Sci-Fi Tracker Performance

M. Ellis - MICE Collaboration Meeting - Wednesday 27th October 2004 1

Sci-Fi Tracker Performance• Software Status

– RF background simulation

– Beam simulation– Reconstruction– Data sample

• Expected performance• Performance• Emittance calculation• Summary

2

RF Background Simulation

• As described by Rikard at VC of 22/9/04• Software used from tag mice-0-9-10• Background generated in 100 jobs of 100

events each on CSF farm at RAL.• Total time to produce 10k events on CSF

was over 4 days!• Output files merged into one file that is then

used as input for each of the 10k event samples.

3

TURTLE Beam

• Added as G4MICE option• In CVS as tag mice-0-9-11• 720,000 events produced using the “June04”

configuration were provided by Kevin Tilley• Sample broken up into 72 sets of 10,000

events each for submission as jobs on CSF farm at RAL

4

Reconstruction

• TDC aspect of Digitisation is now more realistic (exact details of discriminators still to be perfected).

• Duplets (space point made from 2 views in a station) are now reconstructed and used in the pattern recognition.

• Individual clusters are used as separate measurements in the Kalman track fit.

• Still need to add the use of a field map (particularly with the more detailed simulation now in use) – currently assuming a fixed field!

5

Data Sample

• Four sets of events processed:– Various sets of 20k events to study effects of multiple

scattering, non-uniform field, etc...– 720k events with all physics processes, but no RF

background– 720k events with all physics processes and overlaid

RF background events– 7k events with 100x nominal RF background

• All performance plots are from the sample with nominal RF and all physics processes.

• A summary table at the end will show differences between performance with and without RF background

6

Expected Performance

• Expected momentum resolution based on “back of the envelope” calculations.

• Determine effect that multiple scattering will have on resolution.

• Predict resolution as a function of PT and PZ

7

No Multiple Scattering - PT

R

R

PT = Q B · R

PT = 0.52 MeV/c

PT / PT = R / R

PT = Q B R R / R

PT = 1.202 x R

R = 0.431 mm

R = 0.427 * 3.5 / √12

8

PT Resolution• From the previous slide, it is

clear that the PT resolution should be flat as a function of PT: PT = Q B R

• So long as the track does not have an excessively high PZ (resulting in the projection in XY being a small fraction of a circle), the PT resolution should also be flat in PZ

9

No Multiple Scattering - PZ

z

PZ = PT / tan()

tan() = d / dz

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PZ Resolution• PZ = PT / tan()• The resolution in depends on the

radius of curvature: tan() = k / PT

• Therefore the uncertainty on PZ depends on the uncertainty in PT (which is fixed) and that in tan() in quadrature

• For cases of High PT, or Low PZ, the resolution in PT will dominate over the resolution in tan():

PZ = PZ x PT / PT

• High PT (100 MeV/c): PZ = 0.52 / 100 x 225 = 1.15 MeV/c

• Low PZ (150 MeV/c): PZ = 0.52 / 50 x 150 = 1.56 MeV/c

PZ2 = k1

2 + (k2 + k3 PZ)2

PZ2 = (k1 / PT)2 + k2

2

11

With Multiple Scattering

V X W

ms

z = 1.9 mm

X0 = 42 cm → x/X0 = 0.45%

ms = √2 x 13.6 MeV / cp x 0.053

100 < p < 350 MeV/c

68.76 < cp < 335.1 MeV

3.1 < ms < 14.9 mrad

Not to scale!

12

Point Resolution with MCS

• 3.1 < ms < 14.9 mrad

• Station is 1.9 mm thick

• Mean total momentum is 240 MeV/c, giving a typical ms = 5 mrad.

• MCS produces additional error on the point resolution of between 6 and 30 m.

• MCS has no appreciable effect on the resolution of measuring an individual point

13

Multiple Scattering - PT

Typical distance between planes

= 175 mm

Error on position = 175 * 5 mrad

= 0.875 mm

Resolution in R becomes 0.97 mm

PT = 1.202 x R

PT = 1.16 MeV/c

14

Multiple Scattering - PZ

• For case of high PT and high P, expect PZ to depend just on new PT:PZ = PZ x PT / PT

= 160 x 1.16 / 100

= 1.86 MeV/c

• In general, the effects of multiple scattering will increase as P drops, so expect resolution to approach no multiple scattering level at high P and PT, and get worse as the momentum drops.

15

Performance• Position resolution

– X, Y

• Momentum pulls– PX, PY and PZ

• Momentum resolution– PT, PZ

– PT versus PT, PT vs PZ

– PZ versus PT, PZ vs PZ

• “Primes” resolution– X’, Y’, T’

• Efficiency and Purity

16

X Position Resolution

RMS = 48.49 mm RMS = 0.391 mm

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Y Position Resolution

RMS = 57.05 mm RMS = 0.392 mm

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PX PY and PZ Pulls

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PT Resolution

RMS = 28.65 MeV/c RMS = 1.75 MeV/c

20

PZ Resolution

RMS = 25.65 MeV/c RMS = 2.41 MeV/c

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Resolution vs PT

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Resolution vs PZ

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X’ Resolution

RMS = 182.1 mrad RMS = 8.00 mrad

24

Y’ Resolution

RMS = 172.3 mrad RMS = 7.91 mrad

25

T’ Resolution

RMS = 5.48 x 10-2 RMS = 5.06 x 10-3

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Efficiency vs PT

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Efficiency vs PZ

28

Efficiency vs PT / PZ

29

Purity vs PT

30

Purity vs PZ

31

Purity vs PT / PZ

32

Emittance Calculation

• Analysis code developed by Chris:– Trace and phase space– Monte Carlo truth, reconstructed parameters, virtual

planes, ICOOL output files...– Can calculate 2D, 4D, 6D emittance, apply cuts, re-

weighting, etc...– Performance checked against ecalc9f

• For each 10,000 event run, calculate one value of emittance from Monte Carlo truth information and one from reconstructed track information.

• Determine resolution and bias in 4D (XY) emittance (TOF unavailable, hence no 6D emittance).

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Emittance Resolution

  RMS of True

RMS resolution (no RF)

RMS resolution (with RF)

RMS resolution (100x RF)

% RMS/RMS (no RF)

% RMS/RMS (with RF)

% RMS/RMS (100x RF)

X (mm) 48.49 0.390 0.391 0.384 0.80 0.81 0.79

Y (mm) 57.05 0.391 0.392 0.389 0.69 0.69 0.68

PT (MeV/c)

28.65 1.75 1.75 1.69 6.11 6.11 5.90

PZ (MeV/c)

25.65 2.41 2.41 2.43 9.40 9.40 9.47

X’ (mrad)

182.1 8.02 8.00 8.08 4.40 4.39 4.44

Y’ (mrad)

172.3 7.90 7.91 7.58 4.59 4.59 4.40

t’ (x10-3)

5.48 0.506 0.506 0.519 9.23 9.23 9.47

  Efficiency in % Efficiency out % Purity in % Purity out % 4D bias % 4D resolution %

No RF 99.99(85) 99.81(17) 99.15(12) 99.17(66) -0.121 0.060

With RF 99.99(85) 99.83(43) 99.13(14) 99.17(57) -0.138 0.062

100x RF 100.(00) 99.(73) 95.(28) 96.(47) N/A N/A

Performance Summary: