Partial optimization of electrochemical-etching parameters for highly sensitive CR-39 fast neutron dosimeters

Area of Science:

• Nuclear Science and Engineering
• Materials Science

Background:

• CR-39 plastic is a widely used solid-state nuclear track detector.
• Neutron detection often requires sensitive and reliable methods for radiation monitoring.

Purpose of the Study:

• To investigate the effect of voltage gradient and frequency on the electrochemical etching of neutron-irradiated CR-39 plastic.
• To determine optimal parameters for maximizing neutron sensitivity and minimizing background track density.

Main Methods:

• Electrochemical etching of CR-39 plastic using a power supply with variable voltage (up to 1.5 kV rms) and frequency (up to 5 kHz).
• Differential voltage measurements to identify optimal etching conditions.
• Subsequent etching experiments with irradiated and unirradiated CR-39 foils in 9N KOH.
• Introduction of a proton irradiator cover and pre-etching step.

Main Results:

• Optimal electrochemical etching parameters identified as 20 kV/cm and 1.3 kHz.
• Maximum sensitivity achieved with these parameters.
• A 30-fold increase in neutron sensitivity and a decrease in background track density to 4.4 +/- 0.6 tracks/cm² were observed with modifications.
• Achieved sensitivity of 1.3 tracks/cm²/mrem with a minimum detectable dose of 1.4 mrem.

Conclusions:

• Electrochemical etching parameters significantly influence CR-39 plastic's neutron detection capabilities.
• Optimized methods, including a proton irradiator cover and pre-etching, substantially improve neutron sensitivity and reduce background.
• The developed technique offers a sensitive and reliable method for fast neutron dosimetry.