Nuclear shell model

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Sc and 4546 Ca, 4546 and B (E2) for sCalculation of Energy Level Ti by Using Nuclear Shell Model Code OXBASH 4546

Sc and 4546 Ca, 4546 and B (E2) for sCalculation of Energy Level Ti by Using Nuclear Shell Model Code OXBASH 4546

nuclear shell model. For light nuclei, there are several “standard” effective interactions such as the Cohen-Kurath [3] and the USD [4] interactions for the p and sd shells, respectively. On the other hand, in the next major shell, i.e., in the f7-shell, there are also “standard” interaction such as f748pn [5].The spectroscopy of nuclei, in the f7-shell region, has been well described within the shell model framework. The best example for using several model spaces and two-body interactions is that of Brown et al, which is the most remarkable work in this field [6,7]. The starting point in all such shell-model calculations is the derivation of an effective interaction owing to the fact that the f7-shell is the most important for a variety of problems in nuclear structure such as electron capture in supernova explosions. In this work, the shell model calculations are carried out in the f7-shell region for the isotopes 46- 45 Ca, 46-45 Ti and 46-45 Sc, to test the ability of the present effective interactions in reproducing the experiment in this mass region.
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Spectral Fluctuations in A=32 Nuclei Using the Framework of the Nuclear Shell Model

Spectral Fluctuations in A=32 Nuclei Using the Framework of the Nuclear Shell Model

The fluctuation properties of nuclear energy spectrum are obtained via two statistical measures: the nearest-neighbors level spacing distribution P s ( ) and the Dyson-Mehta or ∆ 3 statistics [4, 24]. The staircase function of the nuclear shell model spectrum N E ( ) is firstly build. Here, N E ( ) is defined as the number of levels with excitation energies less than or equal to E . In this study, a smooth fit to the staircase function is performed with polynomial fit. The unfolded spectrum is then defined by the mapping [12]
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Stochastic estimation of level density in nuclear shell-model calculations

Stochastic estimation of level density in nuclear shell-model calculations

Nuclear shell-model calculation is one of the most powerful theoretical frameworks to evaluate the level density. However, the rapid growth in the dimension of the shell-model Hamiltonian matrix remains an inevitable obstacle. An efficient numerical method to solve the eigenvalue problem of the huge sparse matrix and to estimate its eigenvalue distribution has been demanded. Much effort has been paid to develop efficient methods to estimate nuclear level densities based on shell model, e.g. the shell model Monte Carlo (SMMC) [3], the moment-based methods [4, 5], and the Lanczos-based method [6]. In this proceedings, we review stochastic estimation of the eigenvalue distribution based on shifted Krylov-subspace method [7] and its application to nuclear shell model calculations [8]. We also discuss its validity and feasibility.
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Calculation of Energy Levels and B(E2) for 20Ne Isotope by Using Nuclear Shell Model

Calculation of Energy Levels and B(E2) for 20Ne Isotope by Using Nuclear Shell Model

Abstract- In this study, the energy levels and the probability of electric transition B(E2) of the 20Ne nucleus were calculated using the OXBASH code within the sd shell and the use of the effective interaction KUOSD. OXBASH is a computing code to perform a nuclear installation calculation based on a shell mode, Energy levels and the probability of electric transition is acceptable agreement with available experimental data.

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Energy Levels Calculations of 32Cl and 33Cl Isotopes

Energy Levels Calculations of 32Cl and 33Cl Isotopes

In order to calculate the nuclear structure properties of both ground and excited states based on the nuclear shell model one needs to have wave functions of those states. These wave functions are obtained by using the shell-model code OXBASH[4].The code OXBASH for Windows has been used to calculate the nuclear structure for Chlorine nucleus, by employing the SD (independent charges) and SDPN (depending charges) model space with three effective interactions[4]. The first interaction for the lower part of the SD-shell is Chung-Wildenthal particle interaction (CW), secondly, the Universal SD-shell Hamiltonian (USD interaction). In the third interaction the New Universal SD- shell Hamiltonian (USDAPN) is used [4]. Richter et a1[5] used this shell model successfully in the p-shell, and fp-shell [6], [7] and Wildenthal [8] and Brown et al[9] in the SD-shell to describe the systematics observed in the spectra and transition strengths.In the present work, we focus our attention on the description of energy levels of SD shell of Chlorine isotopes 32 Cl and 33 Cl which have configurations 0d 5/2 , 1s 1/2 and 0d 3/2 .
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Energy Levels Calculations of 29S, 30S and 31S Isotopes

Energy Levels Calculations of 29S, 30S and 31S Isotopes

The nuclear shell model has been very successful in our understanding of nuclear structure: once a suitable effective interaction is found, the shell model can predict various observables accurately and systematically. For light nuclei, there are several “standard” effective interactions such as the Cohen-Kurath [1] and the USD [2] interactions for the p and SD shells, respectively. Analysis of neutron-rich SD nuclei has been of intense curiosity in recent years as they present new aspects of nuclear structure [3].Traditional shell-model studies have recently received a renewed interest through large scale shell-model computing in no-core calculations for light nuclei, the 1s0d shell, the 1p0f shell and the 3s2d1g 7/2
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Procedural benchmarks for common fabrication details in plate/shell structures

Procedural benchmarks for common fabrication details in plate/shell structures

This section provides sample solutions for the Reinforcement Plate benchmark E&D2. This benchmark has some commonality with benchmarks E&D1 and E&D3 in that they all include a weld detail (albeit a different weld detail). However, the main object of this benchmark is to examine the issues relating to reinforcing or spreader plates. In a plate/shell fabrication, such plates are typically only connected to the main plate around the periphery. When the designer wants to ensure a higher degree of connectivity, then spot or puddle welds may be specified. Since such detail is common in large fabricated structures, where a ‘solid’ idealisation is often impractical, the goal is to examine the issues relating to shell modelling. The highly refined ‘solid of revolution’ idealisation, in turn, provides a comparison for the shell results. This idealisation does not involve the assumptions inherent in shell theory and can model geometry to a higher degree of accuracy and reproduce non-linear through- thickness stress distributions where they exist. The aim here is to provide a wider educational reference for analysts and engineers working in this general area.
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Interactions and decays of high-spin baryon resonances

Interactions and decays of high-spin baryon resonances

this can be attributed to the role of the Σ(2030). When combined with the other terms, the double-bump structure appeared in the model of Ref. [17] is now absent as shown by the solid lines in Fig. 5(a). This leads us to conclude that the double-bump structure is an artifact of the previous model and that the Σ(2030) of J P = 7 2 + has a key role to make the model predictions to be in a fair agreement with the data. As expected, the contribution from the Σ(2030)7/2 + resonance can hardly be seen at low energies with E γ ≤ 3.2 GeV. Therefore, the results of the present model are very similar to those of
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Realistic shell model and nuclei around 132Sn

Realistic shell model and nuclei around 132Sn

Nuclei around 132 Sn represent a crucial opportunity to investigate the evolution of the shell structure around a heavy, neutron rich doubly-closed shell nucleus far-o ff stability. In the light- and medium-mass regions, struc- tural changes have been evidenced for nuclei with a large excess of neutrons, leading to the breakdown of the tra- ditional magic numbers and the appearance of new ones. These findings have driven a great theoretical e ff ort to un- derstand the microscopic mechanism underlying the shell evolution, with special attention to the role of the di ff erent components of the nuclear force (see, for instance, [5]). It is of great interest to verify if peculiar properties, as those observed in lighter nuclei, may be also observed in the 132 Sn region.
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Realistic shell model description of beta decay

Realistic shell model description of beta decay

A valuable tool to address this problem is given by the realistic shell model (SM) [8, 9]. Within this approach, the SM Hamiltonian and the transition operators are derived from a realistic free nuclear potential by way of many- body perturbation theory on the same footing. In this way, one can account for renormalization effects induced by missing correlations in the nuclear wave functions as re- sulting from truncations of the Hilbert space.

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Polyhedral symmetry and quantum mechanics

Polyhedral symmetry and quantum mechanics

A thorough study of regular and quasi-regular polyhedra shows that the symmetries of these polyhedra identically describe the quantization of orbital angular momentum, of spin, and of to- tal angular momentum, a fact which permits one to assign quantum states at the vertices of these polyhedra assumed as the average particle po- sitions. Furthermore, if the particles are fermions, their wave function is anti-symmetric and its ma- xima are identically the same as those of repul- sive particles, e.g., on a sphere like the spherical shape of closed shells, which implies equilibrium of these particles having average positions at the aforementioned maxima. Such equilibria on a sphere are solely satisfied at the vertices of re- gular and quasi-regular polyhedra which can be associated with the most probable forms of shells both in Nuclear Physics and in Atomic Cluster Physics when the constituent atoms possess half integer spins. If the average sizes of the constituent particles are known, then the average sizes of the resulting shells become known as well. This association of Symmetry with Quantum Mechanics leads to many applica- tions and excellent results.
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Structural analysis of roof slab for proto type fast breeder reactor

Structural analysis of roof slab for proto type fast breeder reactor

A full 3-D finite element modeling of roof has been generated using the ABAQUS FE software employing 8-node shell element. Due to thermal loading (linear axial thermal gradient), slope and deflection analysis of top shield has been carried out. The slope at control plug support flange, LRP support-nearest to axis of top roof slab, LRP support-farthest to axis of top roof slab and LRP support are within allowable limit. The mass of concrete shielding of roof slab is lumped on bottom plate. The masses of IHX, pump DND, IFTM etc. are lumped at their respective support flanges. Seismic analysis has been carried out by response spectra method for OBE & SSE. The maximum stress is found in the stiffeners. The stresses and deflections due to self weight and seismic load are within the allowable limits.
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Shell-model calculations for upper pf-shell nuclei with an effective interaction

Shell-model calculations for upper pf-shell nuclei with an effective interaction

goodness of the symmetries were compared with those ob- tained in the past using another effective interaction while the advantages over them were pointed out as well as the way some previous obstacles were overcome by using the current interaction. Finally, we commented on the possi- bility to make a generalization of a well-known approach for calculations in a mixed-symmetry basis to be applied in case of competing pairing and quadrupole modes (with the possibility of multi-mode further expansion). The goal of this future plan is that with its development we will accel- erate the rate of convergence of our calculations compared to the use of only one of the bases. Thus, we may be able to also address the multi-shell calculations for these nuclei where the use of symmetries becomes crucial.
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Quantum Isomorphic Shell Model: Multi Harmonic  Shell Clustering of Nuclei

Quantum Isomorphic Shell Model: Multi Harmonic Shell Clustering of Nuclei

a) The fermionic nature of nucleons, due to their anti- symmetric wave function, makes them behave as if a repulsive force (of unknown nature) is acting among them. [1]. This repulsive property of nucleons is derived not only by this antisymmetrization, but also by the re- pulsive character of the nuclear force itself, considered as a result of the quark structure of the nucleons. The exis- tence of this force shifts the nuclear many-body problem to the problem of finding the equilibria of repulsive par- ticles on a sphere, like the sphere of a nuclear shell. Ac- cording to [2], such equilibria are possible only for spe- cific numbers of particles and when these particles have most probable positions at the vertices, or middles of faces, or middles of edges, or simultaneously at these characteristic points of regular polyhedra or their deriva- tive polyhedra. Such polyhedra in the present model stand for the most probable forms of nuclear shells which - taken in specific sequence, as we will see below – pre- cisely reproduce the nuclear magic numbers, with no use
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Model studies of timber shell roofs

Model studies of timber shell roofs

DATA FROM TESTS ON MODEL SHELlS TABLE 01 SHEll 1, NAIL-GlUED APP-ROX... LOAD CELL LOAD I NOS LOS NE Sf:' SW.[r]

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Effective nuclear interactions and level properties for the lighter nuclei in the 1p-shell

Effective nuclear interactions and level properties for the lighter nuclei in the 1p-shell

Be at excitation energies of about 10 MeV. Other levels with very large a-particle widths should occur at higher excitation energies, but because they are expected to belong to configurations very different from the lowest shell model configuration, they should have small reduced widths for the other lowest-lying particle channels. Thus these levels should contribute to the general trend of the real part of the a+a phase shifts even when other channels are open, while the

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Morgan, Thomas James
  

(2008):


	Identification of Nilsson Orbitals in the Superdeformed Minimum of 237Pu.


Dissertation, LMU München: Fakultät für Physik

Morgan, Thomas James (2008): Identification of Nilsson Orbitals in the Superdeformed Minimum of 237Pu. Dissertation, LMU München: Fakultät für Physik

inexplicable how an excited state at 3.15 MeV and a lifetime of 0.1 ms could remain stable with respect to γ decay. The first explanation was that these states were metastable high - spin states with spin values larger than 20 ¯ h. Measurements by Flerov et al. [FLE68] showed no increase in isomeric yield when using heavy ions instead of light projectiles in order to increase the trans- fered spin in the reaction, thereby excluding such high - spin states. The consistent theoretical interpretation of these states was given in a series of studies by Strutinsky [STR67, STR68]. In the picture outlined there, these fission isomers result from a second deformed minimum which arises from a superposition of microscopic shell corrections on top of the rather unstructured macroscopic part of the deformation energy described by the liquid drop model. This scenario is illustrated in Fig. 1.1, where the potential energy curve as a function of the nuclear deformation is shown for the case of 237 Pu studied within the present work. Strutinsky therefore concluded
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PeriodicTrendsnotes.pdf

PeriodicTrendsnotes.pdf

Going across a period leads to a larger nuclear charge, as the number of protons increases. There is also an increase in the number of valence electrons, but electrons in the same shell are poor at shielding each other. Going across a row generally leads to a stronger interaction between the nucleus and the

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Translational invariant shell model for Λ hypernuclei

Translational invariant shell model for Λ hypernuclei

Dalitz and Levi Setti, [32], fifty years ago, discussed the possibility that Λ hyperons could stabilize particle- unstable nuclear cores of Λ hypernuclei and thus allow studies of neutron rich baryonic systems beyond the nu- clear drip line. The Λ’s effectiveness to enhance binding is primarily connected with the Pauli principle from which it is exempt allowing it to occupy the lowest 0s Λ orbital. Several unbound-core Λ hypernuclei have been identified in emulsion work, [33], see Table 3.

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Importance of Shear Deformation Theory in Nuclear Containment Design

Importance of Shear Deformation Theory in Nuclear Containment Design

Recently, several studies in limited scope have been conducted to establish the importance of the shell theory considering shear deformation in the design of nuclear containments subjected to static loads [1]. However, very few studies with dynamic loads have been undertaken. The purpose of this research is to conduct a systematic study to understand the importance of shell theory in the design of containments subjected to both static and dynamic loads.

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