Superheated emulsions in neutron spectrometry by varying ambient pressure

The principle of present work lies on the dependence of the threshold neutron energy on the dimensionless quantity “degree of metastability (ss)” of superheated liquids. The response of the superheated emulsions consists of the drops of superheated liquid (C2Cl2F4, b.p. 3.77°C) has been measured at different ‘ss’ by varying ambient pressure at different temperatures, in the presence of neutrons generated in Pb by a (γ,n) reaction from 45MeV electron LINAC of Hokkaido University. To unfold the neutron energy spectrum, a relationship has been developed between the ‘ss’ of superheated liquids and the threshold neutron energy. The spectrum at the detector position has been calculated by the MCNP code and a comparison has been made with the experimental spectrum. The utilisation of ‘ss’ is more flexible as this relation can be applied to both positive and negative ambient pressures as well as at different ambient temperatures.