Development of a new positron counting system with SiPM readout for muon spin spectrometers 1 Sohtaro Kanda / kanda@post.kek.jp 2015. 07. 08 at PD15
μ SR 2 ■ Muon spin rotation and relaxation spin In the presence of B-field, muon spin rotates with Larmor frequency ω µ = − qg µ B muon 2 m µ B-field Spin relaxation occurs due to the B-field distribution ■ Parity violating decay of muon Muon from pion decay is polarized and the parity violating muon decay µ + → e + + ν e + ν µ determines the muon spin via the correlation between the positron momentum and the muon spin direction 2015. 07. 08 at PD15
μ SR for Material Science 3 ■ Investigation of the properties of a superconductor Superconducting shielding volume fraction is obtained via muon spin relaxation in a sample. Relaxation function contains the information about magnetic field distribution inside. M. Hiraishi et al , Nature Physics 10, 300 (2014) 2015. 07. 08 at PD15
μ SR for Particle Physics 4 ■ MuSEUM : Muonium Spectroscopy Experiment Using Microwave 1. Muonium formation Upstream Counter Experimental 2. RF spin flip Procedure 3. Positron asymmetry Muonium decay e+ polarized RF Tuning Bar muon beam RF Cavity Positron Counter Online Beam Monitor Kr Gas Chamber Segmented 2D cross-configured scintillation counter 1.7 T Magnet fiber hodoscope S. Kanda et al ., Proceedings of J-PARC2014 (to be published) 2015. 07. 08 at PD15
J-PARC Muon Beam 5 ■ Japan Proton Research Accelerator Complex has the highest intensity pulsed muon beam MLF J-PARC Muon production target 40 ms Double pulse beam with 100 ns ... 600 ns interval in 25 Hz repetition cycle time 600 ns 2015. 07. 08 at PD15
μ SR Spectrometers 6 8 ■ Beam intensity is expected 1.0 x 10 muon/s at 1 MW beam power ■ High rate capable positron counting system is essential ■ 4 beamlines, 10 branches ■ D-Line: Two branches ■ U-Line: Two branches ■ S-Line: Four branches (partly constructed) ■ H-Line: Two branches (under construction) ■ Cost effective composition is desirable ■ Operation in the presence of (high) B-field CHRONUS at RIKEN RAL (MAPMT+VME discrim.) Segmented plastic scintillator Possible solution: Silicon photomultiplier Custom integrated readout electronics 2015. 07. 08 at PD15
Development Overview 7 ■ Prototype development ‣ Proof of the principle ‣ Optimization of options ‣ Experimental inputs for simulation ■ Readout circuit development ‣ ASIC evaluation ‣ Circuit parameters optimization ‣ FPGA implementation ■ Monte-Carlo Simulation ‣ Detector designing ‣ Event rate estimation ‣ Systematic Uncertainty evaluation 2015. 07. 08 at PD15
Positron Counter for MuSEUM 8 ■ Scintillator pixel+MPPC+Kalliope (ASD+multi-hit TDC) 3 mmt 10 mm 300 mm Hamamatsu MPPC 900 ch/layer x 2 layers 1.3 mm x 1.3 mm active area ■ Prototype was developed and ■ Segmented scintillation counter ■ 300 mm × 300 mm detection area a beam test was performed in ■ 10 mm × 10 mm × 3 mmt uni cell Feb. 2014 2015. 07. 08 at PD15
Kalliope Readout Circuit 9 ■ KEK Advanced Linear and Logic-board Integrated Optical detectors for Positrons and Electrons Trigger ASIC FPGA input Ethernet MPPC input Power HV input is on supply the other side Fast ■ 32ch inputs for MPPC ■ ASIC implemented amplifier, shaper, discriminator ■ FPGA programmed multi-hit TDC (common start) ■ SiTCP data transfer M. M. Tanaka, K. M. Kojima, T. Murakami, S. Kanda, C de la Taille and A. Koda, “MPPC frontend module for muon spin resonance spectrometer” (to be published) 2015. 07. 08 at PD15
Kalliope Analog 10 ■ ASIC diagram ■ 40 dB gain ■ 100 MHz bandwidth ■ 4 bit MPPC bias control ■ 4 bit Threshold control ■ 2 x 4 bit amplifier bias control Two stages of voltage amplifier and comparator Bias voltage of each amplifier is DAC controlled High gain Low gain High gain large undershoot small undershoot small undershoot (optimum) Waveform dependence on amplifier parameters 2015. 07. 08 at PD15
Kalliope Digital 11 ■ TDC implementation ■ Multi-hit TDC Memory Packet TCP TDC ■ 1000 hits depth generator State Trigger ■ 1 ns resolution machine Compose Memory writing ■ Adjustable DAQ window … … with four raw data Memory reading ■ up to 64 μ s clocks Four phase rotating 250 MHz clock realize 1 ns resolution Simulated state machine for time counting 2015. 07. 08 at PD15
Kalliope DAQ 12 ■ DAQ software including ROOT based online monitors DAQ windows and online monitors 2015. 07. 08 at PD15
Prototype Study 13 Prototype of Positron Counter ※ reflector and light shield are not shown S. Kanda et al ., Proceedings of J-PARC2014 (to be published) 2015. 07. 08 at PD15
Prototype Study 14 ■ Beam test setup and result μ + beam Blue: Single MPPC Polystyrene Red: w/the other MPPC hit E<15 MeV Scint.+PMT decay e+ Scint.+PMT Target (Cu) # of Detected 0.5 mmt Pixel Detector Pixel Detector Photon~40 Scint.+MPPC Scint.+MPPC 50 mm Positrons from muon decay were photon number distribution detected at J-PARC MLF MUSE D2 Positron signal can be separated from dark noise of MPPC 2015. 07. 08 at PD15
Prototype Study 15 ■ Beam test results χ χ χ χ − − Relative efficiency 3 10 2nd muon 1st muon 2 10 positron Red: Data prompt (30k pulse) 10 Expected maximum event rate Blue: MC (MuSEUM case) (300k pulse) background 1 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Time (ns) Maximum event rate (MHz) Beam test results Measured and simulated time spectra of Measured event loss muon decay positron Time spectra was consistent with simulation result. Pileup loss at 3 MHz/ch was about 2% of total events. 2015. 07. 08 at PD15
Simulation Study 16 Red: muon Detectors 1.7 T B-field Blue: positron Kr Gas target in the chamber and cavity 300 Position on the vertical axis (mm) Voltage (mV) t t 0.09 700 450 Entries 6e+08 Entries 6e+08 0.08 200 Mean Mean 3133 3133 400 600 RMS RMS 2164 2164 0.07 350 Integral Integral 15.79 15.79 500 100 0.06 300 0.05 400 + -> 250 0 0.04 200 300 -100 0.03 150 200 0.02 100 -200 0.01 100 50 -300 0 0 -300 -200 -100 0 100 200 300 0 2000 4000 6000 8000 10000 12000 14000 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Position on the horizontal axis (mm) Time (ns) Time (ns) Hit map on a detector plane Time spectrum Analog output generation 2015. 07. 08 at PD15
Simulation Study 17 ■ Pileup correction htrue htrue hdata htrue Entries Entries 3e+08 9370201 Event loss Mean Mean 3182 3593 5 10 RMS RMS 2604 2354 Integral Integral 1.335e+07 9.37e+06 2 2 / ndf / ndf χ χ 834.8 / 829 842.5 / 829 Prob Prob 0.4373 0.3646 4 10 p0 p0 1.855e+05 1.861e+05 1.005e+04 1.005e+04 ± ± p1 p1 2203 2202 17.7 17.8 ± ± p2 p2 25.19 25.19 ± ± 0.29 0.29 3 10 2 10 10 0 5000 10000 15000 20000 25000 30000 Time (ns) Maximum event rate (MHz) Red: Ideal detector Blue: Pileup considered Pileup correction factor is obtained from Fitting of time spectrum in lower event loss as a function of event rate region and extrapolation maximum event rate 2015. 07. 08 at PD15
Upgrade Plans 18 ■ ASIC upgrade ■ Temp. feedback ■ Pole zero cancelation ■ WFD readout ■ Simplified DAC parameters ■ 4th generation of MPPC ■ FPGA upgrade ■ Less dark count rate ■ Time over threshold ■ Higher PDE Normalized Dark Rate (kHz/mm2) S10362-11-025C 31.2 mV TOT_ch031 TOT_ch031 3 10 LED signal S10362-11-025C 41.2 mV Entries Entries 5112 5112 100 S13360-1325CS 41.2 mV Mean Mean 70.74 70.74 2 10 RMS RMS 32.45 32.45 80 Integral 4886 Integral 4886 10 60 1 old generation 40 − 1 10 4th generation 20 − 2 10 0 0 20 40 60 80 100 120 140 160 180 200 − 3 10 0 2 4 6 8 10 12 14 16 Time over threshold (ns) Threshold DAC TOT spectrum Dark count threshold scan Y. Matsumoto (Osaka Univ.) 2015. 07. 08 at PD15
Relevant Projects 19 100 mm 400 mm e+ Two layers of 100 um fiber Four layers of 1 mm fiber hodoscope for muon beam profile hodoscope for positron tracking monitoring Kalliope readout EASIROC readout S. Kanda et al., JPS 69th Ann. Meeting (2014) S. Kanda et al., JPS 70th Ann. S. Kanda et al ., JPS Conf. Proc. 2, 010404 (2014) Meeting (2015) 2015. 07. 08 at PD15
Summary and Prospects 20 ■ Muon spin rotation is utilized for both of particle physics and material science as a local spin probe ■ For muon spin spectroscopy with high-intensity pulsed beam, highly segmented positron counter is required ■ Solution is the combination of segmented scintillator, SiPM and fast front-end electronics ■ We are preparing the new experiment for measurement of muonium hyperfine splitting (MuSEUM experiment at J-PARC) ■ Detector prototype was developed and its principle was proofed ■ Realistic full simulator of the positron counting system is under development ■ MuSEUM experiment will be ready for data taking in FY2015 and pilot experiment is scheduled in Nov. 2015 2015. 07. 08 at PD15
21 Supplements
MuSEUM Collaboration 22 MuSEUM : Muonium Spectroscopy Experiment Using Microwave M uSEUM 5 Universities, 3 Institutions 39 people 2015. 07. 08 at PD15
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