A Bonner sphere is a device used to determine the energy spectrum of a
neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
beam.
The method was first described in 1960 by
Rice University
William Marsh Rice University (Rice University) is a Private university, private research university in Houston, Houston, Texas. It is on a 300-acre campus near the Houston Museum District and adjacent to the Texas Medical Center. Rice is ranke ...
's Bramblett, Ewing and
Tom W. Bonner 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
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 ...
. 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 Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested ...
, 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 a remball.
See also
*
Neutron detection
Neutron detection is the effective detection of neutrons entering a well-positioned detector. There are two key aspects to effective neutron detection: hardware and software. Detection hardware refers to the kind of neutron detector used (the most ...
References
Particle detectors
Spectrometers
Neutron instrumentation
Neutron-related techniques
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