4. METHOD OF SOLUTION
The code is run interactively and the user examines the output and chooses what he feels to be the best values for the number of resonances to be considered and for D noting for example that at the higher energies resources may have been missed through lack of resolution, which leads to a steady increase in successive values of D.
The program goes on to calculate the value of the level density parameter which corresponds to the chosen value of D, using a back- shifted Fermi-gas model, and to calculate the values of D for dif- ferent spin states of the compound nucleus. Finally the observed resonance energies are compared with an energy ladder whose rungs are uniformly spaced; the deviations of the resonance from the lad- der energies are tabulated, and their standard deviation. This com- parative table indicates roughly just where resonances may have been missed, supposing the value of D well-chosen. Most probable values are given for the energies of the top bound resonances, these are estimated by use of Dyson's Coulomb gas model.
For materials such as iron the resolved resonances extend nearly to 1 MeV, and over so wide a range D must be expected to decrease steadily by a factor of two. If the resonance energies are input in keV units, DEEBAR uses the level density formalism to allow for the expected energy dependence, both in calculation of D values for zero neutron energy and in the energy ladder.