The branching ratio in the decay of 7Be

1984 ◽  
Vol 62 (11) ◽  
pp. 1139-1144 ◽  
Author(s):  
H. C. Evans ◽  
I. P. Johnstone ◽  
J. R. Leslie ◽  
W. McLatchie ◽  
H.-B. Mak ◽  
...  
Keyword(s):  
Axial Vector ◽  
Branching Ratio ◽  
Experimental Result ◽  
Vector Coupling ◽  
A Value ◽  
Axial Vector Coupling ◽  
Absolute Efficiency ◽  
Γ Rays ◽  
Ge Detector ◽  
The Absolute

A measurement of the branching ratio for electron capture (EC) decay of 7Be to the 478-keV level in 7Li is reported. The reaction 10B(p, α)7Be was used and the 7Be recoils were detected and stopped in a particle detector thin enough to transmit the protons. The absolute γ-ray emission rate of 478-keV γ rays from the implanted detector was determined with a well-shielded intrinsic Ge detector. The absolute efficiency of the Ge detector was established with 22Na, 137Cs, and 88Y standard sources. A value of 11.4 ± 0.7% was obtained for the EC branch to the 478-keV state. Calculations suggest that the axial vector coupling constant GA must be reduced by a factor of 0.94 ± 0.02 to obtain agreement with the experimental result.

Study of a single line of sight gamma ray diagnostics for measurements of the absolute gamma ray emission from JET

2021 ◽  
Vol 16 (12) ◽  
pp. C12019
Author(s):  
G. Marcer ◽  
M. Nocente ◽  
L. Giacomelli ◽  
G. Gorini ◽  
E. Perelli Cippo ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Neutron Emission ◽  
Fusion Reaction ◽  
Branching Ratio ◽  
Plasma Source ◽  
Line Of Sight ◽  
Extended Plasma ◽  
Absolute Efficiency ◽  
The Absolute ◽  
Gamma Ray Emission

Abstract The fusion power produced in a DT thermonuclear reactor is currently determined by measuring the absolute 14 MeV neutron yield of the D(T, α)n fusion reaction. Measurements of 17 MeV gamma rays born from the much less probable D(T, 5He)γ reaction (branching ratio of ∼10−5) have been proposed as an alternative independent method to validate the neutron counting method and also to fulfill the requests of the nuclear regulator for licensing ITER DT operations. However, the development of absolute 17 MeV gamma ray emission measurements entails a number of requirements, such as: (i) knowledge of the 17 MeV gamma ray to 14 MeV neutron emission branching ratio; (ii) the simulation of the gamma ray transport from the extended plasma source to the gamma ray detectors; (iii) a careful determination of the absolute efficiency of previously calibrated gamma ray spectrometers. In this work, we have studied the possibility to infer the global gamma ray emission rate from measurements made with a 3″ × 6″ LaBr3 spectrometer installed at the end of a collimated tangential line of sight at the JET tokamak and using the neutron emission from deuterium plasmas of the most recent experimental campaigns. Results show that 17 MeV gamma ray fluxes at the end of this tangential line of sight have a weak dependence (less than 5%) on the plasma profile and can therefore be used to infer the total emission from the plasma.

On the renormalization of the axial vector coupling constant in β-decay

1960 ◽  
Vol 16 (3) ◽  
pp. 560-568 ◽  
Author(s):  
J. Bernstein ◽  
M. Gell-Mann ◽  
L. Michel
Keyword(s):  
Axial Vector ◽  
Coupling Constant ◽  
Β Decay ◽  
Vector Coupling ◽  
Vector Coupling Constant ◽  
Axial Vector Coupling

Measurement of the vector and axial vector coupling constants in Λ

1981 ◽  
Author(s):  
D. A. Jensen ◽  
M. N. Kreisler ◽  
F. Lomanno ◽  
R. Poster ◽  
M. S. Z. Rabin ◽  
...  
Keyword(s):  
Axial Vector ◽  
Coupling Constants ◽  
Vector Coupling ◽  
Axial Vector Coupling

scholarly journals Two neutrino double-beta decay and effective axial-vector coupling constant

2018 ◽  
Vol 194 ◽  
pp. 02002
Author(s):  
Fedor Šimkovic ◽  
Rastislav Dvornický ◽  
Dušan Štefánik
Keyword(s):  
Beta Decay ◽  
Axial Vector ◽  
Double Beta Decay ◽  
Matrix Elements ◽  
Coupling Constant ◽  
Vector Coupling ◽  
Majorana Particle ◽  
Vector Coupling Constant ◽  
Novel Approach ◽  
Axial Vector Coupling

The theoretical and experimental study of the two-neutrino double-beta decay (2νββ-decay) is of crucial importance for reliable calculation of matrix elements governing the neutrinoless double-beta decay (0νββ-decay). That will allow to determine masses of neutrinos once the 0νββ-decay, which occurs if the neutrino is a massive Majorana particle and the total lepton number is not onserved, will be observed. Experiments studying the 2νββ-decay are currently approaching a qualitatively new level, where high-precision measurements are performed not only for half-lives but for all other observables of the process. In this context an improved formula for the 2νββ-decay is presented. Further, a novel approach for determining the effective axial-vector coupling constant is proposed.

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