Fast neuron spectroscopy with tensioned metastable fluid detectors

A portable system for detecting neutrons comprising a plurality of tensioned metastable fluid detectors (TMFDs), a neutron source, and a tensioned metastable fluid detector controller, wherein the portable system is configured to acquire a vector matrix [EV], generate a response matrix [RM], and derive a neutron energy vector [NE] based on [EV]=[RM]x[NE], wherein [EV] is a vector matrix of results of relative detection time for a range of Pneg values obtained experimentally by placing said plurality of tensioned metastable fluid detectors (TMFDs) equidistance from an unknown neutron source, RM is a response matrix representing a probability matrix for detecting a fraction of neutrons of a certain energy from cavitation detection events, and Pneg is the tensioned negative pressure.