development of cylindrical drift chamber of comet phase-i · master thesis presentation 29th july,...

29th July, 2016Master Thesis Presentation 1

Master student TingSam Wong Osaka University

Development of Cylindrical Drift Chamber of COMET Phase-I

29th July, 2016Master Thesis Presentation

Outline• Introduction

• COMET Phase-I

• Momentum measurement using CDC

• Requirement and motivation

• Experiments

• Experiments on CDC prototype

• Data Acquisition (DAQ)

• Data analysis

• Results

• Conclusion

2

29th July, 2016Master Thesis Defence 29th July, 2016Master Thesis Presentation

Introduction

3


COMET Phase-I

4

Physics charged Lepton Flavour Violation (cLFV) signal: μ- + Al —> e- + Al (μ-e conversion in Al)

background: μ- + N —> e- + νμ + νe + N (Decay-In-Orbit = DIO)

Goal of COMET Phase-I (i) μ - e conversion at 3.1 x 10-15 sensitivity (100 times lower than current limit) (ii) Background measurements

Pions Muons

Monoenergetic 105MeV/c

Cylindrical Drift Chamber (CDC)

signal in helix path

Protons


COMET Phase-I

5

Physics charged Lepton Flavour Violation (cLFV) signal: μ- + Al —> e- + Al (μ-e conversion in Al)

background: μ- + N —> e- + νμ + νe + N (Decay-In-Orbit = DIO)

Goal of COMET Phase-I (i) μ - e conversion at 3.1 x 10-15 sensitivity (100 times lower than current limit) (ii) Background measurements

Pions Muons

ProtonsRequirement : Momentum resolution: 200 keV/c —> DIO: 0.01


Momentum resolution and spatial resolution of CDC

6

B: Magnetic field strength σ: Position resolution N: Number of measurement points Pt: Transverse momentum b: Multiple scattering

[1] reference from PDG

Spatial resolution

[1]

• Comparing σ=200 and 300μm, estimated momentum resolution change only 1%

Assuming X0 = 507 m, N = 70 , L=1m, Pt=103MeV/c and B is uniform at 1T

• Estimation shows that 300μm is acceptable


Research contentPerformance tests of CDC prototype II and III

Spatial resolution measurement

Hit Efficiency measurement

Performance tests of CDC prototype IV in 0T magnetic field



Performance tests of CDC prototype IV in 1T magnetic field



Included In presentation


•

Measurement of x-t relationScintillating counter

Drift chamberμ-

Sense/field wires

t0

t0

Ground (0V)

+2300V

e-

e-

e-e-

e-e-

A unit cell

t1

Time and Charge information Drift time = t1-t0

8


•

Measurement of x-t relationμ-

Sense/field wires

t0

t0

9

Time informationDrift time = t1-t0

The measured drift distance

Use a mapping - x-t relation

Drift circles

Determine x

Do track reconstruction


•

GARFIELD x-t relation


Experiments

11


•

12

Experiments on CDC prototype

x

y z

High Voltage

RECBE

Scintillator (up)

Scintillator (down)

Magnet

MPPC + Scintillator

Prototype-4

RECBE Boards

◉ ◉ ◉ ◉

◉ ◉ ◉ ◉

◉ ◉ ◉ ◉

◉ ◉ ◉ ◉

◉ ◉ ◉ ◉

◉ ◉ ◉ ◉

HV

MPPC signal

Clock Trigger

Coincidence

Optical fibre

Prototype4

MPPC signal

CDC Prototype IVCDC Prototype IV

2 types of gas mixtures

- He—iC4H10(90/10) in 0T and 1T of magnetic field

- He—C2H6(50/50) in 0T and 1T of magnetic field

CDC Prototype IV:• Geometry and material the same as CDC • 8 sensitive layers with sense wires (1 dummy layer) • Sense wire φ25 μm and field wire φ126 μm

SPring-8 KEK


Trigger Logic

13

x

y z

High Voltage

RECBE

Scintillator (up)

Scintillator (down)

An example in SPring-8 beam test


Data Analysis

14


Analysis Procedure

Track finding

Spatial resolution

Raw data

current x-t relation

Calibration

new x-t relation

GARFIELD

Track fitting


•

16

Track findingFind cross points

3 dimension

from KLOE

Thick black line is track


•

17

Track findingDetermining track parameters for track fitting

3 dimension

Thick black line is track

Scanning region


•

18

Track fitting

Residue =Rdata - Rfit

μ-

Rdata

Rfit

χ2 = (Rdata-Rfit)2

σx2Σi

Minimising of X2

Pattern Space[mm]

x [mm]100− 50− 0 50 100 150

y [m

m]

500

520

540

560

580

600

620

640

660

L1W1 fR:-7.51 hR:-7.55 T:340.79

L2W3 fR:-1.26 hR:-1.15 T:26.21

L3W2 fR:-7.55 hR:-7.56 T:341.83L3W3 fR:8.13 hR:8.19 T:553.29

L4W4 fR:-7.24 hR:-7.68 T:354.33

L5W4 fR:0.39 hR:0.57 T:12.67

L6W5 fR:-5.23 hR:-4.66 T:255.38

L7W5 fR:0.60 hR:0.57 T:12.67

L8W6 fR:4.93 hR:4.71 T:129.33

Fitted:-3.1e-01 1.9e+02 4.2e-01 -4.0e+02

Initial:-3.1e-01 1.9e+02 3.9e-01 -3.8e+02

Pattern Space[mm] frame

0 1 2 3 4 5 6 7 8 9 100

1

2

3

4

5

6

7

8

9

10

slope_yx : -3.107164e-01

intersect 1.899324e+02

slope_yz : 4.227287e-01

intersect -3.958826e+02

Gas Mixture (null)

High Voltage 1850[V]

Threshold 0[mV]

Chisquare 14.4083

triggerNumber 23 iev 21

frame waveform_of_Layer1

0 5 10 15 20 25 30100

200

300

400

500

600

700

340.8

Color : Wire 1 waveform_of_Layer1 waveform_of_Layer2

0 5 10 15 20 25 30100

200

300

400

500

600

700

26.2

165.8

383.5 489.8 775.2

Color : Wire 3 waveform_of_Layer2

waveform_of_Layer3

0 5 10 15 20 25 30100

200

300

400

500

600

700

341.8

448.1

Color : Wire 2

553.3

710.6

Color : Wire 3

waveform_of_Layer3 waveform_of_Layer4

0 5 10 15 20 25 30100

200

300

400

500

600

700

354.3

815.8


0 5 10 15 20 25 30100

200

300

400

500

600

700

12.782.5 353.3

489.8 537.7589.8


waveform_of_Layer6

0 5 10 15 20 25 30100

200

300

400

500

600

700

255.4372.0

476.2 638.7

832.5


0 5 10 15 20 25 30100

200

300

400

500

600

700

12.7 241.8

337.7

460.6618.9


0 5 10 15 20 25 30100

200

300

400

500

600

700

129.3

260.6

351.2630.4 838.7



•

19

Measure and fit x-t relationRegion 1

Region 3

Region 2

Region 4

Fitting of x-t relation using 5th order polynomials in 4 regions.


Results

20


Spatial resolution versus drift distnace•

DCA[mm]0 1 2 3 4 5 6 7 8

Spat

ial r

esol

utio

n [m

m]

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4 / ndf 2χ 0.0005811 / 7Primary ions 0.2385± 1.734 Diffusion constant 05− 3.784e±05 − 4.384eDrift velocity 0.02362± 0.02749 Electronics 0.8313± 1.679 Extrapolation 0± 0.094

/ ndf 2χ 0.0005811 / 7Primary ions 0.2385± 1.734 Diffusion constant 05− 3.784e±05 − 4.384eDrift velocity 0.02362± 0.02749 Electronics 0.8313± 1.679 Extrapolation 0± 0.094

The composition of spatial resolutiondata

Primary ion

Diffusion

Drift time from electrons

Fitting Fixed (94.0um)

HV: 1830V , He—iC4H10(90/10) and B=0T


Results of 3 gas mixtures•

• He—iC4H10(90/10) Magnetic field 1T : 215 um , 95% at 1850V Magnetic field 0T : 157 um , 97% at 1800V

• He—C2H6(50/50) Magnetic field 1T : 192 um , 96% at 2400VMagnetic field 0T : 121 um , 99% at 2400V


• Intrinsic Spatial resolution • At 0T, He—C2H6(50/50) and He—iC4H10(90/10) achieve the requirement for CDC.

• At 1T, the spatial resolution (X2<1)• He—C2H6(50/50) achieve the requirement for CDC• He—iC4H10(90/10) has 215+-14μm spatial resolution and it has only 1% change on momentum resolution of CDC by comparing to 200μm

• Hit efficiency for all gas mixture• They have 95%

Low resolution and high efficiency for gas mixture He—C2H6(50/50) and He—iC4H10(90/10) are performed.

Conclusion

23


Backup

24


•

Measurement of x-t relationμ-

Sense/field wires

t0

t0

Time informationDrift time = t1-t0

The measured drift distance

You need a mapping -

x-t relation?

Drift circles

It can measured error, which can be

decomposed

Ideally, they are tangent to the

track line

25


•

26

Calibration of XT parameters

Start of iteration End of iteration

Distance of Closest Approach (DCA) [mm]

5 times iterations


•

Rough estimation of σ and σPt

27

Assuming X0 = 507 m, N = 70 , L=1 and Pt=103MeV

B is uniform at 1T

• He—iC4H10(90/10) 215+-14μm

• Comparing 200 and 300um•Estimated momentum resolution change only 1% and at 190 keV/c

Still have to confirm the spatial resolution


•

29

CDC prototype IV

• Geometry and material the same as CDC • 8 sensitive layers with anode wires (1 dummy layer)


•

30

Motivation of experiments

• Study the performance of CDC in COMET Phase-I

• Study the gas mixtures for the detector

• Spatial resolution of detector in COMET and how it affects momentum resolution


•How to measure spatial resolution ?

Ground (0V)

+2300V

A unit cell

μ-

Rdata

Rdata : Measured drift distance

1. Measured Time or drift time —> DAQ 2. Drift distance (Rdata) = drift velocity x drift time 3. Error of measurement of Rdata

σx

DCA[mm]0 1 2 3 4 5 6 7 8

Spat

ial r

esol

utio

n [m

m]

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35




Primary ion

Diffusion



Uncertainty (σx) is due to 1. Primary ions and diffusion 2. Electronics


Cylindrical Drift Chamber

32

➡ 20 sensitive layers with alternating stereo angles of +- 4 degrees

➡ Stereo wire to recover Z information

➡ Sense wires: Gold plated tungsten 25 μm Field wires: Aluminium 126 μm


•

33

Data analysis — ProcedureRaw data analysis

Track Finding

Track Fitting

Spatial Resolution

Garfield Simulation

Current XT parameter

New XT parameter

Update

Data taking

Result

Stability of XT

No

Yes

Read

Read

Binary to root

Calibration procedure

Noise elimination

XT relation Understanding

Tracking Error simulation

5 times of iterations


•

34

Motivation of Master Thesis

• Study the performance of CDC in COMET Phase-I

• Study the gas mixtures for the detector

• Spatial resolution of detector in COMET and how it affects momentum resolution


•

Signal and background

35

• Momentum resolution: 200 keV/c

Position resolutionB: Magnetic field strength L: Size of the chamber σ: Position resolution N: Number of measurement points X0: Radiation length in gas volume Pt: Transverse momentum

105.0 MeV electron

[1] reference from PDG


•CyDet - CDC

36

CyDet CDC• Helium based gas mixture (Isobutane or Ethane)• Alternating stereo angle +- 4 degree

- Recover Z information• sense wire : φ25μm (Au-W)• field wire : φ126μm (Al)• Cell : about (16 x 16) mm• Number of Layer : 39 (20 sense/field wires)• Readout System : 104 RECBE Boards (one side)


Curved tracksIn 1T magnetic field, straight line fitting approximation

• It consist of straight and curved tracks

• High energy particle are selected by X2

residue [mm]2− 1.5− 1− 0.5− 0 0.5 1 1.5 20

5000

10000

15000

20000

25000

30000

35000

40000

hitR[5]-fitR[5] {nhit[5]>0 && chi2_r<10}Chi2 < 10Chi2 < 5Chi2 < 1Chi2 < 0.5Chi2 < 0.1Chi2 < 0.05

Chi2 cut0 2 4 6 8 10

Spa

tial r

esol

utio

n [m

m]

0.2

0.21

0.22

0.23

0.24

Spatial resolution vs Chi cutSpatial resolution vs Chi cut

Two points of spatial resolution does not change much with even tighter X2 cut —>

Almost all of them are straight lines


•

38

Measurement

DCA [mm]10− 8− 6− 4− 2− 0 2 4 6 8 10

Drif

t tim

e [n

s]

0

50

100

150

200

250GARFIELD - Ethane 0T

GARFIELD - Ethane 1T

Data - Ethane 0T

Data - Ethane 1T

DCA[mm]0 1 2 3 4 5 6 7

Spat

ial r

esol

utio

n [m

m]

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35




Primary ion

Diffusion




Results Spatial resolution•

DCA[mm]0 1 2 3 4 5 6 7 8

Spat

ial r

esol

utio

n [m

m]

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35




Primary ion

Diffusion



Spatial resolution VS incident angles HV 2400[V] TH 20[mV] Helium:Ethane=50:50

Angle[degree]50 60 70 80 90 100 110 120 130

Spat

ial r

esol

utio

n [m

m]

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0.24

Spatial resolution VS incident angles HV 2400[V] TH 20[mV] Helium:Ethane=50:50 Spatial resolution VS Drift Distance HV 2350[V] TH 20[mV] Helium:Ethane=50:50

DCA[mm]0 1 2 3 4 5 6 7 8

Spat

ial R

esol

utio

n[m

m]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7 52 ~ 67.5 degree60 ~ 75.0 degree68 ~ 82.5 degree75 ~ 90.0 degree82 ~ 97.5 degree90 ~ 105.0 degree98 ~ 112.5 degree105 ~ 120.0 degree112 ~ 127.5 degree

Spatial resolution VS Drift Distance HV 2350[V] TH 20[mV] Helium:Ethane=50:50 Spatial resolution VS Drift Distance HV 2350[V] TH 20[mV] Helium:Ethane=50:50

DCA[mm]0 1 2 3 4 5 6 7 8

Spat

ial R

esol

utio

n[m

m]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7 52 ~ 67.5 degree60 ~ 75.0 degree68 ~ 82.5 degree75 ~ 90.0 degree82 ~ 97.5 degree90 ~ 105.0 degree98 ~ 112.5 degree105 ~ 120.0 degree112 ~ 127.5 degree

Spatial resolution VS Drift Distance HV 2350[V] TH 20[mV] Helium:Ethane=50:50

LayersDCA

Angle

DCA with different angle

development of cylindrical drift chamber of comet phase-i · master thesis presentation 29th july,...

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