Silica aerogel threshold Cherenkov counters for the JLab Hall A spectrometers: improvements and proposed modifications
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 5GeV/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.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 796088
- Report Number(s):
- JLAB-PHY-00-36; DOE/ER/40150-2108; TRN: US0201441
- Journal Information:
- Nuclear Instruments and Methods in Physics Research Section A, Vol. 471, Issue 3; Other Information: PBD: 1 Oct 2001
- Country of Publication:
- United States
- Language:
- English
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