Alpha/beta discrimination in a position-sensitive fiber detector based on a pulse height method.

Area of Science:

• Nuclear Instrumentation
• Radiation Detection and Measurement
• Materials Science

Background:

• Surface contamination monitoring is critical for nuclear facility decommissioning.
• Conventional survey meters have limitations in measurement area and alpha/beta discrimination.
• Outer-layer scintillating (OLS) fibers were previously developed for charged particle detection.

Purpose of the Study:

• To develop a one-dimensional position-sensitive detector using OLS fiber.
• To achieve simultaneous alpha and beta particle discrimination over wide areas.
• To evaluate the detector's performance for surface contamination monitoring.

Main Methods:

• Developed a 1D position-sensitive detector utilizing OLS fiber technology.
• Employed pulse height discrimination for alpha/beta particle differentiation.
• Used coincidence measurements with summation signals from silicon photomultipliers to mitigate position dependence.
• Applied time-difference measurements for position sensitivity.

Main Results:

• Simulations confirmed OLS fiber's capability to stop alpha and low-energy beta particles.
• The detector successfully identified alpha-contaminated regions using a fixed threshold on the summation signal under mixed radiation.
• Achieved reliable 1D position sensitivity with a spatial resolution of ~150 mm over a 2.6 m fiber length.

Conclusions:

• OLS fiber-based detectors show feasibility for wide-area alpha/beta identification.
• The developed detector system is promising for surface contamination monitoring in nuclear decommissioning.
• Further validation is needed for longer fiber configurations and diverse operational environments.