Volume 57, Number 12, 2012
Dedicated to Prof. Aureliu Săndulescu's 80 ^{th} Anniversary
F O R E W O R D A. Isar Romanian Journal of Physics 57,
15 (2012)
Aureliu Sandulescu, a Life Dedicated to the Nuclear Physics: from α–Decay Theory to Magic Radioactivity and Superheavy Nuclei D.S. Delion Romanian Journal of Physics 57,
68 (2012)
Isotopic Dependence of the Production Cross Sections of Superheavy Nuclei G.G. Adamian, N.V. Antonenko, W. Scheid Romanian Journal of Physics 57,
917 (2012)
Here, we consider various details of the calculation of evaporation residue cross sections for the production of superheavy elements, as the potential energy surface and the fusion rate. As example we present evaporation residue cross sections for the cold fusion reactions Zn + ^{208}Pb and the hot fusion reactions ^{48}Ca + ^{A}Cm and discuss their isotopic dependence.
Cold Nuclear Phenomena and Collisions between Two NonCoplanar Nuclei Manie Bansal, Raj K. Gupta Romanian Journal of Physics 57,
1835 (2012)
Fusion, fission and cluster radioactivity are predicted as cold nuclear phenomena, prior to experiments, on the basis of the quantum mechanical fragmentation theory. The fundamental result of the theory is the role of (spherical) closed shell effects of one or both the reaction partners for fusion, or decay products for fission and cluster radioactivity. Also, not only that deformed nuclei are used in fusion experiments, not precluded by the theory, and high neutron multiplicity fission data is observed to be associated with hyperdeformation of the fission fragments, more recently, it is shown that static deformations of nuclei also play an important role in the interpretation of available cluster radioactivity data on the basis of the dynamical preformed cluster model. In view of such results, the role of deformation and orientation effects of the two colliding nuclei is studied here for the colliding nuclei to be in the same plane (coplanar) or different planes (noncoplanar). The aim is to look for the best cold reaction valleys for the synthesis of new and superheavy elements, using noncoplanar collisions, in future experiments. The illustrative examples are the excited compound nuclei ^{286}112^{*} and ^{292}114^{*}.
Collective Dipole Modes in Nuclear Systems V. Baran, B. Frecus, M. Colonna, M. Di Toro, R. Zus Romanian Journal of Physics 57,
3648 (2012)
In this work we explore some new features of dipole dynamics in nuclear systems. Within a harmonic oscillator shell model, we generalize an approach introduced first by Brink and identify the dipole normal modes in neutron rich nuclei. Consequently, we obtain an upper limit for the energy weighted sum rule exhausted by the pygmy dipole resonance. By solving numerically the LandauVlasov kinetic equations for neutrons and protons with specific initial conditions, we study the structure of the dipole vibrations in neutron rich nucleus ^{132}Sn identified in the previous model. Our calculations point out the existence of a distinctive collective dipole mode with an energy well below giant dipole resonance. In the last part, based on the same microscopic transport model, we focus on the charge equilibration dynamics in fusion reactions and evidence its relation to the excitation of a large amplitude dipole motion in the entrance channel.
Conformal Maps and Group Contractions in Nuclear Structure Models Dennis Bonatsos Romanian Journal of Physics 57,
4968 (2012)
In mathematics, a conformal map is a function which preserves angles. We show how this procedure can be used in the framework of the Bohr Hamiltonian, leading to a Hamiltonian in a curved space, in which the mass depends on the nuclear deformation β, while it remains independent of the collective variable γ and the three Euler angles. This Hamiltonian is proved to be equivalent to that obtained using techniques of Supersymmetric Quantum Mechanics. Group contraction is a procedure in which a symmetry group is reduced into a group of lower symmetry in a certain limiting case. Examples are provided in the large boson number limit of the Interacting Boson Approximation (IBA) model by a) the contraction of the SU(3) algebra into the [R^{5}]SO(3) algebra of the rigid rotator, consisting of the angular momentum operators forming SO(3), plus 5 mutually commuting quantities, the quadrupole operators, b) the contraction of the O(6) algebra into the [R^{5}]SO(5) algebra of the γunstable rotator. We show how contractions can be used for constructing symmetry lines in the interior of the symmetry triangle of the IBA model.
Systematics of Hindrance Factors in Alpha Decay of EvenEven TransLead Nuclei D. Bucurescu, N.V. Zamfir Romanian Journal of Physics 57,
6981 (2012)
The experimental values of the hindrance factors in the alpha decay of eveneven translead nuclei, corresponding to the states $2_{1}^{+}$, $4^{+}_{1}$, $6^{+}_{1}$, $0^{+}_{2}$, and $1^{}_{1}$ are examined as a function of the mass number and collectivity indicators $N_p N_n$ and $P$. Their evolution is discussed in connection with the main trends of the collectivity in this region.
Electronic Structures and Exchange Interactions in RT_{5} and R_{2}T_{17} Compounds, where R is a Rare−earth or Yttrium and T=Co or Ni Emil Burzo Romanian Journal of Physics 57,
8291 (2012)
Band structure calculations and magnetic measurements were performed on rareearth and yttrium (R)−transition metal (T) compounds having 1:5 and 2:17 type structures. The transition metal moments were shown to be linearly correlated with 3d band exchange splittings and internal fields, respectively. The R5d−T3d exchange interactions and R5d(Y4d) band polarizations were also analysed. The magnetic behavior of cobalt and nickel has been discussed in spin fluctuations model.
Dynamic SingleParticle Excitations in LowEnergy Fission N. Carjan, M. Rizea Romanian Journal of Physics 57,
92105 (2012)
We study the transition of the fissioning nucleus from the saddle to the scission point through a dynamical approach. It involves the numerical solution of the bidimensional timedependent Schrödinger equation (TDSE) with timedependent potential. The axially symmetric extremely deformed nuclear shapes are described by modified Cassini ovals. The Hamiltonian in cylindrical coordinates ρ and z is discretized by using special finite difference approximations of the derivatives. The initial wavefunctions for TDSE are the eigensolutions of the stationary Schrödinger equation whose potential corresponds to the saddle point deformation. The TDSE is solved by a CrankNicolson method associated with transparent conditions at numerical boundaries. The time evolution is calculated until the neck connecting the primary fission fragments suddenly breaks. The numerical solutions have been used to evaluate relevant scission properties in the case of the fissioning nucleus ^{236}U.
Refractive versus Resonant Diffraction Scattering of Loosely Bound Nuclei Florin Carstoiu, Serban Misicu, Livius Trache Romanian Journal of Physics 57,
106137 (2012)
We present a complete analysis of elastic scattering ^{6}Li + ^{16}O at 4 MeV/nucleon. Using either traditional WoodsSaxon or a range of semi microscopic folding form factors we find that the data require deep, highly transparent potentials. The intermediate angle structures and the oscillatory increase of the cross section at large angles is interpreted either as a prerainbow oscillation resulting from the interference of the barrier and internal barrier farside scattering subamplitudes, or, equally well, as a resonant diffraction arising from two Regge poles located in peripheral waves. Both semiclassical and Regge pole approaches allow a dynamical separation of the resonant component of the Smatrix.
Radioactive States in RMatrix Theory H. Comisel, C. Hategan, R.A. Ionescu Romanian Journal of Physics 57,
138148 (2012)
The Radioactive States are approached in framework of LaneRobson theory of nuclear reactions. The Radioactive State is not described by a Rmatrix pole but rather by the channel equation $1 − R_{nn} L_n = 0$ relating Rmatrix element $R_{nn}$ to decay channel logarithmic derivative $L_n$. The dependence of radioactive process on decay channel results into renormalization of reduced width. The renormalization factor is Rmatrix compression factor, i.e. wave function normalization over internal region to normalization over all space including decay channel. Extension of results to multichannel system results into replacement of channel Rmatrix element by its reduced counterpart.
Decay Theory Beyond the Gamow Picture D.S. Delion Romanian Journal of Physics 57,
149158 (2012)
In the cluster emission theory the decay width is a product between the penetrability and reduced width. The first component gives the socalled ”Gamow description” of the decay process, leading to the GeigerNuttall law. The second component is connected to clustering features and satisfies an analytic universal law, which is the next step beyond the standard Gamow rule. As a consequence, the reduced width can be described microscopically by using a mixed single particle basis with two components. The first part describes the usual spectroscopic properties, while the second one is connected to clustering features. The universal law implies that the harmonic oscillator parameter of the cluster part is proportional to the Coulomb parameter.
Approximate Centrifugal Barriers and Critical Angular Momentum A. Diaf , M. Lassaut, R.J. Lombard Romanian Journal of Physics 57,
159164 (2012)
In the $D = 3$ dimensional space, some potentials admit analytical solution of the Schrödinger equation for the $\ell = 0$ states. To extend the analytical results to levels of higher angular momentum, the centrifugal barrier is often approximated by a repulsive term having the radial dependence as the original potential. These approximations are valid for well bound states. They become dubious as $\ell$ approaches a critical value $\ell_c$ above which the states of higher angular momentum are unbound by the original potential. The present work proposes a way to determine an upper bound $\ell^{+}_{c}$ to $\ell_c$. The derived formula is tested against four typical potentials. The excellent agreement found between $\ell^{+}_{c}$ and $\ell_{c}$ in these case proves the present upper bound to be a useful approximation.
The Neutrinoless Double Beta Decay and the Neutrino Mass Amand Faessler Romanian Journal of Physics 57,
165179 (2012)
Neutrinoless Double Beta Decay (0νββ) is presently the only known experiment to distinguish between Dirac neutrinos, different from their antiparticles, and Majorana neutrinos, identical with their antiparticles. In addition 0νββ allows to determine the absolute scale of the neutrino masses. This is not possible with neutrino oscillations. To determine the neutrino masses one must assume, that the light Majorana neutrino exchange is the leading mechanism for 0νββ and that the matrix element of this transition can be calculated reliably. The experimental 0νββ transition amplitude in this mechanism is a product of the light left handed effective Majorana neutrino mass and of this transition matrix element. The different methods, Quasiparticle Random Phase Approximation (QRPA), Shell Model (SM), Projected HartreeFockBogoliubov (PHFB) and Interacting Boson Model (IBM2) used in the literature and the reliability of the matrix elements in these approaches are reviewed. In the second part it is investigated how one can determine the leading mechanism or mechanisms from the data of the 0νββ decay in different nuclei. Explicit expressions are given for the transition matrix elements. It is shown that possible interference terms allow to test CP (Charge and Parity conjugation) violation.
Madelung Fluid Description of a Coupled System of Derivative NLS Equations D. Grecu, A.T. Grecu, Anca Visinescu Romanian Journal of Physics 57,
180191 (2012)
A system of coupled derivative NLS equations is discussed using a Madelung's fluid description. The system is the matrix generalization of the completely integrable derivative NLS equation of ChenLeeLiu. For an arbitrary nonlinearity of the form $\beta \left(\vert\Psi_{1}\vert^{2}+\vert\Psi_{2}\vert^{2}\right)^{q}\;\Psi_{j}$ the bright solitary wave solution is obtained. For the integrable case ($q=1$) the periodic solutions, expressed through Jacobi elliptic functions, are found. When $k^2=1$ ($k$  the modulus of the elliptic function) various shifted bright, gray and dark solutions are obtained as limit cases of the previous periodic solutions.
Gravitational Interaction of YangMills Fields from FreeField Cohomology D. R. Grigore, G. Scharf Romanian Journal of Physics 57,
192204 (2012)
Using cohomological methods we determine the most general form of the interaction between the gravitational field and an arbitrary system of YangMills fields (massless and massive). We solve the corresponding descent equations and obtain the first order chronological product (interaction Lagrangian). Surprisingly enough we find that gravitational ghost and YangMills antighost fields appear in the coupling in the massive YangMills case.
A Demonstration for the Statistical Normal Distribution of Experimental Results E. L. Grigorescu Romanian Journal of Physics 57,
205213 (2012)
The demonstration is based on one side on the well known Bell Type shape of the experimental results, for a variable $X$, with continuous variation. In this case the distribution is represented by the “density of probability”, $f(x)$. The demonstration considers also the classical statistical characterization of each distribution by the normalization condition and by the calculus of dispersion D. These two considerations impose for $f(x)$ in a logic way, five conditions, as it follows: 1. $f(x)$ must depend only on even powers of the deviations from the mean $m$, $t = x – m$; $f(t)$ is resulting 2. $f(t)$ and its derivative must tend to zero for $t$ tending to $\pm\infty$ 3. the derivative must be annulated for $t = m$ 4. $f(t)$ must have no more than two parameters 5. the two integrals which appear in the normalization condition and the calculus of dispersion must have analytical solutions from which the two parameters could be determined. The 5th condition is the most restrictive: For conditions 2 and 4 and (0, +∞) interval, the elementary algebra offers two simple formulae, the exponential and the Lorentz type. Starting from them and fulfilling the conditions 1 to 4, for the (∞, +∞) interval, two types of more complex formulae for $f(t)$ of general form are considered for analysis $$f_1(t) = a e^{b P_1(t)}, \qquad f_2(t)=\frac{1}{c+dP_2(t)},$$ with $P_1$, $P_2$ as polynomials. Condition 5 restricts $f_1(t)$ at $a e^{−bt^2}$ And so, the famous formula is obtained: $f ( t ) = \frac{1}{\sigma\sqrt{2\pi}} e^{\frac{t^2}{2\sigma^2}}$. The f2(t) is not a solution. The combinations as $[(f_1(t) \pm f2(t)]$ or $[f_1(t) f_2(t)]$ do not fulfill the $5^{\mathrm{th}}$ condition. However the ratio $[f_1(t) /f_2(t)]$ in the form $a (1 + t^2)e^{−bt^2}$ is a solution! The demonstration is based on experiment! This demonstration has no mathematical approximations unlike some previous demonstrations from literature.
Study of Superheavy Nuclei at Ship S. Hofmann Romanian Journal of Physics 57,
214226 (2012)
The outstanding aim of experimental investigations is the exploration of the region of spherical 'SuperHeavy Nuclei' predicted to be located at proton numbers 114, 120 or 126 and at neutron number 184. Experimental methods have been developed which allowed for the identification of new elements at production rates of one atom per month. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutrondeficient isotopes of the elements from 107 to 113 were synthesized at GSI in Darmstadt, Germany, and/or at RIKEN in Wako, Japan. In hot fusion reactions of $^{48}$Ca projectiles with actinide targets more neutron rich isotopes of the elements from 112 to 118 were produced at FLNR in Dubna, Russia. Recently, part of these data which represent the first identification of nuclei located on the predicted island of SHEs were confirmed in independent experiments. The decay data reveal that for the heaviest elements, the dominant decay mode is $\alpha$ emission, not fission. Decay properties as well as reaction crosssections are compared with results of theoretical studies.
Coexistence of Cluster and MeanField Dynamics and Duality of ManyNucleon Wave Function Hisashi Horiuchi Romanian Journal of Physics 57,
227246 (2012)
Although cluster states are very different from meanfieldtype states, there is an important link between these different states. It is the duality of wave functions of ground states and some excited states which have both clustering and meanfieldtype characters. The duality is clearly seen in observed large monopole transitions between cluster states and ground state. The existence of cluster states in addition to meanfieldtype states can be said to be an inevitable consequence of the duality of the ground state. We demonstrate this fact by the AMD reproduction of tremendously many observables up to $^{44}$Ti. The duality of the ground state can also be seen in nuclear reactions. We also discuss that the duality of the nuclear wave function is important for understanding clustergas states and the liquidgas phase transition, by utilizing the results of AMD calculation of nuclear caloric curves.
SuperČerenkov Radiations in Dielectric, Nuclear and Subnuclear Media D.B. Ion, M.L.D. Ion Romanian Journal of Physics 57,
247261 (2012)
SuperČerenkov Radiations (SČR), as well as the SČRsignatures in dense media are reviewed. Two general SČR coherence conditions as two natural extremes of the same spontaneous particles in (dielectric, nuclear and hadronic) media are underlined. The main results on the quantum theory of the SČR exotic decays as well as the results of the first experimental test of the supercoherence conditions, and also a test of the anomalous Čerenkov rings, obtained by using the experimental data from BNL and CERN, respectively, are presented.
Evolution of Continuous Variable Correlations in Open Quantum Systems Aurelian Isar Romanian Journal of Physics 57,
262274 (2012)
In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we give a description of the continuous variable quantum entanglement and quantum discord for a system consisting of two noninteracting modes embedded in a thermal environment. We describe the evolution of entanglement in terms of the covariance matrix for Gaussian input states. For all values of the temperature of the thermal reservoir, an initial separable unimodal squeezed state and a squeezed thermal state remain separable for all times. We study the time evolution of logarithmic negativity, which characterizes the degree of entanglement, and show that in the case of an entangled initial squeezed vacuum state and a squeezed thermal state, entanglement suppression (entanglement sudden death) takes place, for nonzero temperatures of the environment. Only for a zero temperature of the thermal bath the initial entangled squeezed state remains entangled for finite times. Independent of its type – separable or entangled, the initial state evolves asymptotically to an equilibrium state which is always separable. We analyze the time evolution of the Gaussian quantum discord, which is a measure of all quantum correlations in the bipartite state, including entanglement, and show that quantum discord decays asymptotically in time under the effect of the thermal bath. Before the suppression of the entanglement, the qualitative evolution of quantum discord is very similar to that of the entanglement. We describe also the time evolution of the degree of classical correlations and of quantum mutual information, which measures the total correlations of the quantum system.
ContextDependent Quadrature Rules. A Way to Improve the Quality of Scientific Codes L. Gr. Ixaru Romanian Journal of Physics 57,
275287 (2012)
We show how the exponential fitting technique can be used for building up quadrature rules of prerequisite forms and with constant coefficients. This includes forms where not only the values of the integrand are accepted in input, as in standard formulas, but also the values of some derivatives of the integrand. The new rules are of substantial help in practical computations because quite often such extra data are available from the previous steps of the computation chain but they are ignored when evaluating integrals. We also give a numerical illustration which clearly demonstrates the accuracy gain to be obtained from the new rules.
Particle–core Coupling Model Approach to Structure of the Low–Lying States of ^{11}B and the Effect of the Pauli Blocking R. V. Jolos, P. von Brentano Romanian Journal of Physics 57,
288295 (2012)
The particlecore coupling model with a restricted configurational space containing only $0^+_1$ and $2^+_1$ states is applied to describe the lowlying states of $^{11}$B. Using only one parameter, a mixing coefficient for the ground state wave function, twelve observables, for which there are known the experimental data, are successfully described. It indicates on the simple correlation relations between data. It is shown that the Pauli blocking effect influences very strongly on the properties of the $7/2^_1$ state of $^{11}$B.
Duality of s and tChannel Exchange in NucleonNucleon Scattering M. I. Krivoruchenko, Amand Faessler Romanian Journal of Physics 57,
296308 (2012)
We specify conditions under which the nucleonnucleon interaction, based on the $t$channel mesonexchange mechanism, is equivalent to an interaction generated through an $s$channel exchange of sixquark bags. The duality is possible provided the alternation of zeros and poles of the nondispersive part of $D$ function takes place in the normalization where the imaginary part of $D$ is nonnegative and the CDD poles are the only poles of $D$.
Nuclear Structures of the NeutronRich Nuclei Around A=120 Y.X. Luo, S.H. Liu, J.H. Hamilton, A.V. Ramayya, J.O. Rasmussen, J.K. Hwang, N.T. Brewer, S.J. Zhu Romanian Journal of Physics 57,
309329 (2012)
Analysis of high statistics triple coincidence fission γ data from ^{252}Cf at Gammasphere including angular correlations yielded wellexpanded highspin level schemes with more complete and reliable spin/parity assignments for ^{118,120,122}Cd and ^{114,115}Rh. Both the quasiparticle/hole couplings and quasirotational degrees of freedom are implied to play roles in these Cd isotopes. Evidence for triaxial shapes and octupole components in the Cd isotopes is presented. These Cd isotopes may have triaxial deformations implied by the Frauendorf SCTAC model calculations. Highspin level schemes of ^{114,115}Rh have been established for the ﬁrst time. The existence of a relatively large signature splitting and an yrare band shows typical features of a triaxially deformed nucleus. This paper is dedicated to our longtime colleague Prof. Aureliu Săndulescu on the occasion of his 80^{th} birthday.
On the Relativistic FieldTheoretical Three Dimensional Equations for the Coupled Nd3N Systems with and without QuarkGluon Degrees of Freedom A. I. Machavariani Romanian Journal of Physics 57,
330351 (2012)
The new relativistic threebody equations for the amplitude of the coupled nucleondeuteron $\Longleftrightarrow$ three nucleon $(Nd \Longleftrightarrow 3N)$ reactions are suggested within the standard fieldtheoretical $S$matrix approach. The suggested equations have the form of the threebody timeordered and three dimensional LippmannSchwinger or Schr\"odinger equations for the connected part of the threebody amplitudes. These relativistic equations allow to construct the complete set of the threebody forces. The form the suggested equations and their potentials is not dependent on the choice of the Lagrangian. Moreover, in the fieldtheoretical formulation with and without quarkgluon degrees of freedom the corresponding twobody and threebody equations and potentials have the same form. The considered fieldtheoretical equations are three dimensional from the beginning and the potential of these equations can be constructed from the onevariable vertex functions. Moreover, these equations satisfy automatically the unitarity and causality conditions even after truncation of multiparticle intermediate states. Therefore, the considered formulation s free of the principal ambiguities which appear in the 4D BetheSalpeter equations and their 3D quasipotential reductions.
Linear and Nonlinear Light Bullets: Recent Theoretical and Experimental Studies D. Mihalache Romanian Journal of Physics 57,
352371 (2012)
I provide a brief overview of recent theoretical and experimental studies of unique spatiotemporal dynamics of linear and nonlinear light bullets in a variety of relevant physical settings.
Superasymmetric Fission Valley in the ^{238}Pu Potential Landscape M. Mirea Romanian Journal of Physics 57,
372379 (2012)
A superasymmetric fission trajectory for the emission of $^{32}$Si from $^{238}$Pu is determined by using the minimal action principle. The deformation energy is computed in the frame of the macroscopicmicroscopic approach while the inertia is obtained within the cranking approximation. The nuclear shape parametrization takes into account five degrees of freedom associated to the elongation, necking, mass asymmetry and deformations of nascent fragments. The single particle energies and the nucleon wave functions are obtained within the superasymmetric WoodsSaxon two center shell model. Our calculations confirm that the cluster decay follows a potential magic valley, starting from the ground state of the parent and reaching a configuration of two touching nuclei at scission.
GroundState Correlations and Structure of the LowLying States in OddEven Spherical and Transitional Nuclei S. Mishev, V.V. Voronov Romanian Journal of Physics 57,
380398 (2012)
The influence of the Pauli principle and the nucleon correlations in the ground states of spherical and transitional eveneven nuclei on the structure of the lowlying states in oddeven nuclei is examined. We study correlations caused by the quasiparticlephonon interaction in the ground state beyond the pairing correlations. The effects owing to the groundstate correlations (GSC) are becoming essential as the number of nucleons in the unclosed shells increase. We reason about this subject using the language of the quasiparticle phonon model which we extend to account for the existence of quasiparticle×phonon configurations in the ground states of the eveneven cores.
Discoveries with Cold HeavyIon Fusion and Shell Stabilised Nuclei Around Hassium G. Münzenberg, M.Gupta Romanian Journal of Physics 57,
399406 (2012)
Cold fusion, using reactions with the doubly magic nucleus ^{208}Pb and its neighbor ^{209}Bi, have lead to the discovery of the shell stabilized nuclei around ^{270}Hs paving the way to the artificial synthesis of superheavy nuclei. In this paper we present a brief history of the discoveries and their importance to the production and investigation of superheavy elements.
New Formula of HalfLives for Proton Emission from Spherical and Deformed Nuclei Dongdong Ni, Zhongzhou Ren Romanian Journal of Physics 57,
407418 (2012)
A unified formula of halflives for $\alpha$ decay and cluster radioactivity has been proposed [Ni, Ren et al., Phys. Rev. C 78, 044310 (2008)]. In this work, a similar formula is proposed for determining halflives of proton emission. This new formula contains the dependence on the centrifugal barrier and the structure of the daughter nucleus. It not only well reproduces the experimental halflives of spherical emitters but also shows excellent agreement with the experimental data of deformed emitters. Moreover, we use it to simultaneously describe the data of spherical and deformed emitters. The agreement between the theoretical values and the experimental data is also reasonably good. The aim of this work is not only to reproduce the experimental data better, but also to achieve a unified description of proton emission, $\alpha$ decay, and cluster radioactivity. The new formula has the form very similar to that for $\alpha$ decay and cluster radioactivity, and the values of three sets of parameters respectively describing proton emission, $\alpha$ decay, and cluster radioactivity are close to each other. This indicates that we have reached a unified law for proton emission, $\alpha$ decay, and cluster radioactivity.
Collective Phenomena in Heavy Ion Collisions M. Petrovici, A. Pop Romanian Journal of Physics 57,
419430 (2012)
A review of the main results of detailed flow analysis in highly central and semicentral heavy ion collisions at SIS energies is presented in the first part of this paper. The influence of the mass of the colliding nuclei and centrality on the collective expansion and the information on the equation of state of compressed and hot baryonic matter is discussed. The second part is dedicated to a similar type of analysis, based on the behavior of the average transverse momentum as a function of mass of different hadrons, at the other extreme of energy range, where free baryonic fireballs are produced. Information on the partonic and hadronic expansion, temperature and degree of thermal equilibrium in p+p and Au+Au central collisions at 200 A·GeV is presented.
Metallic Atomic Clusters D. N. Poenaru, R. A. Gherghescu, W. Greiner Romanian Journal of Physics 57,
431441 (2012)
The nuclear liquid drop model and the the shell correction method, have been adapted for neutral and charged atomic clusters. We used the macroscopicmicroscopic method to investigate neutral hemispheroidal atomic clusters deposited on a surface.The electrostatic energy of charged metallic clusters is studied for hemispheroidal and cylindrical shapes. The maximum value of Coulomb energy of a Na$_{54}^{2+}$ cluster takes place at a superdeformed prolate shape. A finite value of the electric charge makes the cluster less stable and decreases the value of equilibrium deformation. The most important yield in fission of charged metallic clusters is usually obtained when the light fragment is a singly charged trimer, the analog of an $\alpha$particle with magic number of delocalized electrons $n_e=2$. In this case both the shell corrections and the LDM deformation energy have minima at the same mass asymmetry which corresponds to the trimer emission.
FRpnQRPA Approach with the Gauge Symmetry Restored. Application for the 2νββ Decay A.A. Raduta Romanian Journal of Physics 57,
442471 (2012)
A many body Hamiltonian involving the mean field for a projected spherical single particle basis, the pairing interactions for alike nucleons, a repulsive dipoledipole protonneutron interaction in the particlehole ($ph$) channel and an attractive dipolepairing interaction is treated by a gauge restored and fully renormalized protonneutron quasiparticle random phase approximation ($GRFRpnQRPA$) formalism. The resulting wave functions and energies for the mother and the daughter nuclei are used to calculate the $2\nu\beta\beta$ decay rate and the process half life for the emitters: $^{48}$Ca, $^{76}$Ge, $^{82}$Se, $^{96}$Zr, $^{100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{116}$Cd, $^{128,130}$Te, $^{148,150}$Nd, $^{154}$Sm, and $^{160}$Gd. The results of our calculations are compared with the corresponding experimental data as well as with those obtained through other methods. The Ikeda sum rule ($ISR$) is obeyed.
Information about HighEnergy Hadronic Interaction Processes from Extensive Air Shower Observations H. Rebel, O. Sima Romanian Journal of Physics 57,
472492 (2012)
Extensive air showers (EAS) induced by collisions of primary cosmic particles with atoms of the Earth´s atmosphere are a playground for studies of the highenergy hadronic interaction. The hadronic interaction is subject of various uncertainties and debates, in particular in energy regimes which exceed the energies of manmade accelerators and the knowledge from collider experiments. The EAS development is dominantly governed by soft processes which are not accessible to perturbative QCD. Thus one has to rely on QCD inspired phenomenological interaction models like string models, based on the GribovRegge theory. In the present paper the role of EAS observations is illustrated with respect of their information about salient features and tests of various highenergy interaction models, being en vogue as generators for Monte Carlo EAS simulations. The constraints expected from data of the Large Hadron Collider are briefly commented.
AlphaDecay Data of Superheavy Nuclei as a Source of Information about Nuclear States I. Silişteanu, A. I. Budaca Romanian Journal of Physics 57,
493505 (2012)
Two different descriptions of $\alpha$decay rates, namely, microscopic shellmodel approach and phenomenological description are emphasized to study the structure and dynamics of heaviest nuclei. On the structure side, improvements to nuclear models are being explored to take more accurately into account the role of the shell and pairing effects and importance of excitation and deformation. The accuracy of available experimental halflives is discussed and a spectroscopic information is derived from the ratio of theoretical to experimental results. The universality of GeigerNuttall law in nuclei is illustrated within the framework of Brown systematics, $\log T_{\alpha}$ vs. $Z_{d}^{(0.6)}Q_{\alpha}^{1/2}$. This paper will present some of recent results in both structure and reaction studies, and will focus on the issues currently of interest along with possible directions for future experimental and theoretical advances in $\alpha$decay properties.
Description and Predictions of the Properties of Superheavy Nuclei A. Sobiczewski Romanian Journal of Physics 57,
506512 (2012)
A short review of the studies of superheavy nuclei (SHN), done recently in our theoretical group of Warsaw, is presented. Main attention is given to description of the decay properties of SHN. The description is performed with the use of our macroscopicmicroscopic model. Such properties as mass, $\alpha$decay energy and $\alpha$decay halflife are considered. Tests of the model done by a comparison of its results with the experimental ones and with results of other (semiempirical) model are illustrated. After also testing the predictive power of the model, it is used to predict properties of notyetobserved isotopes of the element 120 and their decay products.
Applications of a SemiMicroscopic Cluster Model for Astrophysical Processes H. YépezMartínez, P. R. Fraser, P. O. Hess Romanian Journal of Physics 57,
513542 (2012)
The Semimicroscopic Algebraic Cluster Model (SACM) is applied to the twocluster systems $^{14}$C+$\alpha$ and $^{20}$Ne+$\alpha$, which are of astrophysical interest. The parameters of this algebraic model are adjusted to experimental data, being eigenenergies and $B(E2)$ values. After that, sole $B(M1)$ values and $\alpha$spectroscopic factors are calculated. The last represent a prediction of this model. Also the geometrical mapping of the SACM is shortly reviewed. The geometric potential, as a function of the coherent state parameter $\alpha$ is constructed. The minimum of the potential shows the position of the systems in the phase space diagram.
