1. W. KozaneckiMDI meeting, 5 May 06 Slide 1 Online DCH background analysis  Compare on-line DCH background ratio to Martin's offline analysis  Can we identify the source of the extraneous online DCH backgrounds? W. Kozanecki

2. MDI meeting, 5 May 06 Slide 2 HER-only running, 3 May 06 Lumi bkg or LER b-g or LER b-b or HER b-b ?

3. W. KozaneckiMDI meeting, 5 May 06 Slide 3 HER-only running, 20-21 Apr 06

4. W. KozaneckiMDI meeting, 5 May 06 Slide 4  The online DCH background ratio, with HEB only, is about 0.6-0.7  The typical background ratio, under physics conditions, is 1.0- 1.3. Given that HER contributes only ~ 0.7, this implies about 0.6 units of extra background  This extra background decreases rapidly with dropping e + current. It could be  LER beam-gas  LER beam-beam or dynamic- aperture losses  HER beam-beam  What do the other subdetectors see? Conclusions