Survival and initial chromatid breakage in normal and tumour cells exposed in vitro to gamma rays and carbon ions at the HIRFL

Human hepatoma and normal liver cells were irradiated with (12)C(6+) ion beams (linear energy transfer (LET) = 96 keV microm(-1)) and gamma-rays at the Heavy Ion Research Facility in Lanzhou (HIRFL). The numbers and types of chromatid breaks were detected using the premature chromosome condensation technique. Irradiation with (12)C(6+) ions produced a majority of isochromatid break types, while chromatid breaks were dominant for irradiation with gamma-rays. Experimental results showed that the initial level of chromatid breaks is clearly related to the absorbed dose from (12)C(6+) ions and gamma-rays. The (12)C(6+) ions are relatively more effective at inducing initial chromatid breaks when compared with the gamma-rays. A relative biological effectiveness (RBE) of about 2.5 resulted for the induction of initial chromatid breaks by (12)C(6+) ions relative to gamma-rays in both cell lines.

Measurement of neutrons produced in an intermediate energy heavy ion reaction using an activation technique

The fluence rate, energy, and angular distributions of neutrons produced by the reaction of 50 MeV/u 12C ions on a thick copper target around the experimental target in the physics experimental hall of Heavy Ion Research Facility of Lanzhou were studied. The neutrons were measured with threshold activation detectors. Aluminum, fluorine, carbon, aluminum, and indium activation samples were used to measure neutrons with energies greater than 7 MeV, 11 MeV, 20 MeV, 50 MeV, and thermal neutrons, respectively. The fluence rate, energy and angular distributions of neutrons, total neutron yield of 12C ions, and the emission rate in the forward direction of neutrons with energies over 11 MeV and 20 MeV were obtained.