Search results for "Bohr model"
showing 10 items of 21 documents
Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes
2015
Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po196,198,200,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po200,202, the transitional and diagonal matrix elements of the 2+1 state are determined. In Po196,198 multistep Coulomb excitation is observed, populating the 4+1,0+2, and 2+2 states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po196 onwards. Three model descriptions are used to compare to the data. Calculati…
Quadrupole deformation of Xe-130 measured in a Coulomb-excitation experiment
2020
Physical review / C 102(5), 054304 (2020). doi:10.1103/PhysRevC.102.054304
The Proton Bohr Factor of Native and Crosslinker Treated Hemoglobins - Its Possible Significance for the Efficacy of Hemoglobin Based Artificial Oxyg…
1994
Especially the (alkaline) proton Bohr effect seems to provide an important self regulating mechanism of the organism to deliver specifically oxygen into tissues suffering from O2 deficit. In this way these tissues switch from aerobic to anaerobic metabolism, get lactacid, thereby shifting oxygen hemoglobin binding curve to the right and thus facilitating the oxygen release. The higher the absolute value of the proton Bohr factor (: delta logP50/ delta pH) is the better this mechanism works. To get one characteristic number the proton Bohr factor at pH 7.1 is taken. This pH in blood is about a lower limit for organism and human blood has at this pH its maximum proton Bohr factor which is abo…
Bohr radii of vector valued holomorphic functions
2012
Abstract Motivated by the scalar case we study Bohr radii of the N -dimensional polydisc D N for holomorphic functions defined on D N with values in Banach spaces.
Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes: Coulomb excitation of Hg-182, Hg-184, Hg-186 and Hg-188
2019
The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of $ 0^{+}_{1,2}$01,2+, $ 2^{+}_{1,2}$21,2+and $ 4^{+}_{1}$41+states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate…
A simple expression for electronic stopping force of heavy ions in solids
2012
Abstract A simple expression for the electronic stopping force of heavy ions in solids is proposed based on an adaption of the Bohr’s classical stopping theory. A three-parameter model is constructed by using experimental data for helium, oxygen, argon, krypton and xenon ions in carbon, aluminum, nickel and gold targets at energies from 600 eV/u to 985 MeV/u. Total average agreements between the model and used experimental data are (−4.5 ± 47)% and (−1.6 ± 7.4)% at energies below and above the Bragg peak, respectively. The good overall agreement makes this model a good candidate for future development in stopping force prediction tools.
Energy losses of 252Cf fission fragments in thin foils
2006
Abstract The stopping power of fission fragments from 252Cf(sf) has been measured in thin foils of C, Ni, Au, Al2O3 and Mylar as a function of fragment mass and energy. The chosen stopping materials are frequently used as the backing of sources and targets or entrance windows of gas detectors. The experimental setup allowed registration of velocities of two fission fragments and energy of one of them. In this way fragment masses could be unambiguously determined and the pulse-height defect of the silicon detector verified. The measured stopping power data for fission fragments cover masses between A = 101 and A = 148. The results are compared with semi-empirical predictions of SRIM 2003 cod…
In-beam study of the 128, 130Xe nuclei
1981
Abstract The level structure of 128,130Xe has been studied in the (α, 2nγ) and (3He, 3nγ) reactions on enriched Te targets using in-beam γ-ray spectroscopic methods. For both nuclei the existing information about positive-parity level structure was enriched and many new negative-parity two-quasiparticle states were observed. Isomeric states with the half-lives of 63 ± 12 ns in 128 Xe and 4.8 ± 0.5 ns in 130 Xe were found. For collective positive-parity states the interacting boson model, and calculations based on Bohr hamiltonian were compared with the experimental data.
Multiple Perspectives on the Stern-Gerlach Experiment
2016
Different or conflicting accounts of the same episode in the history of science may arise from viewing that episode from different perspectives. The metaphor suggests that conflicting accounts can be seen as complementary, constructing a multi-dimensional understanding, if the different perspectives can be coordinated. As an example, I discuss different perspectives on the Stern-Gerlach experiment. In a static interpretation, the SGE has been viewed as an experiment that allows the determination of the magnetic moment of silver atoms. Based on the concept of magnetic momentum arising from orbital angular momentum, the original experiment was designed in 1922 as an experimentum crucis to dec…
Energy-loss straggling of 2-10 MeV/u Kr ions in gases
2013
Measurements have been performed on a time-of-flight setup at the Jyväskylä K130 cyclotron, aiming at energy-loss straggling of heavy ions in gases. Theoretical predictions based on recently developed theory as well as an empirical interpolation formula predict that straggling can be more than ten times higher than Bohr straggling in the MeV/u regime. Our measurements with up to 9.3 MeV/u Kr ions on He, N2, Ne and Kr targets confirm this feature. Our calculations show the relative contributions of linear straggling, bunching including packing, and charge exchange. Our results for stopping cross sections are compatible with values from the literature. Funding Agencies|EU||Academy of Finland …