Voyager LECP Pages
C. Y. Fan
For the study of the shock transition regions and the radiation belts of outer planets, we propose to use a small 3 detector telescope. Using six rate outputs it should be possible to achieve (1) large dynamic range intensity measurements, (2) identification of high intensity protons and electrons, and (3) obtain limited spectral information. A stack of three AU-Si surface barrier detectors, designated as D1, D2, and D3, 25 mm2 in area and 200m in depletion depth, each is placed in a malloy-2000 (tungsten alloy) cylinder of 0.5 mm in wall thickness, to form a particle telescope of angle of acceptance 20 deg. (see Figure 1). A malloy-2000 absorber of 0.5 mm thick is sandwiched between D1 and D2 so that D2 and D3 are shielded against direct radiation. The outputs of the system will be (a) two counting rates from D1 at discrimination levels ~60 and 180 keV respectively (N1l and N1h), (b) one single rate each from D2 and from D3, both at discrimination levels of 60 keV (N2 and N3), (c) a D1D2 double coincidence rate (N12) and (d) a D1D2D3 triple coincidence rate (N123). To illustrate the characteristics of the system we consider the following five cases.
From the five sample cases, it is seen that this detector system is a compact but a versatile instrument for the study of the magnetospheres of outer planets. It provides for the detection of shock transition regions, makes a rough estimate of the populations of protons and electrons and their energies. The intensity range is covered through the use of double and triple coincidence counting techniques combined with a coincidence circuit having a resolving time 0.1 msec and a proper scaling factor, a dynamical range of ~106 can be achieved. Including current mode operation for some of these detectors a significant additional increase in intensity dynamical range would be achieved.
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Last modified 8/11/05, Tizby Hunt-Ward
Figure restoration by T. Manweiler.