Frisch Grid

Figure 18.3 Schematic diagram of tin ion chamber that drifts the ionization perpendicular to the particle s path is shown. In this case the anode is segmented and the relative rate of ionization along the path can be determined. The device also contains a Frisch grid between the anode and chamber to improve the pulse-shape response of the device, (c) The schematic version of a detector that drifts the ionization along the particle s path, called a Bragg counter, is shown. The time distribution of the output signal will contain information on the relative rate of ionization all along the particle s path.

The relatively large pulses from alpha particles are measured with a Frisch grid chamber (Knoll 1989) with a resolution of about 40 keV. Its advantage is the capability to measure and perform spectral analysis for samples with relatively large areas, e.g., 500 cm. ... 

Alpha particles are also measured by spectral analysis in Frisch grid chambers (see Section 8.3.1) and specially designed LS counting systems (see Section 7.3.3). Although solid-state detectors are most commonly used, the other detection systems, if available, can simplify the processing of certain samples. 

Total ionization and pulse analysis, Frisch grid ionization chamber Energy measurement -determination of isotope ratios. Convenient, easy to use. High geometry -up to 50%. Tolerates large area sources. Resolution can be improved by collima-tion. Requires gas purification. 

Figure 2 Liquid ionization chamber with Frisch grid. (Redrawn from Bunemann, O., Cran-shaw, T.E., and Harvey, J.A., Can. J. Res., 27,191,1949.)...

G. W. Trucks and M. J. Frisch, Rotational Invariance Properties of Pruned Grids for Numerical Integration, in preparation (1996). 

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