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

ABSORBER NAME   D1 D2 D3
 
     
ABSORBER THICKNESSES, MICRONS 100.0 300.0 700.0 1400.0 2860.0 500.0 3307.0 985.0
ABSORBER MATERIAL ALUM. SILICON SILICON SILICON NICKEL SILICON GOLD SILICON
THICKNESS VARIATION, MICRONS 0.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
CONICAL HALF ANGLE, DEGREES 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5
DETECTOR NOISE, MEV 0.0 0.015 0.0 0.015 0.0 0.010 0.0 0.010
ELECTRONIC NOISE, MEV 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 
NUMBER OF THRESHOLDS SET 0.0 4.0 4.0 1.0 0.0 2.0 0.0 1.0
THRESHOLD LEVEL NO.MEV 1 0.0 0.025 0.025 0.025 0.0 0.025 0.0 0.025
THRESHOLD LEVEL NO.MEV 2 0.0 0.200 0.200 0.0 0.0 0.250 0.0 0.0
THRESHOLD LEVEL NO.MEV 3 0.0 7.500 2.000 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 4 0.0 30.000 35.000 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 6 0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0 
THRESHOLD LEVEL NO.MEV 7 0.0 0.0 0.0  0.0  0.0 0.0  0.0 0.0  
THRESHOLD LEVEL NO.MEV 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
AVERAGE PROJECTED DEPTH, MIC 104.0 311.9 727.7 1455.4 2973.2 519.8 3437.8 1024.0
EST.RMS VARN.PROJ.DEPTH,  MIC 4.1 12.4 28.8 57.7 117.8 20.6 136.2 40.6
NET RMS THICKNESS VARN. (MIC) 4.1 15.9 30.5 58.5 118.2 22.9 136.6 41.8
LOWER LIMIT THICKNESS (MIC) 99.8 296.0 697.2 1396.9 2854.9 496.9 3301.2 982.2
UPPER LIMIT THICKNESS (MIC) 108.1 327.8 758.2 1513.9 3091.4 542.7 3574.4 1065.8


LEMMS_III

ABSORBER NAME   D1 D2 D3
 
     
ABSORBER THICKNESSES, MICRONS 100.0 300.0 700.0 1400.0 2860.0 500.0 3307.0 985.0
ABSORBER MATERIAL ALUM. SILICON SILICON SILICON NICKEL SILICON GOLD SILICON
THICKNESS VARIATION, MICRONS 0.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0
CONICAL HALF ANGLE, DEGREES 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5
DETECTOR NOISE, MEV 0.0 0.015 0.0 0.015 0.0 0.010 0.0 0.010
ELECTRONIC NOISE, MEV 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 
NUMBER OF THRESHOLDS SET 0.0 4.0 4.0 1.0 0.0 2.0 0.0 1.0
THRESHOLD LEVEL NO.MEV 1 0.0 0.025 0.025 0.025 0.0 0.025 0.0 0.025
THRESHOLD LEVEL NO.MEV 2 0.0 0.200 0.200 0.0 0.0 0.250 0.0 0.0
THRESHOLD LEVEL NO.MEV 3 0.0 7.500 2.000 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 4 0.0 30.000 35.000 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 6 0.0 0.0 0.0 0.0 0.0 0.0  0.0  0.0 
THRESHOLD LEVEL NO.MEV 7 0.0 0.0 0.0  0.0  0.0 0.0  0.0 0.0  
THRESHOLD LEVEL NO.MEV 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
THRESHOLD LEVEL NO.MEV 10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
AVERAGE PROJECTED DEPTH, MIC 104.0 311.9 727.7 1455.4 2973.2 519.8 3437.8 1024.0
EST.RMS VARN.PROJ.DEPTH,  MIC 4.1 12.4 28.8 57.7 117.8 20.6 136.2 40.6
NET RMS THICKNESS VARN. (MIC) 4.1 15.9 30.5 58.5 118.2 22.9 136.6 41.8
LOWER LIMIT THICKNESS (MIC) 99.8 296.0 697.2 1396.9 2854.9 496.9 3301.2 982.2
UPPER LIMIT THICKNESS (MIC) 108.1 327.8 758.2 1513.9 3091.4 542.7 3574.4 1065.8


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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Updated 6/10/08, T. Hunt-Ward
tizby@ftecs.com