Ulysses HISCALE Data Analysis Handbook
Appendix A: PI Comments/Explanations and Caveats
Appendix A6.1 (COSPIN/LET / SIM Experiment)
PI Comments/Explanations
The COSPIN Low Energy Telescope is a solid state detector telescope providing count rate and pulse height information for protons (120 MeV) and heavier species up to Fe. The three LET parameters included in the CDF are derived from individual count rate channels as follows:
a) L3+L12 - The sum of LET proton channels L3 (1.83.8 MeV; 2parameter measurement) and L12 (3.88.0 MeV; 3parameter measurement). The nominal geometrical factor (GF) for both L3 and L12 is 0.58 cm2 sr.
b) L24+L25 - The sum of LET He channels L24 (4.09.0 MeV/n) and L25 (9.019 MeV/n). Both are 3parameter measurements and have a nominal GF of 0.58 cm2 sr.
c) L28 - LET heavy ion channel L28, a 2parameter measurement of C, N and O nuclei in the range 2.67.1 MeV/n (Carbon). The nominal GF is 0.58 cm2 sr.
1. The CDF algorithm for the L3+L12 parameter produces an offset in the count rate of approximately 0.05 counts per sec. This effect is under investigation.
2. The energy window corresponding to the CNO channel L28 is species dependent, and does not include a (small) correction for energy losses in the LET aperture foils. Accurate absolute fluxes for species heavier than He can only be derived from the pulse height data (not part of the CDF).
Dr. R.G. Marsden, Space Science Dept. of ESA, ESTEC, P.O.
Box 299, 2200AG Noordwijk (The Netherlands)
Tel. +31 1719 83583;
Fax: +31 1719 84698
Email: ESTCS1::RMARSDEN
12 October 1993
Appendix A6.2 (COSPIN/HET / SIM Experiment)
PI Comments/Explanations
The COSPIN High Energy Telescope (HET) is a solid state detector telescope consisting of 13 silicon detectors surrounded by a plastic scintillator anticoincidence shield. The primary response of the HET is to protons and heavier nuclei which are identified crudely by counting rate logic and with high precision by pulse height analysis information. The energy range for protons which stop in the telescope is ~5 92 MeV. A detailed description of the telescope and the data channels is given by Simpson et al. (Astr. Astrophys Supp. Series, 92, 365, 1992). The parameters provided for the CDF are as follows:
a) H2 counting rate. Nominal principal response is to protons ~1419 MeV with a geometric factor of ~87 cm2 sr. Heavier nuclei may also contribute in energy ranges corresponding to the penetration depth of 1419 MeV protons. Response to electrons is suppressed by requiring a minimum energy loss significantly greater than that of a minimum ionizing particle in the triggered detectors.
b) H5 counting rate. Nominal principal response is to protons and helium nuclei of energy 6892 MeV/n with a mean geometrical factor of ~4.4 cm2 sr. Although counted with low efficiency, electrons with energies in the range ~916 MeV also contribute to this counting rate. Nuclei heavier than helium are excluded by a maximum allowed energy loss in the detectors.
c) H8 counting rate. Nominal response is to electrons in the approximate energy range 35 MeV with a mean geometrical factor of ~15.5 cm2 sr. Response to nucleons is suppressed by requiring nearminimumionizing energy losses in the first detectors in the stack. The efficiency for detection of electrons is not well known, but based on preliminary calibrations is believed to be small, of the order of a few percent.
1. Particles contributing to these counting rates are not uniquely identified. In particular, as noted above, high energy electrons contribute to and in some circumstances dominate the H5 counting rate. Also, during quiet times, examination of pulse height analysis data shows that the majority of events contributing to the counting rates are background events rather than particles in the nominal response ranges quoted above. The source of the background is not fully understood, but it most likely results from RTG effects and from nuclear interactions in the instrument and surrounding spacecraft material. During periods of enhanced fluxes, on the other hand, pulse height analysis shows that the counting rates do respond mainly to particles in the principal response ranges.
2. The energy ranges and geometrical factors given above are based on simple rangeenergy calculations and on analytical calculations of the geometric factor using the separations and dimensions of the sensitive regions of the detectors. There are, however, significant amounts of insensitive material in the telescope so that the actual energy ranges and geometrical factors as a function of energy are complex. Effective "bestchoice" energy ranges and geometrical factors based on extensive montecarlo runs are in the course of being determined and evaluated.
Dr. R.B. McKibben, LASR, Univ. of Chicago, 933 E 56th
St., Chicago, ILL 60637 (USA)
Tel. +1 312 702 7851;
Fax: +1 312 702 6645
Email: LASR::"MCKIBBEN@ODYSSEUS.UCHICAGO.EDU"
3 April 1993
Appendix A6.3 (COSPIN/KET / SIM Experiment)
PI Comments/Explanations
The COSPIN Kiel Electron Telescope (KET) uses solid state detectors and Cherenkov detectors to distinguish between electrons and nuclei. A scintillation guard counter is used to reduce background. The telescope measures electron fluxes between 2.5 and 6000 MeV, and determines energy spectra in the range 7 170 MeV. It also provides measurements of proton and alpha particle fluxes in several energy windows between 3 and >2100 MeV/nucleon. The two KET parameters included in the CDF are derived from counting rate channels as follows:
a) E4 nominal response to electrons in the approximate energy range 2.5 7 MeV, 3parameter measurement, spinaveraged over eight sectors, time averaged to yield 17.066 min time resolution for all TLM bitrates. The effective geometric factor is 0.26 cm2 sr.
b) E12 nominal response to electrons in the approximate energy range 7 170 MeV, 4parameter measurement, spinaveraged, time averaged to yield 17.066 min time resolution for all TLM bitrates. The effective geometric factor is 0.40 cm2 sr.
1. There is a background counting rate in E4 and E12, which is nonnegligible during quiet times. In E4 the source of this background are probably RTG generated gammarays which produce Compton electrons, or electronpositron pairs. In E12 the source of this background are probably high energy cosmic ray protons interacting with the matter of the spacecraft to produce gamma rays. Background correction is not implemented for CDF channels. E4 offset: approximately 1.3 103 counts/s; E12 offset: approximately 0.5 103 counts/s.
2. The guard counter with its large geometric factor is a major source of deadtime increase during high flux solar flare events or Jovian radiation belt passage. Corrections are nonnegligible when the E4 counting rate exceeds the level of 1 count/s. Dead time correction is not implemented for CDF channels.
3. Do not use E4 and E12 fluxes when
(a) KET is not in nominal observation mode: KET status word in word 5, bits 011, not equal 640 hex;
(b) KET is switching modes during accumulation interval: KET status word is 640 hex, but "Varying status flag" is set, i.e., word 5 bits 2431 not equal 00 hex;
(c) "Questionable data flag" is set, i.e., word 5 bits 1623 not equal 00 hex;
(d) Some variables needed to calculate averaged fluxes are not defined, i.e., tertiary header, word 11, bit 13 = 1 or bit 14 = 1 or bit 15 = 1.
Dr. R. MuellerMellin, IFKKI, Univ. of Kiel,
Olshausenstrasse 4060, D2300 Kiel (Germany)
Tel. +49 431 880 3227;
Fax: +49 431 85660;
Email: IFKKI::MUELLER_M
5 May 1993
Next: Appendix A7 (URAP/STO Experiment)
Return to Appendix 3 Main Table of Contents Page
Return to Ulysses HISCALE Data Analysis Handbook Table of Contents
Updated 8/8/19, Cameron Crane
QUICK FACTS
Mission End Date: June 30, 2009
Destination: The inner heliosphere of the sun away from the ecliptic plane
Orbit: Elliptical orbit transversing the polar regions of the sun outside of the ecliptic plane