Search results for "Ground state"
showing 10 items of 928 documents
Construction of the ground state in nonrelativistic QED by continuous flows
2006
AbstractFor a nonrelativistic hydrogen atom minimally coupled to the quantized radiation field we construct the ground state projection Pgs by a continuous approximation scheme as an alternative to the iteration scheme recently used by Fröhlich, Pizzo, and the first author [V. Bach, J. Fröhlich, A. Pizzo, Infrared-finite algorithms in QED: The groundstate of an atom interacting with the quantized radiation field, Comm. Math. Phys. (2006), doi: 10.1007/s00220-005-1478-3]. That is, we construct Pgs=limt→∞Pt as the limit of a continuously differentiable family (Pt)t⩾0 of ground state projections of infrared regularized Hamiltonians Ht. Using the ODE solved by this family of projections, we sho…
A step further in the A = 33−35, N ≃ 21, island of inversion: the structure of 33Mg
2003
Experimental indications have been found in the seventies for the deformation of neutron-rich A ≃ 32 nuclei [1]. This could be explained by Hartree-Fock calculations, predicting deformed configurations in the ground state of nuclei in the A = 33−35, N ≃ 21 mass region. This exotic region, called the island of inversion [2], knows a renewed interest since it can be now experimentally accessible for detailed studies.
Decay of theN=126, Fr213nucleus
2016
gamma rays following the EC/beta(+) and alpha decay of the N = 126, Fr-213 nucleus have been observed at the CERN isotope separator on-line (ISOLDE) facility with the help of gamma-ray and conversion-electron spectroscopy. These gamma rays establish several hitherto unknown excited states in Rn-213. Also, five new a-decay branches from the Fr-213 ground state have been discovered. Shell model calculations have been performed to understand the newly observed states in Rn-213.
β decay of the very neutron-deficient Ge60 and Ge62 nuclei
2021
We report here the results of a study of the $\beta$ decay of the proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of $^{62}$Ge (73.5(1) ms), $^{60}$Ge (25.0(3) ms) and its daughter nucleus, $^{60}$Ga (69.4(2) ms). We measured individual $\beta$-delayed proton and $\gamma$ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total $\beta$-delayed proton-emission branching ratio of 67(3)% has been obtained for $^{60}$Ge. New information has…
Isotope shifts and hyperfine structure in the $\mathsf{ 3d ^2D_J \rightarrow 4p ^2P_J}$ transitions in calcium II
1998
The isotope shift and hyperfine structure in the three \(\) - transitions in Ca II have been studied by fast ion beam collinear laser spectroscopy for all stable Ca isotopes. The metastable 3d states were populated within the surface ionization source of a mass separator with a probability of about 0.1%. After resonant excitation to the 4p levels with diode laser light around 850 nm the uv photons from the \(\) transitions to the ground state were used for detection. Hyperfine structure parameters A and B for the odd isotope 43Ca, as evaluated from the splittings observed, agree well with theoretical predictions from relativistic many-body perturbation theory. Field shift constants \(\) and…
Spectroscopy of very neutron-deficient 187,189Bi isotopes
2003
Shape coexistence is well known to occur in nuclei, in particular near closed shells [1], where particle-hole excitations across the shell gap can create deformed intruder states. In the neutron-deficient lead isotopes (Z = 82), deformed structures appear at low excitation energy. The isotope 188Pb [2] shows for example a triple shape coexistence with oblate and prolate excited 0+ states that compete with the spherical ground state. The study of the odd-proton single-particle excitations in Bi isotopes allows to obtain information on the orbitals involved in the different shapes observed in this mass region.
Triangle Singularity as the Origin of the a1(1420)
2021
The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a 1 ( 1420 ) , decaying to f 0 ( 980 ) π . With a mass too close to and a width smaller than the axial-vector ground state a 1 ( 1260 ) , it was immediately interpreted as a new light exotic meson, similar to the X , Y , Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a 1 ( 1260 ) resonance into K * ( → K π ) K ¯ and subsequent rescattering through a triangle singularity into the coupled f 0 ( 980 ) π channel. The amplitude for this process is calculated using a new a…
Laser spectroscopy of the (1s(2)2s2p) P-3(0)-P-3(1) level splitting in Be-like krypton
2011
15th International Conference on the Physics of Highly Charged Ions, HCI2010, Fudan Univ, Shanghai, PEOPLES R CHINA, AUG 29-SEP 03, 2010; International audience; Heavy few-electron ions, such as He-, Li- and Be-like ions, are ideal atomic systems to study the effects of correlation, relativity and quantum electrodynamics. Very recently, theoretical and experimental studies of these species achieved a considerable improvement in accuracy. Be-like ions are interesting because their first excited state, i.e. (1s(2)2s2p) P-3(0), has an almost infinite lifetime (tau(0)) in the absence of nuclear spin (I), as it can only decay by a two-photon E1M1 transition to the (1s(2)2s(2)) S-1(0) ground stat…
Double-resonance-ionization mapping of the hyperfine structure of the stable Cu isotopes using pulsed narrowband Ti:sapphire lasers
2015
We present two approaches to enhance the resolving power for measuring hyperfine structure constants using resonance ionization spectroscopy. The first method employs a 2D-resonance ionization spectroscopy scanning technique with pulsed, narrowband Ti:sapphire lasers (1 GHz linewidth), allowing us to resolve hyperfine components that cannot be separated using the standard 1D-scanning method across only one optical transition. In a second refinement, the resolving power is further enhanced through the use of a ring design of the laser cavity. This layout leads to a reduction of the laser linewidth from 1 GHz to below 50 MHz, resulting in experimental linewidths of about 150 MHz. Motivated by…
Experimental studies of the NaRb ground-state potential up to thev″=76level
2002
Laser induced fluorescence spectra of the C {sup 1}{sigma}{sup +}-X {sup 1}{sigma}{sup +} system of {sup 23}Na{sup 85}Rb and {sup 23}Na{sup 87}Rb have allowed vibrational levels of the electronic ground state up to v{sup ''}=76, spanning 99.85% of the potential well to be observed. The ground-state term values have been fitted to a Dunham polynomial expansion, and also to a direct modified Lennard-Jones (MLJ) potential. The analytical MLJ construction allowed us to match previous measured term values for v{sup ''}{<=}30 with long-range behavior of the potential through the intermediate internuclear distance region covered by the present investigation.