A POSITION-SENSITIVE IONIZATION-CHAMBER FOR MEASUREMENT OF FISSION FRAGMENTS AND MEDIUM MASS HEAVY-IONS

A position sensitive ionisation chamber telescope is described with DE LTAE(gas)-Eg.s sections which can measure simultaneously the specific energy loss DELTAE, energy E and the position of heavy ion reaction pr oducts in the median plane. The position information is derived by hav ing a split DELTAE structure and by adopting the pulse division method for the signals collected by the two DELTAE sections. For on-line ang le calibration, the E-part of the anode structure is also split into f ive segments. The detector was tested with fission fragments from a Cf -252 spontaneous fission source and with heavy ions from the pelletron tandem accelerator. Simultaneous measurement of DELTAE and E gives go od separation for heavy and light fission fragment groups. The positio n resolution is found to be 1.1 mm for fission fragments. The detector has been used in heavy ion reaction studies for measuring fission fra gments, providing good separation from projectile-like particles.