The VETO Power
Introduction
The Soudan Underground Laboratory is a 710 m (2090 mwe) deep laboratory in northern Minnesota, which has been operated by the University of Minnesota since 1980. It includes two experimental halls, each 15 m wide by 16 m high. The Cryogenic Dark Matter Search (CDMS II) occupies the 70 m long West Hall and the 5,500 ton MINOS Far Detector is located in the 82 m East Hall. The Soudan 2 Proton Decay experiment [1] stopped data-taking in 2001 and its kiloton calorimeter was finally removed from the back section of the West Hall in 2005, leaving its muon veto shield intact. This created a 13 m x 10 m x 40 m lab space located 2341 ft deep (2090 m.w.e.) surrounded by more than a thousand gas proportional tubes lining the walls, ceiling and floor. The veto tubes on the floor were removed since there is only ~1 upward-going muon per week and lots of gaps due to support structures. All the veto panels were pressure tested and run to HV under gas. Signals were observed from the preamps and noisy or dead channels were repaired. A new gas handling system was built, including gas checkers to monitor oxygen content in the input gas.
In order to create a multi-user facility which could take advantage of a muon-shielded room, the CAMAC-based trigger logic was replaced by a PC-based system with custom electronics based on CPLDs, which then provides a database (GPS-based time stamp and track location) of every entering muon. It thus can be used as an offline muon veto for any experiment or screening device located inside its coverage and even has sensitivity to neutrons whose muons do not enter the cavern, via accompanying charged shower products at the cavern wall. In addition, as a large-area, moderate-granularity muon and electromagnetic shower fragment detector, it can be used to understand underground showers in general, and benchmark cosmogenic Monte Carlo simulations.
Figure 1. The layout of the Soudan Underground Laboratory, showing the location of
The Soudan Underground Laboratory is a 710 m (2090 mwe) deep laboratory in northern Minnesota, which has been operated by the University of Minnesota since 1980. It includes two experimental halls, each 15 m wide by 16 m high. The Cryogenic Dark Matter Search (CDMS II) occupies the 70 m long West Hall and the 5,500 ton MINOS Far Detector is located in the 82 m East Hall. The Soudan 2 Proton Decay experiment [1] stopped data-taking in 2001 and its kiloton calorimeter was finally removed from the back section of the West Hall in 2005, leaving its muon veto shield intact. This created a 13 m x 10 m x 40 m lab space located 2341 ft deep (2090 m.w.e.) surrounded by more than a thousand gas proportional tubes lining the walls, ceiling and floor. The veto tubes on the floor were removed since there is only ~1 upward-going muon per week and lots of gaps due to support structures. All the veto panels were pressure tested and run to HV under gas. Signals were observed from the preamps and noisy or dead channels were repaired. A new gas handling system was built, including gas checkers to monitor oxygen content in the input gas.
In order to create a multi-user facility which could take advantage of a muon-shielded room, the CAMAC-based trigger logic was replaced by a PC-based system with custom electronics based on CPLDs, which then provides a database (GPS-based time stamp and track location) of every entering muon. It thus can be used as an offline muon veto for any experiment or screening device located inside its coverage and even has sensitivity to neutrons whose muons do not enter the cavern, via accompanying charged shower products at the cavern wall. In addition, as a large-area, moderate-granularity muon and electromagnetic shower fragment detector, it can be used to understand underground showers in general, and benchmark cosmogenic Monte Carlo simulations.
Figure 1. The layout of the Soudan Underground Laboratory, showing the location of