Instrument Overview
  ===================
    The Dynamic Albedo of Neutrons (DAN) is an active/passive neutron
    spectrometer that measures the abundance and depth distribution of
    H- and OH-bearing materials (e.g., adsorbed water, hydrated
    minerals) in a shallow layer (~1 m) of Mars' subsurface along the
    path of the MSL rover.  In active mode, DAN measures the time decay
    curve (the 'dynamic albedo') of the neutron flux from the
    subsurface induced by its pulsing 14 MeV neutron source.  A
    detailed description of the DAN instrument and scientific
    investigation can be found in Litvak et al. (2008).  The experiment
    is contributed by the Federal Space Agency of Russia.
 
    The DAN instrument is expected to be used during rover traverses
    (e.g., during short stops at ~1 m intervals) and while the rover
    is parked.  Short-duration (< 2 min) measurements will provide a
    rough estimate of the water-equivalent hydrogen distribution with
    an accuracy of ~1% by weight.  Longer-duration (~30 min)
    measurements are necessary to derive the vertical distribution of
    water-equivalent hydrogen with an accuracy of 0.1-0.3% by weight.
 
    DAN performs layering structure analyses of the Martian
    sub-surface, to measure the distribution of H- and OH-bearing
    materials, with a vertical resolution of < 1 m and horizontal
    resolutions of 0.5 - 100 m along the path of the rover.
 
    For further information about the DAN instrument and the
    DAN experiment please see LITVAKETAL2008.
 
 
  Scientific Objectives
  =====================
 
    The science objectives of the DAN instrument are as follows:
    1) Detect and provide a quantitative estimation of the hydrogen
    in the subsurface throughout the surface mission;
    2) Investigate the upper <0.5 m of the subsurface and determine
    the possible layering structure of hydrogen-bearing materials in
    the subsurface;
    3) Track the variability of hydrogen content in the upper soil
    layer (~1 m) during the mission by periodic analysis; and
    4) Track the variability of neutron radiation background (neutrons
    with energy < 100 keV) during the mission by periodic analysis.
 
 
 
  Calibration
  ===========
    Calibration information for the DAN instrument is provided
    in the DAN Calibration Report
    (calib/DAN_calibration_report.pdf).
 
 
  Operational Modes
  =================
    DAN has three different modes of operations:  Standby, Passive,
    and Active.
    STANDBY:  Low voltage electronics are on, no science observations
    PASSIVE:  Background observations collected
    ACTIVE: Neutron pulses are produced and science observations
                collected.