MPGD2011, 30 Aug 2011 Neutron Imaging Detector based on the µPIC Joe Parker Cosmic Ray Group, Kyoto University
MPGD2011, 30 Aug 2011 KYOTO UNIVERSITY, COSMIC RAY GROUP J.D. Parker, K. Hattori, S. Iwaki, S. Kabuki, Y. Kishimoto, H. Kubo, S. Kurosawa, K. Miuchi, H. Nishimura, T. Sawano, T. Tanimori, K. Ueno JAPAN ATOMIC ENERGY AGENCY, MATERIALS AND LIFE SCIENCE FACILITY DIVISION M. Harada, T. Oku, T. Shinohara, J. Suzuki Neutron Imaging Detector based on the µPIC Prototype system and basic operation. Demonstration measurements. Future improvements.
Neutron imaging detector prototype (µNID) ALUMINUM VESSEL DRIFT CAGE 400 µm 9.0 cm µPIC 10 cm 3 2 . 8 c 10-cm µPIC m mfr. by DNP Ar-C 2 H 6 -He 3 (up to 2 atm total pressure). ALUMINUM DRIFT PLANE (0.3 mm) Gas gain < 1000 for neutron imaging. TPC measures 3D proton-triton tracks. Compact, high-rate FPGA-based DAQ. 2.5 cm Energy deposition estimated by time- above-threshold method. Efficiency up to ~30%, position res. of Prototype with ~120 µm, time res. of ~1 µs. top removed.
DAQ and FPGA logic (ATLAS, KEK) Amplifier-Shaper-Discriminators PROTON-TRITON TRACKS FPGA VME encoder Position Entries Entries 28 28 µPIC 50 memory Relative clock pulse 33-bit LVDS 45 ( ! 2) 40 35 VME bus 30 32 bits: 25 orientation, 20 15 time, 10 External 5 position, gate PC 0 0 10 20 30 40 50 60 Digital out X (strips) edge Energy Deposition (256 ch ! 2) 30 Time-above-threshold (clocks) 25 20 DATA ENCODING 15 µPIC µPIC 10 Threshold Threshold Two words per 5 pulse. 0 0 10 20 30 40 50 60 X (strips) ‘edge bit’ saved ASD ASD Simultaneous measurement 0 1 with each data of position and ‘energy word. Time-above-threshold deposition’ at high rates. ( ∝ energy deposit)
DAQ and FPGA logic (ATLAS, KEK) Amplifier-Shaper-Discriminators PROTON-TRITON TRACKS FPGA VME encoder Position Entries Entries 29 29 µPIC 50 memory Relative clock pulse 33-bit LVDS 45 ( ! 2) 40 35 VME bus 30 32 bits: 25 orientation, 20 15 time, 10 External 5 position, gate PC 0 0 10 20 30 40 50 60 Digital out Y (strips) edge Energy deposition (256 ch ! 2) 30 Time-above-threshold (clocks) 25 20 DATA ENCODING 15 µPIC µPIC 10 Threshold Threshold Two words per 5 pulse. 0 0 10 20 30 40 50 60 Y (strips) ‘edge bit’ saved ASD ASD Simultaneous measurement 0 1 with each data of position and ‘energy word. Time-above-threshold deposition’ at high rates. ( ∝ energy deposit)
DAQ and FPGA logic (ATLAS, KEK) Amplifier-Shaper-Discriminators PROTON-TRITON TRACKS FPGA VME encoder Position Entries Entries 25 25 µPIC 50 memory Relative clock pulse 33-bit LVDS 45 ( ! 2) 40 35 VME bus 30 32 bits: 25 orientation, 20 15 time, 10 External 5 position, gate PC 0 0 10 20 30 40 50 60 Digital out X (strips) edge Energy Deposition (256 ch ! 2) 30 Time-above-threshold (clocks) 25 20 DATA ENCODING 15 µPIC µPIC 10 Threshold Threshold Two words per 5 pulse. 0 0 10 20 30 40 50 60 X (strips) ‘edge bit’ saved ASD ASD Simultaneous measurement 0 1 with each data of position and ‘energy word. Time-above-threshold deposition’ at high rates. ( ∝ energy deposit)
DAQ and FPGA logic (ATLAS, KEK) Amplifier-Shaper-Discriminators PROTON-TRITON TRACKS FPGA VME encoder Position Entries Entries 25 25 µPIC 50 memory Relative clock pulse 33-bit LVDS 45 ( ! 2) 40 35 VME bus 30 32 bits: 25 orientation, 20 15 time, 10 External 5 position, gate PC 0 0 10 20 30 40 50 60 Digital out X (strips) edge Energy Deposition (256 ch ! 2) 30 Time-above-threshold (clocks) NEUTRON 25 20 PROTON DATA ENCODING 15 µPIC µPIC TRITON 10 Threshold Threshold Two words per 5 pulse. 0 0 10 20 30 40 50 60 X (strips) ‘edge bit’ saved ASD ASD Simultaneous measurement 0 1 with each data of position and ‘energy word. Time-above-threshold deposition’ at high rates. ( ∝ energy deposit)
Test experiments at J-PARC Tokai, Ibaraki Experiments in Nov. 2009, June 2010, J-PARC and Feb. 2011. Beam power ~120 kW. Carried out at NOBORU beam line. Fill gas: Ar-C 2 H 6 - 3 He (63:7:30) at 2 atm, efficiencies ~28%(5 cm), ~13%(2.5 cm). Materials and Life Science Facility (MLF) NOBORU (BL10) De Detect ector or Bandwidth chopper position position Rotary collimator NOBORU BEAM LINE Moderator-to-detector distance of ~14.5 m. Max. beam size: 10 × 10 cm 2 . 25 Hz pulse rate, 10 Å band- width. Adjustable B 4 C slits
Long term operability AMPLIFIER-SHAPER- DISCRIMINATORS and 3 He usage (ASD) Same gas filling used for first two µNID experiments (separated by 8 months). No degradation in performance seen in June experiment. Gain recovered by increasing anode voltage. Prototype in Detector remained operable after more SAMPLE experimental area than 1 year on single gas filling. HOLDER at NOBORU. Strategies to extend operation Time after Gain filling (% of initial) Annealing of vessel and µPIC against outgassing. 1 st Exp (2009) 0 months 100 Careful selection of materials. 2 nd Exp (2010) 8 months 67 Gas purification system (c.f. Dec 2010 13 months 30 Nakamura’s talk, 16:45 today).
DAQ performance at NOBORU EXTERNAL TOF GATE Time-averaged data rates from off 200 kHz ~ 9.4 MHz. on Neutron rate of 80~100 kHz. Neutron Counts 3 10 pulses Large dead time (40 ~ 85%). 2 10 DAQ BOTTLENECKS 10 FPGA 0 10 20 30 40 50 60 70 80 90 100 VME Time (ms) encoder VME-to-PC data 40 ms memory 33-bit LVDS transfer creates ( ! 2) Reduction in incoming data dead time. VME bus 32 bits: means fewer VME readouts. orientation, time, External Effectiveness depends on position, gate PC edge details of TOF distribution and gate. * LIMITATIONS CAN BE Encoder FIFO REDUCED WITH FURTHER Useful for Bragg transmission, buffers limit DEVELOPMENT OF DAQ resonance absorption. DAQ rate. HARDWARE.
Neutron-gamma separation Escape Fully-contained Event pile-up, SAMPLE TOF DISTRIBUTIONS events neutrons scattered protons No. of neutrons and gammas Time-above-threshold vs. Track length No. of events 5 Polyethylene 10 Time-above-threshold (clocks) 500 degrader 4 n 10 3 10 400 3 10 γ γ /n < 10 -7 2 300 10 2 10 10 200 n 10 1 100 0 5 10 15 20 25 30 35 40 γ TOF (ms) 0 1 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 No. of neutrons and gammas Length (cm) No. of events Bi filter 4 10 Both neutrons and γ ’s are detected ( γ n efficiency ~10 -3 ). 3 10 γ /n < 10 -9 Neutrons selected by cuts in total time- 2 10 above-threshold and 3D track length. 10 γ Fraction of detected γ ’s surviving 1 neutron cuts < 10 -6 (effective gamma 0 5 10 15 20 25 30 35 40 TOF (ms) sensitivity of < 10 -9 ). Data taken at NOBORU, J-PARC in June 2010.
Position resolution with PID Cd TEST CHART 2 mm slits Position from mid- point of track. Resolution: ~1 mm ( σ ) No PID With PID 5 cm Resolution with PID: Proton direction from 349 ± 36 µm ( σ ) shape of distribution Energy deposition 30 Time-above-threshold (clocks) (Includes beam 25 dispersion.) 20 15 10 5 Preliminary 0 0 10 20 30 40 50 60 Y (strips) Track length from end-points Data taken at NOBORU, J-PARC in Nov. 2009.
Refining position Track length Pulse width from peaks Energy deposition resolution 30 Time-above-threshold (clocks) Track length from 25 extrapolation 20 Two methods: End-Point Extrapolation 15 10 (EPE) and Peak Interpolation (PI). 5 Combining both methods produces best 0 0 10 20 30 40 50 60 Y (strips) result of σ = 118.4 ± 0.2 µm. NO REFINEMENT EPE ONLY EPE + PI ( σ = 315 µm) ( σ = 182 µm) ( σ = 118 µm) 0.5 mm slits Preliminary 5 cm Data taken at NOBORU, J-PARC in Feb. 2011.
Image of a wristwatch µPIC (29 MIN.) IMAGING PLATE (200 MIN.) ~3.5 cm Preliminary Courtesy of Ohi, J-PARC Bin size: 200 µm × 200 µm. Bin size can be decreased with higher statistics. Image processing techniques could improve image. Data taken at NOBORU, J-PARC in Feb. 2011 (µPIC).
MPGD2011, 30 Aug 2011 Demonstration measurements Small-angle neutron scattering. Resonance imaging. Bragg-edge transmission.
Small-angle neutron scattering Spherical SiO 2 nanoparticles (diameter ~200 nm). Sample-to-detector distance of 1666 mm. Exposure time of 35 min. Radial position of peak depends on wavelength but is constant in momentum transfer, q. Expected pattern for spherical particles seen in q. ~1 cm Distance from beam center Momentum transfer vs. wavelength Arbitrary units Preliminary -2 7 Å 10 8 Å -3 10 Preliminary 0 2 4 6 8 10 12 14 16 18 20 Radial distance (mm) Data taken at NOBORU, J-PARC in Nov. 2009.
Small-angle neutron scattering Spherical SiO 2 nanoparticles (diameter ~200 nm). Sample-to-detector distance of 1666 mm. Exposure time of 35 min. Radial position of peak depends on wavelength but is constant in momentum transfer, q. Expected pattern for spherical particles seen in q. ~1 cm q projection (6 < λ < 10 Å ) Distance from beam center Arbitrary units Arbitrary units -2 7 Å 10 -2 10 8 Å -3 10 -3 10 -4 10 Preliminary Preliminary 0 0.004 0.008 0.012 0.016 0.02 0 2 4 6 8 10 12 14 16 18 20 -1 q ( Å ) Radial distance (mm) Data taken at NOBORU, J-PARC in Nov. 2009.
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