Development of a threshold aerogel Cherenkov detector for K/pi separation in the H-dibaryon search at J-PARC

Abstract

We have developed a new threshold Cherenkov detector for online triggering in the H-dibaryon search experiment at the K1.8 beam line at J-PARC. Silica aerogel radiators with a refractive index of n = 1.04 will cover an effective area of 550 x 220 mm(2) . The Cherenkov detector will be placed in a high magnetic field between two spectrometer magnets. Three prototypes and a real-size mockup module have been tested using pions and protons from photoproduction at SPring-8. For momentum ranging from 1.0 to 1.1 GeV /c, a suppression factor of 10(3) could be achieved for pions, with a factor of 10 (-2) for proton misidentification.