A twin ionization chamber setup as detector for light charged particles with energies around 1 MeV applied to the B-10(n, alpha)Li-7 reaction

The setup and operating conditions of a gridded twin ionization chamber wit h sample change facility to study light charged particle properties in the 1 MeV region is described. Detailed studies of different grid geometries in connection with the choice of an eligible counting gas mixture and the app lied high voltage have been performed. Due to the high overall amplificatio n of the small electrical chamber signals obtained from such low-energy par ticles, special filters have been developed in order to increase the signal -to-noise ratio. Timing properties of the chamber signals are discussed in detail. Information available from chamber signals and encoding methods are elucidated by spectra of alpha particles created by U-234,U-235 spontaneou s alpha decay. The detector permits the independent and simultaneous measur ement of energy and angular distribution of particles in both sides of the chamber. Finally, preliminary results and related analysis methods will be presented for the investigation of the B-10(n, alpha(0))/B-10(n, alpha(1)y) branching ratios. (C) 2000 Elsevier Science B.V. All rights reserved.