Multistep processes in the (d, 6Li) reaction

doi:10.1016/0370-2693(72)90550-3

Physics Letters B

Volume 40, Issue 4, 24 July 1972, Pages 456-458

https://doi.org/10.1016/0370-2693(72)90550-3 Get rights and content

Abstract

At 28 MeV, the (d, ⁶Li) reaction on A = 4n targets in the 1p and 2s-1d shells systematically populates unnatural-parity states with large relative cross sections. This results suggests the presence of multistep reaction processes, making questionable the extraction of nuclear-structure information with DWBA.

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Cited by (14)

Coupled-reaction-channel analysis of the (d, 6Li) reaction on 24Mg and 26Mg to low-lying states
1986, Nuclear Physics, Section A
Experimental spectroscopic factors of the alpha-transfer reaction on nuclei of the sd-shell show rather strong inconsistencies and scatter much more strongly than explainable by the quoted errors. The poorer the quality of agreement between experimental and theoretical angular distribution shapes, the more inconsistent the comparison of spectroscopic factors either between different experiments or between theory and experiment. In view of the strong deformation of nuclei in the lower part of the sd-shell, higher-order reaction mechanisms are expected. A coupled-reaction-channel analysis for the transitions to the 0⁺, 2⁺, and 4⁺ states of the ground-state bands in ²⁰Ne and ²²Ne excited via the (d, ⁶Li) reaction yields good agreement between experimental and theoretical angular distribution shapes as well as spectroscopic information.
Four-nucleon pickup reaction on 12 ≤ A ≤ 94 nuclei
1984, Nuclear Physics, Section A
The differential cross sections for the (d, ⁶Li) reaction on targets of ¹²C, ¹⁶O, ²⁴Mg, ⁴⁰Ca, ⁵⁸Ni and ⁹⁴Mo have been measured at E_d = 54.2 MeV. The measured angular distributions have been analyzed by finite-range DWBA calculations, and spectroscopic factors for an α-cluster transfer have been extracted. In the DWBA analysis using an optical model with a phenomenological Woods-Saxon potential, the spin-orbit part of the deuteron optical potential played a significant role in reproducing the measured angular distributions but the spin-orbit part of the ⁶Li optical potential had a minor effect. Relative spectroscopic factors extracted from the present data were compared with theoretical predictions together with the results from the (p, pα) reaction. The relative spectroscopic factors for 1p-shell nuclei were in quantitative agreement with theoretical predictions. However, there were certain discrepancies between the spectroscopic factors extracted from the (d, ⁶Li) reaction and those from the (p, pα) reaction, and the discrepancies increased with target mass number.
The (d, 6Li) reaction on 12C, 16O, 24Mg, 40Ca and 58Ni at 54.25 MeV
1980, Physics Letters B
The (d, ⁶Li) reaction was studied at E_d = 54.25 MeV on the target nuclei ¹²C, ¹⁶O, ²⁴Mg, ⁴⁰Ca and ⁵⁸Ni. The data were analyzed with finite-range DWBA calculations. The absolute values of the α-cluster spectroscopic factors and the target mass dependence of the relative S_α were in agreement with those in the (p, pα) reaction at E_p = 100 and 157 MeV. The theoretical calculations of the relative S_α were in better agreement with the experimental data at higher energy than at the lower energies.
A survey of the (3He, 7Be) reaction at 70 MeV
1976, Nuclear Physics, Section A
A study of the (³He, ⁷Be) reaction has been undertaken using a 70 MeV ³He beam. By surveying a wide range of target nuclides, namely ^{12, 13}C, ¹⁶O, ^{24, 26}Mg, ^{40, 42, 44}Ca, ^{58, 60, 62, 64}Ni, ⁹⁰Zr, ^{120, 124}Sn, ¹⁴⁴Sm and ²⁰⁶Pb, systematics of the α-clustering phenomenon were investigated. In addition, masses and energy levels of ⁶⁰Fe and ¹²⁰Cd were measured. The ⁷Be particles were detected in a single wire proportional counter backed by a plastic scintillator in the focal plane of an Enge spectrometer to ensure adequate particle identification. Total energy resolution as small as 140 keV full width at half maximum was obtained, although in most cases the target thickness limited the energy resolution to larger values. Differential cross sections as low as 20 nb/sr were measured. The finite range programs LOLA and LOLITA were used to calculate differential cross sections for comparison to data, assuming the reaction to proceed by a direct α-transfer. The spectroscopic factors which were extracted show a marked decrease with increasing atomic mass number, implying a decrease in surface α-clustering for heavier nuclei.
The (d, 6Li) reaction on 24Mg, 26Mg and 28Si at 35 MeV
1976, Nuclear Physics, Section A
Data for the (d, ⁶Li) reaction on targets of ²⁴Mg, ²⁶Mg and ²⁸Si have been obtained at 35 MeV bombarding energy. Angular distributions were measured for low-lying states in the residual nuclei. Zero-range distorted-wave Born approximation (DWBA) calculations have been used to analyze the data. The DWBA calculations account for the shapes of the experimental distributions reasonably well. The observation of significant population of unnatural parity states implies, however, that other transfer mechanisms may be important. The experimental spectroscopic factors are in qualitative agreement with those obtained from SU(3) theory.
Alpha-particle spectroscopic amplitudes for sd shell nuclei
1975, Nuclear Physics, Section A
Theoretical predictions for spectroscopic amplitudes corresponding to α-particle stripping and pickup reactions on all stable sd shell nuclei with 16 ≦ A ≦ 28 are tabulated. A pure (Os)⁴ configuration for the internal wave function of the transferred nucleons is assumed. Initial and final states of the target and residual nuclei are taken to be members of pure rotational bands obtained by angular momentum projection from a single irreducible representation of SU(3). Using the tabulated results, the effect of representation mixing can be assessed. The predicted results for ¹⁸O + α ²²Ne and ²⁰Ne + α ²⁴Mg are compared to results obtained with wave functions for ¹⁸O and ²⁰Ne generated in shell model calculations. The results show that structural detail can be important, but rarely changes the simple prediction by more than a factor of two with transfers predicted to be strong/weak remaining so when representation mixing is taken into account.

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^☆: Supported by the National Science Foundation and also, in part, by the US Atomic Energy Commission at Princeton University.

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Physics Letters B

Abstract

References (9)

Phys. Lett.

Nucl. Phys.

Ann. Rev. Nucl. Sci

Cited by (14)

Coupled-reaction-channel analysis of the (d, <sup>6</sup>Li) reaction on <sup>24</sup>Mg and <sup>26</sup>Mg to low-lying states

Four-nucleon pickup reaction on 12 ≤ A ≤ 94 nuclei

The (d, <sup>6</sup>Li) reaction on <sup>12</sup>C, <sup>16</sup>O, <sup>24</sup>Mg, <sup>40</sup>Ca and <sup>58</sup>Ni at 54.25 MeV

A survey of the (<sup>3</sup>He, <sup>7</sup>Be) reaction at 70 MeV

The (d, <sup>6</sup>Li) reaction on <sup>24</sup>Mg, <sup>26</sup>Mg and <sup>28</sup>Si at 35 MeV

Alpha-particle spectroscopic amplitudes for sd shell nuclei

Multistep processes in the (d, 6Li) reaction☆

Abstract

Phys. Lett.

Nucl. Phys.

Ann. Rev. Nucl. Sci

Multistep processes in the (d, ⁶Li) reaction☆