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UW classification: background rejection. (An update – more details at future meetings). Review, tree status. Training samples 5M allgamma from v7r0p2 (SLAC farm) DC2 background: 4% of a day from v7r0p2 (UW farm)
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UW classification:background rejection (An update – more details at future meetings) T. Burnett
Review, tree status • Training samples • 5M allgamma from v7r0p2 (SLAC farm) • DC2 background: 4% of a day from v7r0p2 (UW farm) • Packages classifier and GlastClassify : perform the training, save the resulting decision trees as data in GlastClassify • Current GR v7r1 tag has all the above trees. • Package merit : applies above trees to other tuple variables to define the CT tuple variables: CTgoodCal, CTvertex, CTgoodPsf, CTgamma T. Burnett
Bill’s DC1 Background Analysis • Issues: • What is the residual rate? Can one satisfy the SR signal/noise of 105:1 and the Aeff requirement of 0.8 m2 ? • How does it compare with the extragalactic diffuse rate? • Can we identify characteristics of the remaining events allowing better rejection? • The background rate is now X2 more than for DC1. T. Burnett
My requirement:Be able to measure the spectrum of the extragalactic diffuse to from 30 Mev to >100 Gev. Science issues: • is there an excess above 1 GeV that can only be explained by WIMP annihilation? • To what energy are we really sensitive? When does background overwhelm the extragalactic diffuse? • Note: I use the EGRET measurement as a reference: it is surely an overestimate. • We need to understand the background energy distribution! The following is based on 0.01 day DC2 background generated by v7r1 at UW, and the Extragalactic_diffuse source T. Burnett
Current, very preliminary status CTgamma cut 0.9 0.96 0.99 T. Burnett
Current estimate: current background dominates above ~10 GeV So what are the characteristics of those events? Bill noticed this clue: one suggestion was that the MIP finding might help separate the residual background. T. Burnett
I confirm Bill’s observation Clearly see downward and upward events 0.90 0.96 0.99 McZdir Tkr1Zdir T. Burnett
So, what about the MIP finder? • First attempt to use it in the classification tree was not a success. But this is a small fraction of the original population. Will look at it for these remaining events. • First, for all background: • CalMipZDir shows the fraction for which there is a measurment: • And for these, there is clear correlation with the actual incoming direction, both up- and down-going T. Burnett
And now, the residual: Preliminary result disappointing: no apparent signal. McZdir Tkr1Zdir T. Burnett
Next steps • Import Bill’s new cal tree definitions • Use v7r1 for training background: better ACD should help • 0.04 day already done at UW, we can do 0.01 day in a day. • Try MIP finder again, and review (with Bill, all the variables). T. Burnett