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Gas radiator system

The two RICH detectors will have separate gas systems, because different radiator gases are needed for the different momentum ranges to be covered by the two detectors.

The RICH1 detector will be operated with C tex2html_wrap_inline3066 F tex2html_wrap_inline3068 as radiator gas. As this gas is used in the Forward RICH of DELPHI and will be used in the RICH of HERA-B, experiences and knowledge gained there can be relied upon. For instance, the recirculation gas system can be modelled after DELPHI's Forward RICH (see Fig.5 in [19]).
An estimation of the cost for the different items (condenser unit, evaporator vessel, purifiers, compressor, differential pressure gauge and actuators, valves and pipes) leads to 100 kCHF. In addition, a monitoring system for H tex2html_wrap_inline3070 O and O tex2html_wrap_inline3070 concentrations, for UV-light transmission and for gas composition will be needed ( tex2html_wrap_inline2848 75 kCHF).

As radiator for RICH2 we now plan to use C tex2html_wrap_inline3070 F tex2html_wrap_inline3078 /N tex2html_wrap_inline3070 rather than C tex2html_wrap_inline3070 F tex2html_wrap_inline3078 / Ne as indicated in the proposal. With this choice we can use most of the existing gas system of the Omega RICH. Chromatic aberrations using nitrogen rather than neon increase somewhat. On the other hand the dispersion figure for C tex2html_wrap_inline3070 F tex2html_wrap_inline3078 we have used in our proposal and which was obtained by a first order extrapolation from refractive-index measurements of liquid C tex2html_wrap_inline3070 F tex2html_wrap_inline3078  [20] is contradicted by later measurements [21] so that the difference is probably not very large.

The Omega RICH gas system has been operated either with pure N tex2html_wrap_inline3070 (WA89) or with a C tex2html_wrap_inline3070 F tex2html_wrap_inline3078 /N tex2html_wrap_inline3070 mixture (WA94). Parts of this system need to be upgraded in order to preserve its proper functioning and its reliability. This applies in particular to the gas compressor and to the control system. The system includes monitoring devices for H tex2html_wrap_inline3070 O and O tex2html_wrap_inline3070 concentration, for UV transmission, and for gas composition. The cost for the upgrade is estimated to be tex2html_wrap_inline2848 25 kCHF.

Bielefeld will take up responsibility for the gas system and provide funds (in part).

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next up previous contents
Next: Photon detectors Up: RICH Previous: Laboratory Responsibilities

Lars Schmitt
Wed May 22 16:44:09 METDST 1996