On Gravitational Radiation Graviton Number Density: Application to a Nambu String

A formalism is developed to compute the number density of gravitons, of specified energies, produced by an arbitrary external energy-momentum tensor source at any temperature. The formalism is applied to a simple Nambu string without making the usual assumption of a long wavelength approximation (L.W.A.). This exact result is also compared to the L.W.A.