1/t tail cancellation (Double PZC network) s 1 st 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. Kamiji 1 , N. Sasao 2 , T. Nomura 3 , H. Nanjo 1 , N. Kawasaki 1 , D. Naito 1 , Y. Maeda 1 , S. Seki 1 , K. Nakagiri 1 1 Dep. of Phys., Kyoto Univ., 2 Dep. of Phys., Okayama Univ., 3 KEK C0 1pF 51Ohm R0 C1 1pF R2 47kOhm R6 6.8kOhm 4.7kOhm R7 C4 10pF R8 200Ohm R9 200Ohm R5 1kOhm C3 4.7pF R3 100 R4 910 C2 47pF R10 13kOhm 22kOhm R11 C5 47pF R12 200Ohm R13 200Ohm U1 U2 U3 U4 R14 5.1kOhm 1kOhm R15 C6 4.7pF R16 220Ohm R17 100Ohm U5 INPUT Test Output 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 K L p 0 Particles beyond the SM can contribute via the loop Target: 2g (p 0 →2g) on EMCal + “Nothing Else” “Nothing” is assured by hermetic veto detectors K L 2g p 0 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 p 0 K L 2g p + p - BHCV 300 mm 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 A 1 =0.79 a 1 =1.6 A 2 =0.185 a 2 =13.5 A 3 =0.024 a 3 =113 Pulse Width: O(10 ms) -> 100 ns AMP 90 Sr 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: - at 0 -> 4.7 ns (time constant of 1 st 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: CF 4 :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 - p 0 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