Measurements of low-energy (d,n) reactions for BNCT
N. Colonna · L. Beaulieu · L. Phair · G. J. Wozniak · L. G. Moretto · W. T. Chu · B. A. Ludewigt
Abstract and summary · read the original at the source · none found
In one page
Boron neutron capture therapy needs a very particular kind of neutron: slow enough to be captured in a tumour, not so fast that it burns the skin on the way in. Reactors make them, but a small accelerator would be cheaper, safer and installable in a city hospital — so the question is which nuclear reaction to fire the beam at. Colonna and his colleagues at the Lawrence Berkeley National Laboratory, with Bari’s nuclear-physics institute, went and measured it. Using 1.5 megaelectronvolt deuterons from the laboratory’s 88-inch cyclotron, they counted the neutrons coming off beryllium, carbon-12 and carbon-13 targets, timing each one against the cyclotron’s own radio-frequency clock to get its energy, at five angles at once. The answer is specific: beryllium is spoiled by a hard 3.6 megaelectronvolt component, carbon-12 is clean but too weak, and carbon-13 is the one worth pursuing — plentiful, low in energy, and reachable with a very small machine.
Why it matters hereChapter 12 is about getting useful nuclear output at the lowest beam energy you can arrange, and this is that question asked with a detector in front of it: what does a deuteron at one and a half million volts actually produce, reaction by reaction, angle by angle. It is also a clean model of the discipline the chapter depends on — the yield, the spectrum and the contamination are measured and reported together, so the next person can build on the number instead of the hope.
What it claims
01The target list is chosen by physics before anything is measured. To keep the accelerator small the deuteron energy must stay low, which restricts the search to reactions with a positive or only slightly negative Q-value; the Coulomb barrier then restricts the targets to light elements; and the requirement of a stable, mechanically and thermally convenient material leaves essentially lithium-6, beryllium-9, boron-10, carbon-12 and carbon-13.LBNL-42219, section 1, Introduction
Published and peer-reviewed02The measurement is a time-of-flight measurement against the accelerator’s own clock. Deuteron beams of 1.5 megaelectronvolts and proton beams of 2.5 megaelectronvolts were taken from the 88-inch cyclotron at Berkeley; neutrons were counted in five liquid-scintillator cells 12.7 centimetres across and 5 centimetres thick, set at 0, 30, 60, 90 and 140 degrees at half a metre from the target, and each neutron’s energy was read from its flight time relative to the cyclotron radio-frequency signal. A detection threshold near 10 kiloelectronvolts electron-equivalent was held throughout so that neutrons as slow as 100 kiloelectronvolts would still be counted.LBNL-42219, section 2, Experimental Method
Published and peer-reviewed03Beryllium-9 looks promising and is not. The reaction does give the strong 400 kiloelectronvolt neutron peak that had been proposed as a therapy source, but a second peak sits at about 3.6 megaelectronvolts, from the 2.15 megaelectronvolt level of the boron-10 residue. After efficiency correction the high-energy neutrons are about 38 per cent of the total yield for a thin target and about 50 per cent for a thick one, and the authors judge it unlikely that raising or lowering the bombarding energy will bring that fraction low enough for therapy.LBNL-42219, section 3A, the beryllium-9 reaction
Published and peer-reviewed04Carbon-12 is the clean one and the weak one. Its slightly negative Q-value of minus 0.28 megaelectronvolts gives a clean low-energy emission peaked at 500 kiloelectronvolts with no high-energy contamination at all, and carbon’s very high melting point makes it an easy target to cool — but the yield at every angle is too small for practical use, with preliminary estimates calling for a deuteron beam of several hundred milliamperes at this energy.LBNL-42219, section 3, the carbon-12 subsection, and Table 1
Published and peer-reviewed05Carbon-13 is the result. At 1.5 megaelectronvolts the total neutron yield of the carbon-13 reaction is about 1.9 times ten to the eighth neutrons per microcoulomb of beam, some 30 per cent below the 2.4 times ten to the eighth that published cross-sections imply — a gap comparable to the uncertainty in their own absolute normalisation. About 30 per cent of the neutrons come out above 1 megaelectronvolt, but most of those sit just above 1 megaelectronvolt and only 6 per cent exceed 2 megaelectronvolts. Preliminary moderator calculations indicate that a beam current below 100 milliamperes would keep treatment time under an hour, at a beam quality superior to currently available reactor beams.LBNL-42219, section 3, the carbon-13 subsection, and Table 1
Published and peer-reviewed06What to watch is stated by the authors as an invitation rather than a conclusion. Because of the limited resolution for high-energy neutrons and the uncertainty on the absolute yield, they write that the present results are by no means conclusive and are meant to stimulate further discussion and measurement — while recording their own verdict that carbon-13 is the only potentially interesting alternative among the deuteron-induced reactions studied so far. The measurements that would settle it are named: a better absolute yield, and a full simulation of reflection and moderation.LBNL-42219, section 4, Summary and Conclusions
What to watch
Read it · abstract
Abstract
Neutron yields and energy spectra have been measured for various deuteron-induced reactions at low energy. The main features of these reactions are presented and discussed with regards to their potential use as a source of epithermal neutron beams for Boron Neutron Capture Therapy (BNCT). Among the studied reactions, the 13C(d,n)14N presents features potentially interesting for an accelerator-based neutron source for BNCT.
Keywords: Boron Neutron Capture Therapy (BNCT); Accelerator-based neutron source; Neutron-producing reactions.
N. Colonna, Istituto Nazionale di Fisica Nucleare, Bari; L. Beaulieu, L. Phair, G. J. Wozniak, L. G. Moretto, W. T. Chu and B. A. Ludewigt, Lawrence Berkeley National Laboratory. Medical Physics 26, number 5, pages 793 to 798 (1999). Abstract as printed in the authors’ preprint, Lawrence Berkeley National Laboratory report LBNL-42219, August 1998; mass numbers are written inline here because the site’s pages carry no superscripts.
(Abstract only — see the rights note above for why the six pages of spectra, angular distributions and yield tables are not reproduced here. The published article is at the source, and the preprint is public in the University of California eScholarship repository.)
The neighbouring measurements on this site: the design of a compact linear neutron source is at /library/stm-f71f3bdcb2; the deuteron-plus-deuteron reactions inside a metal lattice, and how easily their measurement goes wrong, are at /library/stm-cd71abdcaa and /library/stm-f5eb4f4d1a; the screening energies those experiments extract are surveyed at /library/stm-8cc2371f17 and /library/stm-d764ed59a9; and the same low-energy deuteron physics driven from inside a solid instead of from a beam line is NASA Glenn’s lattice confinement fusion at /library/stm-e25595eb3b and /library/stm-2bee598802.
The way in
https://doi.org/10.1118/1.598599WHAT THIS IS. Medical Physics volume 26, number 5, pages 793 to 798 (May 1999). Affiliations as printed: N. Colonna, Istituto Nazionale di Fisica Nucleare, Bari, Italy; L. Beaulieu, L. Phair, G. J. Wozniak and L. G. Moretto, Nuclear Science Division, Lawrence Berkeley National Laboratory; W. T. Chu and B. A. Ludewigt, Life Sciences Division, Lawrence Berkeley National Laboratory. LICENCE. The journal version is closed — Crossref carries only the Wiley Online Library terms, and Unpaywall reports the publisher copy closed. THE PUBLISHED ABSTRACT IS NOT REPRODUCIBLE AS TEXT: Wiley deposited it with every numeric value and every reaction symbol replaced by an inline image reference, so the sentences arrive with holes in them. WHAT WAS READ INSTEAD. The complete preprint, Lawrence Berkeley National Laboratory report LBNL-42219, August 1998, submitted to Medical Physics, deposited in the University of California eScholarship repository at escholarship.org/uc/item/0n1762rh and downloaded and read in full on 2026-09-08. Its abstract, reproduced below, is the authors’ own and is complete. Every claim on this page is located against a numbered section or the table of that report. RIGHTS ON THE REPORT. It is not promoted past abstract-only. It is a preprint of a journal article, its cover carries the standard Department of Energy disclaimer naming both the United States Government and the Regents of the University of California, it carries no ‘approved for public release, distribution unlimited’ marking, and the eScholarship deposit carries no Creative Commons statement — so the site treats it as a source to read rather than a text to republish. The work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of Nuclear Physics of the U.S. Department of Energy under contract DE-AC03-76SF00098, and by the Istituto Nazionale di Fisica Nucleare; the Office of Scientific and Technical Information carries it as record 895789. FIGURES. The four figures are not reproduced; the numbers quoted in the claims are read from the text and from Table 1.
How to cite it
N. Colonna, L. Beaulieu, L. Phair, G. J. Wozniak, L. G. Moretto, W. T. Chu, B. A. Ludewigt (1999) Measurements of low-energy (d,n) reactions for BNCT. doi:10.1118/1.598599
Where it sits in the curriculum