Journal of Physical Studies 3(4), 431–436 (1999)
DOI: https://doi.org/10.30970/jps.03.431
FINAL-STATE INTERACTION AND QUASI-FREE SCATTERING IN THE FOUR-BODY
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B. Struzhko
Institute for Nuclear Research
of the National Academy of Science of Ukraine
47 Nauky Pr., Kyiv, UA-03028, Ukraine
Two–dimensional proton–proton ($pp$) and proton–proton–neutron ($ppn$ ) coincidence spectra from $d+d\longrightarrow p+p+n+n$ four–body break–up are calculated. Quasifree scattering (QFS) of protons in the plane wave impulse approximation and final state interaction of neutron–proton pairs in the Watson–Migdal approximation are taken into account. Calculations are in reasonable agreement with the experimental data obtained at the deuteron beam energy $E_{0}=46.7$~MeV, proton angles in the lab. system $ \vartheta _{1}=\vartheta _{2}=$ $38.75^{\circ},$ $φ _{1}-φ _{2}=180^{\circ}$ and the neutron one $\vartheta _{n}=0^{\circ}$ which are the $pp$ QFS kinematic conditions. Contribution from the sequential $d+d\longrightarrow d^{\ast }+d^{\ast }\longrightarrow p+p+n+n$ process is found to prevail in the double pp coincidence spectrum while only about the fourth part of all events are from $pp$ QFS. This conclusion is supported by a direct comparison of the model and measured ratios of triple $ppn$ coincidence events to the double pp ones.