Because helium-4 is very stable, there is a strong tendency on the part of two deuterium nuclei to combine to form helium-4 .

This is the total spin of the deuterium nucleus.

It has been synthesised in the laboratory by bombarding tritium with fast-moving deuterium nuclei.

Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron.

This is why brown dwarfs (so-called failed stars) cannot utilize ordinary hydrogen, but they do fuse the small minority of deuterium nuclei.

For instance, when two deuterium nuclei fuse, they often produce helium-3 and a free neutron.

The figure on page 28 shows the make-up of these simplest nuclei and illustrates what happens when two deuterium nuclei collide.

Palmer believed that the helium-3 in the atmosphere comes from the fusion of two deuterium nuclei or 'deuterons'.

Its final energy for protons, and later deuterium nuclei, was 10 G eV.

Then you will have a deuterium nucleus (a proton and neutron bound together, permanently stable), and a free electron.