  This paper describes the design and construction of a Cherenkov detector
conceived with regard to high energy Compton polarimeters for the International
Linear Collider, where beam diagnostic systems of unprecedented precision must
complement the interaction region detectors to pursue an ambitious physics
programme. Besides the design of a prototype Cherenkov detector, detailed
simulation studies are presented. Results of a first testbeam campaign with the
main objective of validating the simulation in terms of the light distribution
inside the channels and the channel response are presented. Furthermore, a new
method for aligning the detector without the need of dedicated data taking has
been developped.
