Response of C_(2)H_(2)F_(4)superheated emulsion to quasi-mono-energetic neutrons at low frequency

Background The response of superheated emulsion detector with different halocarbons as active liquid to poly-energetic and mono-energetic neutrons has been carried out by different workers.The C_(2)H_(2)F_(4)detectors have not been explored much.This liquid has shown the potentiality of sensitivity to low-mass dark matter.The previous calibration of this liquid was carried out with the poly-energetic neutrons.Purpose In the present work,to better characterize the detector with neutrons,it is irradiated with quasi-mono-energetic neutrons and the results are compared with neutrons from 241Am-Be.To run the detector for the dark matter search,it is required to calibrate it with neutrons,preferably with mono-energetic neutrons.But mono-energetic neutron is not available at all establishments;hence,it was calibrated with quasi-mono-energetic neutrons.Method The response of superheated emulsion consisting of the droplets of C_(2)H_(2)F_(4)has been studied using the quasi-mono-energetic neutrons.The superheated droplets have been fabricated in a visco-elastic gel matrix.The shock waves generated by the passage of the energetic particles are detected by the acoustic sensors coupled to the emulsion.The measurement has also been carried out for the blank target and beam-off conditions.Results and conclusion It is observed that the(Pvar)response of the emulsion in the low-frequency range is sharper for the quasi-mono-energetic neutrons from 7Li(p,n)reaction and wider for the poly-energetic neutrons from 241Am-Be.The fundamental frequency associated with bubble nucleation(FF values)is similar for the neutrons from 7Li-target and 241Am-Be source.The precise characterization of such detector is required for the application in neutron measurement as well as for the dark matter search experiment apart from the basic understanding of the radiation-induced bubble nucleation.

Monoenergetic electron parameters in a spheroid bubble model

A reliable analytical expression for the potential of plasma waves with phase velocities near the speed of light is derived.The presented spheroid cavity model is more consistent than the previous spherical and ellipsoidal models and it explains the mono-energetic electron trajectory more accurately,especially at the relativistic region.The maximum energy of electrons is calculated and it is shown that the maximum energy of the spheroid model is less than that of the spherical model.The electron energy spectrum is also calculated and it is found that the energy distribution ratio of electrons △E/E for the spheroid model under the conditions reported here is half that of the spherical model and it is in good agreement with the experimental value in the same conditions.As a result,the quasi-mono-energetic electron output beam interacting with the laser plasma can be more appropriately described with this model.