Fundamental Technologies Cassini MIMI Pages

(Fax from E. Kirsch to T. P. Armstrong, dated 5/26/93)

Concerning the LEMMS High Energy Detector I have the following news:

1. I learned also that the 5mm thick Li-drifted Si-detectors cannot be used without bias voltage during enhanced temperature (Venus flyby). From "Ortec" I got the information that they cannot presently manufacture 5mm thick surface barrier detectors. Thus we have to use a stack of 700 micron thick Canberra detectors (=standard maximum thickness).
2. I found in the literature a model calculation for Saturnian x-rays published by Barbosa (Geophys. Res. Lett., 17, 1029, 1990, fig. 2). The x-ray energies and fluxes are much smaller than expected.  Thus we do not need necessarily a 5mm thick detector.  Only during the high inclination orbits of Cassini would we still have a chance to detect Saturnian x-rays. I propose therefore to use for D2 a 700 micron Canberra detector (300 mm², 9 keV FWHM noise) and for D3 two 700 micron detectors connected to one amplifier chain (300 mm², 13 keV FWHM noise expected). D2 and D3 can then be used for x-ray detection.  Such a change has also consequences for the ion and electron channels.  We could also add a passive absorber in order to reach the thickness of the old design (D2 + D3 = 5300 micron S1).

May 31, 1993
Preliminary 700 m LEMMS

LEMMS_II

LEMMS_III

	Figure 1		Figure 2
	Figure 3		Figure 4
	Figure 5		Figure 6
	Figure 7		Figure 8
	Figure 9		Figure 10
	Figure 11		Figure 12

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