1

TPC Meeting

Institute of Physics,Academia Sinica

Jia-Ye Chen2007.6.21

2

Outline

• Pile-up Pulse Decomposition Study• Pulse Identification, Fitting (Well & Failure)• Statistics, Efficiency, Residual and Further

more ...

• Pad Response Function (PRF)• Smearing Effect and Parameterization of PRF• Experimental Measurement & Analysis

3

Pile-up Pulse Decompisition

• Algorithm for Identification• Single Pulse & Shape Parameterization• Pile-up Pulse, Shoulder Pulse and Coupled• Failed Fitting (small pulse, plateau pulse)• Efficiency : Percentage of Pulse• Residual• Question & Problem

4

Algorithm for Identification

• Pile-up Pulse• peakAdc > threshold (dynamic threshold)• Separation of peakTdc > 2 clocks• Pulse valley away from prevPeakTdc > 2 cloc

ks• Shoulder Pulse ( By Su-Yin Wang )

• Δ(ΔADC ) < -8.• Separation to neighboring peakTdc > 3.

5

Single Pulse

6

Single Pulse

7

Pile-up Pulse

8

Pile-up Pulse

9

Shoulder Pulse

10

Shoulder Pulse

11

Shoulder Pulse

12

Pile-up & Shoulder Pulse

13

Failed Pulse : Saturated

14

Failed Pulse : Saturated

15

• number pileup pulse = 76946• number of single pulse = 41787 (54.31%) • number of double pulse = 33531 (43.58%) • number of triple pulse = 1294 ( 1.68%)• number of quadruple pulse = 334 ( 0.43%)

Percentage of Pulse ID

• number of good pulse = 2692664• number of single pulse = 2198194 (81.64%) • number of double pulse = 484378 (17.99%)• number of triple pulse = 7106 ( 0.26%)• number of quadruple pulse = 2986 ( 0.11%)

GOOD

Pileup

16

Percentage of Failure

• number of pileup pulse = 54260• number of single pulse = 30534(56.24%) • number of double pulse = 22563(41.58%)• number of triple pulse = 956 ( 1.76%)• number of quadruple pulse = 247 ( 0.46%)

• number of (1) pulse =18 (0.0074%)• (percentage in double pulse (0.0177%))• (chi_square>4 , single pulse)

• number of (1+2+3+4) pulse =89 (0.16%) • (percentage in double pulse (0.39%))• (chi_square>4 , single pulse)

17

Efficiency & Residual

Run 30501 : First 500 Events & only double-pulse event w/o triple-, quadru-, …

OLDOLD

6 Events/sec6 Events/sec

NEWNEW

1.5 Events/sec1.5 Events/sec

18

Question & Problem

• Can we believe the fitting?• Yes, which should be fitted, which not?

• Polynomial Approximation, instead of exact Error Function Fitting?

• Computing Time : much slower than previous one.

19

Smearing Effects to PRF

PWWdl

vD

W

D

D

T

22

12cos

220 costantan

2

2

2220

2WDDPRF l

transverse diffusion coefficient

drift velocity of electron

drift length

wire spacing

Lorentz angle due to ExB effect

TD

Dv

Dl

d

20

FWHM of the PRFTRIUMF TRIUMF TPCTPC

Pad rows are parallel to the Pad rows are parallel to the sense wire.sense wire.

21

Angle(T,W) vs Angle(P,W)

22

Angle(T,W) vs Angle(P,W)

23

Angle(T,W) vs Angle(P,W)

24

Angle(T,W) vs Angle(P,W)

25

Angle(P,W) Slices

26

Angle(P,W) Slices

27

Angle(P,W) Slices

28

Angle(P,W) Slices

29

Angle(P,W) Slices

30

Angle(P,W) Slices

31

Angle(P,W) Slices

32

Angle(P,W) Slices

33

Angle(P,W) Slices

34

Angle(P,W) Slices

35

Angle(P,W) Slices

36

Angle(P,W) Slices

37

Parameterization of PRF

38

Parameterization of PRF

39

Backup Slices

40

Pad Response Function

The induced charge distribution is called “Pad The induced charge distribution is called “Pad Response Function”. Response Function”.

Width of PRFWidth of PRF

1.1.Direct measure of Direct measure of the power to the power to distinguish distinguish between two between two close-by close-by coordinates.coordinates.

2.2.Determine the Determine the two-track two-track resolution.resolution.

41

: chamber-specific pad response width, often normalized to the pad width ΔP by

Parameterization of PRF

Under the optimal design of pad widthG : the distance between sense wire and cathode plane

20

2

2exp)(

i

i

xxCxP

P 0ˆ

GP 2

0

42

Smearing Effects to PRF

• The transverse diffusion• The angular wire effect

• The angle under which the tracks cross the wire-normal.

• The E × B effect close to the sense wires• The angular pad effect

• If tracks cross the normal on a pad-row under a non-zero angle.

• If more than one wire contributes to a pad signal.

43

Experimental Measurement

New New

TPCTPC

By Nakatsugawa Yohei

Line Fitting (Lab. Line Fitting (Lab. Frame)Frame)