Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device

Area of Science:

• Nuclear Physics
• Radiation Biology
• Dosimetry

Background:

• Improvised nuclear devices (INDs) pose unique radiation hazards.
• Simulating realistic neutron spectra from INDs is crucial for biological research and biodosimetry.
• Existing facilities often use neutron spectra that differ from those encountered in real-world scenarios.

Purpose of the Study:

• To describe a novel accelerator-based neutron irradiation facility.
• To generate neutron fields mimicking those from an IND at relevant distances.
• To evaluate the facility's capability for biological studies and biodosimetry.

Main Methods:

• Neutrons generated using a mixed proton/deuteron beam on a beryllium target.
• Neutron spectra characterized using proton-recoil proportional counters and liquid scintillators.
• Neutron and gamma dose rates measured with tissue-equivalent ionization chambers and Geiger-Mueller dosimeters.
• Micronucleus yields assessed in human lymphocytes exposed to simulated neutron fields.

Main Results:

• The facility produces a broad neutron energy spectrum (0.2–9 MeV) matching Hiroshima bomb estimates at 1.5 km.
• Measured spectra differ significantly from standard reactor fission spectra.
• Micronucleus yields in human lymphocytes showed a 3- to 5-fold enhancement compared to equivalent X-ray doses.
• The facility is operational for irradiating mice and human blood samples.

Conclusions:

• The developed facility effectively simulates IND-relevant neutron fields.
• Demonstrated higher biological effectiveness of simulated IND neutrons compared to X-rays.
• The facility is valuable for advancing neutron-specific biodosimetry assays.
• Future work will focus on dose reconstruction in mixed radiation fields.