Instrument Overview
  ===================
 
  The Lunar Prospector Alpha Particle Spectrometer (APS) consists of
  five pairs of 3 cm by 3 cm square ion-implant silicon detectors, each
  pair placed on one face of a cube.  They are covered by thin,
  Al-coated polypropylene foils to exclude sunlight. The sensors have a
  spectral resolution of about 100 KeV at 5.5 MeV.  The combined
  field-of-view for the 5 sensor pairs is nearly 3-pi steradians, with
  the only blind spot being in the direction of the spacecraft bus. The
  APS has a mass of 4 kg and uses about 7 w of power [BINDERETAL1998].
 
 
  Science Objectives
  ==================
 
  A major science objective of the Alpha Particle Spectrometer is
  measure the number and distribution of transient lunar outgassing
  events and their role as sources of the tenuous lunar atmosphere. The
  experiment will investigate possible correlations of outgassing
  events with locations of young impact craters and tectonic features.
 
  Platform Mounting Descriptions
  ==============================
 
  The APS is mounted on one of the three Lunar Prospector booms.  The
  Alpha Particle Spectrometer is mounted on a chassis that is shared
  with the Neutron Spectrometer.
 
  Operational Considerations
  ==========================
 
  The APS searches for gas release events by detecting alpha particles
  produced by the decay of gaseous Rn-222 and solid Po-210.
 
  Operation and Sampling Modes
  ============================
 
  The Alpha Particle Spectrometer is designed to operate continuously
  during the Lunar Prospector Primary Mission.
 
  Principal Investigator
  ======================
 
  The Co-I and spectrometer group leader for the Lunar Prospector Alpha
  Particle Spectrometer experiment is Dr. William Feldman of Los Alamos
  National Laboratory.