INSTRUMENT: LOW ENERGY CHARGED PARTICLE
SPACECRAFT: VOYAGER 2
Instrument Id : LECP Instrument Host Id : VG2 PI Pds User Id : KRIMIGIS PI Full Name : STAMITIOS M. KRIMIGIS Instrument Name : LOW ENERGY CHARGED PARTICLE Instrument Type : CHARGED PARTICLE ANALYZER Build Date : 1977-08-20 Instrument Mass : 6.652000 Instrument Length : UNK Instrument Width : UNK Instrument Height : UNK Instrument Serial Number : 01 Instrument Manufacturer Name : JOHNS HOPKINS UNIVERSITYAPPLIED PHYSICS LABORATORY
The low energy charged particle experiment employs a set of many solid state detectors arranged to characterize, with various levels of energy, directional, and compositional discriminations, the in-situ charged particle environment of the spacecraft, both within interplanetary and planetary magnetospheric regions. Electrons can be characterized, with various electron rate energy channels, between 22 keV and greater than 10 meV (mode dependent). Ions, without mass species discriminations, can be characterized with various ion rate energy channels between 28 keV and greater than 152 keV (mode dependent). Rate data is telemetered as simple counts per accumulation time period. The different channels correspond to different onboard energy discrimination windows (for ions the discrimination values are mass species dependent, leading to some ambiguity). Above about 200 keV/nucleon, the ions can be discriminated as to their mass species composition by the use of multiple parameter measurements. These measurements consist of the energies that individual particles deposit in more than one detector. This information is telemetered both as ion rate data, obtained by on-board species identification circuitry (with various channels representing various energy-species combinations), and as particle multiple parameters data, consisting of pulse- height-analysis values from each of the affected particle detectors for each analyzed particle. (A maximum of about 2 to 5 particles per second can be analyzed in this fashion due to telemetry limitations. A priority scheme avoids saturation by one species group. there are three such groups defined: atomic number z = 1,2 each group in a rotating fashion.) Angular information is obtained through mechanical rotation of the detectors. The main detectors look within a single scan plane that is rotated 360 degrees, stopping at 8 different look sectors (one of the sectors is blocked to obtain a background measurement: sector 8). The lower energy detectors have full width viewcones of about 45 degrees. The scan plane is oriented such that a line that passes exactly between sectors 8 and 1, and also exactly between sectors 4 and 5, is exactly parallel to the roll axis of the spacecraft (which nominally points at earth). When the roll orientation of the spacecraft is such that the star sensor is locked on canopus, the scan plane is tilted about 30 degrees out of the ecliptic plane, with sector 3 tilting towards north ecliptic (and also in the direction that is retrograde with respect to the planetary orbits). Sectors 1 and 8 point in the general direction of earth. The scan rate is variable between 48 seconds to 48 minutes per 360 degree scan. There are some electron detectors (whose properties are not as well established as the others) that view out of the scan plane described here (see [KRIMIGISETAL1977]). Some of the data is subject to substantial contamination depending on the region under consideration. Before the data from this instrument can be used, it is vital that the contamination descriptions be examined ('CONTAMINATION_ DESC') for each contamination type ('CONTAMINATION_ID') and that the contaminations levels be determined ('DATA_QUALITY_ID' AND 'DATA_QUALITY_DESC'). While sector 8 is the background sector for most (and generally the most used) data channels, sector 4 is the background sector for some channels. Of those channels documented in this catalog, sector 4 is the background sector for channels: ESA0,ESB0, AB10, AB12, AB13, PSA1, PSA2, PSA3, PSB1, PSB2, and PSB3.