Author/Authors :
Lagamba، نويسنده , , L. and Cisbani، نويسنده , , E. and Colilli، نويسنده , , S. and Crateri، نويسنده , , R. and De Leo، نويسنده , , R. and Frullani، نويسنده , , S. and Garibaldi، نويسنده , , F. and Giuliani، نويسنده , , F. and Gricia، نويسنده , , M. and Iodice، نويسنده , , M. and Iommi، نويسنده , , R. and Leone، نويسنده , , A. and Lucentini، نويسنده , , M. and Mostarda، نويسنده , , A. and Nappi، نويسنده , , E. and Perrino، نويسنده , , R. and P، نويسنده ,
Abstract :
Recently approved experiments at Jefferson Lab Hall A require a clean kaon identification in a large electron, pion, and proton background environment. To this end, improved performance is required of the silica aerogel threshold Cherenkov counters installed in the focal plane of the two Hall A spectrometers. In this paper we propose two strategies to improve the performance of the Cherenkov counters which presently use a hydrophilic aerogel radiator, and convey Cherenkov photons towards the photomultipliers by means of mirrors with a parabolic shape in one direction and flat in the other. The first strategy is aerogel baking. In the second strategy we propose a modification of the counter geometry by replacing the mirrors with a planar diffusing surface and by displacing in a different way the photomultipliers. Tests at CERN with a 5 GeV/c multiparticle beam revealed that both the strategies are able to increase significantly the number of the detected Cherenkov photons and, therefore, the detector performance.
