Decay Electron Analysis for Energy-Scale group: SKdetsim meeting - - PowerPoint PPT Presentation

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,
• nly µ- was included.

s) µ t ( 1 2 3 4 5 6 7 8 9 10 Count

2

10

3

10

Decay Time

Data MC

OLD

s) µ t ( 1 2 3 4 5 6 7 8 9 10 10

2

10

Time to decay

Data MC True

NEW

s) µ t ( 1 2 3 4 5 6 7 8 9 10 10

2

10

Time to decay

Electron Positron

NEW

Momentum (MeV/c) 10 20 30 40 50 60 70 Count 100 200 300 400 500 600 700

Reconstructed Momentum of Michelle Electron

Data MC

OLD

Momentum (MeV/c) 10 20 30 40 50 60 70 50 100 150 200 250

Reconstructed Momentum of Michelle Electron

Data MC

NEW

n 50 100 150 200 250 300 350 400 100 200 300 400 500 600 700

n50

Data MC

OLD

n50 is the number of hits within a 50 µs time window around decay

n 50 100 150 200 250 300 350 400 50 100 150 200 250

n50

Data MC

NEW

All remaining plots are

NEW

Electron Decay Vertices Data MC True

decay e vertex x

decay e vertex y

decay e vertex z

Momentum (MeV/c) 10 20 30 40 50 60 70 20 40 60 80 100 120 140 160 180

s) µ Reconstructed Momentum of Electron (2−4

Momentum (MeV/c) 10 20 30 40 50 60 70 10 20 30 40 50 60 70 80

s) µ Reconstructed Momentum of Electron (4−6

Momentum (MeV/c) 10 20 30 40 50 60 70 5 10 15 20 25 30 35

s) µ Reconstructed Momentum of Electron (6−8

Electron Momentum

2-4 µs 4-6 µs 6-8 µs Data MC

n 50 100 150 200 250 300 350 400 20 40 60 80 100 120 140 160 180

s) µ n50 (2−4

n 50 100 150 200 250 300 350 400 10 20 30 40 50 60 70

s) µ n50 (4−6

n 50 100 150 200 250 300 350 400 5 10 15 20 25 30

s) µ n50 (6−8

Number of hits in 50 µs time window

2-4 µs 4-6 µs 6-8 µs Data MC

dist (cm) 50 100 150 200 250 100 200 300 400 500

electron vertex recon distance

Difference between true and reconstructed vertex in MC

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.