[PPT] - Monitoring and control system for MPPCs for the upgraded koto CsI PowerPoint Presentation

SLIDE 1

Monitoring and control system for MPPCs for the upgraded koto CsI calorimeter

Nobuhiro Hara 2017/12/28 Kuno and Yamanaka Group Year-End Presentation

SLIDE 2

KOTO EXPERIMENT

2

CsI

▸ Search for the rare decay (BR~3×10-11 @SM) ▸ Signal — 2γ@CsI + nothing@other detectors KL → π0ν¯ ν

SLIDE 3

NEUTRON BACKGROUND

▸ Misidentify neutrons as photons. ▸ That B.G. was already reduced to 1/100 the Pulse shape cut. ▸ Furthermore, we need to reduce that B.G. by a factor 10.

3

γ

CsI π0

KL ν ¯ ν

CsI B.G. signal

neutron

SLIDE 4

BOTH-END READOUT SYSTEM

Timing difference

→discriminate b/w photons and neutrons

4

γ

neutron

light

CsI

upper stream

γ : Radiation length (~2cm) neutron : Interaction length (~40cm)

SLIDE 5

▸ Current

5

BOTH-END READOUT SYSTEM

CsI

beam

500mm

PMT

▸ Both-end readout

CsI

PMT MPPC beam KOTO CsI calorimeter

Small (25×25mm) Large (50×50mm)

25 25 50 50

Total 4096 MPPCs 4 MPPCs are connected → 1024ch

SLIDE 6

MONITORING & CONTROL SYSTEM

▸ We need the system that monitor and control 1024ch

MPPCs.

๏ Necessary function ✓ Monitor dark current of MPPCs 

(to check that MPPCs are working normally  & to monitor the amount of radiation damage)

✓ Monitor & control high-voltage supplied to MPPCs ✓ Monitor temperature of the board ✓ Low power consumption

6

SLIDE 7

MONITORING & CONTROL SYSTEM

7

Current Sensor ADC signal ADC

Switch Temp Sensor

PC

HV power Supply Switch Controller

MPPCs

×16ch

▸ Overall picture of the system

SLIDE 8

CURRENT SENSOR

8

MPPCs

0.1uF 51Ω

0.1uF

510Ω 510Ω

pamp

LTC2055

+

signal

ADC

Signal of MPPC

~100ns

AC coupling

current sensor

▸ Design

SLIDE 9

MONITORING DARK CURRENT

➡Large dynamic range(0-200uA)

▸ Dark current of MPPC 

0.5uA(initially) →about 50uA(after irradiation) 

4MPPCs are connected → ~200uA

▸ to measure I-V curve to check MPPCs 

→need to measure small current(~0.01uA)

9

Requirement

SLIDE 10

MONITORING DARK CURRENT

▸ OPAMP(single power supply) can’t work well @ small current region ➡Change to dual power supply

10

Current[uA]

0.01 0.02 0.03 0.04 0.05 0.06 0.07

Output[uV]

200 400 600 800 1000 1200 1400 1600

/ ndf

2

χ 0.03072 / 12 Prob 1 p0 24.16 ± 14.62 p1 674.7 ± 2.249e+04 / ndf

2

χ 0.03072 / 12 Prob 1 p0 24.16 ± 14.62 p1 674.7 ± 2.249e+04

Output of OPAMP (single/dual-power supply)

Red : single power supply Blue : dual power supply

+

+
+V

+V GND

single dual

SLIDE 11

MONITORING DARK CURRENT

▸ I-V curve of normal MPPCs & irrad MPPCs

11

normal irrad

Voltage[V] 50 51 52 53 54 55 56 Current[uA] 1 2 3 4 5 6 / ndf 2 χ 5.993 / 21 Prob 0.9994 p0 0.04245 ± 51.28 p1 0.009034 ± 0.2326 p2 0.001222 ± 0.002016 p3 0.009394 ± 0.007587 / ndf 2 χ 5.993 / 21 Prob 0.9994 p0 0.04245 ± 51.28 p1 0.009034 ± 0.2326 p2 0.001222 ± 0.002016 p3 0.009394 ± 0.007587 Voltage[V] 50 51 52 53 54 55 56 Current[uA] 20 40 60 80 100 120 140 160 / ndf 2 χ 1.602 / 21 Prob 1 p0 0.0205 ± 52.35 p1 0.5331 ± 12.58 p2 0.003909 ± 0.008891 − p3 0.009736 ± 0.02205 / ndf 2 χ 1.602 / 21 Prob 1 p0 0.0205 ± 52.35 p1 0.5331 ± 12.58 p2 0.003909 ± 0.008891 − p3 0.009736 ± 0.02205

I-V curve

SLIDE 12

SUMMARY

▸ We will install 4096 MPPCs to reduce the neutron B.G. . ▸ I developed the control & monitoring system for

MPPCs.

▸ That system has some functions. 

Monitor MPPCs, measure temperature, etc..

▸ I will solve some problem and improve the system.

12

SLIDE 13

BACKUP

13

SLIDE 14

14

SWITCH

PhotoMOS Transistor

Power consumption (HV on）

~0W 300uW/ch

Power consumption (HV off）

10~  30mW/ch ~0W speed of switching ~0.1ms ~1ms

n-

resistonce 25Ω <1Ω leak current < 1µA < 1µA

HV

controller

Photo  MOS

Plan A : PhotoMOS relay Plan B : Transistor

SLIDE 15

PHOTOMOS RELAY

▸ High insulation (>200MΩ) ▸ Low power consumption ~10mW ( other relays ~ 1W) ▸ Normally close type → simple circuit ▸ reduce #parts used in the switch

15

▸ Turn on/off

MOSFET(switch) by LED

LED MOSFET

SLIDE 16

MONITORING DARK CURRENT

▸ Requirement

๏No effect to the signal readout ๏Large dynamic range

▸ Dark current of MPPC 

0.5uA(initially)   →about 50uA(after 1.5×109 n/cm2 irradiation) 

4MPPCs are connected → 2~200uA

๏Resolution (~0.01uA) ▸ to measure the I-V curve to check MPPCs

16

SLIDE 17

MONITORING DARK CURRENT

17

10 ns 1 mV

signal

noise < 100uV

→No effect to the signal(~100mV)

▸ Noise from OPAMP → affect the signal readout ➡ checked the Noise

Output of OPAMP

SLIDE 18

MONITORING DARK CURRENT

▸ Calibration(previous version)

18

Current[uA] 20 40 60 80 100 ADC[count] 5000 10000 15000 20000 25000 30000 / ndf 2 χ 3.221 / 18 Prob 1 p0 0.04016 ± 294.5 p1 1.855 ± 2.921 − / ndf 2 χ 3.221 / 18 Prob 1 p0 0.04016 ± 294.5 p1 1.855 ± 2.921 − Current[uA] 20 40 60 80 100 Residual[ADC] 10 − 5 − 5 10

Residual = ADC -(Fit)

DC POWER SUPPLY

A

MY SYSTEM

PC

SLIDE 19

DARK CURRENT OF IRRADIATED MPPC

19

This value is the sum

f 5 series connected

MPPCs.

** From Kotera-san’s slide  @2017July KOTO collaboration MT

SLIDE 20

SIMULATION OF SWITCH

20

Use LTSpice
All parts are

realistic one.

SLIDE 21

▸ Bias voltage of MPPCs ~60V 

12bit ADC→ 1Count = 0.015V  Vover =V-Vbr~ 3 → 0.015V/3V =0.5%  → We can observe 0.5% variation in Vover.

21

MONITORING HIGH VOLTAGE

HV

12bit ADC

to MPPCs 10MΩ 430kΩ

Voltage follower

SLIDE 22

MONITORING TEMPERATURE

▸ temperature sensor IC 

This IC outputs voltage proportionally to the temperature.  The voltage is converted to the digital value by a 12bit ADC.

22

Temperature (measured by thermocouple) Temperature (measured by my system) 8℃ 8.3±2.4 ℃ 17℃ 17.1±2.4 ℃ 24℃ 24.8±2.4 ℃ 30℃ 30.3±2.4 ℃

This IC can measure the temperature precisely.