Searcharxiv⌕ Search

arXiv subjects

Arun Kingan

Publications and source records attributed to Arun Kingan.

9 recordsLinked to original sources
arXiv2020

Distribution of Magnetic Dipole Strength -Binning

In previous works we examined the systematics of magnetic dipole transitions in a single j shell. We here extend the study to large space calculations. We consider Ti and Cr isotopes.. In this work we focus on the B(M1) strength as a function of excitation of energy. The initial state is the lowest J= state. T=1 state in a specified nucleus. The final states are J=0 T=2 , all in one plot, and J=2 T=2 in another. The initial figures have points all over the map although there is a suggestion of an exponential trend. To reduce clutter we perform binning operations in which the summed strength in a given energy interval is represented by a single point. The new binning curves show more clearly the exponential fall of B(M1)'s with energy.

nucl-th↗
arXiv2018

Matrix Model of Strength Distribution: Extension and Phase Transition

In this work we extend a previous study of matrix models of strength distributions. We still retain the nearest neighbor coupling mode but we extend the values the coupling parameter v. We consider extremes, from very smal v to very large v. We first use the same transiiton operator as before \textless{}n T(n+1)\textgreater{} =constat(=1). For this case we get an exponential decreasefor small v but we get a phase transition beyond v=10. In that case we get an even-odd effect-separate exponentials for even n and for odd n. We now also consider also the dipole choice--where \textless{}nT(n+1)\textgreater{} = $\sqrt{(n+1)}$ .

nucl-th↗
arXiv2018

Matrix Models of Strength Distributions

In this work we use matrix models to study the problem of strength distributions. This is motivated by noticing near exponential fall offs of strengths in calculated magnetic dipole excitations. We emphasize that the quality of the exponential fall offs depend on the parameters in our matrices, especially the relative size of the couplings to the unperturbed level separations. We also find a matrix for which all transitions vanish.

nucl-th↗
arXiv2018

The Spin and Orbital Contributions to Magnetic Dipole Transitions

In previous works we examined they systematics of magnetic dipole transitions in a single j shell. We here extend the study to large space calculations.We consider the nuclei $^{44}$ Ti, $^{46}$Ti and $^{48}$C. Of particular interest is the contributions to B(M1) of the spin and orbital parts of the magnetic dipole operator. Whereas usual scissors mode analyses have as an initial state the J=0+ ground state (of an even-even nucleus) we here start with the lowest J=1+ T=1 state. This enables us to reach many more states e.g. J=2,T=0,1, and 2 and thus getter a better picture of the collectivity of this state.

nucl-th↗
arXiv2018

Study of the Q.Q Interaction- Single Particle Behavior to Elliott's Rotations

We perform shell model calculations using a quadrupole-quadrupole interaction (Q.Q).We show results in single j shell spaces and the full S-D shell . We show that one gets useful results with Q.Q in both spaces.. We emphasize the importance of the choice of single particle energies in order to obtain the results of Elliott using a Q.Q interaction without the momentum terms. We show a J(J+1) spectrum for a ground state band but with B(E2)'s different from the rotational model. We also show excited J(J-1), J((J-1) and J(J+3) spectra.We find spectra starting with J=0 which have both even J and odd J members.

nucl-th↗
arXiv2017

Selection rules for ^48Cr

In the single j shell(f_{7/2}){}^{48} Cr is the first even-even nucleus for which there are T=0 (Isoscalar) J=1^{+} states and T=1J=0^{+}These states are here studied. This nucleus ,in the same model space, is mid-shell for both neutrons and protons and this leads to many selection rules.

nucl-th↗
arXiv2017

Schematic Interactions with Many Degeneracies

In previous works we examined the spectra for systems of 2 protons and 2 neutrons, in a single j shell calculation, by obtaining matrix elements from experiment. More recently we considered schematic interactions in the same model space. We continue in this vein here. The present work and the former can be regarded as 2 bookends on a bookshelf.

nucl-th↗
arXiv2016

Manifestations of Isospin in Nearest Neighbor Spacing Distributions for the f-p Model Space

The strong interactions are charge independent. If we limit ourselves to the strong interactions, we have the isospin $T$ as a good quantum number. Here we consider the lack of level repulsion of states of different isospin and how this effect manifests in nearest neighbor spacing (NNS) histograms, which provide a visual and statistical context in which to study distributions of energy level spacings. In particular, we study nucleons in the f-p model space for the nucleus $^{44}$Ti. We also study the effect of the Coulomb interaction on the level spacing distribution.

nucl-th↗