Absolute Negative Pressure Primer
As most readers are most likely not very familiar with Absolute Negative Pressure (ANP) I have attached a link below to a lecture by Dr Seth Putterman of UCLA discussing “sonoluminescence” an absolute negative pressure phenomena which is a good primer to understanding Absolute Negative Pressure. Please note that sonoluminescence doesn't emit neutron and is a electronic (i.e. electron) physical process not a nuclear physical process.
Absolute Negative Pressure discussion of "sonoluminescence"