Measurement of low neutron fluences with polycarbonate foils electrochemically etched with methyl alcohol-KOH solution.

Electrochemical etching of polycarbonate foils was performed using a KOH solution with a high concentration of methyl alcohol under different conditions of field strength, frequency, temperature and etching time. these studies showed that the highest neutron sensitivity relative to the inherent background in the foil was obtained under the following etching conditions: 52 kV/cm, 1 kHz, 30 degrees C, 30 min in a solution of 45 gm KOH + 80 cc CH3OH + 20 cc H2O. Under these conditions, 100 mrem of neutrons from a Ra-Be source gave 70 pits per cm2 while background was 7 +/- 3 pits per cm2 (10 +/- 5 mrem). The pit diameters were about 90 micrometers. This sensitivity (giving lowest measurable dose of 15 mrem) is quite sufficient for personnel neutron dosimetry applications and the size of the pits is large enough for easy counting using a microscope at a magnification of 40 X.