The Bonner sphere spectrometer consists of an array of He-3 proportional counter thermal neutron detectors, each housed in a spherical HDPE moderator of different diameters. 

BSS is proposed in two main configurations, adjustable according to the requirements, for single or multiple detectors.

An unfolding software (RUFUS), used to calculate the neutron spectrum, is also available for both configurations.

Each proportional counter is connected to a compact electronic module (2.5 cm diam. x 7.6 cm), providing:

  • Precision wide band charge sensitive pre-amplifier and amplifier
  • Twelve-turn trim pot to finely tune the high voltage (0-2200 V) to the desired level to obtain a good high voltage plateau


  • Discriminator circuit that produces, when a charged event is detected, a TTL pulse
  • Amplifier gain control trim pot controlling the discriminator level
  • Analog monitoring test point allowing direct monitoring of amplified signal using an oscilloscope
  • Test point to measure the high voltage setting

A user-friendly dedicated acquisition software can be installed on the PC managing the BSS, allowing the user to start and stop the measurements, to modify the parameters and to visualize the saved data.

Additional Info

  • Main features:
    • Worldwide standard
    • Turnkey solution
    • Customizable moderator assembly and quantity
    • He-3 proportional counter detector
    • HDPE spherical moderators, from Ø 3” to Ø 18”
    • Accessory extension set for energy range up to 10 GeV
    • Proprietary unfolding code available
    • Optional special electronics for use in pulsed fields
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