Bonner sphere

Bonner spheres are used to determine the energy spectrum of a neutron beam. The methodology, which was first described in 1960 by Rice University's Bramblett, Ewing and Bonner, employs thermal neutron detectors embedded in moderating spheres of different sizes. Comparison of the neutrons detected by each sphere allows accurate determination of the neutron energy.

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Because of the complexity with which neturons interact with the environment, precise determination of the neutron energy is quite difficult. Bonner sphere spectrocopy (BSS) is one of the few methods that provide an accurate measure of the neutron spectrum.

A single Bonner sphere of an appropriate size can be used for dosimetry, as the sensitivity of the detector will approximate the radiation weighting factor across a range of neutron energies. Such Bonner spheres are sometimes known as remballs.

See also

• Neutron detection

References

• A. Esposito and M. Nandy, "Measurement and unfolding of neutron spectra using Bonner Spheres", Radiation Protection Dosimetry 2004 110(1-4):555-558 (doi:10.1093/rpd/nch385)
• Bramblett, R.L.; Ewing, R.I.; Bonner, T.W., "A New Type of Neutron Spectrometer." Nuclear Instruments & Methods; Vol: 9, Oct 1, 1960.