Search for long lived heaviest nuclei beyond the valley of stability

The existence of long lived superheavy nuclei (SHN) is controlled mainly by spontaneous fission and $\alpha$-decay processes. According to microscopic nuclear theory, spherical shell effects at Z=114, 120, 126 and N=184 provide the extra stability to such SHN to have long enough lifetime to be observed. To investigate whether the so-called "stability island" could really exist around the above Z, N values, the $\alpha$-decay half lives along with the spontaneous fission and $\beta$-decay half lives of such nuclei are studied. The $\alpha$-decay half lives of SHN with Z=102-120 are calculated in a quantum tunneling model with DDM3Y effective nuclear interaction using $Q_\alpha$ values from three different mass formulae prescribed by Koura, Uno, Tachibana, Yamada (KUTY), Myers, Swiatecki (MS) and Muntian, Hofmann, Patyk, Sobiczewski (MMM). Calculation of spontaneous fission (SF) half lives for the same SHN are carried out using a phenomenological formula and compared with SF half lives predicted by Smolanczuk {\it et al}. Possible source of discrepancy between the calculated $\alpha$-decay half lives of some nuclei and the experimental data of GSI, JINR-FLNR, RIKEN are discussed. In the region of Z=106-108 with N$\sim$ 160-164, the $\beta$-stable SHN $^{268}_{106}Sg_{162}$ is predicted to have highest $\alpha$-decay half life ($T_\alpha \sim 3.2hrs$) using $Q_\alpha$ value from MMM. Interestingly, it is much greater than the recently measured $T_\alpha$ ($\sim 22s$) of deformed doubly magic $^{270}_{108}Hs_{162}$ nucleus. A few fission-survived long-lived SHN which are either $\beta$-stable or having large $\beta$-decay half lives are predicted to exist near $^{294}110_{184}$, $^{293}110_{183}$, $^{296}112_{184}$ and $^{298}114_{184}$. These nuclei might decay predominantly through $\alpha$-particle emission.Comment: 14 pages, 6 figures, 1 tabl

Alpha-decay properties of superheavy elements Z=113−125Z=113-125 in the relativistic mean-field theory with vector self-coupling of ω\omega meson

We have investigated properties of $\alpha$-decay chains of recently produced superheavy elements Z=115 and Z=113 using the new Lagrangian model NL-SV1 with inclusion of the vector self-coupling of $\omega$ meson in the framework of the relativistic mean-field theory. It is shown that the experimentally observed alpha-decay energies and half-lives are reproduced well by this Lagrangian model. Further calculations for the heavier elements with Z=117-125 show that these nuclei are superdeformed with a prolate shape in the ground state. A superdeformed shell-closure at Z=118 lends an additional binding and an extra stability to nuclei in this region. Consequently, it is predicted that the corresponding $Q_\alpha$ values provide $\alpha$-decay half-lives for heavier superheavy nuclei within the experimentally feasible conditions. The results are compared with those of macroscopic-microscopic approaches. A perspective of the difference in shell effects amongst various approaches is presented and its consequences on superheavy nuclei are discussed.Comment: Revised version, 14 pages, 12 eps figures. To appear in PRC. Discussion on shell effects is shortened in the revised version. However, commonality of the role of shell effects in extreme superheavy regions and in the regions near the r-process path is maintained. Existence of a secondary superdeformed minimum for Z=113 is verified with another Lagrangian se

Образ сім’ї в художній творчості дітей, позбавлених батьківського піклування

Problems of relations between children and parents have been represented in the article. The term of reluctant orphanhood was implemented in the beginning of XX century. This category refers to children who have parents but, despite this fact, they live on the street. Such problem is always very interesting for politics, sociology and pedagogics as young generation is the natural fund of the social development. The problem of lack of adequate procedures of the child’s personality study is considered to be very important in the modern society, especially for kids who are at the shelters. Special techniques, based on the natural activity, are used by foreign scientists to study individual child’s world, i.e. drawing. In our country, researchers have begun to pay more attention to drawing as a mean of getting knowledge about personality only during recent years. The drawing is the highly informative mean of learning the child’s personality. It shows how kids see themselves or others, their feelings and experiences. Drawing allows the researcher to give more attention to changes in the child’s emotional state and to distinguish the painting processes. The colour by itself can express certain feelings, moods and even describe emotional atmosphere of relations.The image of the family, interpersonal family relationships, values and behaviour are analysed on the basis of empirical material results of the drawing techniques’ use. The research has been conducted in the specialized shelter of Odessa. The main objective of the study is to identify the specifics of family images in the world picture of the orphan. Particular attention has been paid to the problems of emotional experience of the kids. The inner world of the kids with orphan status has been studied during the research. It has been found that the image of the family in the inner world of orphans has such characteristics, which are grounded on the content of life experience. During the research, it has been found out that the image of the family is presented in two opposite ways in children’s pictures. On the one hand, the image of the family is fragmented, characterized by complex interfamilial microclimates, which is typical for kid’s native real family. On the other hand, there is an idealistic image of the family which kid wants to have in future.В данной статье представлены проблемы взаимоотношений детей и родителей. В начале 90-х годов в украинской действительности появилось такое явление, как вынужденное сиротство. Это дети, имеющие родителей, но вынужденные жить вне своего дома. Данная проблема всегда вызывала особое внимание со стороны политиков, педагогов, социологов. И это вполне обосновано, поскольку молодое поколение является естественным резервом социального развития. Именно поэтому необходимость изучения представлений детей о своей (ориентационной) семье и будущей семье обуславливают актуальносaть представленного в данной статье исследования.У даній статті представлені проблеми взаємин дітей і батьків. На початку 90-х років в украінськый дійсності з’явилося таке явище, як вимушене сирітство. Це діти, які мають батьків, але змушені жити поза своєю домівкою. Дана проблема завжди викликала особливу увагу з боку політиків, педагогів, соціологів. І це цілком обгрунтовано, оскільки молоде покоління є природним резервом соціального розвитку. Саме тому необхідність вивчення уявлень дітей про свою (орієнтаційну) сім’ю і майбутню сім’ю обумовлюють актуальність представленого в даній статті дослідження

Alpha-decay chains of 173288115^{288}_{173}115 and 172287115^{287}_{172}115 in the Relativistic Mean Field theory

In the recent experiments designed to synthesize the element 115 in the $^{243}$Am+$^{48}$Ca reaction at Dubna in Russia, three similar decay chains consisting of five consecutive $\alpha$-decays, and another different decay chain of four consecutive $\alpha$-decays are detected, and the decay properties of these synthesized nuclei are claimed to be consistent with consecutive $\alpha$-decays originating from the parent isotopes of the new element 115, $^{288}115$ and $^{287}115$, respectively\cite{ogan.03}. Here in the present work, the recently developed deformed RMF+BCS method with a density-independent delta-function interaction in the pairing channel is applied to the analysis of these newly synthesized superheavy nuclei $^{288}115$, $^{287}115$, and their $\alpha$-decay daughter nuclei. The calculated $\alpha$-decay energies and half-lives agree well with the experimental values and with those of the macroscopic-microscopic FRDM+FY and YPE+WS models. In the mean field Lagrangian, the TMA parameter set is used. Particular emphasis is paid on the influence to both the ground-state properties and energy surfaces introduced by different treatments of pairing. Two different effective interactions in the particle-particle channel, i.e., the constant pairing and the density-independent delta-function interaction, together with the blocking effect are discussed in detail.Comment: 17 pages, 5 figure

Alpha decay chains study for the recently observed superheavy element Z=117 within the Isospin Cluster Model

The recently observed $\alpha$-decay chains $^{293-294}117$ were produced by the fusion reactions with target $^{249}Bk$ and projectile $^{48}Ca$ at Dubna in Russia. The reported cross-sections for the mentioned reaction are $\sigma=0.5(+1.1,-0.4)$pb and $\sigma$=1.3(+1.5,-0.6)$pb$ at $E^{*}=35MeV$ and $E^{*}=39MeV$, respectively. The Q-values of $\alpha$-decay and the half-lives $Log_{10}T^{\alpha}_{1/2}$(s) are calculated for the $\alpha$-decay chains of $^{293-294}117$ nuclei, within the framework of Isospin Cluster Model (ICM). In the ICM model the proximity energy is improved by using the isospin dependent radius of parent, daughter and alpha particle. The binding energy $B(A_{i}, Z_{i})$ (i=1,2) of any nucleus of mass number A and atomic number Z was obtained from a phenomenological and more genaralized BW formula given by \cite{samanta02}. The calculated results in ICM are compared with the experimental results and other theoretical Macro-Microscopic(M-M), RMF(with NL3 and SFU Gold forces parameter) model calculations. The estimated values of $\alpha$-decay half-lives are in good agreement with the recent data. The ICM calculation is in favor of the persence of magic number at N=172

Relativistic Energy Density Functional Description of Shape Transition in Superheavy Nuclei

Relativistic energy density functionals (REDF) provide a complete and accurate, global description of nuclear structure phenomena. A modern semi-empirical functional, adjusted to the nuclear matter equation of state and to empirical masses of deformed nuclei, is applied to studies of shapes of superheavy nuclei. The theoretical framework is tested in a comparison of calculated masses, quadrupole deformations, and potential energy barriers to available data on actinide isotopes. Self-consistent mean-field calculations predict a variety of spherical, axial and triaxial shapes of long-lived superheavy nuclei, and their alpha-decay energies and half-lives are compared to data. A microscopic, REDF-based, quadrupole collective Hamiltonian model is used to study the effect of explicit treatment of collective correlations in the calculation of Q{\alpha} values and half-lives.Comment: 23 pages, 10 figure

Superheavy nuclei with the vector self-coupling of the ω\omega-meson in the relativistic mean-field theory

We have studied properties and shell structure of the superheavy elements from Z=102 to Z=120 within the framework of the RMF theory. The region of study spans nuclides with neutron numbers N=150-190. The Lagrangian model NL-SV1 with the inclusion of the vector self-coupling of the omega-meson has been employed in this work. We have performed RMF + BCS calculations for an axially deformed configuration of nuclei. The ground-state binding energies, single-particle properties and quadrupole deformation of nuclei have been obtained from the mean-field minimizations. Two-neutron separation energies, $Q_\alpha$ values and alpha-decay half-life have been evaluated. It is shown that a large number of nuclides exhibit the phenomenon of shape-coexistence over a significant region of the superheavy elements. Shape coexistence of a prolate and an oblate shape is prevalent in nuclides far below N=184, whilst nuclei in the vicinity of N=184 tend to show a shape coexistence between a spherical and an oblate shape. The shell structure and 2-neutron separation energies obtained with the RMF theory reinforce the neutron number N=184 as a major magic number. It is shown that the neutron number N=172 acts akin to a magic number in the deformed region. It is suggested that the combination Z=120 and N=172 has the potential of being a doubly magic number in the superheavy region.Comment: 30 pages, 17 figures; Bibliography and citations corrected; To appear in J. Phys G: Nucl. Part. Phy

Relativistic mean field study of the properties of Z=117 nucleus and the decay chains of 293,294^{293,294}117 isotopes

We have calculated the binding energy, root-mean-square radius and quadrupole deformation parameter for the recently synthesized superheavy element Z=117, using the axially deformed relativistic mean field (RMF) model. The calculation is extended to various isotopes of Z=117 element, strarting from A=286 till A=310. We predict almost spherical structures in the ground state for almost all the isotopes. A shape transition appears at about A=292 from prolate to a oblate shape structures of Z=117 nucleus in our mean field approach. The most stable isotope (largest binding energy per nucleon) is found to be the $^{288}$117 nucleus. Also, the Q-value of $\alpha$-decay $Q_\alpha$ and the half-lives $T_{\alpha}$ are calculated for the $\alpha$-decay chains of $^{293}$117 and $^{294}$117, supporting the magic numbers at N=172 and/ or 184.Comment: 6 Pages and 8 Figure

Fission barriers in covariant density functional theory: extrapolation to superheavy nuclei

Systematic calculations of fission barriers allowing for triaxial deformation are performed for even-even superheavy nuclei with charge number $Z=112-120$ using three classes of covariant density functional models. The softness of nuclei in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers are considerably affected by triaxiality and octupole deformation. General trends of the evolution of the inner and the outer fission barrier heights are discussed as a function of the particle numbers.Comment: 24 pages, 8 tables, 12 figure

Deformation Energy Minima at Finite Mass Asymmetry

A very general saddle point nuclear shape may be found as a solution of an integro-differential equation without giving apriori any shape parametrization. By introducing phenomenological shell corrections one obtains minima of deformation energy for binary fission of parent nuclei at a finite (non-zero) mass asymmetry. Results are presented for reflection asymmetric saddle point shapes of thorium and uranium even-mass isotopes with A=226-238 and A=230-238 respectively.Comment: 5 pages, 2 Postscript figures, REVTeX, Version 4.