1

PMT Test

1.PMT HV Plateau Curve

To find out the optimal HV for PMT

HV vs A*B/A(B)

2.Pulse shape & height distribution

Data taking by Fast Oscilloscope

2

Block diagram

Please also Octavia’s block diagram.

Counter FastOscilo.

Light shied box

PMT

LSO

Discrim. Coinci.Na-22LinearFanout

3

Plateau curves

High Voltage(V) of PMT A 800 900 1000 1100 1200 1300 1400 1500 1600

Nor

mal

ized

Rat

io o

f C

ount

s( (

A*B

)/B

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04 Plateau of PMT A: (A*B)/B Plateau of PMT A: (A*B)/B

High Voltage(V) of PMT B 800 900 1000 1100 1200 1300 1400 1500 1600

Nor

mal

ized

Rat

io o

f C

ount

s( (

B*A

)/A

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04 Plateau of PMT B : (B*A)/A Plateau of PMT B : (B*A)/A

Measure counting rate per 1 minute.Based on these curves, HV were set to -1300V for PMT A, -1450V for PMT B.

4

Gain difference of PMTs

Time(ns)0 100 200 300 400 500 600 700 800

Am

plitu

de(m

V)

-800

-700

-600

-500

-400

-300

-200

-100

0

100Event# 20 : PMT AEvent# 20 : PMT A

Time(ns)0 100 200 300 400 500 600 700 800

Am

plitu

de(m

V)

-800

-700

-600

-500

-400

-300

-200

-100

0

100Event# 20 : PMT BEvent# 20 : PMT B

Data taken by fast oscilloscope.1.6ns sampling.HV were set to -1300V for PMT A & B.Vertical scale is before the 10x attenuator.

5

Pulse height at -1300V

0 5 10 15 20 25 300

10

20

30

40

50

60

70

80

90

Pulse Height : PMT A

Entries 1000

Mean 11.6

RMS 4.96

Integral 994

/ ndf 2χ 7.772 / 15

Constant 4.17± 79.99

Mean 0.04± 15.01

Sigma 0.0269± 0.8509

Pulse Height : PMT A 0 5 10 15 20 25 30

0

10

20

30

40

50

60

70

80

90

Pulse Height : PMT B

Entries 1000

Mean 10.41

RMS 3.745

Integral 994

/ ndf 2χ 27.75 / 18

Constant 4.71± 88.65

Mean 0.03± 12.87

Sigma 0.0276± 0.8072

Pulse Height : PMT B

Integrated pulses in 290~600ns timing region.~8% difference.( 12.87/15.01)Horizontal axis unit is arbitrary.

6

Pulse shape and height

Fast Oscilloscope.( 50ps sampling)Use attenuators(x10 times) for protection.

HV( PMT A = -1300V, B = -1400V)

Discriminator Threshold : -100mV

Width ; 170ns

Coincidence : logic A & B from discrim.

7

Data Format

800 events in total.

8000points with 50ps sampling

Csv format : 214MB*2

Wfm format : 12MB*2

Text format : 384MB

Root format : 15MB

8

Pulse shape( normal)

Time(ns)0 50 100 150 200 250 300 350 400

Am

plitu

de(m

V)

-1200

-1000

-800

-600

-400

-200

0

200Event# 0 : PMT AEvent# 0 : PMT A

Time(ns)0 50 100 150 200 250 300 350 400

Am

plitu

de(m

V)

-1200

-1000

-800

-600

-400

-200

0

200Event# 0 : PMT BEvent# 0 : PMT B

Cf. Vertical scale is before the 10x attenuator.

9

Pulse shape( abnormal)

Time(ns)0 50 100 150 200 250 300 350 400

Am

plit

ude(

mV

)

-1200

-1000

-800

-600

-400

-200

0

200Event# 55 : PMT AEvent# 55 : PMT A

Time(ns)0 50 100 150 200 250 300 350 400

Am

plit

ude(

mV

)-1200

-1000

-800

-600

-400

-200

0

200Event# 55 : PMT BEvent# 55 : PMT B

How to avoid ‘cut off’ of pulse shape?

->Change vertical scale larger(?)

10

Some other events

Time(ns)0 50 100 150 200 250 300 350 400

Am

plit

ude(

mV

)

-1200

-1000

-800

-600

-400

-200

0

200

Event# 60 : PMT AEvent# 60 : PMT A

Time(ns)0 50 100 150 200 250 300 350 400

Am

plit

ude(

mV

)-1200

-1000

-800

-600

-400

-200

0

200

Event# 60 : PMT BEvent# 60 : PMT B

Pulsel timigs are different.

11

Selection condition

Rejected abnormal events for pulse height24 events among 800.

Events with cut off(17):55, 126, 166, 200, 333, 352, 381, 421,429, 490, 540, 631, 664, 700, 776, 781,796

Events with wrong timing(7):14, 60, 171, 510, 583, 696, 798

Some events are duplicated.

12

Pulse height distribution

0 100 200 300 400 500 600 700 800 900 10000

10

20

30

40

50

60

70

80

Pulse Height : PMT A

Entries 776

Mean 366.1

RMS 141.9

Integral 776

/ ndf 2χ 13.39 / 11

Constant 4.63± 82.69

Mean 1.0± 464.6

Sigma 0.71± 22.27

Pulse Height : PMT A0 100 200 300 400 500 600 700 800 900 1000

0

5

10

15

20

25

30

35

40

45

Pulse Height : PMT B

Entries 776

Mean 509.4

RMS 217.5

Integral 775

/ ndf 2χ 10.17 / 20

Constant 2.43± 39.92

Mean 2.2± 685.4

Sigma 1.7± 43.1

Pulse Height : PMT B

HV: PMT A = -1300V, PMT B = -1450V.Integrated pulse in 75ns ~ 275ns timing region.Vertical unit is # of events.Horizontal unit is arbitrary.

13

Pulse Height : A vs B

PMT A 0 100 200 300 400 500 600 700 800 900 1000

PMT

B

0

100

200

300

400

500

600

700

800

900

1000Pulse Height : A vs B Entries 776

Mean x 366.2

Mean y 509.4

RMS x 141.9

RMS y 217.5

Integral 775

Pulse Height : A vs B

PMT A 0 100 200 300 400 500 600 700 800 900 1000

PMT

B

0

100

200

300

400

500

600

700

800

900

1000

Entries 776

Mean x 366.2

Mean y 509.4

RMS x 141.9

RMS y 217.5

Integral 775

Entries 776

Mean x 366.2

Mean y 509.4

RMS x 141.9

RMS y 217.5

Integral 775

Pulse Height : A vs B

PMT A 0 100 200 300 400 500 600 700 800 900 1000

PMT

B

0

100

200

300

400

500

600

700

800

900

1000

Entries 776

Mean x 366.2

Mean y 509.4

RMS x 141.9

RMS y 217.5

Integral 775

Entries 776

Mean x 366.2

Mean y 509.4

RMS x 141.9

RMS y 217.5

Integral 775

Pulse Height : A vs B

14

Plans1. Measure plateau curve again.

2. Timing analysis.

3. Test Discriminator card.

Set threshold

Read out the TDC timing

4.Test BLAB