https://spdf.gsfc.nasa.gov/pub/data/ibex/background_monitor/aareadme.txt

The IBEX Background Monitor measures IBEX's high-energy proton
background by integrating the flux of >~14 keV protons over a 
7 deg (FWHM) conical field of view.  The Background Monitor is 
housed with, and coaligned with, IBEX-Hi.  A full description 
is given by Allegrini et al, Sp. Sci. Rev. (2009), 146: 105-115.

This directory provides 8-day (one orbit) files containing 0.24-s
resolution >14 keV proton counts along with instrument pointing 
information and spacecraft ephemeris data at the same resolution.  
It also contains a descriptive file on IBEX-Lo, IBEX-Hi and 
Background Monitor time series data with which the file content 
may be understood.