Spherical Proportional Counters
Reliable omni-directional neutron detection with customisable performance.
The SP9 Spherical (Omni-Directional) Proportional Counter is a highly sensitive neutron detector designed for precise and reliable measurements. Utilising ³He gas, it delivers omni-directional response and exceptional performance in thermal neutron monitoring and neutron spectrometry applications.
Engineered for adaptability, the SP9 can be filled with a variety of gas mixtures and pressures to optimise voltage, resolution, sensitivity, and gamma rejection. With rugged construction and customisable options, it is particularly suited for REM monitors in health and safety environments.
Spherical Proportional Counters
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Electrical and Performance
| Paramètre | Valeur |
|---|---|
| Operating Voltage (For Gas Gain ≈ 20) | 152 cm Hg gas pressure: 800 V 304 cm Hg gas pressure: 850 V 532 cm Hg gas pressure: 1000 V |
| Plateau Length | 300 V Min. |
| Plateau Slope | Approx. 2% per 100 V |
| Max. Charge Per Pulse | 3.5 × 10⁻¹⁵ × M Coulombs, where M is the gas gain used |
| Operating Temperature | Limited to 80 °C max. by the insulation of the connector |
| Capacitance | 8 pF |
Typical Sensitivity:
These counters are primarily designed for use in spherical REM counters (see also Bonner Spheres). The standard (152 cm Hg gas pressure) counter, when mounted in a 208 mm dia. sphere of polyethylene, has a nominal sensitivity of 8 cps for 32 μSv·h-1 neutron dose.
Increasing gas fill pressure increases sensitivity. By comparison with the 152 cm Hg pressure counter above, counters filled to 304 cm Hg have a sensitivity increased, typically, by a factor of 1·65. For counters filled to 532 cm Hg this factor is 2·3.
Description
The SP9 Spherical (Omni-Directional) Proportional Counter is part of Exosens' advanced range of ³He neutron detectors, offering unmatched sensitivity and omni-directional response. Its spherical geometry provides consistent detection capabilities regardless of the incident neutron angle, making it a reliable solution for a wide range of monitoring and measurement applications.
Built for versatility, the SP9 can be tailored with different gas fill pressures and mixtures, allowing optimisation of operating voltage, resolution, sensitivity, and gamma rejection. This adaptability ensures accurate neutron detection performance across diverse scientific, industrial, and safety environments. The counters are designed to operate with a gas multiplication factor of around 20, striking a balance between high sensitivity and long operational life.
Durability and reliability are central to the SP9’s design. Its operating temperature range depends on the selection of connectors and cables, with careful component choices enabling use in high-temperature or high-pressure environments. This robust construction ensures that the SP9 can withstand demanding conditions while maintaining measurement precision.
One of the most notable applications of the SP9 is its integration into REM (Roentgen Equivalent Man) monitors, where it plays a vital role in assessing human neutron dose for health and safety compliance. This makes it an indispensable tool for radiation protection, workplace monitoring, and nuclear facility safety.
Exosens also offers customisation options to meet specific customer needs, including bespoke gas mixtures, fill pressures, and connector configurations. By combining precision engineering with customer-focused flexibility, the SP9 provides a dependable neutron detection solution for both standard and specialised applications.