Beam tests of WPC-8 and WPC-9 prototypes of the wire pad chambers for the LHCb muon system

Two new prototypes, WPC-8 and WPC-9, of the Wire Pad Chambers have been constructed at PNPI. The design of these double-gap wire chambers was similar to the previously tested WPC-7 prototype with one important difference: the anode wire planes were electrically independent, which allows to operate the new prototypes either in the double-gap or in the single-gap modes. The prototypes have been tested in the T11 beam at CERN, and this report presents the results of the tests. As in the previous tests, the PNPI front-end electronics based on the discrete elements was used in the read out channels. In addition, a new option of the FE electronics based on the SONY chip has been developed (SONY++) with an active adapter at the input of the chip allowing to reduce the input impedance and the width of the shaped signals. The SONY++ option was tested with the WPC-9 prototype with very satisfactory results. The performance proved to be identical to that with the PNPI FE electronics.