Recent developments in the shell model Monte Carlo approach to nuclei

The shell model Monte Carlo (SMMC) approach provides a powerful method for the microscopic calculation of statistical and collective nuclear properties in model spaces that are many orders of magnitude larger than those that can be treated by conventional methods. We discuss recent applications of the method to describe the emergence of collectivity in the framework of the configuration-interaction shell model and the crossover from vibrational to rotational collectivity in families of rare-earth nuclei. We have calculated state densities of these rare-earth nuclei and find their collective enhancement factors to be correlated with the pairing and shape phase transitions. We also discuss an accurate method to calculate the ground-state energy of odd-even and odd-odd nuclei, circumventing the sign problem that originates in the projection on an odd number of particles. We have applied this method to calculate pairing gaps in families of isotopes in the iron region.Comment: 7 pages, 5 figures, Proceedings of Horizons of Innovative Theories, Experiments, and Supercomputing in Nuclear Physics (HITES 2012

Recent Advances in the Application of the Shell Model Monte Carlo Approach to Nuclei

The shell model Monte Carlo (SMMC) method is a powerful technique for calculating the statistical and collective properties of nuclei in the presence of correlations in model spaces that are many orders of magnitude larger than those that can be treated by conventional diagonalization methods. We review recent advances in the development and application of SMMC to mid-mass and heavy nuclei.Comment: 6 pages, 5 figures, Proceedings of the Eleventh International Spring Seminar on Nuclear Physic

Correlations between the ranks of submatrices and weights of random codes

AbstractThe results of our study are twofold. From the random matrix theory point of view we obtain results on the rank distribution of column submatrices. We give the moments and the covariances between the ranks (q−rank) of such submatrices. We conjecture the counterparts of these results for arbitrary submatrices. The case of higher correlations gets drastically complicated even in the case of three submatrices. We give a formula for the correlation of ranks of three submatrices and a conjecture for its closed form. From the code theoretical point of view our study yields the covariances of the coefficients of the weight enumerator of a random code. Particularly interesting is that the coefficients of the weight enumerator of a code with random parity check matrix are uncorrelated. We give a conjecture for the triple correlations between the coefficients of the weight enumerator of a random code

Shell Model Monte Carlo method in the pnpn-formalism and applications to the Zr and Mo isotopes

We report on the development of a new shell-model Monte Carlo algorithm which uses the proton-neutron formalism. Shell model Monte Carlo methods, within the isospin formulation, have been successfully used in large-scale shell-model calculations. Motivation for this work is to extend the feasibility of these methods to shell-model studies involving non-identical proton and neutron valence spaces. We show the viability of the new approach with some test results. Finally, we use a realistic nucleon-nucleon interaction in the model space described by (1p_1/2,0g_9/2) proton and (1d_5/2,2s_1/2,1d_3/2,0g_7/2,0h_11/2) neutron orbitals above the Sr-88 core to calculate ground-state energies, binding energies, B(E2) strengths, and to study pairing properties of the even-even 90-104 Zr and 92-106 Mo isotope chains

Determination of Anthocyaninsin Red Grape Juices Made From Different Varieties by HPLC

This study was conducted to determine the anthocyanin profiles of red grape juice. As research material, twelve different red grape varieties which were collected from the main producing regions in Turkey and red grape juice samples made from them were analyzed. The anthocyanins peaks on HPLC-chromatograms in red grapes were identified as cyanidin-3-glucoside, delphinidin-3-glucoside, malvidin-3-glucoside, peonidin-3-glucoside and petunidin-3-glucoside. According the results, the pre-dominant anthocyanins of red grape juice was malvidin-3-glucoside which was found between 21.77-277.54 mg/L. It was followed by peonidin-3-glucoside which was found between 3.05-74.26 mg/L and then cyanidin-3-glucoside which was found between 3.02-16.94 mg/L. Delphinidin-3-glucoside and petunidin-3-glucoside were not detected in most red grape juices. This work is important to chemical description of local grape varieties and selection of suitable raw material for fruit juice industry

Parity-Projected Shell Model Monte Carlo Level Densities for fp-shell Nuclei

We calculate parity-dependent level densities for the even-even isotopes 58,62,66 Fe and 58 Ni and the odd-A nuclei 59 Ni and 65 Fe using the Shell Model Monte Carlo method. We perform these calculations in the complete fp-gds shell-model space using a pairing+quadrupole residual interaction. We find that, due to pairing of identical nucleons, the low-energy spectrum is dominated by positive parity states. Although these pairs break at around the same excitation energy in all nuclei, the energy dependence of the ratio of negative-to-positive parity level densities depends strongly on the particular nucleus of interest. We find equilibration of both parities at noticeably lower excitation energies for the odd-A nuclei 59 Ni and 65 Fe than for the neighboring even-even nuclei 58 Ni and 66 Fe.Comment: 5 pages, 4 figures, submitted to Phys. Rev.

Laser induced spinodal dewetting of Ag thin films for photovoltaic applications

Plasmonics is a promising approach to enhance light trapping properties of thin-film solar cells. Excitation of surface plasmons is characterised by a strong scattering and an enhancement of the electric field in the vicinity of the metal nanoparticle. These properties can be used to reduce the optical losses due to incident light reflection and to increase the optical absorption within the cell. Absorption can be enhancenced in the required wavelength region by tuning the surface plasmon resonance controlling the nanoparticle's size, shape, and local dielectric environment. Ag nanoparticles obtained by laser induced dewetting of metastable Ag thin films on SiO2 have been characterized. Size and characteristic patterning length dependency of nanoparticles on film thickness have been determined and spinodal dewetting has been identified as the process responsible for nanoparticle formation. The tunability of the plasmon resonance has been demonstrated through the manipulation of particle size and dielectric environment

Assessment of children presenting with rheumatic complaints to a tertiary center in Turkey: differences in an Eastern Mediterranean population

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