An analysis of BCS solutions with realistic interactions

We adopt the principle that the BCS solution can be regarded as a generating function for ground states of neighbouring nuclei. A parametrisation of the binding energy in terms of the number of particles is assumed and the assumption tested. Using an ansatz from statistical mechanics, a formula for the distribution of the number of particles is developed and the formula is shown to give accurate answers. The concept of temperature is introduced and its interpretation in many-particle theory is clarified.