Residual Track Research Articles

Thermal stability of fission tracks in apatite and sphene: Using confined-track-length measurements

Confined track lengths have been used to monitor the annealing behaviour of fission tracks in Durango apatite and in two natural sphene samples subjected to laboratory annealing treatment. The residual track length and residual track density in apatite are found not to follow a linear one-to-one relationship. Comparison of the spontaneous and induced fission track lengths in sphene samples shows no evidence for the natural fading as is observed in apatite. No significant difference is found between the stability of neutron-induced and spontaneous fission track lengths in sphene over the temperature and time combinations employed. The behaviour of confined track lengths in sphene is found to follow Arrhenius law over the experimental domain investigated. On the basis of the Arrhenius law, our results indicate that, corresponding to a time-period of 10 6 yr, the closure temperature would be 123 ± 10°C for Durango apatite and 423 ± 27°C for the sphene sample investigated.

On a Method to Determine the Charges of Nuclei Stopping in Nuclear Emulsion

By means of width measurements with a filar micrometer the charges of nuclei stopping in nuclear emulsion can be determined. The method of measurement is tested on tracks of 100 stopping cosmic ray nuclei of known nuclear charge Z = 5-26 in G5-emulsion in the residual range interval 0 ⩽ R ⩾ 400 μm. The widths are measured according to a special procedure of measurement.The study shows that it is possible to apply the method of identification on low energy heavy nuclei stopping in the emulsion. The method is a valuable complement to photometric methods at residual track ranges less than 400 μm and is to advantage applicable to fragments emitted in nucleus-nucleus interactions in emulsion at least if the dip angles of the fragments are less than about 35°.