1/t tail cancellation (Double PZC network)

s

1st Pole-Zero Cancellation Inverting polarity of output signal Change time constant - 47 ns -> 4.7 ns

Pre-Amplifier

Prototype Amplifier for the New BHCV

Development of Amplifier and Shaper for High-Rate MWPC I. Kamiji1, N. Sasao2, T. Nomura3, H. Nanjo1, N. Kawasaki1, D. Naito1, Y. Maeda1, S. Seki1, K. Nakagiri1

1Dep. of Phys., Kyoto Univ., 2Dep. of Phys., Okayama Univ., 3KEK

C0

1pF

51Ohm

R0

C1

1pF

R2

47kOhm

R6

6.8kOhm

4.7kOhm

R7

C4

10pF

R8

200OhmR9

200Ohm

R5

1kOhmC3

4.7pF

R3

100R4

910

C2

47pFR10

13kOhm

22kOhm

R11

C5

47pF

R12

200OhmR13

200Ohm

U1U2 U3

U4 R14

5.1kOhm

1kOhm

R15

C6

4.7pF

R16

220OhmR17

100Ohm

U5

INPUT

TestOutput

Schematic Diagram * PZC = Pole-Zero Cancellation * Ux (x = 1 – 5): ADA4817 (Op-Amp)

Output signal of MWPC

Double Pole-Zero Cancellation Network

Goal of the KOTO Experiment Discovery of

- Direct CP violation -suppressed in the SM: BR = 2.4 x 10-11 - Small theoretical uncertainty (2%)

→ Sensitive to new physics beyond the SM

KL p0

Particles beyond the SM can contribute via the loop

Target: 2g (p0→2g) on EMCal + “Nothing Else” “Nothing” is assured by hermetic veto detectors

KL

2g p0

Veto Detectors

2n (through away)

BHCV

EM Calorimeter

J-PARC E14 (KOTO) Experiment

BHCV (Beam Hole Charged Veto) - In-beam veto detector for charged particles at the downstream part of the KOTO detectors - Incident rate of in-beam neutral particles (g and neutron) is up to a few GHz → Signal loss due to fake vetoes

p0

KL

2g

p+

p-

BHCV

30

0 m

m

300 mm

2 cm gang/ch 2mm

Au-W anode wire (φ50 mm) Side Front

zoom

1.6 mm Gas Volume BHCV Upgrade

3mm thick MWPC

Performance Test w/ Single-Channel Prototype of the New BHCV Effect of 1/t tail Cancellation

Pulse Width: 100 ns

Requirement & Solution ✓ Good S/N for ¼ MIP peak events -> Charge Sensitive Amp. w/ Low Noise Op-amp

✓ Capability for high-rate operation up to 800 kHz w/o baseline shift -> 1/t tail Cancellation Circuit

A1=0.79 a1=1.6

A2=0.185 a2=13.5

A3=0.024 a3=113

Pulse Width: O(10 ms) -> 100 ns

AMP

90Sr Plastic Scintillator (trigger)

Prototype BHCV to oscilloscope

Side View

Wires (x13)

2 cm

30 cm Top View

Single Channel Prototype * Read only inner 11 wires * HV: 3000 V

connection

Amp. in shield case

Peak Height Distribution

S/N wrt ¼ MIP peak 46mV/5mV = 9.2

* Normalized for peak height

b-ray

MIP Peak: 184 mV

Charge Gain 7.6 V/pC Charge Gain (Pre-Amp) 680 mV/pC

Std. Dev. of Output Noise 5 mV

Equivalent Noise Charge 4000 e

Basic Performance

change the time constant: - at0 -> 4.7 ns (time constant of 1st PZC)

Charge sensitive amplifier - Time constant: 47 ns Low noise, high speed op-amp - 4nV/√Hz, 2.5fA/√Hz - Gain-Bandwidth: 410 MHz

Additional PZC

Requirement for BHCV - Efficiency: 99.5% - High rate operation

The prototype amplifier and shaper for high-rate MWPC have been developed

- Good S/N for ¼ MIP peak events - Narrow pulse width (100 ns)

Conclusion Next Steps: - Finalize multi-channel amp. and shaper - Install and Operate BHCV for KOTO

Efficiency of BHCV: 99.5% 800 kHz operation w/ little baseline shift

Measurement Measurement

Calculation

- Gas: CF4:n-Pentane (55:45) - Mean Energy Deposit: 1.4 keV - High Voltage: 3000 V - Capacitance: 50pF/ch - Hit Rate: 800kHz (Max.)

Ex.) KL → p+p-p0 background

Remaining tail: 1% of peak height & 400 ns width

Calculation

Remaining Tail

The test chamber is the same one shown in the poster No.P-603

Detail discussion -> poster No.P-603

are expected

Cancelled