Abstract
The fission track spark counting has been widely used for neutron monitoring by polycarbonate film. We have studied spark counting characteristics using polycarbonate detector films of different thickness and aluminized polycarbonate sheets of different aluminum thickness for an electrode, and observed the etch-pit sizes in relation to spark counting. Results obtained are as follows:
1. On spark counting of high density of etch-pits, round etch-pits seemed to be easily spark-punched and rod-like etch-pits remained unpunched.
2. The size of etch-pits due to uranium fission fragments appeared to be somewhat larger than due to thorium fission fragments. And the percentage of rod-like etch-pits to all etch-pits due to uranium fission fragments is smaller than that due to thorium fission fragments.
3. As the thickness of detector films decreases, percentage of round etch-pits to all etch-pits increased and spark counting efficiency increased. From our experiments, Makrofol KG of 10μm thick or Lumirror of 6μm thick appears to be suitable for routine use.
4. As the aluminum thickness of aluminized sheet electrode increases, spark counting efficiency increases slightly, range of spark counting plateau shortens, and multiple sparks occur at low voltage.
