Search results for "Isotopes of calcium"

Quantifying the evolution of animal dairy intake in humans using calcium isotopes

2021

International audience; The contribution of dairy products to modern human diets has a debated role in the expansion of Neolithic economies and the dynamics of demographic transitions. While current methods allow discussing dairy production and processing, no approach allows reconstructing quantitatively its effective consumption. Calcium isotopes (δ44/42Ca) potentially represent such a marker due to the abundance of isotopically fractionated Ca in dairy products. Here, we test Ca isotope sensitivity to dietary intake of dairy product: we first used a dietary model based on a compilation of available data of dietary Ca sources; we then compared the modelled outputs to available and newly ac…

Die Calcium-Umsatzgeschwindigkeit ruhender und kontrahierender Vorhofmuskulatur in vitro

1964

The calcium content and the Ca45 uptake and loss were estimated in resting and beating left atria of guinea pigs. The tissue calcium was determined by fluorescence titration, and the Ca45 was counted in a liquid scintillation counter.

Isotope shifts and hyperfine structure in the transitions of stable calcium isotopes and calcium-41

1998

Isotope shifts and hyperfine structure in the 4s2 1S0 → 4s4p 1P1 and 4s2 1S0 → 4s4d 1D2 transitions of calcium have been measured with high-precision laser spectroscopy. Calcium atoms in an atomic beam were excited with single-frequency cw dye and titanium sapphire lasers and then photoionized with the 363.8 nm or 514.5 nm line of an argon ion laser. The resulting ions were analyzed and detected with a quadrupole mass spectrometer. Isotope shifts for all stable calcium isotopes and the radionuclide 41Ca have been measured in both transitions. The corresponding field shift and specific mass shift coefficients as well as hyperfine structure constants for the isotopes 41, 43Ca have been derive…

Ultratrace analysis of calcium with high isotopic selectivity by diodelaser resonance ionisation mass spectrometry

1997

A resonance ionisation mass spectrometer for the ultratrace determination of calcium isotopes is presented. It achieves high overall efficiency, ultra-high isotopic abundance sensitivity of more than 1010 and complete suppression of isobars. The system can be used for isotope ratio studies on stable and long-lived trace isotopes with the final goal of radiodating via 41Ca-determination. For the different applications optical one-, two- or three-step resonance excitation and subsequent ionisation is applied using simple and inexpensive diodelasers. Additional mass analysis is accomplished in a commercial quadrupole mass spectrometer. The experimental set-up and first results on synthetical a…

The mean square nuclear charge radius of

1996

We report on a collinear laser spectroscopy measurement of the nuclear charge radius of (I = 3/2), yielding . Within the experimental accuracy, the N = 20 neutron shell closure has no influence on the charge radii of the calcium isotopes.

Unexpectedly large charge radii of neutron-rich calcium isotopes

2016

Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain "magic" numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly-magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known Ca isotopes have been successfully described by nuclear theory, it is still a challenge to predict their charge radii evolution. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theo…

The ionic dependence of calcium efflux from guinea pig auricles.

1968

Influence of intracellular sodium concentration on calcium influx in isolated guinea pig auricles.

1969

Isotope shifts and hyperfine structure in calcium 4snp and 4snf F Rydberg states

2000

Isotope shifts and hyperfine structure have been measured in 4snp 1 P1 and Rydberg states for all stable calcium isotopes and the radioisotope 41Ca using high-resolution laser spectroscopy. Triple-resonance excitation via Rydberg state was followed by photoionization with a CO2 laser and mass selective ion detection. Isotope shifts for the even-mass isotopes have been analyzed to derive specific mass shift and field shift factors. The apparent isotope shifts for 41Ca and 43Ca exhibit anomalous values that are n-dependent. This is interpreted in terms of hyperfine-induced fine-structure mixing, which becomes very pronounced when singlet-triplet fine-structure splitting is comparable to the h…