A proposed experiment for determining the neutron-neutron effective range by means of doubly quasi-free scattering in the D+D reaction

A proposal for determining the effective range rsub(nn) and possibly phases at higher energy for the n-n interaction is dealt with. The reason for the need of measured n-n parameters is the dependence of the Coulomb corrections on the off-shell-behaviour of the N-N interaction. In principle D(n,2n)p is the simplest source of two interacting neutrons. As rsub(nn) governs the scattering process in the region of several MeV relative energy one would chose kinematical conditions corresponding to quasi-free scattering of the two neutrons. But the form of resulting spectra is rather insensitive to rsub(nn), whereas the absolute value of the cross section is influenced more strongly. However precision absolute measurements with neutrons as incident particles are very difficult to achieve experimentally. The task would be very much facilitated if charged particles directly from an accelerator could be used. Now one can find kinematic conditions for quasifree scattering of two neutrons in the D(d,2n)2p reaction with zero momentum transfer to each of the remaining protons (doubly quasifree scattering DQFS). In order to get a certain impression about the expected spectra some calculations in the impulse approximation were done. (Auth.)