1

CC update – momentum resolution

• Software news:– Converted code to read Sue’s ntuples. Allows

use of Chris’s analysis framework (including event display)

– Using ntuple files generated by Chris (Feb ’04)

• This talk:– Compare PID results using new ntuples to that

presented at previous phone meeting– Look at SR muon momentum resolution

D. A. Petyt April 2004

2

Reco. efficiency – new ntuple

Reconstructed event must contain at least 1 track

CC

NC

0<y<0.25 0.25<y<0.5 0.5<y<0.75 0.75<y<1.0

3

Reco. effic. – old ntuple

Track finding efficiency much higher for NC in old file. Why?

4

Recoselection effic - new

5

Recoselection effic - old

6

PID performance

• These curves combine both reconstruction and selection efficiencies, although the effect of the trigger is not accounted for

• NEW file seems somewhat better at higher E

NEW OLD

7

SR muon momentum resolutionContained events - range

TruthReconstructed

Truth (10% smearing)

Resolution function shows small (2%) negative bias and long +/- tails. Momentum resolution ~7%.

8

Track hits

Tracking failure in v-z view

reco

truth

9

Select clean tracks: low y events only

Apply cuts: mc_y<0.2; trk_plane_n>20; trk_end radius>40cm

TruthReconstructed

Tails are reduced (high-side tail eliminated) and resolution improved, but bias is still present

10Demux failure in v-z view (low-side tail)

11Tracking stops prematurely (-ve bias)

12Tracking stops prematurely (-ve bias)

13

Contained events – q/p

TruthQ/P

Range

Right-side plot: q/p momentum resolution. High-side tail (muon momentum overestimated) is more prominent

14q/p thrown off by multiple scattering?

15Disappearing muon?

16Disappearing muon – x,y,z projections

17

Range/momentum comparison

Momentum from range biased low wrt. momentum from curvature

18

Resolution – range vs q/p

Multiple scattering?

In general, range measurement preferred over q/p for contained tracks.

19

Partially-contained events

TruthReconstructed

20

All events

TruthReconstructed

Use range measurement for contained tracks, q/p for partially-contained.

21

Summary & conclusions

• Looked at SR muon momentum resolution for clean CEV/PCE tracks:– Obtained resolutions of ~6% for contained tracks, ~12% for

partially-contained– Range measurement is biased low (~2%). I think this is probably

due to the track finder stopping prematurely at the end of tracks (either because of excessive scattering or high p.h. hits)

– Low-side tail evident for CEV/PCE – demux and tracking errors contribute to this.

– Would be useful if someone could look at some of the rogue events in detail and see where/how the reconstruction is failing

• Observed large differences in reconstruction efficiencies (especially for NC) between two reconstruction passes of the same MC file– My hunch is that this is caused by different JobModule

configurations – needs looking into.