Reaction dependence of nuclear decay linewidths

doi:10.1016/0375-9474(81)90290-6

Nuclear Physics A

Volume 366, Issue 2, 17 August 1981, Pages 299-319

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Abstract

Various light- and heavy-ion reactions, 20 < E < 100 MeV, have been used to study the reaction dependence of α-decay widths for ⁸Be^∗(2 ⁺ , 2.9 MeV) and ¹⁶O^∗(1⁻, 9.6 MeV). Although slight differences (< 20 %) are found for the observed line shapes (Γ), the resonance widths inferred (Γ_R) are self-consistent and indicate little if any reaction dependence (< 10 %). Near a decay threshold one may expect Γ < Γ_R by 20 % or more, however, and thus care must be taken in comparing decay widths inferred from nuclear reactions with those from scattering resonances. Reduced formal α-decay widths of γ_λ² = 680 ± 100 keV (s = 4.8 fm) and γ_λ² = 350 ± 50 keV(s = 5.4 fm), corresponding to θ_λ² = 0.50 and θ_λ² = 0.49 are deduced for ⁸Be^∗(2 ⁺ , 2.9 MeV) and ¹⁶O^∗(1⁻, 9.6 MeV) using the nuclear-reaction Γ_R values and a particular set of α-nucleus potentials.

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A detailed study of the d + 10B system, for nuclear reaction analysis - Part B: The 10B(d,α<inf>0</inf>)8Be reaction in the energy region E<inf>d,lab</inf> = 900-2000 keV
2007, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
The differential cross-sections of the ¹⁰B(d,α₀) reaction, for the determination of the depth distribution of boron in near-surface layers of materials, have been determined in the projectile energy region E_d,lab = 900–2000 keV. The experiment was carried out in energy steps of 25 keV and for eight detector angles between 135° and 170° (in steps of 5°). The obtained experimental data are suitable for nuclear reaction analysis (NRA) studies. The various aspects of the ¹⁰B(d,α) reaction, namely the absence of the α₁ transition from the experimental spectra, the induced background from three-body kinematics and the ⁸Be breakup are discussed and analyzed. The results are compared to the ones already existing in the literature and an attempt is made to explain the occurring similarities and differences. A qualitative description of the observed cross-section variations through the influence of overlapping resonances in the d+¹⁰B system is also attempted.
Energy levels of light nuclei A = 16-17
1993, Nuclear Physics, Section A
Ghost anomaly and first excited state of 8Be in the 9Be(d, tα)4He reaction at 7 MeV
1991, Nuclear Physics, Section A
The three-body reaction ⁹Be + d → t + α + α has been investigated in kinematically complete experiments at E_d = 7.0 MeV for θ_t = −40° and θ_t = 40°, θ_α = −72.5° to −162.5. The experimental spectra are dominated by sequential processes via intermediate excited states of ⁸Be and ⁷Li. R-matrix theory was employed to describe the line shape of the first excited state and the ghost anomaly of the ground state of ⁸Be. Use was made of the αα phase shifts. The best fits were obtained assuming a channel radius of a_αα = 4.5 fm. The average intensity of the ghost anomaly for E_αα = 0.35–1.0 MeV is 4.3%/MeV (θ_t = 40°) and 8%/MeV (θ_t = 100°). For the first excited state of ⁸Be we find E_x = 3.00 MeV and Γ_x = 1.23 MeV(FWHM).
Energy levels of A = 21-44 nuclei (VII)
1990, Nuclear Physics, Section A
The experimentally determined properties of A = 21–44 nuclides are complied and evaluated with special emphasis on nuclear spectroscopy.
Separate tables for each of the nuclides reviewed present the available information about the following properties (in this order):
- •
  - excitation energies E_x,
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  - γ-ray branching ratios b(γ),
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  - γ-ray mixing ratios σ,
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  - lifetimes γ_m or widths Λ,
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  - neutron, proton, or α-particle resonances,
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  - partial widths,
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  - arguments for spin and parity (J^π) and isospin (T) assignments.
For each nuclide a master table summarizing the “best” or adopted values for E_x, J^π; T and τ_m or Λ precedes the auxiliary tables listed above.
The review of each A-chain concludes with a discussion of isospin multiplets.
Figures are presented of the level schemes of all nuclei and, for each A-chain, an overview of the relative energies of the ground states and lowest analogue states of all nuclei in the chain.
The first excited state of 8Be studied in the 7Li(p, γ)8Be reaction
1990, Nuclear Physics, Section A
In order to study the intrinsic line shape of the broad first excited 2⁺ state of ⁸Be, the radiative capture reaction ⁷Li(p,γ)⁸Be has been investigated in an energy range close to the center of the giant dipole resonance built upon this state. A large NaI(Tl) spectrometer with a well-known response function is employed. The data are fitted with spectral density functions derived from αα phase shifts in the framework of the R- matrix theory. The optimum value of the channel radius obtained from the fits, a = 4.5 fm, is in agreement with the value deduced from a similar analysis of a kinematically complete coincidence study of the ⁹Be(d,tα)⁴He reaction. The calculated spectral density function for a = 4.5 fm reaches its maximum at E_x = 2.91 MeV, the width (FWHM) is 1.23 MeV.
Microscopic clustering in light nuclei
2018, Reviews of Modern Physics

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^†: Supported in part by the National Science Foundation. (Grant Phy78–07754).

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Nuclear Physics A

Abstract

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Cited by (14)

A detailed study of the d +<sup> 10</sup>B system, for nuclear reaction analysis - Part B: The <sup>10</sup>B(d,α<inf>0</inf>)<sup>8</sup>Be reaction in the energy region E<inf>d,lab</inf> = 900-2000 keV

Energy levels of light nuclei A = 16-17

Ghost anomaly and first excited state of <sup>8</sup>Be in the <sup>9</sup>Be(d, tα)<sup>4</sup>He reaction at 7 MeV

Energy levels of A = 21-44 nuclei (VII)

The first excited state of <sup>8</sup>Be studied in the <sup>7</sup>Li(p, γ)<sup>8</sup>Be reaction

Microscopic clustering in light nuclei