Wind SMS Suite SupraThermal Ion Composition Spectrometer (SMS/STICS) Ion Velocity Distribution Functions (VDFs), Level 2 (L2), 3-minute Data in Magnetosphere

The data include Wind STICS 3-minute 3D velocity distribution functions (VDFs) in three units (phase space density, differential number flux and counts), together with their statistical errors, for selected ion species using triple coincidence (H+, He+, He2+, C5+, O+, O6+, and Fe10+) and double coincidence (H+, He+, He2+, O+, O6+) measurements in the magnetosphere. For details, see https://spdf.gsfc.nasa.gov/pub/data/wind/documents/wind_stics_lv2_release_notes_revD.pdf.The Suprathermal Ion Composition Spectrometer (STICS) is a time of flight (TOF) plasma mass spectrometer, capable of identifying mass and mass per charge for incident ions up to 200 keV/e. It uses an electrostatic analyzer to admit ions of a particular energy per charge (E/Q) into the TOF chamber. The E/Q voltage is stepped through 32 values, sitting at each value for approximately 24 sec., to measure ions over the full E/Q range of 6 - 200 keV/e. Ions then pass through a carbon foil and TOF chamber, before finally impacting on a solid-state detector (SSD) for energy measurement. STICS combines these three measurements of E/Q, TOF and residual energy, producing PHA words. This triple-coincidence technique greatly improves the signal to noise ratio in the data. Measurements of E/Q and TOF without residual energy also produce PHA words. These double-coincidence measurements are characterized by better statistics since ions whose energy does not allow them to be registered by the SSD can still be counted in double-coincidence measurements. However, ion identification in double-coincidence measurements are limited to a select number of ions that are well separated in E/Q - TOF space. The STICS instrument provides full 3D velocity distribution functions, through a combination of multiple telescopes and spacecraft spin. The instrument includes 3 separate TOF telescopes that view 3 separate latitude sectors, as shown in Figure 1 (https://spdf.gsfc.nasa.gov/pub/data/wind/documents/wind_stics_lv2_release_notes_revD.pdf). In addition, the WIND spacecraft spins, allowing the 3 telescopes to trace out a nearly 4π steradian viewing area. The longitudinal sectors are shown in Figure 2. The solar direction is in sectors 8-10 while the earthward direction is in sectors 0-2.

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  "026:00"
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  "026:000"
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  "Heliophysics"
]