The Entice Instrument

The number of GCR nuclei that ENTICE will detect in a 3-year mission is ~ 20 times that measured by the HEAO-3 C3 experiment. This is a result of the larger geometry factor and the fact that HEAO-3 flew at solar maximum, while HNX will fly at solar minimum. Even more important than the large increase in numbers of particles is the improved charge resolution that ENTICE will achieve. This will enable us to clearly measure the abundance of every indi­vidual element instead of identifying  only groups of elements, as was the case for HEAO-3 C3.

ENTICE is an electronic instrument that is small by comparison to ECCO. ENTICE is com­posed of two silicon arrays, two Cherenkov counters with different refractive indices, and a scintillating fiber hodoscope. This combination of detectors will determine the charge, velocity, and trajectory of each cosmic ray.

ENTICE has an active area of 4 m² and an effective geometry factor of 4.5 m²sr, which is sufficient to collect more than 600 nuclei in the platinum group (75<Z<79), several thousand events in the 50<Z<60 charge range, and tens of thousands of events in the 30<Z<40 charge range. In addition, it should collect ten to twenty actinide nuclei. It is a high-resolution instrument having sufficient resolution and dynamic range to resolve all individual elements over the charge range 10<Z<83. Since both ENTICE and ECCO can be expected to measure precisely the abun­dances of nuclei in the Pt-Pb region, ENTICE also provides a normalization of the ECCO actinide abundances to iron, which is important for interpretation of the data.