A hadron-blind-detector for PHENIX

C. Aidala, S. Stoll and C. Woody,
Brookhaven National Laboratory, Upton, NY11973, USA

B. Azmoun and T. Hemmick,
State University of New York, Stony Brook, NY11974, USA

A. Kozlov, Z Fraenkel, B. Khachaturov, A. Milov, I. Ravinovich, I. Tserruya and S. Zhou, 
Weizmann Intitute, Rehovot, Israel

A Hadron Blind Detector (HBD) is proposed as upgrade of the PHENIX detector at RHIC, BNL. The HBD will allow the measurement of low-mass e+e- pairs --the light vector mesons rho, omega, phi and the low-mass continuum- in Au-Au collisions at sqrt(s_NN)= 200 GeV. From general considerations, the HBD has to identify electrons with a high efficiency (>90%) and with a double hit recognition power better then 90%, it must have a pion rejection factor of ~200 and a very low radiation budget, of the order of 1% of a radiation length. The choice that emerges is a windowless Cherenkov detector, operated with a CF4 based gas mixture in a special proximity focus configuration with a CsI cathode evaporated on GEMs. This talk presents the current status and recent results of the HBD R&D program.