INSTRUMENT: LOW ENERGY CHARGED PARTICLE
  SPACECRAFT: VOYAGER 1
 
  Instrument Information
  ======================
    Instrument Id                  : LECP
    Instrument Host Id             : VG1
    PI Pds User Id                 : KRIMIGIS
    PI Full Name                   : STAMITIOS M. KRIMIGIS
    Instrument Name                : LOW ENERGY CHARGED PARTICLE
    Instrument Type                : CHARGED PARTICLE ANALYZER
    Build Date                     : 1977-09-05
    Instrument Mass                : 6.652000
    Instrument Length              : UNK
    Instrument Width               : UNK
    Instrument Height              : UNK
    Instrument Serial Number       : 03
    Instrument Manufacturer Name   : JOHNS HOPKINS UNIVERSITY
                                     APPLIED PHYSICS LABORATORY
 
 
  Instrument Overview
  ===================
    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 26 keV and
    greater than 10 meV (mode dependent).  Ions, without mass
    species discriminations, can be characterized with various ion
    rate energy channels between 30 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.
 
 
  Science Objectives
  ==================
    Characterize the energy spectra, angular distributions, species
    composition, spatial structures, and temporal variations of the
    hot plasmas, energetic particles, and particulate radiation
    that exist in the vicinity of the outer planets (Jupiter,
    Saturn, Uranus, and Neptune) and within the interplanetary
    environment.  To study the mechanisms by which such particles
    are energized and transported throughout such systems.  To
    study in particular the energization and transport processes
    associated with hot plasmas and particulate radiation in the
    vicinity of planetary bow shocks, magnetopauses, magnetotail
    plasma sheets, inner radiation zones, the auroral zones, etc.,
    and to study the interaction of such media with planetary
    satellites and the planetary atmospheres and ionospheres.
 
 
  Operational Considerations
  ==========================
    Instrument operates continuously sampling data over uniform
    accumulation intervals.  The accumulation intervals are
    different for the different channels of information (almost 100
    channels).  The scan head of the LECP Instrument usually scans
    back-and-forth continuously (forward by 315 degrees and then
    back by 315 degrees).  The scanning head pauses at 8 different
    scan sectors for periods ranging between 6 seconds and 48
    seconds (for the encounter time periods) and takes about 0.5
    seconds to scan between the sectors.  Specially scanning modes
    for Voyager 2 at Uranus and Neptune have been developed whereby
    1 or 2 quick scans are performed followed by 6 to 12 minutes of
    no scanning.  Also, for Voyager 2 at Jupiter there was an
    extended period of no scanning.  The roll orientation of the
    spacecraft is of crucial importance as to the type of data
    returned since that orientation determines the orientation of
    the scan plane of the LECP Instrument.  That orientation also
    has safety consequences since a poor orientation could expose
    the LECP detectors to ring particulate damage.
 
 
  Calibration
  ===========
    The instrument was calibrated on the ground by placing it into
    beam chambers (e.g.  Van DeGraf machines) and firing calibrated
    beams of known composition at it.  Also, a radioactive source
    is positioned behind the 'sunshield' positioned at sector 8 for
    in-flight calibration of some detector-electronic gains.  Also,
    the instrument has a calibration mode whereby pulses of known
    strength are sent into the pre-amplifier chains following the
    detectors.  Information about calibration can be found in:
    [KRIMIGISETAL1977], [KRIMIGISETAL1981], [ARMSTRONGETAL1981],
    and [HAMILTONETAL1981].
 
 
  'LECP' Detector
  ===============
    Total Fovs                     : 8
    Data Rate                      : 600
    Scan Mode Id                   : UNK
    Sample Bits                    : 10
 
    Detector Type                  : SOLID STATE
    Detector Aspect Ratio          : 0.000000
    Nominal Operating Temperature  : 273.000000
 
    The LECP Instrument consists of a variety (about 28) of 'Solid
    State Detectors' that are used individually and in combinations
    (using coincidence and anti-coincidence criterion) to detect
    and characterize nuclear particles.  The detector thicknesses
    range from 2 to 2450 microns to cover a very broad range of
    particle energy and mass characteristic.
 
    Detectors count particles that have appropriate discriminated
    characteristics with an efficiency that approaches 1.
    Therefore the sensitivity is strictly a function of the
    geometric factors of the detectors (geometric factors
    associated with different data channels are documented
    elsewhere in this catalog) and the energy and species
    band-widths of the data channels (also documented elsewhere).
    The geometric factors have units of area X Steradians (CM^2 X
    STR).
 
 
    'LECP' Section Parameter 'ELECTRON RATE'
    ----------------------------------------
      Instrument Parameter Name      : ELECTRON RATE
      Sampling Parameter Name        : ENERGY PER NUCLEON
      Instrument Parameter Unit      : COUNTS/SECOND
      Minimum Instrument Parameter   : 0.000000
      Maximum Instrument Parameter   : 0.000000
      Minimum Sampling Parameter     : 0.026000
      Maximum Sampling Parameter     : 20.000000
      Noise Level                    : 0.000000
      Sampling Parameter Interval    : 0.000000
      Sampling Parameter Resolution  : 0.000000
      Sampling Parameter Unit        : MEV PER NUCLEON
 
      A measured parameter equaling the number of electrons hitting
      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).
 
 
    'LECP' Section Parameter 'ION RATE'
    -----------------------------------
      Instrument Parameter Name      : ION RATE
      Sampling Parameter Name        : ATOMIC NUMBER
      Instrument Parameter Unit      : COUNTS/SECOND
      Minimum Instrument Parameter   : 0.000000
      Maximum Instrument Parameter   : 0.000000
      Minimum Sampling Parameter     : 1.000000
      Maximum Sampling Parameter     : 26.000000
      Noise Level                    : 0.000000
      Sampling Parameter Interval    : 0.000000
      Sampling Parameter Resolution  : 0.000000
      Sampling Parameter Unit        : ATOMIC NUMBER
 
      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/nucleon or energy/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).
 
 
    'LECP' Section Parameter 'PARTICLE MULTIPLE PARAMETERS'
    -------------------------------------------------------
      Instrument Parameter Name      : PARTICLE MULTIPLE PARAMETERS
      Sampling Parameter Name        : ATOMIC NUMBER
      Instrument Parameter Unit      : MEV X MEV
      Minimum Instrument Parameter   : 0.000000
      Maximum Instrument Parameter   : 0.000000
      Minimum Sampling Parameter     : 1.000000
      Maximum Sampling Parameter     : 26.000000
      Noise Level                    : 0.000000
      Sampling Parameter Interval    : 0.000000
      Sampling Parameter Resolution  : 0.000000
      Sampling Parameter Unit        : ATOMIC NUMBER
 
      A set of measured parameters which yield multiple pieces of
      information about each particle (generally ions) that Q
      enters the system.  These pieces of information can, for
      example, consist of the energy deposited by a single particle
      in two or more separate detectors, or the time-of-flight
      between two different detectors plus the energy deposited in
      a third, etc..  The multiple pieces of information can be
      used to perform mass, atomic number, and/or charge state
      discriminations on ions.  The information can be
      discriminated on-board and telemetered in the form of ion
      rate channels, or the multiple information about each
      particle analyzed can be telemetered for obtaining the finest
      species discriminations.
 
 
      (the following table is excerpted from: [MAUKETAL1991])
 
      TABLE 1. Voyager 2 LECP Channel Characteristics
      ----------------------------------------------------------
                               Effective
                               Field
                               of         Energy
      Channel      Species,    View,      Passband,*     [epsilon]G,
      Designation     Z        deg        MeV/nucleon    cm^2 sr
      ----------------------------------------------------------
                               Ion/Proton Channels
      PL01            Z>=1        45      0.028-0.043   1.13x10^-1
      PL02            Z>=1        45      0.043-0.080   1.13x10^-1
      PL03            Z>=1        45      0.080-0.137   1.13x10^-1
      PL04            Z>=1        45      0.137-0.215   1.13x10^-1
      PL05            Z>=1        45      0.215-0.540   1.13x10^-1
      PL06            Z>=1        45      0.54-0.99     1.13x10^-1
      PL07            Z>=1        45      0.99-2.14     1.13x10^-1
      PL08            Z>=1        45      2.14-3.5      1.13x10^-1
      39              Z>=2        60      0.035-0.069**  9.7x10^-2
      38              Z>=6        60      0.069-0.20**   9.7x10^-2
      32              Z=1         60      0.33-0.61      2.6x10^-3
      1               Z=1         60      0.52-1.45      4.4x10^-1
      33              Z=2         60      0.23-0.48      9.7x10^-2
 
                               Electron Channels
      E[beta]01                   45      0.022-0.035      6x10^-3
      E[beta]02                   45      0.035-0.061      6x10^-3
      E[beta]03                   45      0.061-0.112      6x10^-3
      E[beta]04                   45      0.112-0.183    3.9x10^-3
      E[beta]05                   45      0.183-0.5        2x10^-3
      E[gamma]06                  45     >0.252          8.1x10^-3***
      E[gamma]07                  45     >0.480          3.5x10^-3***
      E[gamma]08                  45     >0.853          1.7x10^-4***
      E[gamma]09                  45     >1.20
       ----------------------------------------------------------
          Note: this table shows only a subset (the most commonly
                    used) of the channels available.
 
          * For Z>=1 channels, passband is given for protons only.
         ** Indicates oxygen passband.
        *** [epsilon]G for the difference between adjacent integral
            channels.
 
 
  Electronics
  ===========
    Timed accumulations of particle counts satisfying various
    analog pulse-height discrimination levels.  Timed accumulations
    of particle counts satisfying simultaneous analog pulse-height
    discriminations for multiple detectors.  Pulse-height
    analog-to- digital conversions from multiple, simultaneous
    detectors for direct telemetry.
 
 
  Operational Modes
  =================
 
    FAR ENCOUNTER
    -------------
      Data Path Type                 : UNK
      Instrument Power Consumption   : 4.725000
 
      Used in the vicinity of planetary encounters.  High intensity
      detectors turned off (A, B, DELTA, DELTA PRIME).  (Affected
      channels are documented in detailed level catalog.) Bit Rate
      allocated 1/3 for Particle Multiple Parameters (PMP) data,
      also called Pulse Height Analysis data, and 2/3 for Rate data
      (counts/second).  Full composition discrimination
      capabilities enabled (in both Rate and PMP forms).  Angular
      scanning is typically 6.4 minutes per 360 degree scan but is
      often changed.  Experiment Bit Rate is 600 bits per second.
      Electrons measured up to 0.5 MEV.  minimum sample time is 0.4
      sec.
 
 
    NEAR ENCOUNTER
    --------------
      Data Path Type                 : UNK
      Instrument Power Consumption   : 4.525000
 
      Sometimes used at the closest-in positions during a planetary
      encounter.  The high intensity detectors are turned on (A, B,
      DELTA, DELTA PRIME).  (Affected channels are documented in
      the detailed level catalog.) Particle Multiple Parameter
      (PMP) composition discrimination capabilities are turned off
      (including the rate channels derived from the multiple para-
      meter information).  All data appears in rate (counts/second)
      form.  Angular scanning is typically 6.4 minutes per 360
      degrees scan but is often changed.  Scanning cyclics driven
      by the spacecraft computer are included.  Experiment Bit Rate
      is 600 bits per second.  Electrons are measured up to greater
      than 10 MEV.  Minimum sample time is 0.4 sec.
 
 
  Instrument Mounting
  ===================
    Cone Offset Angle              : UNK
    Cross Cone Offset Angle        : UNK
    Twist Offset Angle             : UNK
 
    LECP Instrument is mounted on the science boom about half way
    between the boom's spacecraft anchor point and imaging scan
    platform.  The mounting is such that the 360 degree scan plane
    of the LECP scanning head (not to be confused with the scanning
    of the imaging instruments) is coplanar with the spacecraft's
    roll axis.  Also, on the Canopus star lock the LECP scan plane
    is about 30 degrees rotated away from the ecliptic plane.  A
    line passing between sectors 1 and 8, and between sectors 4 and
    5, is parallel to the spacecraft roll axis.  Sectors 1 and 8
    point in the general direction or earth, and with the Canopus
    lock, sector 3 points generally in the retrograde direction
    (referring to the direction with respect to the directions of
    motion of the orbiting planets) and about 30 degrees north of
    the ecliptic.