A study of 26Al by the 25Mg(3He, d) reaction

doi:10.1016/0375-9474(78)90380-9

Nuclear Physics A

Volume 299, Issue 3, 1 May 1978, Pages 412-428

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Abstract

In the ²⁵Mg(³He, d)²⁶Al reaction, at a bombarding energy of 18.0 MeV, angular distributions were measured for 55 levels below 6.9 MeV in excitation, and l-assignments are made for 44 of them. Spectroscopic strengths are compared with theoretical ones from the Nilsson model and from a naive shell model. New J^π information is given for many levels.

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Cited by (35)

The 25Mg(p, γ) 26Al reaction at low astrophysical energies
2012, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
In the present work we report on a new measurement of resonance strengths ωγ in the reaction ²⁵Mg(p, γ)²⁶Al at $E_{cm} = 92$ and 189 keV. This study was performed at the LUNA facility in the Gran Sasso underground laboratory using a 4π BGO summing crystal. For the first time the 92 keV resonance was directly observed and a resonance strength $ω γ = (2.9 \pm 0.6) \times 10^{- 10} eV$ was determined. Additionally, the γ-ray branchings and strength of the 189 keV resonance were studied with a high resolution HPGe detector yielding an ωγ value in agreement with the BGO measurement, but 20% larger compared to previous works.
Renaissance of the Nilsson-model approach to light nuclei: The case of the A = 26 system
1998, Nuclear Physics A
The farthest reaching interpretation of a light nuclear system in terms of the Nilsson-model is obtained for A = 26. The T = 1 and T = 0 levels of either parity in ²⁶Mg and/or ²⁶Al are shown to be grouped in more than 35 rotational bands together containing some 55 levels in ²⁶Mg and 170 in ²⁶Al. The Nilsson-model configurations and deformations of bands are deduced from measured spectroscopic factors and electromagnetic transition rates. The experimental data are amended by shell-model calculations in the complete s-d basis space based on the universal s-d Hamiltonian. The rotational structure of positive-parity states is completely contained in the shell-model results. The Nilsson diagram gives a natural explanation of all bands. An important facet is the observation of particle-hole configurations with large K which arise from the complete alignment of particle and hole angular momenta along the major axis of deformation.
Spectroscopic factors from one-proton stripping reactions on sd-shell nuclei: experimental measurements and shell-model calculations
1994, Nuclear Physics, Section A
The (³He,d) reaction has been investigated at 25 MeV on the target nuclei ¹⁶O, ¹⁸O, ¹⁹F, ²³Na, ²⁴Mg, ²⁵Mg, ²⁶Mg, ²⁷Al, ²⁸Si, ²⁹Si, ³⁰Si, ³¹P, ³²S, ³⁴S, ³⁵Cl, ³⁷Cl and ³⁹K. Attention is restricted to the few even-parity levels in each final nucleus which are strongly populated. Values of the single-nucleon Spectroscopic factors C²S are obtained from the differential cross sections measured for these levels by analyzing them in the framework of the DWBA theory of nuclear reactions. The DWBA calculations use sets of ³He and deuteron optical-potential parameters which are experimentally validated and internally consistent. The absolute values of C²S thus extracted are rather insensitive to which sets of equivalent optical-model parameters are used in the DWBA analyses (variations of the order of ±15%) and the variations in the relative values for the different transitions are very insensitive to these choices. Most of the sensitivity which does exist can be traced to the specification of the absorptive part of the deuteron potential. The values of C²S are not sensitive to the presence of spin-orbit terms in either the deuteron or the ³He potential. Contrary to the case for optical-model potentials, however, absolute values of C²S are very sensitive to the radius parameter r₀ chosen for the potential which binds the transferred proton, although relative values are almost completely insensitive to this choice. The effects of the spin-orbit part of this bound-state potential on $j = l + 12 and j = l − 12$ transitions have also been carefully investigated. Evidence is developed that the radius parameter r_s.o. of the spin-orbit part of the bound-state potential should be smaller than that of the central part. The values of C²S extracted from the present data both with standard DWBA analyses (r₀ = r_s.o. and a₀ = a_s.o.) and with analyses which incorporate a modified treatment of the spin-orbit term of the bound-state potential (r₀ ≠ r_s.o. and a₀ ≠ a_s.o.) are compared with the predictions of the USD shell-model hamiltonian. The ratios between the experimentally based spectroscopic factors and the model predictions exhibit a marked difference between transitions into the $1 d_{32}$ orbit and transitions into the $1 d_{52}$ orbit when the standard DWBA analysis is used. However, this difference between $1d_{32}$ and $1d_{52}$ transitions is greatly reduced if, while the conventional values r₀ = 1.25 fm and a₀= 0.65 fm continue to be used for the central component of the bound-state potential, values of r_s.o. = 1.00 fm and a_s.o. = 0.52 fm are used for the spin-orbit part.
Measurements of differential cross-section ratios for single-nucleon transfer reaction pairs near A = 25
1991, Nuclear Physics, Section A
Differential cross sections for the (d, p), (³He, d), (α, t), and (α,³He) reactions involving seventy-one residual states in ²³Na, ²⁵Mg, ²⁵Al, and ²⁷Al have been measured at a forward angle with incident energies of 17.5, 20.2, 34.8, and 34.8 MeV, respectively. The ratio of cross-section pairs involving formation of the same residual state is determined for forty-five cases where both the angular momentum transfer and single-particle spectroscopic strength have been previously established. These are compared to values calculated with conventional distorted-wave Born approximation analyses, and the utility of this technique for identifying some levels which are possible s- or p-wave resonances is demonstrated and discussed for states in the vicinity of proton thresholds. An application is made involving proton threshold states in ²⁷Al.
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,
- •
  - γ-ray branching ratios b(γ),
- •
  - γ-ray mixing ratios σ,
- •
  - lifetimes γ_m or widths Λ,
- •
  - neutron, proton, or α-particle resonances,
- •
  - partial widths,
- •
  - single-nucleon transfer reactions,
- •
  - beta-decay,
- •
  - 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.
Spectroscopic factors for proton unbound levels in 26Al and their influence on stellar reaction rates
1990, Nuclear Physics, Section A
The reaction ²⁵Mg(³He, d)²⁶Al at a bombarding energy of 15 MeV was used to populate proton unbound states in ²⁶Al. Angular distributions were measured and spectroscopic factors extracted for nine levels from 6343 to 6680 keV excitation in ²⁶Al. This excitation energy range corresponds to resonance energies for the ²⁵Mg(p, γ)²⁶Al reaction from 37 to 374 keV in the center-of-mass. Direct measurements of the resonance strengths, ωγ, had been reported for states in ²⁶Al with E_x ⩾ 6496 keV. To obtain resonance strengths for states between 6343 and 6469 keV we combined the spectroscopic factors from the present experiment with values of ωγ and Γ_γ/Γ for the directly-measured resonances. We used these resonance strengths to calculate the stellar reaction rate for ²⁵Mg(p, γ)²⁶Al. These results show that the p-wave resonance at 92 keV (E_x = 6399 keV) dominates the reaction rate in the temperature range 0.06 < T₉ < 0.13.

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^☆: Work supported by National Science Foundation.

^††: Present address Yale University, New Haven, Connecticut 06520.

^†††: Presently at Oxford University on leave from University of Pennsylvania.

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Nuclear Physics A

Abstract

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Cited by (35)

The <sup>25</sup>Mg(p, γ) <sup>26</sup>Al reaction at low astrophysical energies

Renaissance of the Nilsson-model approach to light nuclei: The case of the A = 26 system

Spectroscopic factors from one-proton stripping reactions on sd-shell nuclei: experimental measurements and shell-model calculations

Measurements of differential cross-section ratios for single-nucleon transfer reaction pairs near A = 25

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

Spectroscopic factors for proton unbound levels in <sup>26</sup>Al and their influence on stellar reaction rates

A study of 26Al by the 25Mg(3He, d) reaction☆

Abstract

Can. J. Phys.

Can. J. Phys.

Nucl. Phys.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Nucl. Phys.

Nucl. Phys.

Phys. Rev.

A study of ²⁶Al by the ²⁵Mg(³He, d) reaction☆