Conversion Background and Albedo Studies

John P. Sullivan

Los Alamos National Laboratory

• Formula to esimate "How close does a secondary track traceback to the vertex?"
• PISA picture of the shape of the old nosecone - overlay for the following dot plots
• PISA picutre of the shape of the new nosecone - overlay for the following dot plots
• Dots show the vertex location for the 2ndary electrons -- old nosecone
• Dots show the vertex location for 2ndary electrons -- new nosecone
• Summary of electron background differences between old and new nosecone
• Recent changes in PISA version of MVD design
• Table comparing background from old and new electronics design
• More detailed tables comparing background from old and new electronics
• Mass**2 spectra (GeV**2) for background e+- pairs without MVD (top left), from Dalitz+ the beam pipe (top right), from the MVD only (bottom left), and from all sources including the MVD (bottom right).
• Ratio of Mass**2 spectra for background e+- pairs with and without the MVD with a pt (e+-) > 0.15 GeV/c with no additonal cuts (top left), with a cut accepting only tracks which trace back to within 5 cm of the vertex (top right), with a cut accepting only tracks with verteces -35 cm < Zvertex < 19 cm (bottom left), and with a cut accepting only tracks satisfying both cuts (bottom right).
• Conclusions