Ulysses Cosmic Ray and Solar Particle Investigation (COSPIN) High Energy Telescope (HET) Full Resolution PHA Events, 5 s Data

A Directory containing Daily FTP downloadable Files containing full Information for every Non-zero HET PHA Event returned in Telemetry, including Raw Channels and Discriminator States, the Energy Deposits corresponding to the Channels, and certain derived Quantities including Particle Charge and Trajectory through the Telescope. PHA is performed for Electrons and Nuclei with Penetrating Power equivalent to that of Protons with Energy greater than 14 MeV. The Naming Convention of the Files is uly_het_full_pha_YYYDDD.txt, where YYY indicates the three digit Year since 1900 (e.g. YYY=090 for 1990, and YYY=102 for 2002) and DDD indicates the three digit Day of Year (January 1 = 1). At the Start of each File there is a detailed Description of the Format, in which each Event is represented by a Line with 54 Columns that provide complete Information about the Event. The first four Columns give the Time of the opening of the Window in which the Event was recorded as Fractional Year (to 12 Decimal Places) and as Year since 1900, Day of Year, and Milliseconds of Day. At the most common Science Telemetry Rate, 2048 bps, six Events are collected in every 32 s Telemetry Format. Because of the large Geometrical Factor of the Telescope, almost every available PHA Slot contains an Event. Since far more Events are recorded in the Telescope than can be returned as PHA Events in the Telemetry, only a Sample of the Events incident on the Telescope can be sent down as PHA Events. With the PHA Data for an Event, the Charge, Mass, Kinetic Energy, and Trajectory of the Particle through the Telescope can be determined. While most of the Nuclei incident on the HET are Protons, a three level Priority System selects Events for PHA and return in the Telemetry so as to assure Capture of almost all of the relatively rare Heavy Element Nuclei that stop in the Telescope. The lowest Priority (P3) Events are those that satisfy the most basic Criteria for being an analyzable Event, as determined by the Combination of Discriminators on various Detectors in the Telescope that fire. A higher Priority (P2) is given to Events that stop in the Telescope, and the highest Priority (P1) is given to Events that stop in the Telescope and that are identified as Heavy Nuclei by the Size of their Energy Deposits in the Detectors. The highest Priority Event that occurs in each Window for Accumulation of PHA Events is selected for inclusion in the Telemetry Data returned to the Ground. Thus, in large Solar Energetic Particle Events with abundant Heavy Nuclei, few Protons may be included in the PHA Events transmitted via Telemetry. The Counting Rates, however, Count every Event, and in such Cases it can usually be assumed the Counting Rates that respond to Protons are dominated by the Proton Flux. Absolute Fluxes for individual Elements may be derived by identifying PHA Events that would contribute to Counting Rates (i.e. that have the same Discriminator Configuration as one of the Counting Rates) and determining the Ratio between Events counted by the Rate and returned in Telemetry during a given Interval. Appropriate Counting Rates exist that Match each of the three PHA Priority States. The Priority Levels corresponding to the Counting Rates are listed in Table 7 of J.A. Simpson et al., Astron. Astrophys. Suppl. Ser. 92, 365-399, 1992. *** N.B. Three Corrections are necessary in Table 7. *** 1) The (H) Discriminator Logic should include the Discriminator K6H orred with the other seven Discriminators listed. 2) the middle Term of the P2 (Medium Priority) Logic should include D4 as well as D1, D2, and D6 as required Detectors. 3) Because of an Error in the Logic Design Counting Rate H3, listed as responding to P3 (Lowest Priority) Events, also includes P2 Events, which satisfy the first Term in the P2 Logic. Thus H3 should not be used for deriving Absolute Fluxes of P3 Events from PHA Data.

Tags: energeticparticles
Organization: National Aeronautics and Space Administration