Seminar in Nuclear Physics: Search for a bound di-neutron by comparing 3He(e,e’p)d and 3H(e,e’p)X measurements

Abstract:

We report on a search for a bound di-neutron by comparing electron-induced proton-knockout measurements from Helium-3 (3He) and Tritium (3H). The measurements were performed at Jefferson Lab Hall A with a 4.326 GeV electron beam, and kinematics choosen to minimize contributions from non  quasi-elastic (QE) reaction mechanisms.

Analyzing the measured 3He missing mass (Mmiss) and missing energy (Emiss) distributions, we can distinguish the two-body break-up reaction, in which the residual proton-neutron system remains bound as a deuteron. In the 3H mirror case, under the exact same kinematic conditions, we do not identify a signature for a bound di-neutron with similar binding energy to that of the deuteron. We calculate exclusion limits as a function of the di-neutron binding energy and find that, for  binding equivalent to the deuteron, the two-body break-up cross section on 3H is less than 0.9% of that on 3He in the measured kinematics at the 95% confidence level. Our sensitivity degrades rapidly as the di-neutron binding energy decreases.