摘要
Kalbach Mann systematics is a very useful formula to discrete the double-differential cross sections of emitted particles. However, the energy balance by using this systematics is still a task to be studied. In the form of Legendre polynomial expansion the energy balance has been proved analytically. In terms of this approach, the formula to determine the prc-equilibrium fraction r factor of Kalbach Mann systematics has been obtained for keeping energy balance strictly. This formula could be straightforwardly applied for describing the double-differential cross sections of all projectile types in the eontinuum spectrum emissions. It indicates that Legendre expansion coefficient with l= 1 is the key term in the energy balance.
