A new measurement of the branching ratio for 10C superallowed Fermi decay and its significance for the weak vector interaction

doi:10.1016/0375-9474(72)90505-2

Nuclear Physics A

Volume 181, Issue 2, 21 February 1972, Pages 645-659

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Abstract

The branching ratio for the pure Fermi decay ¹⁰C(β⁺)¹⁰B^∗∗ to the second excited state of ¹⁰B has been measured by an accurate determination of the ratio of the intensities of 1.022 and 0.718 MeV γ-rays following this decay and the Gamow-Teller transition to the first excited state of ¹⁰B. Computer programmes were devised for accurate analysis of the intensities of the full energy peaks obtained with a Ge(Li) detector, and for deducing the detector relative efficiency from calibration source data. The results were averaged with those from previous measurements of comparable accuracy to give β₁ = (98.53 ±0.02) % and β₂ = (1.465 ± 0.014) % as the best values of the branching ratios for positon decay to the first and second excited states of ¹⁰B respectively. The ft value of the Fermi transition was deduced as 3155±40 s with radiative corrections, and the corresponding vector coupling constant as G_β^V = (1.396 ± 0.009) × 10⁻⁴⁹ erg · cm³.

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Nuclear Data Sheets for A = 207
2011, Nuclear Data Sheets
Evaluated nuclear structure and decay data for all nuclei within the A=207 mass chain are presented. The experimental data are evaluated and best values for level and gamma-ray energies, quantum numbers, lifetimes, gamma-ray intensities, and other nuclear properties are recommended. Inconsistencies and discrepancies that exist in the literature are noted. This work supersedes the earlier evaluation by M.J. Martin (1993Ma73), published in Nuclear Data Sheets 70, 315 (1993).
Wide energy range efficiency calibration method for Ge detectors
2002, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A new method is proposed for the relative efficiency calibration of HPGe detectors in the energy range from 50 keV to 11 MeV. By simultaneously fitting all separately measured data sets from calibrated and uncalibrated multigamma sources as well as neutron capture γ-rays with a sum of orthogonal polynomials on a log–log scale, accuracies better than 0.5% between 100 and 3500 keV and better than 1% up to 6000 keV could be achieved for relative full energy peak efficiencies. Dividing the energy range and fitting piecewise with lower-order polynomials does not offer any advantage. Moreover, none of the popular non-linear empirical functions are able to fit the full range. The polynomial fit is nearly indistinguishable from a semiempirical fit. If at least one calibrated γ-ray source is included, the method can be used for absolute efficiencies as well.
A new measurement of the strength of the superallowed Fermi branch in the beta decay of 10C with GAMMASPHERE
1999, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
We report a new measurement of the strength of the superallowed 0⁺→0⁺ transition in the β-decay of ¹⁰C. The experiment was done at the LBNL 88-inch cyclotron using forty-seven GAMMASPHERE germanium detectors. The technique used in this measurement was similar to that of an earlier experiment, but the systematic corrections were significantly different. The measured branching ratio: 1.4665±0.0038×10⁻² is used to compute the superallowed Fermi ft, which gives the weak vector coupling constant and the u to d element of the Cabibbo–Kobayashi–Maskawa quark mixing matrix.
Methodology for superallowed Fermi beta-decay Part III. Analysis
1993, Nuclear Inst. and Methods in Physics Research, A
This final paper of the group discusses the various radiative corrections, both outer and inner, that must be applied to the experimental $ƒt- values$ , derived in Part II, before extracting the primitive vector coupling constant G_v for confrontation with the muon (Fermi) coupling constant G_μ. There is considerable discussion of the correction of the experimental data for the nuclear mismatch that is due to the T₃-dependence of the nuclear structure along an isospin multiplet; it is maintained that, as far as possible, this mismatch should be determined by reference to the data themselves. The final result is: G_v/(khc)³ = (1.13775±0.00096)×10⁻⁵ GeV⁻², which, inserted into the unitarity test for the first row of the Cabibbo-Kobayashi-Maskawa matrix gives: $¦V_{ud} ¦^{2} + ¦V_{us} ¦^{2} +¦V_{ub} ¦^{2} = 1.0001 ± 0.0018$ . The operational vector coupling constant $G_{v}^{∗} is: G_{v}^{∗} /(khc)^{3} = (1.15122 ± 0.00091) × 10^{−5} GeV^{−2}$ .
A method for determining the branching ratio for the superallowed decay: 10C(0+, gs) → 10B(0+, 1.74 MeV) + e+ + ν
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K and total internal conversion coefficients of the 1063.6 keV M4 transition of 207Pb
1988, Nuclear Inst. and Methods in Physics Research, A
Precise K and total internal conversion coefficients for the 1063.6 keV transition as well as γ- and K conversion electron intensity ratios of the 1063.6 and 569.6 keV transitions of ²⁰⁷Pb are derived from earlier measurements. The recommended values are $α_{K}^{1063} = 0.0945 ± 0.0022, α_{T}^{1063} = 0.126 ± 0.003, I_{γ}^{1063} I_{γ}^{569} = 0.758 ± 0.004 and I_{e}^{1063} I_{e}^{569} = 4.58 ± 0.05$ . Both internal conversion coefficients deviate slightly from the theoretical values as expected.

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^†: Present address: Institute of Nuclear Sciences, Lower Hutt, New Zealand.

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Nuclear Physics A

Abstract

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Nuclear Data Sheets for A = 207

Wide energy range efficiency calibration method for Ge detectors

A new measurement of the strength of the superallowed Fermi branch in the beta decay of <sup>10</sup>C with GAMMASPHERE

Methodology for superallowed Fermi beta-decay Part III. Analysis

A method for determining the branching ratio for the superallowed decay: <sup>10</sup>C(0<sup>+</sup>, gs) → <sup>10</sup>B(0<sup>+</sup>, 1.74 MeV) + e<sup>+</sup> + ν

K and total internal conversion coefficients of the 1063.6 keV M4 transition of <sup>207</sup>Pb