Alpha-cluster break-up and reaction mechanism in (p, α) reactions on light nuclei

doi:10.1016/0375-9474(83)90482-7

Nuclear Physics A

Volume 398, Issue 2, 25 April 1983, Pages 189-202

https://doi.org/10.1016/0375-9474(83)90482-7 Get rights and content

Abstract

The differential cross sections for the ¹¹B(p, α)⁸Be and ²³Na(p, α)²⁰Ne reactions were measured at bombarding energies between 6 and 24 MeV. The observed angular distributions can be divided into two domains: at low energies the shapes vary rapidly with incident energy indicating a compound nucleus reaction ; at higher energies rather stable diffraction patterns are seen exhibiting a direct reaction mechanism and DWBA calculations are able to describe the shapes. The change from one region to the other is rather abrupt and this behaviour seems typical for reactions having an α-like compound nucleus. The energy at which this change occurs corresponds to an excitation energy in the compound nucleus of about 20 MeV above the α-threshold.

References (41)

K. van der Borg et al.
Nucl. Phys.
(1976)
B.F. Bayman et al.
Nucl. Phys.
(1979)
J.W. Smits et al.
Nucl. Phys.
(1979)
T. Kammuri et al.
Phys. Lett.
(1980)
F. Brunner et al.
J. of Phys.
(1980)
H.J. Hauser et al.
F. Hoyler
K. Schenk et al.
Phys. Lett.
(1974)
J.F. Cavaignac et al.
Nucl. Phys.
(1971)
W. Buck et al.
Nucl. Phys.
(1977)

H.D. Holmgren et al.

Phys. Rev.

(1963)

D.G. Kamke et al.

Nucl. Phys.

(1971)

R.M. Devries et al.

Nucl. Phys.

(1972)

S.Abdel Kariem et al.

Verhandl. DPG (VI)

(1982)

T. Nakamura et al.

J. Phys. Soc. Japan

(1962)

C.J. Kost et al.

Nucl. Phys.

(1969)

I. Nonaka et al.

J. Phys. Soc. Japan

(1967)

P. D. Kunz, DWUCK 4, DWBA code,...

D. Kurath et al.

Nucl. Phys.

(1975)

F. Pellegrini et al.

Phys. Rev.

(1977)

F. Pellegrini et al.

Phys. Rev.

(1978)

Cited by (14)

Experimental verification of efficacy of pBCT in terms of physical and biological aspects
2023, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Proton–boron capture therapy (pBCT) has recently attracted attention as a method for enhancing the efficacy of proton therapy. In pBCT, boron-accumulated cancer cells are irradiated with protons to induce the p +¹¹B $\to$ 3 $α$ reaction. The biological efficacy of pBCT has been confirmed by cell-based experiments. However, the actual 3 $α$ reaction cross section is relatively small, and the number of $α$ particles produced by this reaction is known to be significantly less than that in the primary proton beam. Therefore, the effectiveness of pBCT has not been theoretically elucidated, and its physical origin and biological effects remain controversial. Consequently, in this study, we sought to clarify these mechanisms by verifying their physical and biological aspects. First, we explored the possibility that other $α$ -particle production channels as alternatives to the 3 $α$ reaction were the cause of the pBCT effect. The results suggested the existence of other $α$ -particle production reaction channels, as predicted by theoretical calculations. However, these cross sections were not large enough to support the effectiveness of pBCT. Thus, to investigate the efficacy of pBCT, including biochemical factors that are not limited to $α$ -particle production, experiments were performed to measure the cell viability during proton irradiation. The measurements used boronophenylalanine (BPA) and sodium borocaptate (BSH), which are two boron delivery agents used in boron neutron capture therapy (BNCT). However, no significant changes were observed with respect to the conventional proton therapy. Based on these results, the biological efficacy of pBCT remained unconfirmed under our experimental conditions, and the effectiveness of pBCT needs to be carefully discussed in the future.
Analytical approach to the reaction cross section of the fusion of protons with boron isotopes aimed at cancer therapy
2019, Applied Radiation and Isotopes
Citation Excerpt :
Nevertheless, the handbook also recommends to set this threshold to zero by default for protons and pions, allowing to score stars for energies favourable for the proton-boron fusion. There are some works in literature reporting experimental data regarding this reaction's channel, e.g. Segel et al., in 1965 (Segel et al., 1965), Buck et al., in 1983 (Buck et al., 1983) and Becker et al., in 1987 (Becker et al., 1987), covering the protons kinetic energy range between 22 keV and 45 MeV. PBF cross section presents a sharp resonance at 163 keV and a broad resonance around 675 keV, together with other resonances corresponding to different carbon nucleus energy levels at higher energies, as depicted in Fig. 2.
In recent years, the nuclear reaction known as proton-boron fusion has been thoroughly investigated, because it has been proposed as a suitable agent capable of significant improvements in cancer therapy with protons. Thereby, precise knowledge about physical properties involved represents the main strategy to assess actual potential of the proposed treatment method based on proton-boron fusion. In this work, the effective reaction cross section is studied from a theoretical point of view, and a direct application to the inelastic collisions distribution provided by Monte Carlo simulations is reported, weighting the importance of the reaction in the energy deposition process, and hence providing useful insight in the localized nature of the technique.
Energy levels of light nuclei A = 12
2017, Nuclear Physics A
Mechanism of the 15N(p, α)12C reaction at E<inf>p</inf>=9.09-43.7 MeV
2006, Applied Radiation and Isotopes
The spectroscopic-factor amplitudes for the triton-cluster transfer are used in distorted wave born approximation (DWBA) analyses for the first six ¹²C states, up to E_x=17.76 MeV, in the reaction ¹⁵N(p, α) for E_p=9.09–43.7 MeV. Agreements are obtained for most ¹²C states between the theoretically predicted spectroscopic factors (S) and both of experimental and theoretical forward integrated cross-section values (at E_p∼43.7 MeV) and their sequence states with the same nuclear parameters. The theoretical spectroscopic factors failed to predict the transition strengths for the two ¹²C states at 7.6542 and 17.76 MeV, while the DWBA predictions failed to reproduce the strengths of the three ¹²C states at 7.6542, 14.083 and 17.76 MeV. This is probably, in the first case, due to the inclusion of other direct mechanisms and (or) to the multi-step processes in their mechanism, while for the second case, it is may be due to either the angular momentum mismatching effect or the choice of the optical parameters. The agreement between theoretical and experimental data for the first six investigated ¹²C states indicate the success of the Cohen–Kurath wave-functions itself and their accuracy. They also indicate the success of the model of calculations of spectroscopic factors.
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.
The 13C(p, α)10B reaction in the energy range between 18 and 45 MeV
1988, Nuclear Physics, Section A
The differential cross sections for the $^{13} C(p, α)^{10} B$ reaction were measured at proton energies between 18 and 45 MeV. A semi-microscopic distorted-wave Born approximation (DWBA) analysis reproduces the angular distributions in the forward direction over a wide range of incident energies. At higher energies the cross sections for the transitions observed up to E_x = 7.5 MeV are well reproduced by relative spectroscopic factors for the three-particle transfer, indicating the presence of a direct interaction, whereas at lower energies more complicated reaction mechanisms like resonant processes are involved.

View all citing articles on Scopus

^†: Present address: Institut Berlin, Physikalisch-Technische Bundesanstalt Braunschweig und Berlin, D-1000 Berlin 10, Germany.

View full text

Article preview

Nuclear Physics A

Abstract

References (41)

Nucl. Phys.

Nucl. Phys.

Nucl. Phys.

Phys. Lett.

J. of Phys.

Phys. Lett.

Nucl. Phys.

Nucl. Phys.

Phys. Rev.

Nucl. Phys.

Nucl. Phys.

Verhandl. DPG (VI)

J. Phys. Soc. Japan

Nucl. Phys.

J. Phys. Soc. Japan

Nucl. Phys.

Phys. Rev.

Phys. Rev.

Cited by (14)

Experimental verification of efficacy of pBCT in terms of physical and biological aspects

Analytical approach to the reaction cross section of the fusion of protons with boron isotopes aimed at cancer therapy

Energy levels of light nuclei A = 12

Mechanism of the <sup>15</sup>N(p, α)<sup>12</sup>C reaction at E<inf>p</inf>=9.09-43.7 MeV

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

The <sup>13</sup>C(p, α)<sup>10</sup>B reaction in the energy range between 18 and 45 MeV