Baksan Underground Scintillation Telescope upgrade and DAQ of additional layers

The project of the Baksan Underground Scintil- lation Telescope (BUST) upgrade is presented. Additional outer layers of the detectors with fine spatial resolution will be mounted around BUST. Optimal dimensions of a counter, 0.125m◊ 0.125m◊ 0.03m were chosen with a simulation program. The functional diagram of BUSTs DAQ additional layers is presented. Modernization allows us to study the knee region using muon number spectrum measurements. BUST located underground at a depth of 850 m of wa- ter equivalent was designed to solve a number of physical problems which predetermined its construction and location (Alekseev et al., 1998). The telescope is a four-store building with dimensions of 16.7m◊ 16.7m◊ 11.1m and consists of four horizontal and four vertical planes. The total number of detectors is 3180. The analysis of the muon groups registered by BUST gives us an opportunity to obtain information about spectrum and composition of primary cosmic rays in the energy range of 1013 1016 eV (Petkov et al., 2008). The coordinates of fired detectors give the initial information for identification parameters of muon groups (arrival direction and number of muon tracks). In general, the number of muons cross- ing the telescope, n, and the number of the reconstructed muon tracks in a selected event, ntr, should not necessar- ily coincide with each other. When two or more muons are crossing BUST close enough to each other (comparable with the size of the detector), the number of reconstructed muon tracks will be less than the number of muons crossing BUST. Construction of additional external scintillation layers pro