Search results for "shell"

Ritz Solution for Transient Analysis of Variable-Stiffness Shell Structures

2020

The dynamic response of thin-walled structures is driven by mass and stiffness distribution. As such, variable-stiffness (VS) composites offer opportunities to tune structural dynamic responses. To this extent, efficient analysis tools become increasingly important for structural analysis and design purposes. In this work, an efficient and versatile Ritz method for free vibrations and linear transient analysis of VS doubly curved shell structures is presented. VS shell structures are modeled as an assembly of shell-like domains. The shell kinematics is based on the first-order shear deformation theory, and no further assumption is made on the shallowness or on the thinness of the structure.…

Characterisation of single semiconductor nanowires by non-destructive spectroscopies

2015

Los nanohilos semiconductores (NWs, de su nombre inglés, nanowires) tienen una amplia gama de aplicaciones en el campo de la optoelectrónica (emisores de luz y diodos láser), nano-electrónica (circuitos lógicos y transistores de efecto de campo), y detección y producción de energía (células solares). En términos generales, los NWs pueden ser descritos como nanoestructuras de forma alargada con diámetros que van típicamente de decenas a cientos de nanómetros, y con longitudes que oscilan desde pocas hasta las decenas de micras. Dicha morfología ofrece dos ventajas principales en comparación con las capas: su alta relación superficie-volumen y su mayor calidad cristalina, ambas beneficiosas p…

Studying Gamow-Teller transitions and the assignment of isomeric and ground states at $N=50$

2022

Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new QEC=5437±67 keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+…

Spectroscopy of 70Kr and isospin symmetry in the T = 1 f pg shell nuclei

2016

International audience; The recoil-β tagging technique has been used in conjunction with the 40 Ca(32 S ,2n) reaction at a beam energy of 88 MeV to identify transitions associated with the decay of the 2 + and, tentatively, 4 + states in the nucleus 70 Kr. These data are used, along with previously published data, to examine the triplet energy differences (TED) for the mass 70 isobars. The experimental TED values are compared with shell model calculations, performed with the JUN45 interaction in the fpg model space, that include a J = 0 isospin nonconserving (INC) interaction with an isotensor strength of 100 keV. The agreement is found to be very good up to spin 4 and supports the expectat…

Spectroscopic studies of 173Pt and 175Pt

2014

First candidates for γ vibrational bands built on the [505]11/2⁻ neutron orbital in odd-A Dy isotopes

2020

Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the 155Gd(α,2n)157Dy and 148Nd(12C,5n)155Dy reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2+γ vibrational band, built on the [505]11/2− neutron orbital, in both odd-A155,157Dy isotopes. The coupling of the first excited K=0+ states or the so-called β vibrational bands at 661 and 676 keV in 154Dy and 156Dy to the [505]11/2− orbital, to produce a Kπ=11/2− band, was not observed in both 155Dy and 157Dy, respectively. The implication of these findings on the interpretation of the first excited 0+ states in the cor…

b-decay of 116Agm and the vibrational structure of 116Cd

2001

The structure of near neutron midshell 116 Cd has been investigated via β decay of 116 Ag m by β-γ and γ-γ coincidence spectroscopy. The 116 Ag m activity was produced by symmetric fission of natural uranium induced by 25 MeV protons. The ion guide technique has been employed to produce online mass separated sources. The decay scheme of 116 Ag m has been considerably extended by adding 19 new excited states of 116 Cd . The newly identified 116 Cd state at 1869.7 keV, along with other four levels near 2 MeV, are interpreted as forming the complete three-phonon quintuplet. The vibrational structure of 116 Cd is discussed in the context of an anharmonic vibrator. peerReviewed

Shell-model computed cross sections for charged-current scattering of astrophysical neutrinos off 40Ar

2018

Charged-current (anti)neutrino- 40 Ar cross sections for astrophysical neutrinos have been calculated. The initial and final nuclear states were calculated using the nuclear shell model. The folded solar-neutrino scattering cross section was found to be 1.78 ( 23 ) × 10 − 42 cm 2 , which is higher than what the previous papers have reported. The contributions from the 1 − and 2 − multipoles were found to be significant at supernova-neutrino energies, confirming the random-phase approximation (RPA) result of a previous study. The effects of neutrino flavor conversions in dense stellar matter (matter oscillations) were found to enhance the neutrino-scattering cross sections significantly for …

Characterization of thin plastic foils for applications in X-ray optics technology

2007

Thin plastic foils are being investigated to build shell optics for X-ray telescopes. Compared to polished glass optics, the advantage is in terms of increased collecting area, light weight and lower cost. Plastic material is also desirable to allow deformation into a complete surface of revolution. We collected plastic materials of common use for industrial applications and also specialty materials developed for the electronic industry. A comparative study was then performed to evaluate the optical quality of the selected plastic films. Surface analysis was carried out with topographic instruments to investigate the microroughness of our samples at different scan lengths. Preliminary resul…

Raman Investigations to Identify Corallium rubrum in Iron Age Jewelry and Ornaments

2016

International audience; During the Central European Iron Age, more specifically between 600 and 100 BC, red precious corals (Corallium rubrum) became very popular in many regions, often associated with the so-called (early) Celts. Red corals are ideally suited to investigate several key questions of Iron Age research, like trade patterns or social and economic structures. While it is fairly easy to distinguish modern C. rubrum from bone, ivory or shells, archaeologists are confronted with ancient, hence altered, artifacts. Due to ageing processes, archaeological corals lose their intensive red color and shiny surface and can easily be confused with these other light colored materials. We pr…