Decay Electron Analysis for Energy-Scale group: SKdetsim meeting Josh Albert Duke University March 4/5, 2009
Sample Makeup • The sample used for this is made up of data and MC events for SK-IV which are identified as stopping muons. Then apply: • pass stmufit goodness (bgood != -1) • one probable decay electron found • no other cuts applied on the muon position or direction, for this particular analysis • Newest plots have 5777 MC events, and 40893 data events, before any decay-e selection cuts are applied. • For comparison, old plots have 14044 MC events, 30479 data events.
Selection Cuts • The following cuts were used, attempting to duplicate Ishihara-san’s cuts: • 2µs<t<8µs • n50 (# hits in 50 µs time window)>60 • egood (e recon goodness)>0.5 • Electron reconstructed vertex in FV
Plots • All plots are scaled to the number of MC events • Error bars are sqrt(N) before scaling. • Red for MC, Blue for data, and Green for true information, if applicable. • We changed a few things in the last couple days, affecting our plots...
Recent Changes • New waterjob! Attenuation length and PMT gain have been adjusted. • MC generation fixed for raw charge → corrected charge calculation. • Cut based on MC truth info removed. • MC now includes both µ + and µ - . Before, only µ - was included.
Decay Time Count Data 3 10 MC OLD 2 10 0 1 2 3 4 5 6 7 8 9 10 t ( s) µ
Time to decay Data MC True 2 10 NEW 10 0 1 2 3 4 5 6 7 8 9 10 t ( s) µ
Time to decay Electron 2 10 Positron NEW 10 0 1 2 3 4 5 6 7 8 9 10 t ( s) µ
Reconstructed Momentum of Michelle Electron 700 Count 600 Data OLD MC 500 400 300 200 100 0 0 10 20 30 40 50 60 70 Momentum (MeV/c)
Reconstructed Momentum of Michelle Electron 250 Data NEW MC 200 150 100 50 0 0 10 20 30 40 50 60 70 Momentum (MeV/c)
n50 700 600 Data 500 MC 400 OLD 300 200 100 0 0 50 100 150 200 250 300 350 400 n n50 is the number of hits within a 50 µs time window around decay
n50 250 Data 200 MC 150 NEW 100 50 0 0 50 100 150 200 250 300 350 400 n
All remaining plots are NEW
Electron Decay Vertices decay e vertex x 200 180 160 140 Data 120 100 80 MC 60 40 20 True 0 − 1500 − 1000 − 500 0 500 1000 1500 x (cm) decay e vertex y 200 180 160 140 120 100 80 60 40 20 0 − 1500 − 1000 − 500 0 500 1000 1500 y (cm) decay e vertex z 160 140 120 100 80 60 40 20 0 − 1500 − 1000 − 500 0 500 1000 1500 z (cm)
Reconstructed Momentum of Electron (2 − 4 s) µ 180 Data 160 140 2-4 µs 120 MC 100 80 60 Electron Momentum 40 20 0 0 10 20 30 40 50 60 70 Momentum (MeV/c) Reconstructed Momentum of Electron (4 − 6 s) µ 80 70 60 4-6 µs 50 40 30 20 10 0 0 10 20 30 40 50 60 70 Momentum (MeV/c) Reconstructed Momentum of Electron (6 − 8 s) µ 35 30 25 6-8 µs 20 15 10 5 0 0 10 20 30 40 50 60 70 Momentum (MeV/c)
n50 (2 − 4 s) Number of hits in 50 µs time window µ 180 160 Data 140 2-4 µs 120 MC 100 80 60 40 20 0 0 50 100 150 200 250 300 350 400 n n50 (4 − 6 s) µ 70 60 4-6 µs 50 40 30 20 10 0 0 50 100 150 200 250 300 350 400 n n50 (6 − 8 s) µ 30 25 6-8 µs 20 15 10 5 0 0 50 100 150 200 250 300 350 400 n
electron vertex recon distance 500 Difference between 400 true and reconstructed vertex in MC 300 200 100 0 0 50 100 150 200 250 dist (cm)
Quantitative results • Mean reconstructed e-momentum and hits in 50µs time window as a function of decay time: 2-4µs 4-6µs 6-8µs amome MC 39.2 MeV 38.4 MeV 39.2 MeV amome data 39.0 MeV 39.0 MeV 39.3 MeV n50 MC 224.6 221.6 225.4 n50 data 219.6 220.2 221.5
Conclusions • The Data and MC seem to match up pretty well. • µ + and µ - spectra differ slightly, this probably caused some of the earlier data/MC differences, matching is now improved • There is no clear trend in the data or MC for effect of decay time on other parameters. • More statistics needed before final e-scale can be calculated.
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