Precise Measurement of pi+ -> e+ nu Branching Ratio
  The PEN Collaboration is conducting a new measurement of the pi+ -> e+ nu branching ratio at the Paul Scherrer Institute, with the goal uncertainty of delta B/B(pie2)=5E-4 or lower. At present, the combined accuracy of all published pie2 decay measurements lags behind the theoretical calculation by a factor of 40. In this contribution we report on the PEN detector configuration and its performance during two development runs done in 2007 and 2008. 
E. Frle\v{z} (1), L. P. Alonzi (1), V. A. Baranov (2), W. Bertl (3),   M. Bychkov (1), Yu.M. Bystritsky (2), N.V. Khomutov (...