Correlations in nuclear interactions between ECM/u and unexplained experimental observables

A new concept is introduced for the classification of 'unresolved problems' in the understanding of interactions in thick targets irradiated with relativistic ions: The centre-of-mass energy per nucleon of a hypothetical compound nucleus from a primary interaction, ECM/u, is calculated and correlated with several experimental observations in thick target irradiations. One observes in various reactions of relativistic primary ions with thick targets that there appears to be a threshold for reactions leading to 'unresolved problems' which lies around ECM /u ∼ 150 MeV where E is the kinetic energy of the beam. A thick target is defined so that products from the first nuclear interaction will make secondary nuclear interactions. All 'unresolved problems' are exclusively observed above this threshold, whereas below this threshold no 'unresolved problems' are found. Another (the same?) threshold exists at a nuclear temperature of 158±3 MeV as a threshold for massive pion production in nuclear interactions. Hagedorn had proposed this threshold decades ago and it is known as the Hagedorn limit. In this paper we will only mention, but not elaborate on Hagedorn's theoretical concept any further. Some considerations will be presented and further studies in this field will be suggested.