The following footnote, which deals with the p + Li7 → 2α + energy reaction, was taken from Ken Ford’s new (2015) book, titled “Building the H-Bomb. His book can be downloaded from http://www.worldscientific.com.
*This reaction can be viewed as a kind of fission process. The combination of a proton and a Li7 nucleus creates, momentarily, a beryllium-8 nucleus (containing four protons and four neutrons), which then splits into two alpha particles, each with two protons and two neutrons. This fission process is an exception to the rule explained later in this chapter that fission releases energy for heavy nuclei, whereas fusion releases energy for light nuclei. That rule applies only for stable or long-lived nuclei. The highly unstable, and very short-lived Be8 nucleus does release energy when it undergoes fission.