Resonant neutron capture in 40Ca☆
Abstract
The neutron capture cross section of 40Ca has been measured with ≈ 0.2 % energy resolution below En = 300 keV. Resonance parameters have been extracted for many new p- and d-wave resonances. Gamma-ray spectra were also measured following capture in one doublet and two resolved resonances below 50 keV. Strong feeding of low-lying p-wave levels was observed in all cases. Calculations showed that valence transitions were inadequate to account for the observed dominance of these transitions and a further mechanism is required. The average resonance parameters obtained from the data are as follows: 〈D〉 = 37 + 4keV, 104S1 = 0.16 ± 0.05, 104S2 = 2.0 ± 0.7. The average radiative widths and standard deviations of their distributions were found to be strongly l-dependent as follows: 〈Γγ〉s = 1.5 ± 0.9 eV, 〈Γγ〉p = 0.36 ± 0.09 eV and 〈Γγ〉d = 0.7 ± 0.4 eV.
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Nuclear Data Sheets for A = 41
2016, Nuclear Data SheetsAvailable information pertaining to the nuclear structure of all nuclei with mass numbers A=41 ranging from Al (Z=13) to Ti (Z=22) are presented. The experimental reaction and decay data are evaluated and any inconsistencies or discrepancies are noted. The adopted values for various level properties (such as the spin, parity and and halflife) and gamma properties (energy, intensity and multipole character) are given.
Since the prior evaluation several new measurements have expanded our knowledge of A=41 nuclides. The half-life of the ground state of 41Si has been determined and a single excited state identified. Excited levels in 41P have been observed for the first time. In 41Cl, seven new excited states have been identified in deep inelastic and heavy ion transfer reactions. Half-lifes for four states in 41Ar have been updated and additional levels with gammas have been included from a new measurement using the multiple ion transfer reaction. In 41Ca via charge-exchange reaction measurements, several new excited states were observed. A number of new resonances in 41K have been identified via the (p,γ) reaction.
There remains a significant discrepancy in the half-life of the first excited state (980 keV) in 41K, with measurements differing by more than an order of magnitude. Transfer reactions suggest that this M1 transition should be l-forbidden, however, several measurements yield a lifetime which suggests a sizable M1 strength. Further measurements to resolve the current conflicts would be beneficial.
Nuclear Data Sheets for A = 246
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Energy levels of A = 21-44 nuclei (VI)
1978, Nuclear Physics, Section AThe experimentally determined properties of the A = 21–44 nuclei are compiled and evaluated, special emphasis being given to nuclear structure.
Separate tables for each of the nuclides reviewed give all available information about the following properties in this order: - excitation energies (Ex),
- •
- γ-ray branching ratios,
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- γ-ray mixing ratios (δ),
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- lifetimes (τm) or widths (Λ),
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- spin and parity (Jπ) and isospin (T) assignments, and
- •
- any other data, on single-particle transfer, resonance levels, etc.
The “best” (or adopted) values for Ex, τm or Λ, Jπ and T are summarized in a master table.
The review of each A-chain concludes with - a discussion of isospin multiplets,
- •
- a few remarks about the experimental situation, and
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- a compilation of references to relevant theoretical papers.
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- ☆
Research sponsored in part by ERDA under contract to Union Carbide Corporation.