Liquid Scintillation Spectrometer Wallac Guardian

Wallac 1414-003 Gurdian (1999)

Technical data

Liquid scintillation spectrometer for alpha and beta radiation, equipped with anticoincidence shield against cosmic rays. Parallel acquisition of both alpha and beta spectra is possible as well as elimination of chemical luminescence. Spectrometer has sample changer and stabilization of temperature. It is controlled by dedicated PC.


Liquid scintillation alpha/beta spectrometer Wallac 1414-003 Guardian designed for determination of relatively low activity concentrations of alpha and beta emitters in environmental samples.
In Institute spectrometer is mainly used in measurements of 90Sr, 241Pu as well as 3H, 99Tc , 63Ni etc. The possibility of simultaneous acquisition of alpha and beta gives profit in measurements of 241Pu when the total alpha activity plays role of internal tracer.
Investigated radionuclides are separated using radiochemical procedures, finally separated desired fraction is mixed with liquid scintillation cocktail. This provides a full solid angle geometry of counting. The another advantage is lack of any material between sample and detection system. Both those features produce high efficiency and enables measurements of hard to detect low-energy beta emitters like 3H (Emax=19 keV) or 241Pu (Emax=20 keV).
Spectrometer can be also used as Cerenkov radiation counter for high energy beta radiation from 90Y (Emax=2.2 MeV) or 32P (Emax=1.7 MeV). Sample is then mixed with regular water instead of scintillation cocktail.

Fig. 1. Spectrometer Wallac Guardian at IFJ PAN.

Fig. 1. Spectrometer Wallac Guardian at IFJ PAN.

Laboratory in which the equipment is in use

Environmental Radioactivity Laboratory, Building 6, Department of Nuclear Physical Chemistry (NZ64)