The Ultra Low Energy Isotope Spectrometer (ULEIS) measures energetic ion fluxes over the charge range
from He through Ni from about 20 keV/nucleon to 10 MeV/nucleon with mass resolution less than or equal to 0.3 amu.
Ultra-heavy species (above Ni) are also measured in a limited energy range near 0.5 MeV/nucleon. The ULEIS telescope
is a time-of-flight (TOF) mass spectrometer which identifies ions by TOF and by residual kinetic energy E of
particles which enter the 24 deg. x 20 deg. aperture and stop in one of an array of silicon solid state detectors.
The geometric factor is about one sq.cm.-sr. The TOF measurement is determined by start and stop signals from
microchannel plate (MCP) assemblies detecting secondary electrons emitted from incident ion passage through a
thin entrance foil and other such foils within the telescope. In order to prevent electronic pile-up during intense
flux periods, a mechanical shutter ('iris') slides partially closed under on-board control dependent on the start
MCP singles counting rate. The iris can decrease the ULEIS geometric factor by up to a factor of 100 during the
most intense events. Full analysis of individual ions requires 128 bits/event for up to six events per second. Two
types of rate data are included: sectored singles rates for each detector with 8 sectors for 18 rates at 12
bits/rate in compressed format; sectored counts of 5 particle species in 20 energy ranges and 8 sectors at 12
bits/s (compressed). These rate data are read out every 60 seconds at 189 b/s. Housekeeping and other
miscellaneous data require 43 b/s, the total data rate being about 1 kbps. The ULEIS experiment manager
is Dr. Robert E. Gold of the Applied Physics Laboratory of Johns Hopkins University.