CBM -Russia meeting, ITEP, 5 November 2004 DEVELOPMENT OF LOW RESISTIVE GLASS FOR HIGH RATE RPC F.Guber, INR, Moscow C B M

Schematic view of the TOF - Total area about 130 sq. m. -Standard material properties sufficient for ~ 70% of solid angle - Different concepts for different polar angles Window glass

Properties of different kind of materials Window glassSemiconductive glass Bakelite  (  ·cm) – Mass production yesNo (no market) yes Surface quality good no Stability with freons Some problemsbadgood Type of conductivity ionelectronion Polarization yesnoyes Semiconductive glasses – phosphate glasses, - silicate glasses, - vanadium glasses Yu.Pestov, NIM A494(2002)447

Progress in the low resistive glass development - development of glass samples with resistivity near 10 9 Ωcm (special semiconductor “black” (phosphate) glasses ) and production of the glass samples 30 x30 x 5 mm 3 ; - production of few plates 100 x 100 x 2 mm - construct prototype RPC detector - tests on the beam test of RPC prototype in ITEP (Results have been presented by A.Smirnitsky– previous report) The work has been done in the close cooperation between INR, ITEP and IHEP

Low Resistive Glass for first RPC Prototype - Phosphate glass - electron conductivity - low resistive Problem – difficult for mass production U=1000v

First sample of phosphate low resistive glass Plates produced by cut and polishing from glass block, size 100 x 100 x 2 mm

Silicate glasses - few samples 30 x 30 x 5 mm are available - low resistivity - more technological for industrial production Problems to be solved: - development of the technology of glass block production (regimes of heating and cooling, crystallization problems etc.) - very aggressive melt - needs special crucible from platinum - development of large sizes glass sheets production method U = 1 kV

The nearest plans - to produce low resistive silicate plates 100 x 100 x 2 mm, - to construct new RPC prototype from these plates, - test the RPC prototype on the ITEP test beam, December 2004 ? (INR-ITEP-IHEP) - production of silicate glasses by semi industrial way (by extraction from glass melt) the plate with size about 1000 x 200 x (1-2) mm and with the thickness even less than 0.5 mm - to write the contribution for the Technical Proposal Long-range plans of INR team -Development of low resistive glasses for production of high rate RPCs, - New type of detectors for TOF (APDs -??)