Symmetrical Tripartition ofU235by Thermal Neutrons

Making use of an ionization chamber divided into three sections and triple coincidence circuit in conjunction with either a gated ten-channel amplitude discriminator or a double coincidence circuit, it has been found possible to determine the frequency of symmetrical triple fissions in ${\mathrm{U}}^{235}$ relative to the frequency of binary fissions. The results of the experiment are that triple fissions occur to the extent of 6.7±3.0 per ${10}^6$ binary fissions in the case where the fragments come off with comparable masses.