Extinction Related Background Degrading the extinction by a

Extinction Related Background • Degrading the extinction by a factor of 10 Estimated Backgrounds for nominal beam conditions and directly scales ALL of these background design sensitivity contributions by the same factor, meaning we Source m decay in orbit Events 0. 25 Tracking errors Radiative m capture Beam em decay in flight p decay in flight Radiative p capture Anti-proton induced Cosmic ray induced Total Background < 0. 006 < 0. 005 < 0. 04 < 0. 001 0. 07 0. 004 0. 45 Michael Hebert, UC Irvine go from ~ 1/2 background event to nearly 2 expected background events • Compare this to the 5 signal events we would observe for a putative signal at Rme=10 -16 • In short, we CANNOT relax the extinction requirement. Status and Perspectives of MECO, the Muon to Electron Conversion Exp. June 10, 2003 1

Proton Throughput Estimated Backgrounds for • As stated yesterday we have a cosmic ray nominal beam conditions and background that scales with exposure time design sensitivity • A first look indicates that we are not Source Events background compromised by doubling the m decay in orbit 0. 25 running time Tracking errors Radiative m capture Beam em decay in flight p decay in flight Radiative p capture Anti-proton induced Cosmic ray induced Total Background Michael Hebert, UC Irvine < 0. 006 < 0. 005 < 0. 04 < 0. 001 0. 07 0. 004 0. 45 • Of course, what we save in beam development up front we are likely to more than pay for in additional integrated running costs Status and Perspectives of MECO, the Muon to Electron Conversion Exp. June 10, 2003 2