BDS – Bubble Detector Spectrometer


Bubble detectors are the most sensitive, accurate, neutron dosimeters available and have been used for over 25 years by nuclear facilities, research institutes, military personnel, and the medical community. Bubble detectors provide instant visible detection and measurement of neutron dose. Inside the detector, tiny droplets of superheated liquid are dispersed throughout a clear polymer. When a neutron strikes a droplet, the droplet immediately vaporizes, forming a visible gas bubble trapped in the gel. The number of bubbles provides a direct measurement of the tissue-equivalent neutron dose.

The Bubble Detector Spectrometer (BDS) is a complete low-cost neutron spectrometer package consisting of 36 bubble detectors that have been specifically formulated with six different energy thresholds. Each spectral measurement can be made with 18 detectors (three of each threshold supplied – 10, 100, 600, 1000, 2500, 10000 keV). Similar to fast-neutron activation detectors, the measured spectrum from the BDS is derived by “unfolding” the response of the different detectors of the BDS. Detectors can be re-used through recompression in a pressure chamber (available from BTI).

The BDS has two very important properties–it is completely insensitive to gamma rays allowing it to be used in areas with intense gamma background and, since it is passive, it can be used in pulsed radiation fields. The BDS is ideal as a low-cost method for assessing the energy of a neutron field, especially where the neutron field is only a very small fraction of the total radiation field. Specialized versions of the BDS have been used to determine the neutron spectrum in space and is often used in connection with pulsed reactor operations and for assessing the neutron field from medical (or research) accelerators.

Notes: Ideal for low-cost neutron spectral characterization

All bubble detectors offer:

  • Zero gamma sensitivity
  • Energy-independent above threshold, dose rate-independent, tissue-equivalent dose measurements
  • Isotropic angular response
  • 90 day warranty

Technical Specifications

  • Energy Range Six thresholds: 10, 100, 600, 1000, 2500 and 10000 keV
  • Dose Range ~ 50 mrem; ~535 μSv
  • Sensitivity (User Selectable) 1 - 2 bubbles/mrem; 0.1 - 0.2 bubbles/μSv
  • Automatic Temperature Compensation No
  • Optimum Temperature Range 20 °C
  • Size 80 mm length x 16 mm diameter
  • Weight 20 g
  • Reuse > 10 cycles
  • Recompression Method External recompression chamber required