# Pioneer 10 Charged Particle Instrument Description

  INSTRUMENT_HOST_ID         = P10
  INSTRUMENT_ID              = CPI

  INSTRUMENT_NAME            = Charged Particle Instrument
  INSTRUMENT_TYPE            = Charged Particle Telescope

References:

Fimmel, R.O., W. Swindell, E. Burgess, Pioneer Odyssey, NASA SP-396.

Simpson, J.A., D. Hamilton, G. Lentz, R.B. McKibben, A. Mogro-Campero, M.

## Instrument Overview

    The charged particle detector had four measuring systems: two
    particle telescopes that operated in interplanetary space, and two
    that measured the intense trapped electrons and protons inside the
    Jovian radiation belts.

    During the interplanetary phase of the mission, before and after
    encounter with Jupiter, the experiment sought to identify the
    chemical elements hydrogen, helium, lithium, beryllium, boron,
    carbon, and nitrogen, and to separate hydrogen, deuterium, helium-3
    and helium-4 in an attempt to differentiate between particles coming
    from the Sun and those from the Galaxy. The instrument was also used
    to determine how the streams of high energy particles from the Sun
    travel through interplanetary space. The main telescope of seven
    solid-state detectors measured the composition of cosmic rays from 1
    to 500 million electron volts (MeV), and a three-element, low
    energy telescope measures 0.4 to 10 MeV protons and helium nuclei.

    Two types of sensors were used to cope with the extremely high
    intensities of trapped radiation in the magnetosphere of Jupiter. A
    solid-state electron current detector, operating below -40
    degrees C, was designed to detect those electrons above 3 MeV that
    generate the decimetric radio waves emitted from Jupiter. A trapped
    proton detector contains a foil of thorium which undergoes nuclear
    fission when impacted with protons above 30 MeV, but is insensitive
    to electrons.