactions in Dubna. As a new result, one ??-decay chain was measured, which terminates after four ?? decays by spontaneous fission. The ?? energies of the second-to-fourth decay are considerably higher than those measured for the ?? decays of ²⁸⁹114, ²⁸⁵Cn, and ²⁸¹Ds and the spontaneous fission half-life is significantly longer than that of ²⁷⁷Hs measured in previous experiments. A possible assignment is discussed in the frame of excited quasiparticle states of nuclei populated in the decay chain from ²⁹³116. Also other possible assignments were considered and are discussed. At an excitation energy of 45.0MeV no events were observed resulting in a one-event cross-section limit of 1.6 pb. The technical aspects related with the use of radioactive target material at SHIP are described in detail. The experience gained in this experiment will serve as a basis for future experiments aiming to study still heavier elements at the velocity filter SHIP.     

Contribution of vector resonances to the \bar{B}_{d}^{0}\to\bar {K}^{*0}\mu^{+}\mu^{-} decay

The fully differential angular distribution for the rare flavor-changing neutral current decay $\bar{B}_{d}^{0} \to\bar{K}^{*0} (\to K^{-} \pi^{+}) \mu^{+}\mu^{-} $ is studied. The emphasis is placed on accurate treatment of the contribution from the processes $\bar{B}_{d}^{0} \to\bar{K}^{*0} (\to K^{-} \pi^{+}) V $ with intermediate vector resonances V=??(770),??(782),?(1020),J/??,??(2S),?? decaying into the ?? ⁺ ?? ^? pair. The dilepton invariant-mass dependence of the branching ratio, longitudinal polarization fraction f _L of the $\bar{K}^{*0}$ meson, and forward?Cbackward asymmetry A _FB is calculated and compared with data from Belle, CDF and LHCb. It is shown that inclusion of the resonance contribution may considerably modify the branching ratio, calculated in the SM without resonances, even in the invariant-mass region far from the so-called charmonia cuts applied in the experimental analyses. This conclusion crucially depends on values of the unknown phases of the B ⁰??K ^?0 J/?? and B ⁰??K ^?0 ??(2S) decay amplitudes with zero helicity.     

Three-body continuum structure and response functions of halo nuclei (I): 6He

Three-body scattering states of the Borromean two-neutron halo nuclei are explored in a core + n + n model using the method of hyperspherical harmonics. We analyse the continuum structure (the properties of the continuum wave functions) separately from the continuum response (the magnitudes of one-step transitions from the ground state to the continuum). Predictions are made for the positions and strengths of the isoscalar monopole, electric dipole and quadrupole excitations, as well as for nuclear inelastic and charge-exchange response functions, for the ⁶He nucleus. The known 2⁺ resonance in ⁶He is reproduced. We find 1⁻ strength concentrations at lower energies in the proximity of the three-body threshold, and predict new 2⁺, 1⁺ (and possibly 0⁺) resonances at slightly higher energies in ⁶He.     

Nanostructuration of i-Al64Cu23Fe13 quasicrystals produced by arc-furnace

We have measured several Q values at JYFLTRAP for superallowed ?? decays that contribute to testing the Standard Model and candidate nuclei that one could use for the search of neutrinoless double-?? decay. These results play important roles in the research of fundamental physics that have scopes beyond Standard Model.     

���Ѧ� Interaction Leading to N* and ��* Resonances

We have performed a calculation for the three-body ????? system by using the fixed center approximation to Faddeev equations, taking the interaction between ?? and ??, ?? and ??, and ?? and ?? from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known I?=?1/2, 3/2 and J ^P ?=?1/2⁺, 3/2⁺ and 5/2⁺ baryon states.     

Influence of a continuum on cluster-decay processes

A microscopic approach to cluster decay including single-particle states in a continuum is given. The equations of motion describing cluster-like states are derived within the multistep shell-model approach. The lowest collective two-particle eigenmodes are used as building blocks for α-like states. Good agreement with low-lying states in ²¹²Po is obtained. The spectroscopic factor for the α decay between ground states is reproduced. It is shown that only by including the continuum part of the single-particle spectrum is the decay width for α-and cluster-decay processes reproduced. The α-like structure of the lowest states in ²¹²Po is analyzed, and strong high-lying resonances are predicted.     

On the Standard Model prediction for \mathcal{B}(B_{s,d} \to \mu^{+} \mu^{-})

The decay B _s →μ ⁺ μ ^? is one of the milestones of the flavor program at the LHC. We reappraise its Standard Model prediction. First, by analyzing the theoretical rate in the light of its main parametric dependence, we highlight the importance of a complete evaluation of higher-order electroweak corrections, at present known only in the large-m _t limit, and leaving sizable dependence on the definition of electroweak parameters. Using insights from a complete calculation of such corrections for $K\to\pi\nu\bar{\nu}We present O(?? _s ) results on the decays of polarized W ^± and Z bosons into massive quark pairs. The NLO QCD corrections to the polarized decay functions are given up to the second order in the quark mass expansion. We find a surprisingly strong dependence of the NLO polarized decay functions on finite quark mass effects even at the relatively large mass scale of the W ^± and Z bosons. As a main application we consider the decay t??b+W ⁺ involving the helicity fractions ?? _mm of the W ⁺ boson followed by the polarized decay $W^{+}(\uparrow)\to q_{1}\bar{q}_{2}$ for which we determine the O(?? _s ) polar angle decay distribution. We also discuss NLO polarization effects in the production/decay process $e^{+}e^{-}\to Z(\uparrow)\to q\bar{q}$ .     

9 Be Low-Lying Spectrum Within a Three-Cluster Model

The energy spectrum of ⁹Be is studied within the cluster model ???+ ???+?n. Configuration space Faddeev equations are applied to calculate energies of the bound state and resonances. LS coupling is used for partial wave analysis. The ⁹Be low-lying levels are classified as members of spin-flip doublets, in compliance with the total orbital momentum of the ???+????+?n system. The ⁹Be spectral data are well reproduced by the proposed model.     

Two-body beta decay of stored few-electron ions

The combination of the projectile fragment separator FRS and the cooler-storage ring ESR at the accelerator facility of GSI Darmstadt offers the unique opportunity to study beta decay of stored highly-charged ions. Basic nuclear properties such as masses and half-lives are measured by applying the mass- and time-resolved Schottky Mass Spectrometry (SMS). The relative mass-to-charge ratio is directly correlated to the relative revolution frequency. The SMS is sensitive to single stored ions and the decay of each stored ion can be precisely determine by steady monitoring of the corresponding revolution frequencies. On this basis the single particle decay-spectroscopy has been developed which allows for an unambiguous time-resolved and background-free identification of a certain decay branch. In this contribution we discuss experiments on the orbital electron capture (EC) of radioactive ions in the ESR. Fully ionized, hydrogen- and helium-like ¹⁴⁰Pr and ¹⁴²Pm ions have been selected for these studies. These nuclei decay to stable daughter nuclei via either the three-body ?? ^?+?- or the two-body EC-decay by a single allowed Gamow?CTeller (1^?+? ??0^?+?) transition.     

Fusion cross-section measurements for the 13C+13C reaction

Absolute γ-ray yields from characteristic low-lying levels in nuclei produced in the ¹³C+ ¹³C reaction have been measured from E_c.m. = 4.0 to 15.8 MeV using an intrinsic germanium detector. Statistical-model calculations of the decay modes of the compound nucleus have been used to deduce absolute cross sections for the production of the observed residual nuclei and to determine the fusion cross section. Consistency checks on the adopted procedure lead to an estimated absolute uncertainty of ± 15 % on the deduced cross sections. Over the energy range covered, no striking evidence has been found for either broad single-particle resonances or for narrow non-statistical resonances in the cross sections for individual channels. Comparisons are made with optical-model calculations of the reaction cross section and with different expressions for the fusion cross section.     

Radiative recombination of ions and nuclei in electron cooling systems

Experimental data on rates for the radiative recombination of nuclei (from helium to uranium) and various ions in interaction with an electron beam in electron cooling systems are reviewed. An analysis of the experimental data has yielded the dependence of the radiative recombination rate on the relative electron energy appreciably differently than the theoretical models obtained earlier by H. Kramers and R. Schuch. In addition, it is shown that the radiative recombination rate of nuclei in the experiment depends on the transverse electron energy as T _?? ^?0.82 ,which is also different from the results of the calculations by the theoretical model proposed by M. Bell and J. Bell. Experimental data on the cooling of ions in intermediate charge states are analyzed and the dependence of the radiative recombination rate on the charge state of the ion (electron-shell configuration) is shown. For some ion charge states, the rate of the process is of a resonance character. Loss to radiative recombination in the electron cooling system of the NICA Booster is evaluated for the Au³²⁺, Au³³⁺, Au⁵⁰⁺, and Au⁵¹⁺ ion beams. Limitations imposed on the Au79+ beam lifetime by radiative recombination in the electron cooling system of the NICA Collider are analyzed. Possible ways to decrease the radiative recombination rate of nuclei by selecting the parameters of the electron cooling system for the NICA Collider are proposed.     

QCD factorization for forward hadron scattering at high energies

We calculate the branching ratios and CP asymmetries of the B???Ц?, ?Ц? decays in the perturbative QCD factorization approach up to the next-to-leading-order contributions. We find that the next-to-leading-order contributions can interfere with the leading-order part constructively or destructively for different decay modes. Our numerical results have a much better agreement with current available data than previous leading-order calculations, e.g., the next-to-leading-order corrections enhance the B ⁰???? ⁰ ?? ⁰ branching ratios by a factor 2.5, which is helpful to narrow the gaps between theoretic predictions and experimental data. We also update the direct CP-violation parameters, the mixing-induced CP-violation parameters of these modes, which show a better agreement with experimental data than many of the other approaches.     

QQG hybrid mesons in the MIT bag model

We suggest that hybrid (q$\text{q}$g) mesons could exist with rather light masses. The spectrum of the ground state nonets, J^PC = (0, 1, 2)^?+; 1^?? is calculated in the MIT bag model including O(α_s) energy shifts. We discuss hadronic transitions among these states, consider their possible production at LEAR and SPEAR and indicate some interesting decay signatures.     

Quantum physics of an elementary system in de Sitter space

We present the coherent states of a scalar massive particle on 1+3-de Sitter space. These states are vectors in Hilbert space, and they are labeled by points in the associated phase space. To do this, we use the fact that the phase space of a scalar massive particle on 1+3-de Sitter space is a cotangent bundle “T ^?(S ³)” which is isomorphic with the complex sphere “ $S_{\mathbb{C}}^{3}We present the performances of a 330?g zinc molybdate (ZnMoO₄) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double beta decay of ¹⁰⁰Mo. The energy resolution, evaluated at the 2615?keV ??-line of ²⁰⁸Tl, is 6.3?keV FWHM. The internal radioactive contaminations of the ZnMoO₄ were evaluated as <6???Bq/kg (²²⁸Th) and 27±6???Bq/kg (²²⁶Ra). We also present the results of the ?? vs ??/?? discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone.     

Excitation and neutron decay of xenon studied by forward-angle scattering of high-energy 17O ions

Excitation energy spectra and neutron decay of xenon have been measured in extreme forward angle scattering of 250A and 400A MeV ¹⁷O ions, using one quadrant of the CELSIUS storage ring as a magnetic spectrometer. The observed excitation energy spectrum, ranging from 12 to 36 MeV, has been compared with Coulomb cross section calculations. Neutron and missing energy spectra are compared with statistical decay calculations using the code CASCADE. In addition to statistical decay from giant resonances and other continuum excitations, a large fraction of forward peaked fast neutrons was observed throughout the entire excitation energy region. A possible reaction mechanism behind these fast neutrons is discussed.