The Lucas cell: the standard for radon, radium and thoron

The Lucas cell: for radon, radium and thoron

  • Named after its inventor, Henry Lucas (1957), the Lucas cell is also known as scintillation cell or radon cell. The Lucas cell is a hollow cylinder, sealed with a glass window at one end a "quick connect" at the other end. The inside is coated with silver activated zinc sulfide, or ZnS(Ag). This phosphor emits a pulse of light or scintillates when an alpha particle hits it. The cell is viewed by a photomultiplier tube and the scintillations counted by electronics. The Lucas cell is the size of a drinking cup because that is the range of an alpha particle in air -- a few inches.
  • Radon is an alpha-emitting noble gas and readily separated from solution in water into a gas phase and passed into a Lucas cell where its radiation is counted. There are no interferences. As an alpha detector the Lucas cell offers low background counts, much lower than one count per minute (cpm), making it suitable for environmental levels. The parent-daughter pair radium-radon grows into equilibrium in a few days and thus the Lucas cell provides a very sensitive method for the analysis of both these elements. The Lucas cell provides the basis for EPA Method 903.1 for radium in drinking water and can easily be applied to radium in food etc. as well as radon. At standards somewhat less rigorous than the EPA our system can provide quick turn-around at environmental levels. Many samples can be analysed in a work day.
  • We measure: radon - radium - thoron - radon daughters - alpha radiation.
  • The Lucas cell is recognized as the most sensitive and reliable method for these elements.
  • Our instruments are used around the world in exploration for uranium, oil & gas, groundwater and hydrothermal, and in environmental protection, health physics, earthquake prediction, and evaluation of hydrocarbon and NAPL contamination.
  • In the radon business since 1968, our latest major instrument update was 2015.
  • Modern, low-power, field-rugged electronics. Some earlier versions still working after 35 years.
  • Continuous real-time monitoring and data recording.
  • Winter and summer, from the Sahara Desert to the Canadian Shield, our instruments have faced up to severe field conditions.
  • Intrinsically safe functions.
  • Sensitive to geochemical trace levels necessary for radon in lake water and for radon-thoron isotope ratios.
  • Can work in a tent without electricity or be carried from point to point in the field.
  • 50 readings per day. Results available immediately.
  • Rechargeable battery pack good for a long day in the field and recharges in a few hours.
  • Can be operated by junior personnel if carefully supervised.
  • Same instruments used for radon and radium in soil, sediment, plant parts, rocks, water, soil gas, air, and snow, and for radon daughters in air.
  • EPA compliant.
  • Click here for more details of instruments.
  • Click here for or other instruments, components and accessories we provide
  • Technical specification sheets and pictures of our instruments provided on request.
  • Multilingual consulting and training (if required).
For instruments contact
R.H. Morse & Associates Ltd.
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Click here for studies of radon in uranium exploration
Lucas, Henry F., 1957: Improved low-level alpha scintillation counter for radon, Rev. Sci. Instruments, vol 28, No. 9, pp 680-683. Credited with invention of the Lucas cell, a hollow cylinder sealed at one end with a glass window and coated on the inside with silver-activated zinc sulfide. This material emits a photon of light (scintillates) and this scintillation is detected by a photomultiplier tube and counted by an electronic apparatus. The Lucas cell is the size of a drinking cup because that is the range of an alpha particle in air.
Dyck, 1969: Radon determination apparatus for geochemical prospecting for uranium, Geol. Survey of Canada, paper 68-21. Developed a portable Lucas cell system which is the predecessor of our instrument. We have been providing battery operated radon instruments since 1972.
K.P. Eappen * , R.N. Nair, Y.S. Mayya, 2008: Simultaneous measurement of radon and thoron using Lucas scintillation cell, Radiation Measurements 43 (2008) 91 – 97. Developed a method for the simultaneous measurement of radon (222Rn) and thoron (220Rn) using the Lucas scintillation cell. This paper presents a mathematically rigorous version of the formula for radon and thoron which I published in 1976

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