This constant, (`m_alpha *c^2`), represent the energy equivalence of the mass of an alpha particle expressed in Joules.

Notes

An alpha particle, `m_alpha`, is two protons and two neutrons bound together as a particle identical to a helium nucleus.  The principle of mass-energy equivalence defines a universal proportionality relationship between equivalent amounts of energy and mass, and that definition defines the proportionality constant to be the speed of light squared.  Thus the mass in this constant is multiplied by `c^2`.

This constant is specified with a standard uncertainty (standard deviation) of: 0.00000026E-10 J