Calculation of correla- tions in four-proton decay by Monte-Carlo method

Abstract

Relatively light stable isotopes are characterized by roughly equal numbers of neutrons and protons in the nucleus. At the same time, the characteristic binding energy of a nucleon is a few MeV. Such nuclei form a “nuclear stability valley” on the isotope map. Changes in the ratio of the number of protons to that of neutrons result in a decrease of the binding energy. If protons (neutrons) are in excess, the binding energy of the proton (neutron) decreases, crosses zero at some moment of time, and becomes negative. As a result the nucleus becomes unstable (unbound). On the isotope map the areas of bound and unbound nuclei are separated by the lines called “driplines”. The properties of nuclei near the driplines are significantly different from those of stable nuclei. The dynamics of the two-proton 2p decay may be an example. For stable nuclei the separation energy of two protons ( ) is higher than that of a single proton ( ). The 2p decay proceeds by successive population of intermediate states. In the vicinity of driplines, however, it is possible that > and direct 2p decay is observed. (i.e., simultaneous emission of protons without population of the intermediate state). There are indications of the existence of nuclear systems bound to decay with emission of four protons from the ground state. This type of decay has a fairly complex dynamics and its study is a challenge for both theorists and experimentalists. In this work the theoretical study of the four-proton 4p decay was carried out: correlations of decay products were calculated. Analytically, wave function antisymmetrization leads to very complex, cumbersome calculations. Therefore, in the work the calculation was carried out by means of the numerical Monte Carlo method.