Measurement of mass and total kinetic energy distribution of fission fragments using newly developed compact MWPC detectors

Abstract

Two large area (12.5 cm × 7.5 cm) position sensitive compact multiwire proportional counter detectors have been developed for the study of fission reactions for bombarding energies near the Coulomb barrier. Each detector provides one negative fast signal (anode signal) which is used for the time of flight measurement, in addition to four position signals. The timing signal from anode and delayed timing signal from position frames are processed through non-inverting and inverting fast preamplifiers developed in-house. These preamplifiers are based on monolithic microwave integrated circuits. The position resolutions were measured using a mask made of aluminium. The X and Y-position resolutions were found to be ≈ 1.3 and 1.4 mm respectively. The time spread obtained from the sum spectra of position signals extracted from both the ends of the same position frame, was ≈ 1.6 ns. The detectors were used successfully in an in-beam experiment to detect the fission fragments in the 19F+238U reaction. The time correlation spectra between two anode signals provide clean identification of fission events. Difference of those recorded time was used to measure the mass distribution and hence the total kinetic energy distribution of the fission fragments.