A mobility spectrometer for measurement of initial properties of 218Po

Measurement of Mass Transfer to Agglomerate Aerosols

“…The lead atom is probably surrounded by water or other molecules which lower the lead's density and diffusivity. Previous measurements suggest that the effective diameter of the lead cluster is between 0.5 and 3 nrn (Porstendorfer et al, 1979;Strydom et al, 1990;Su et al, 1990). We have constrained the density by assuming that all molecules attached to the lead have a unit specific gravity.…”

Novel ion mobility analyzers and filters

“…This outlet may be either a second slit or orifice through which the ions are extracted (Hewitt, 1957) or a well-defined region in which the ion charge is collected (Tammet, 1970, p. 151). While a small flow of gas usually accompanies the ions as they are injected into and/or extracted from the analyzing region, ions may be introduced into or extracted by purely electric means, without a net flow of gas, as for example in the inlets of Strydom, Leuschner, and Stoker (1990). Whether an ion is drawn by the gas or by the electric field at the outlet, it will be said to be collected at the outlet.…”

Analysis of the electrostatic field distribution in the hemispherical internal cell of radon monitors to estimate the collection efficiency of Po-218

“…The experiments of Fontan et al found that the mobility depends on the nature of the used carrier gas, and the mobility of Po-218 is 3.3 cm 2 /(Vs) in helium [19]. R. Strydom et al measured a mobility of 1.6 cm 2 /(Vs) at a low relative humidity, which is lower than the 1.8-2.2 cm 2 /(Vs) reported by Bricard et al [20][21][22][23][24]. Chu and Hopke derived a value of 1.87 cm 2 /(Vs) in nitrogen containing about 25 ppm (0.09% RH at 20 • C) of water vapor [15].…”