A Bonner sphere is a device used to determine the energy spectrum of a
neutron beam.
The method was first described in 1960 by
Rice University's Bramblett, Ewing and
Tom W. Bonner
Tom Wilkerson Bonner (19 October 1910, Greenville, Texas – 6 December 1961 Houston, Texas) was an American experimental physicist who developed important instruments and techniques for neutron physics and nuclear physics ( Bonner sphere).
Biogr ...
and 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. This detector system utilizes a few channel unfolding techniques to determine the coarse, few group neutron spectrum. The original detector system was capable of measuring neutrons between thermal energies up to ~20 MeV. These detectors have been modified to provide additional resolution above 20 MeV to energies up to 1 GeV.
Bonner sphere spectroscopy
Because of the complexity with which neutrons interact with the environment, precise determination of the neutron energy is quite difficult. Bonner sphere spectroscopy (BSS) is one of the few methods that provide an accurate measure of the
neutron spectrum
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...
.
Remball
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
Equivalent dose is a dose quantity '' H '' representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the ph ...
across a range of neutron energies. Such Bonner spheres are sometimes known as a remball.
See also
*
Neutron detection
References
Particle detectors
Spectrometers
Neutron instrumentation
Neutron-related techniques
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