Study of a gold-foil-based multisphere neutron spectrometer

Area of Science:

• Nuclear instrumentation
• Radiation detection and measurement

Background:

• Active thermal neutron detectors in multisphere spectrometers suffer from pulse pile-up and dead-time effects in high-intensity radiation fields.
• Passive detection systems are needed to overcome these limitations for accurate neutron spectrometry.

Purpose of the Study:

• To investigate a multisphere neutron spectrometer utilizing passive gold foils.
• To evaluate the performance of two gold-foil holder designs (aluminum-polyethylene and polyethylene) for neutron detection.
• To assess the angular response of the gold-foil spectrometer.

Main Methods:

• Calculated the neutron energy responses of a gold-foil-based Bonner sphere neutron spectrometer for two holder designs.
• Simulated responses for four incident neutron beam directions: parallel, perpendicular, and +/-45 degrees.
• Verified computed responses by measuring the neutron spectrum of a Californium-252 (252Cf) source.

Main Results:

• The polyethylene holder design demonstrated a more isotropic response to neutrons across the tested incident directions compared to the aluminum-polyethylene holder.
• Calculated responses were validated through experimental measurements using a calibrated 252Cf neutron source.

Conclusions:

• A gold-foil-based Bonner sphere neutron spectrometer is a viable alternative for high-intensity radiation fields.
• The polyethylene holder design offers improved angular response, making it more suitable for diverse neutron measurement applications.