Particular aspects related to the even-odd effects in prompt emission

Abstract

The present paper focuses on several particular aspects related to the even-odd effects in prompt emission in fission synthesized as follows: 1) The even-odd effects in prompt emission are the result of two contributions, a dominant one due to the even-odd nuclear character of fission fragments reflected in their properties and consequently in the emitted prompt neutrons and gammas, and a weaker contribution brought by the even-odd effect in the fragment distribution (over which the prompt emission matrices are averaged). Oscillations with a periodicity of about 5 mass units are present in different prompt emission quantities corresponding to even-Z and odd-Z fragmentations independent of the size of the even-odd effect in the charge yield Y(Z). 2) The oscillation periodicity ΔA≈5 in the charge polarization ΔZ(A) and rms(A) of the isobaric charge distribution as well as in the fragment mass yields Y(A) of even-Z and odd-Z fragmentations is also due to the periodicity of nuclear properties being independent of the size of the even-odd effect in Y(Z). Only the magnitude of the oscillation amplitudes of ΔZ(A), rms(A) and Y(A) of even-Z and odd-Z fragmentations reflects in different ways the size of the even-odd effect in Y(Z). 3) Not only the basic features of the global even-odd effect in fragment yields and prompt mission are the same but also the local even-odd effect in prompt emission --reported for the first time in this paper-- exhibits the same behaviour as the experimental data of the local even-odd effect in Y(Z). 4) A correlation between the even-odd effect in Y(Z) and prompt emission quantities (e.g., ν(Z) exists. This interrelation is through the nuclear properties of the fission fragments. The presence of oscillations with a period ΔA≈5 in both Y(A) and prompt emission quantities corresponding to even-Z and odd-Z fragmentations cannot be directly linked to the size of the even-odd effect in Y(Z).