• Data Set Overview

• =================

• Data Set Description

• ====================

This Encounter Data Set consists of Resampled Electron and Ion Data from the Low Energy Charged Particle (LECP) Experiment on Voyager 2 while the Spacecraft was within the Vicinity of Uranus.

The LECP Instrument measures the Intensities of in situ Charged Particles (>26 keV Electrons and >30 keV Ions) with various Levels of Discrimination based on Energy Range, Mass Species, and angular Arrival Direction. A Subset of almost 100 LECP Channels are included in this Data Set. The LECP Data are globally calibrated to the extent possible (see below).

These LECP Data are Time averaged to about 15 min Time Intervals with the exact Beginning and Ending Times for those Intervals matching the LECP instrumental Cycle Periods (the angular Scanning Periods).

The LECP Instrument has a rotating Head for obtaining angular Anisotropy Measurements of the Medium Energy Charged Particles. A gear-drive Motor steps through eight equal angular Sectors per Revolution for Data Collection.

The Cycle Time for the Rotation is variable, but during Encounters it is always faster than 15 min. This Browse Data Set provides only Scan Average Data. No Angular Information is included.

The Data were originally collected in the Form of "Rate" Data which were not always converted to the usual Physical Units. The Reason is that such a Conversion would depend on uncertain Determinations such as the Mass Species of the Particles and the Level of the Background. Both the Mass Species and the Background are generally determined from context during the Study of particular Regions. To convert "Rate" to "Intensity" for a particular Channel, one performs the following Tasks:

• 1. Decide on the Level of Background Contamination and subtract that off the given Rate Level. The Background is to be determined from context and from making use of Sector 8 Rates (Sector 8 is covered by a 2 mm Aluminium Sunshield and is used for Data Calibration).
• 2. Divide the Background-corrected Rate by the Geometric Factor of the Channel and by the Energy Bandpass of the Channel.

The Geometric Factor is found in the Entry for CHANNEL_GEOMETRIC_FACTOR as associated with the CHANNEL_ID of each Channel.

To determine the Energy Bandpass, one must judge the Mass Species of the detected Particles (for Ions but not for Electrons). The Energy Bandpasses are given in the Entries MINIMUM_INSTRUMENT_PARAMETER and MAXIMUM_INSTRUMENT_PARAMETER in Table FPLECPENERGY, and are given in the Form of "Energy per Nucleon". For Channels that begin their Names with the Designations "CH", these Bandpasses can be used on Mass Species that are accepted into that Channel. See the Entries for MINIMUM_INSTRUMENT_PARAMETER and MAXIMUM_INSTRUMENT_PARAMETER in Table FPLECPCHANZ, which give the Minimum and Maximum "Z" Value accepted. Note that these Entries are Blank for Electron Channels. For other Channels the given Bandpass refers only to the lowest Z Value accepted. The Bandpasses for other Z Values are not all known, but some are given in the Literature (e.g., Krimigis et al., (1979a)). The final Product of these Instructions will be the Particle Intensity in Units of counts/(cm^2 s sr keV). LECP Data can also be expressed in the Form of Flux, whose Units are (cm^2 s sr)^-1.

Some Channels are subject to serious Contamination Issues, and many of the Contamination Effects cannot be removed except with a Region-by-Region Analysis, which has not been done for these Data. Thus, to use this Data, it is absolutely vital that the Contamination Types (CONTAMINATION_ID,CONTAMINATION_DESC) and the Levels of Contamination (DATA_QUALITY_ID corresponding to the Definitions DATA_QUALITY_DESC) be carefully examined for all Regions of Study. A Dead Time Correction Procedure has been applied in an attempt to correct the Linear Effects of Detector Overdrive (Pulse Pileup). This Procedure does not fix severely overdriven Detectors. A Procedure is available for correcting the Voyager 2 LECP Electron Contamination of the low Energy Ion Channels, but its effectiveness has been evaluated only for the Uranus Data Set. Thus, Corrections have been applied only to the Uranus Data Set.

+----------------------------------------+
| Parameter Characteristics | Value |

| Processing Level ID | 4 |
| Software Flag | Y |
| Processing Start Time | 1987-02-01 |
+----------------------------------------+

• Parameters

• ==========

• Data Set Parameter ELECTRON RATE

• ================================

A measured Parameter equaling the Number of Electrons striking a Particle Detector per specified Accumulation Interval. The counted Electrons may or may not be discriminated as to their Energies (e.g., greater than E1, or between E1 and E2).

+-----------------------------------------------+
| Parameter Characteristics | Value |

| Sampling Parameter Name | TIME |
| Data Set Parameter Name | ELECTRON RATE |
| Sampling Parameter Resolution | 15.000000 |
| Sampling Parameter Interval | 15.000000 |
| Data Set Parameter Unit | COUNTS/SECOND |
| Noise Level | 0.000000 |
| Sampling Parameter Unit | MINUTE |
+-----------------------------------------------+

• Data Set Parameter ION RATE
• ===========================

A measured Parameter equaling the Number of Ions striking a Particle Detector per specified Accumulation Interval. The counted Ions may or may not be discriminated as to their Energies (e.g., Energy per Nucleon or Energy per Charge between E1 and E2 or greater than E1) and/or as to their Ion Composition (Atomic Number Z or Mass Number greater than Z1 or M1, or between Z1 and Z2 or M1 and M2).

+-----------------------------------------------+
| Parameter Characteristics | Value |

| Sampling Parameter Name | TIME |
| Data Set Parameter Name | ION RATE |
| Sampling Parameter Resolution | 15.000000 |
| Sampling Parameter Interval | 15.000000 |
| Data Set Parameter Unit | COUNTS/SECOND |
| Noise Level | 0.000000 |
| Sampling Parameter Unit | MINUTE |
+-----------------------------------------------+