Bonner Spheres
Precision neutron measurement solutions for accurate, reliable energy spectra for research, calibration, and radiation protection.
Exosens' Bonner Spheres are precision-engineered neutron moderators designed for accurate, energy-resolved neutron measurement in laboratory settings. Each sphere features a high-quality polyethylene shell surrounding a centrally mounted 3He detector, ensuring uniform moderation and isotropic sensitivity. Using a set of spheres of varying sizes allows a comprehensive analysis of neutron energy spectra across a broad range.
Bonner Spheres
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Electrical and Performance
(Standard product fitted with spherical, 152 cmHg, 3He detector type SP9 )
| Parameter | Specification |
|---|---|
| Range of Measurement, Neutron Energy | 0.025 eV – 10 MeV |
| Range of Measurement, Neutron Intensity | 0.1 – 10000 μSv/hr |
| Neutron Sensitivity | 6 cps per 25 μSv/hr |
| Normal Operating Voltage | 800 – 900 V |
| Amplifier Charge Sensitivity at Operating Discriminator Level | 1.6 × 10−14 coulombs |
| Operating Temperature | 80 °C max. |
Option
A range of Bonner sphere sizes are available, consisting of standard-density polyethylene of diameters:
| 3” (76.2 mm) | 4.5” (114.3 mm) | 7” (177.8 mm) | 9.5” (241.3 mm) | 15” (381 mm) |
| 3.5” (88.9 mm) | 5” (127 mm) | 8” (203.2 mm) | 10” (254 mm) | 18” (457.2 mm) |
| 4” (101.6 mm) | 6” (152.4 mm) | 9” (228.6 mm) | 12” (304.8 mm) | — |
Each Bonner Sphere is designed to accommodate a standard body-length SP9 thermal neutron detector with a PET137 connector*, fully interchangeable across all sphere sizes. When neutrons interact with the polyethylene moderator, many are slowed down (moderated) to thermal energies, making them readily detectable by the centrally mounted SP9 detector.
The moderation effect depends on sphere size: larger spheres increase the likelihood of capturing higher-energy neutrons, while smaller spheres are more effective for lower-energy ranges. By carefully combining measurements from spheres of different diameters, users can achieve accurate and relatively linear detection of neutrons across a wide energy spectrum.
*other connectors available at request
Description
Exosens Bonner Spheres provide highly accurate neutron spectral measurement through precision construction and thoughtful design. Each sphere consists of a high-grade polyethylene shell with a centrally mounted 3He detector, ensuring consistent moderation in all directions for reliable, isotropic neutron detection.
Available in multiple diameters, these spheres allow researchers to reconstruct detailed neutron energy spectra by comparing responses across the set. The modular design makes them ideal for nuclear physics research, radiation protection studies, and calibration laboratories.
3He counters are supplied with standard 2-atmosphere filling, with custom pressures available for enhanced sensitivity. Various mounting options and connectors ensure easy integration into existing instrumentation or free-standing laboratory setups.
Designed for versatility, Exosens Bonner Spheres connect seamlessly to remote electronics or data acquisition systems, providing precise, energy-resolved neutron data for demanding research and calibration applications.