Abstract: Publication date: Available online 22 January 2020Source: Nuclear Physics AAuthor(s): F.A. Danevich, M. Hult, D.V. Kasperovych, G.P. Kovtun, K.V. Kovtun, G. Lutter, G. Marissens, O.G. Polischuk, S.P. Stetsenko, V.I. TretyakAbstractThe first ever search for 2ε and εβ+ decay of 174Hf was realized using a high-pure sample of hafnium (with mass 179.8 g) and the ultra low-background HPGe-detector system located 225 m underground. After 75 days of data taking no indication of the double beta decay transitions could be detected but lower limits for the half-lives of the different channels and modes of the decays were set on the level of limT1/2∼1016–1018 a.

Abstract: Publication date: Available online 22 January 2020Source: Nuclear Physics AAuthor(s): A.M. Khalaf, A.M. Ismail, A.A. ZakiAbstractThe shape structure of even-even Hafnium isotopic chain 160–180Hf is investigated within the framework of sd-version of interacting boson model (IBM1) using coherent state formalism, the Hamiltonian operator of the model contains Casimir operators of the dynamical symmetries U(5) and SU(3) of the IBM1 besides the Casimir operator of the subgroup O(3). The potential energy surfaces (PES's) are calculated by diagonalizing the Hamiltonian between the coherent states. The PES's are analyzed in terms of the shape variables β, γ and the essential parameters r1, r2 and the locus of the critical points are identified. The model parameters for each nucleus are adjusted so as to reproduce some selected low lying energy levels and reduced electric quadrupole transition probabilities B(E2) with corresponding experimental data.For each nucleus the calculations are performed using the computer codes PHINT, BEFM besides a simulated fitting search program to give best fit between IBM and experimental values. The characteristic of energy ratios and B(E2) values are studied and analyzed with respect to increasing of the total number of bosons.It is concluded that the Hf isotopes lies in shape transition U(5) – SU(3) region of the IBM1 such that lighter isotopes comes very close to spherical vibrator limit U(5), while the heavier isotopes tends to be near the deformed rotator limit SU(3).

Abstract: Publication date: Available online 21 January 2020Source: Nuclear Physics AAuthor(s): R. Arnold, C. Augier, A.S. Barabash, A. Basharina-Freshville, S. Blondel, S. Blot, M. Bongrand, D. Boursette, R. Breier, V. Brudanin, J. Busto, A.J. Caffrey, S. Calvez, M. Cascella, C. Cerna, J.P. Cesar, A. Chapon, E. Chauveau, A. Chopra, L. DawsonAbstractThe double-beta decay of 82Se to the 01+ excited state of 82Kr has been studied with the NEMO-3 detector using 0.93 kg of enriched 82Se measured for 4.75 y, corresponding to an exposure of 4.42 kg⋅y. A dedicated analysis to reconstruct the γ-rays has been performed to search for events in the 2e2γ channel. No evidence of a 2νββ decay to the 01+ state has been observed and a limit of T1/22ν(Se82,0gs+→01+)>1.3×1021y at 90% CL has been set. Concerning the 0νββ decay to the 01+ state, a limit for this decay has been obtained with T1/20ν(Se82,0gs+→01+)>2.3×1022y at 90% CL, independently from the 2νββ decay process. These results are obtained for the first time with a tracko-calo detector, reconstructing every particle in the final state.

Abstract: Publication date: Available online 21 January 2020Source: Nuclear Physics AAuthor(s): P.C. Bruns, A. CieplýAbstractWe critically examine the K¯N coupled-channel approach presented in [38] and demonstrate that it violates constraints imposed by chiral symmetry of QCD. The origin of this violation can be traced back to the off-shell treatment of the chiral-effective vertices, in combination with the use of non-relativistic approximations and the chosen regularization scheme. We propose an improved version of the approach, which is directly given by a resummation of relativistic Feynman graphs of baryon chiral perturbation theory, and is in accord with the chiral symmetry constraint. Within this improved model, two poles are generated dynamically in the isoscalar πΣ−K¯N coupled channels sector, in contrast with the non-relativistic model of [38] in which only one such pole was reported.

Abstract: Publication date: Available online 17 January 2020Source: Nuclear Physics AAuthor(s): B. Mukeru, M.L. Lekala, J. Lubian, Lauro TomioAbstractIn a theoretical approach, the complete and incomplete fusions are investigated by considering the Li8+208Pb reaction, within a three-body model where the projectile is described as n−7Li with binding energy εb. By decreasing εb from its known experimental value, the complete fusion is shown to have no meaningful dependence on such variations, whereas the incomplete fusion strongly depends on that. The complete and incomplete fusion cross sections are calculated by using a combination of both continuum-discretized coupled-channel and sum-rule models. To this end, an incident-energy dependent cut-off angular momentum Lc is first obtained by using the available complete fusion experimental data, within an approach which is extended to model results obtained for other incident-energies. An approximated fitted expression linking Lc to the well-known critical value Lcrit derived by Wilczyński (1973) [28] suggests that the sum-rule model could be generalized to energies around and below the Coulomb barrier.

Abstract: Publication date: Available online 17 January 2020Source: Nuclear Physics AAuthor(s): N.G. Kelkar, D. Bedoya Fierro, H. Kamada, M. SkurzokAbstractThe proximity of the η N threshold to the mass of the N⁎(1535) allows us to consider the η-nucleus interaction below the η threshold as a series of excitations, decays of the N⁎ on the constituent nucleons and the eventual decay of the N⁎ to a nucleon and a pion. Experimental searches for η-mesic nuclei rely on this model in their analysis of data where an η-mesic nucleus could have been formed. However, the momentum distribution of an N⁎ is often approximated to be the same as that of a nucleon inside the nucleus. Our aim is to obtain an estimate of the error introduced by this assumption and hence we calculate the momentum distribution of the N⁎ formed inside 3He. This distribution is found to be narrower than that of a nucleon inside 3He. The latter affects the outgoing particles kinematics and reduces the determined acceptance of their experimental registration by the detection setup. This reduction is crucial for the determination of cross sections in the search for η-mesic helium.

Abstract: Publication date: Available online 15 January 2020Source: Nuclear Physics AAuthor(s): A.S. Barabash, V.B. Brudanin, A.A. Klimenko, S.I. Konovalov, A.V. Rakhimov, E.N. Rukhadze, N.I. Rukhadze, Yu.A. Shitov, I. Stekl, G. Warot, V.I. UmatovAbstractNew limits on β+EC and ECEC processes in 74Se have been obtained using a 600 cm3 HPGe detector and an external source consisting of 1600 g of a natural selenium powder. For different β+EC and ECEC transitions (to the ground and excited states) obtained limits are on the level ∼(0.2−4.8)×1019yr at 90% C.L. In particular, for the potentially resonant transition into the 1204.2 keV excited state of 74Ge a lower half-life limit of 1.1×1019yr at 90% C.L. has been obtained. Possibility to increase the sensitivity of such measurements is discussed.

Abstract: Publication date: Available online 14 January 2020Source: Nuclear Physics AAuthor(s): Z.X. Ren, P.W. Zhao, S.Q. Zhang, J. MengAbstractThe toroidal states in 28Si with spin extending to extremely high are investigated with the cranking covariant density functional theory on a 3D lattice. Thirteen toroidal states with spin I ranging from 0 to 56ħ are obtained, and their stabilities against particle emission are studied by analyzing the density distributions and potentials. The excitation energies of the toroidal states at I=28, 36, and 44ħ reasonably reproduce the observed three resonances extracted from the seven-α de-excitation of 28Si. The possible existence of α clustering in these toroidal states is discussed based on α-localization function.

Abstract: Publication date: Available online 10 January 2020Source: Nuclear Physics AAuthor(s): J. Acharya, S. Mukherjee, G.F. Steyn, S.V. Förtsch, F.D. Smit, R.T. Newman, J.J. Lawrie, O.V. Fotina, A. ChatterjeeAbstractIn this work, the results of measured inclusive double differential cross sections of α particles emitted in the interaction of 14N with 59Co and 93Nb at incident energy of 250 MeV are presented. The experimental data were collected in a wide angular range from 8 to 100 degrees in the laboratory system. The analysis of these data suggests that the measured alpha spectra contains contributions of alpha particles originating from various reaction mechanisms, all of which are important at this high energy. We have also compared our experimental results with the calculations by using a recently developed theoretical model code. This recently developed pre-equilibrium model code is hereby put to a stringent test as to how it performs in case of heavy ion reactions at such high energies.

Abstract: Publication date: Available online 8 January 2020Source: Nuclear Physics AAuthor(s): T. Ghasemi, O.N. GhodsiAbstractIn this paper, the variation of the nuclear matter properties during the fusion reaction and also its relationship with the hindrance phenomenon are examined in the 64Ni+64Ni reaction. For this purpose, the inter-nuclear potential is calculated by using the Skyrme energy density functional formalism in which the used forces are in a wide range of the incompressibility values. The obtained results indicate that by increasing bombarding energy the nuclear matter incompressibility is increasing. Also, this variation shows that nuclear matter exhibits a very soft behavior when moving from the sub-barrier to the deep sub-barrier region in this reaction, which can cause a large overlapping between the interacting nuclei. Since the repulsion arising from the Pauli exclusion principle affects this large overlapping, so it can lead to the fusion hindrance and the fall-off of the cross-sections in the 64Ni+64Ni reaction.

Abstract: Publication date: Available online 8 January 2020Source: Nuclear Physics AAuthor(s): Olena Gritzay, Anna Grymalo, Volodymyr Pshenychnyi, Vitaliy Venedyktov, Viktor ShachovAbstractExperimental determination of the total neutron cross section for natural hafnium was carried out at the Kyiv Research Reactor using the neutron filtered beams with the energies 2, 54, 59, and 145 keV. The transmission method was used in these measurements. The results are presented together with the analysis of the previous experimental data and the evaluated nuclear data from the ENDF libraries.

Abstract: Publication date: Available online 8 January 2020Source: Nuclear Physics AAuthor(s): A.D. Duisenbay, N. Kalzhigitov, K. Katō, V.O. Kurmangaliyeva, N. Takibayev, V.S. VasilevskyAbstractWe investigate how the Coulomb interaction affects the energy E and width Γ of resonance states in mirror nuclei. We employ a three-cluster microscopic model to determine position of resonance states in two- and three-body continua. Two parameters are introduced to quantify effects of the Coulomb interactions. As the energy and width of the corresponding resonance states of mirror nuclei are displayed on an E-Γ plane, these parameters determine a rotation and a dilatation. With the help of these parameters we found resonance states with strong, small and medium effects of the Coulomb interaction. We also found two different scenarios of the motion of resonance states due to the Coulomb interaction. The first standard (major) scenario represent resonance states with the larger energy and larger width than their counterparts have. The second rear scenario includes resonance states with the larger energy but smaller width.

Abstract: Publication date: March 2020Source: Nuclear Physics A, Volume 995Author(s): Mujeeb Hasan, Binoy Krishna Patra, Bhaswar Chatterjee, Partha BagchiAbstractIn this article we have investigated the effects of strong magnetic field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and then studied the quasi-free dissociation of quarkonia due to the Landau-damping. Thermalising the Schwinger propagator for quarks in the lowest Landau levels and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Finally the inverse Fourier transform of the permittivities encrypt the effect of hot QCD medium in the presence of strong magnetic field into both real and imaginary parts of heavy quark potential. We have found that the magnetic field largely affects the large-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to its counterpart in the absence of magnetic field. The real part of the potential is thereafter solved numerically by the Schrödinger equation to obtain the energy eigenvalues and energy eigenfunctions of the charmonium states. We have noticed that in the presence of strong magnetic field, the size (r2) of J/ψ and ψ′ are swelled whereas χc gets shrunk, unless the temperature is very high. Similarly the magnetic field affects the binding of J/ψ and χc differently, i.e. it decreases the binding of J/ψ but increases for χc. On contrary the magnetic field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied the dissociation due to the Landau damping and found that the dissociation temperatures become higher in the presence of magnetic field. For example, with eB=6mπ2 the J/ψ is dissociated at 2Tc, and with eB=4mπ2 the χc is dissociated at 1.1Tc in comparison, with eB = 0 the J/ψ is dissociated at T=1.6Tc and χc is dissociated at T=0.8Tc. However, with the further increase of magnetic field the dissociation temperatures decrease.

Abstract: Publication date: March 2020Source: Nuclear Physics A, Volume 995Author(s): M.G. Srinivas, H.C. Manjunatha, K.N. Sridhar, N. Sowmya, Alfred Cecil RajAbstractThe half-lives of one-proton emitters in the actinide region are presented using the coulomb and proximity potential method. The studied proton decay half-lives are compared with that of other decay modes such as alpha decay, spontaneous fission and beta decay. We have identified proton emitters in the actinide region and also it is the competing decay mode for all the observed proton emitters. We have included the effects of deformations in the present study. One-proton decay half-lives of present study have shown good agreement with the available experimental values.

Abstract: Publication date: March 2020Source: Nuclear Physics A, Volume 995Author(s): Akihiko MonnaiAbstractElectromagnetic aspects of a QCD matter have been a hot topic in recent years. High-energy heavy-ion experiments revealed that flow harmonics of direct photons are not well-explained by most hydrodynamic models. In this work, I discuss possible effects of refraction by the hot medium since it can work as a lens which converts its geometrical anisotropy into momentum anisotropy of photons. Flow harmonics of prompt photons are estimated numerically. The results indicate that the effect of refraction is small but phenomenologically non-trivial, exhibiting sensitivity to the QCD refractive index.

Abstract: Publication date: Available online 2 January 2020Source: Nuclear Physics AAuthor(s): Dalip Singh Verma, KushmakshiAbstractThe angular momentum effects on the reaction mechanism in the decay of a hot system, formed in 48Ti + 40Ca → Mo⁎88 reaction at three excitation energies, have been studied using the dynamical cluster-decay model based on the quantum mechanical fragmentation theory. Angular momentum windows have been defined for the compound and non-compound nucleus processes (like deep inelastic collisions etc.) with respect to the angular momentum variation of the fission barriers of the incoming channel. First, the angular momentum distributions of the summed up preformation, penetration probabilities and the cross-sections for light particles, intermediate mass fragments and fission fragments have been calculated by considering the angular momentum up to the critical value. Then, the mass and charge distributions (with isotopic compositions) of the cross-sections have been calculated in accordance with the defined angular momentum windows. The cross-sections for fragments coming both from the compound nucleus decay and from other processes have been calculated and the total reaction cross-section is compared with the one presented in the work of Valdré and co-workers. The ratios of the observed fusion-evaporation and total fusion cross-sections to the total reaction cross-sections of (i) our calculation and (ii) presented in the work of Valdré and co-workers, are compared and found comparable. The change of the reaction mechanism has been analyzed as a function of the angular momentum variation of the cross-sections of the fission fragments. Finally, the effect of the incident energy on the compound nucleus formation and survival probabilities has been studied.

Abstract: Publication date: Available online 19 December 2019Source: Nuclear Physics AAuthor(s): H. Rashidi, S. Zaryouni, H.R. MoshfeghAbstractThe lowest order constrained variational (LOCV) formalism is formulated for the Nijmegen soft-core potential, which is fitted by the proton-proton (pp) scattering phase shift. The calculations are performed for the equation of state (EOS) of both nuclear and neutron matter. The state-dependent correlation functions are calculated by the minimization of two-body cluster energy, and the resulting Euler Lagrange equations are solved for this kind of potential. It is shown that LOCV calculations can work with this kind of interaction as well as other interactions in configuration space. The state-dependent correlation functions are calculated by minimization of two-body cluster energy for each channel with various JLSTMT, by using Nijmegen interaction. The correlation functions are compared with those coming from UV14 interaction in LOCV formalism. It is shown that unlike UV14, AV14, and AV18 potentials, the binding energy obtained from Nijmegen in the LOCV framework is −16.81 MeV that is close to the experimental value. Finally, it is recognized our LOCV results with Nijmegen interaction are similar to calculations with different interactions and different many-body methods.

Abstract: Publication date: Available online 19 December 2019Source: Nuclear Physics AAuthor(s): S. Chakraborty, H.P. Sharma, S.S. Tiwary, C. Majumder, P. Banerjee, S. Ganguly, S. Rai, Pragati, Mayank, S. Kumar, A. Kumar, R. Palit, S.S. Bhattacharjee, R.P. Singh, S. MuralitharAbstractThe electromagnetic properties of the γ-transitions, decaying from the γ-vibrational states of 126Xe, have been studied via 122Sn(9Be, 5nγ) fusion-evaporation reaction at a beam energy of 48 MeV. The level scheme has been updated by placing the 82+→81+ (ΔI=0) and the 71+→61+ (ΔI=1) γ-transitions. Spin and parity of several excited states have been assigned on the basis of angular correlation and linear polarization results. Systematic of the γ-band in even-even Xe isotopes has been discussed.