The Half-Life of 14C—Why Is It So Long?

Radiocarbon ◽  
2019 ◽  
Vol 61 (5) ◽  
pp. 1135-1142 ◽  
Author(s):  
Walter Kutschera
Keyword(s):  
Half Life ◽  
Nuclear Physics ◽  
Transition Matrix ◽  
Transition Probability ◽  
Transition Matrix Element ◽  
Nuclear Model ◽  
Nuclear Transition ◽  
Normal Strength ◽  
Nuclear Model Calculation ◽  
Gamow Teller

ABSTRACTThe half-life of radiocarbon (14C) is 5700 ± 30 yr, which makes it particularly useful for dating in archaeology. However, only an exceptional hindrance of the beta decay from 14C to 14N—a so-called Gamow-Teller ß-decay—makes this half-life so long. A normal strength would result in a half-life of only a few days, completely useless for archaeological dating. The unusual hindrance is based on the nuclear structure of the two nuclei, resulting in strongly destructive interferences of the nuclear transition matrix element. Nuclear model calculation with great computational efforts have been performed in the literature to reproduce the very low transition probability. Here, we will attempt to describe the nuclear physics behind this most unusual half-life.

Theoretical ionization energies and oscillator strengths for the sodium isoelectronic sequence

1969 ◽  
Vol 47 (8) ◽  
pp. 835-838 ◽  
Author(s):  
R. P. McEachran ◽  
C. E. Tull ◽  
M. Cohen
Keyword(s):  
Matrix Element ◽  
Transition Matrix ◽  
Transition Matrix Element ◽  
Wave Functions ◽  
Oscillator Strengths ◽  
Isoelectronic Sequence ◽  
Ionization Energies ◽  
Core Approximation

Orbital wave functions for a number of 2S, 2P0, 2D, and 2F0 states of Na, Mg+, and Al2+ have been calculated by means of the frozen core approximation. The oscillator strengths of all allowed dipole transitions have been determined using both length and velocity formulations for the transition matrix element; these results agree with each other to within a few percent.

scholarly journals Bratislava Radiocarbon Measurements II

Radiocarbon ◽  
1977 ◽  
Vol 19 (3) ◽  
pp. 389-391
Author(s):  
S Usačev ◽  
J Chrapan ◽  
J Oravec ◽  
B Sitár
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
Nuclear Physics ◽  
Radiocarbon Dating ◽  
Initial Conditions ◽  
Sample Pretreatment ◽  
Active Volume ◽  
Statistical Errors ◽  
Sample Count

Radiocarbon dating facilities were built at the Department of Nuclear Physics, Comenius University in 1967 (Usačev et al, 1973). Initially, sample pretreatment and combustion systems for a proportional counter filled with CO2 were installed (Chrapan, 1966). One group adopted methods based on the use of methane (Usačev et al, 1973), a second group continued radiocarbon dating using an Oeschger-type proportional counter filled with CO2 (Chrapan, 1968). Later a modified Oeschger-type proportional counter with 1L active volume and with a background of approximately 8.10–2 bq was built (Schmidt and Chrapan, 1970). The pressure used in this counter is 105 Pa. 0.95 NBS oxalic acid is used as a standard of the present biosphere and the year 1950 refers to the zero year. Calculated radiocarbon ages are based on a 5568 ± 30 year half-life as recommended by the 8th International Radiocarbon Dating Conference. Statistical errors are calculated as a combination of the 3σ standard deviations of the sample count and the background. Samples were treated by HCl, NaOH or other chemicals according to their initial conditions.

scholarly journals Research on the Combination Method of Temporal Conflict Evidence Based on Transition Matrix

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bin Wu ◽  
Xiao Yi
Keyword(s):  
Transition Matrix ◽  
Transition Probability ◽  
Evidence Theory ◽  
Research Topic ◽  
Combination Method ◽  
Evidence Based ◽  
Important Research ◽  
Transition Matrices ◽  
Important Research Topic ◽  
Evidence Combination

Conflict evidence combination is an important research topic in evidence theory. In this paper, two kinds of transition matrices are constructed based on the Markov model; one is the unordered transition matrix, which satisfies the commutative law, and the other is the temporal transition matrix, which does not satisfy the commutative law, but it can handle the combination of temporal evidence well. Then, a temporal conflict evidence combination model is proposed based on these two transition matrices. First, the transition probability at the first n time is calculated through the model of unordered transition probability, and then, the transition matrix from the N + 1 time is used to solve the combination problem of temporal conflict evidence. The effectiveness of the transition matrix in the research of conflict evidence combination method is proved by the example analysis.

scholarly journals Nuclear Transition Matrix Elements for Double-β Decay Within PHFB Model

2019 ◽  
Vol 7 ◽  
Author(s):  
P. K. Rath ◽  
Ramesh Chandra ◽  
K. Chaturvedi ◽  
P. K. Raina
Keyword(s):  
Transition Matrix ◽  
Nuclear Transition ◽  
Matrix Elements ◽  
Β Decay ◽  
Transition Matrix Elements ◽  
Double Β Decay

scholarly journals Nuclear transition matrix elements for neutrinoless double-β decay within mechanisms involving light Majorana neutrino mass and right-handed current

2019 ◽  
Vol 28 (01n02) ◽  
pp. 1950001
Author(s):  
Yash Kaur Singh ◽  
R. Chandra ◽  
K. Chaturvedi ◽  
Tripti Avasthi ◽  
P. K. Rath ◽  
...  
Keyword(s):  
Neutrino Mass ◽  
Transition Matrix ◽  
Weak Coupling ◽  
Majorana Neutrino ◽  
Nuclear Transition ◽  
Matrix Elements ◽  
Β Decay ◽  
Hartree Fock ◽  
Transition Matrix Elements ◽  
Majorana Neutrino Mass

Employing the projected-Hartree-Fock-Bogoliubov (PHFB) model in conjunction with four different parametrizations of pairing plus multipolar effective two-body interaction and three different parametrizations of Jastrow short-range correlations, nuclear transition matrix elements for the neutrinoless double-[Formula: see text] decay of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] isotopes are calculated within mechanisms involving light Majorana neutrino mass and right-handed current. Statistically, model specific uncertainties in sets of twelve nuclear transition matrix elements are estimated by calculating the averages along with the standard deviations. For the considered nuclei, the most stringent extracted on-axis limits on the effective light Majorana neutrino mass [Formula: see text], the effective weak coupling of right-handed leptonic current with right-handed hadronic current [Formula: see text], and the effective weak coupling of right-handed leptonic current with left-handed hadronic current [Formula: see text] from the observed limit on half-life [Formula: see text] of [Formula: see text] isotope are [Formula: see text][Formula: see text]eV, [Formula: see text] and [Formula: see text], respectively.

OPTICAL PROPERTIES OF RANDOM III–V TERNARY SEMICONDUCTING ALLOYS

2002 ◽  
Vol 16 (24) ◽  
pp. 3681-3695
Author(s):  
BIPLAB GANGULI ◽  
ABHIJIT MOOKERJEE
Keyword(s):  
Optical Properties ◽  
Matrix Element ◽  
Ternary Alloy ◽  
Transition Matrix ◽  
Optical Transition ◽  
Transition Matrix Element ◽  
Semiconducting Alloys

The formalism developed earlier for the study of optical properties of random semiconducting alloys has been applied to the ternary alloy GaAs x Sb 1-x. The effects of randomness in the optical transition matrix element has been shown within the formalism.

MARKOV CHAIN AS A MATHEMATICAL MODEL OF BUILDING STRUCTURE WORKING UNDER LOAD

2017 ◽  
Vol 7 (1) ◽  
pp. 4-8
Author(s):  
Andrey N. DAVYDOV
Keyword(s):  
Mathematical Model ◽  
Markov Chain ◽  
Transition Matrix ◽  
Transition Probability ◽  
Probabilistic Method ◽  
External Factors ◽  
Numerical Characteristic ◽  
Building Structure ◽  
Structure Transition ◽  
Reliability Performance

Markov process as a probabilistic method for evaluation of the reliability of constructions is considered. The essence of the building structure transition from one state to another, from the infl uence of external factors is disassembled. The transition matrix as an analytical model of Markov chains to evaluate the reliability of the building structure is analyzed. Transition probability as a numerical characteristic of a mathematical model of the Markov chain is considered. A mathematical model of a building structure under load is described. Formulation of the problem to determine the assessment of the reliability performance of the building structure is proposed.

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