Performance test of new MPPC for a new neutrino detector WAGASCI Fuminao Hosomi The University of Tokyo, for the WAGASCI collaboration 9th July 2015, PhotoDet 2015, International Conference on New Photo-detectors 6th – 9th July 2015, Art School for Children, Moscow, Troitsk, Russia Детская школа искусств , Москва , Троицк , Россия
Contents Motivation for WAGASCI experiment Performance test of new MPPCs Preparation for mass test 2
Neutrino oscillation • Mixture between flavor eigenstate and mass eigenstate ν e ν 1 νμ ν 2 = U PMNS ν 3 ντ Flavor eigenstate Mass eigenstate • Measured with neutrino-nucleus interaction • Critical to understand this interaction 3
Motivation for WAGASCI experiment T2K experiment ν μ ν e , ν μ , ν τ // J-PARC ND280 Super-Kamiokande 30 GeV proton CH target H 2 O target π μ+ν Forward scattering 4π acceptance Need to improve ν μ → ν e ν μ → ν μ Systematic error sources cross section Cross section error measurement 4.7 % 5.0 % due to nuclear difference WAGASCI experiment Total 6.8 % 7.7 % 4
WAGASCI experiment μ - Water Grid And Scintillator Goal: Measure cross section ratio n between H 2 O/CH with 3% accuracy ν μ H 2 O CH p Site: J-PARC neutrino monitor hole Target MRD (Not to scale) veto Configuration: • H 2 O and CH Target • Sandwich structure with H 2 O and CH • 3D grid-like scintillator • Muon range detector (MRD) • Iron and scintillator 3D grid-like scintillator 5
Target of WAGASCI detector 3D grid-like scintillator • x + grid + y + grid + … layers • 4π angular acceptance • Readout by using WLS fibers and MPPCs • Thin plastic scintillators (3 mm) • To maximize the H 2 O fraction (79%) • light yield is a concern Need high photon detection efficiency and low noise rate New MPPC will be used 6
Development of MPPC 1 p.e. 2 p.e. 50 mV 3 p.e. 20 ns S10362 type: T2K INGRID and ND280 S10362-11-050C Around 56,000 MPPCs have been used since 2009 Afterpulse and dark noise suppression S12825 type: released in summer 2013 S12825-050C Crosstalk suppression S13081 type: released in winter 2014 100x amplified Over voltage = 2.0 V * All MPPCs in this page are 1.3 x 1.3 mm 2 devices p.e. = photon equivalent S13081-050CS 7
S10362-11-050C S12825-050C Micrographs Trench to prevent crosstalk of MPPC 50x50 μm 2 pixel S13081-050CS 8
Performance evaluation Measured performance of three types of MPPC For measuring • Using dark noise and self trigger • Dark noise rate For monitor • Crosstalk rate LED: 470 nm • Using LED light source • Gain Photosensitive • Relative PDE Type number Features area (photon detection efficiency) S10362-11-050C Old MPPC * 1x1 mm 2 S12825-050C Afterpulse suppression 1.3x1.3 mm 2 S13081-050CS(X1) Crosstalk suppression 1.3x1.3 mm 2 Pixel size: 50x50 μm 2 * Same type as T2K INGRID and ND280 (S10362-13-050C) but different photosensitive area 9
Dark Noise Rate Self trigger with 0.5 p.e. threshold Over voltage = (Bias voltage) – (Breakdown voltage) S12825 type and S13081 type have 1/10 dark noise rate as S10362 type We can operate the new MPPCs with higher over voltage * Normalized to 1 mm 2 active area ** Measured by using discriminator and scaler *** Dead time of scaler: 25 ns 10
Crosstalk Rate Crosstalk rate = 1.5 p.e. threshold dark noise 0.5 p.e. threshold dark noise Compare to S10362 type: • Same rate for S12825 type • 1/10 reduction for S13081 type It become possible to lower signal threshold level * Measured by using discriminator and scaler 11
Gain MPPC Gain = [(1 p.e. ADC ch)−(pedestal ADC ch)] × (ADC charge per ch) elementary charge • Same gain but wider operation voltage for newer MPPCs • With higher over voltage: • Higher gain • Relatively unaffected by temperature changes * Measured by using charge integrated ADC ** ADC gate width: 120 ns *** LED gate width: 20 ns 12
Relative PDE # of photons detected by each MPPC Relative PDE = # of photons detected by S10362 MPPC with Δ V=1.0 V • # of photons = -ln(P 0 ) • P 0 = fraction of pedestal events • To avoid the effect of afterpulse and crosstalk • With higher over voltage, higher PDE achieved for new MPPCs * Measured by using charge integrated ADC ** Effect of dark noise subtracted *** ΔV = over voltage **** Normalized to 1 mm 2 active area 13
Comparison of performance Summary of new MPPCs’ performance Red text shows ratio of value to that of S10362 type Noise rate Crosstalk rate Gain Relative (kcps) (%) (x10 6 ) PDE S10362-11-050C 179 4.18 0.666 1.12 Over voltage=1.1 V * 1 1 1 1 S13081-050CS(X1) 13.7 N/A 0.709 0.969 Over voltage=1.1 V 0.077 N/A 1.1 0.87 S13081-050CS(X1) 44.4 0.896 2.46 2.09 Over voltage=4.0 V 0.25 0.21 3.6 1.9 * Over voltage=1.1 V is used in T2K INGRID and ND280 for operating MPPCs 14
Checking light yield • 3 mm thin scintillator + crosstalk suppression type MPPC • Injecting 600 MeV positron beam • 10 p.e. light yield event in the edge of scintillator > 10 p.e. • 99% detection efficiency 15
MPPCs used in WAGASCI detector MRD: ceramic type MPPC • Ceramic type MPPC (2,750 ch) • Same method as T2K INGRID and ND280 • Array type MPPC (168 x 32 ch) • Newly developed for WAGASCI • Consists of 32 ch MPPCs • 50 x 50 μm 2 pixel size • 1.5 mm diameter active area to fit WLS fibers • Crosstalk suppression type • Compact readout for large amount Target: array type MPPC of channels 1.5 mm φ 16
Mass test of WAGASCI MPPCs • In total 8,126 ch will be used Incubator • Mass test under preparation LED PC • Items of measurement • Gain MPPCs • Relative PDE • Dark noise rate EASIROC • Crosstalk + Afterpulse rate module • Goal: 128 ch at once • Using NIM-EASIROC (General purpose MPPC readout module) 17
Mass test Gain PDE • Array type MPPC • Ceramic type MPPC (for comparison) • Measured 16 ch at once Dark noise rate Crosstalk rate • Array type MPPC has same performance as ceramic type MPPC 18
Summary • Propose a new neutrino detector WAGASCI • Measure the performance of crosstalk suppression type MPPCs • Low noise rate and crosstalk rate • Higher PDE Achieve high detection efficiency S13018-050CS with even thin scintillator • Develop array type MPPC for WAGASCI target • Prepare mass test of 8,126 ch MPPCs 19
Thank you! … and Backup
WAGASCI Collaborators — The University of Tokyo — F. Hosomi, N. Chikuma, A. Izmaylov, T. Koga, M. Yokoyama — Institute for Nuclear Research of the Russian Academy of Sciences — I. Karpikov, M. Khabibullin, A. Khotjantsev, Y. Kudenko, A. Mefodiev, O. Mineev, T. Ovsjannikova, S. Suvorov, N. Yershov — Laboratoire Leprince-Ringuet Ecole Polytechnique — A. Bonnemaison, R. Cornat, O. Drapier, O. Ferreira, F. Gastaldi, M.Gonin, Th. A. Mueller — University of Geneva — A. Blondel, F. Cadoux, Y. Favre, E. Noah, M. Rayner — Kyoto University — T. Hayashino, A. K. Ichikawa, A. Minamino, K. Nakamura, T. Nakaya, B. Quilain — Osaka City University — J. Harada, K. Kin, Y. Seiya, K. Yamamoto — Institute for Cosmic Ray Research — Y. Hayato 21
Schedule • Aug. 2015: Construction of prototype • Dec. 2015: Installation of prototype • Apr. 2016: Date taking with prototype • Summer 2016: Construction of full WAGASCI • Early 2017: Data taking with full WAGASCI 22
WAter Grid And SCIntillator WAGASCI Box for Japanese sweets (Wagashi) 23
Candidate Site • The B2 floor of the T2K near detector hall 24
Multi-Pixel Photon Counter Photon counting device using multiple APD developed by Hamamatsu Photonics • Good linearity between gain and Over voltage = (Bias voltage) – (Breakdown voltage) • High gain / High photon detection efficiency (PDE) • Dark noise: produced by thermally generated carriers • Afterpulse: trapped carriers by lattice defects • Crosstalk: secondary photons detected by other pixels 25
Scintillator and WLS etc. • Scintillator • Wavelength shifting fiber • Processed by Fermilab • Y-11(200)MS – Kuraray • Polystyrene • 1 mm diameter • PPO 1.0% • Blue to Green • POPOP 0.03% • Core: Polystyrene • Wavelength: 420 nm • Inner cladding: PMMA • Outer cladding: FP • Reflective paint • Optical cement • EJ-510 – ELJEN Technology • TiO 2 based • EJ-500 – ELJEN Technology • May be supplanted? • Optically bonding plastic scintillators and acrylic (PMMA) light guides 26
Typical Charge Distribution Using ADC with 0.25 pC/ch Crosstalk suppression type: pedestal over voltage = 3.0 V Fitting with double Gaussian 1 p.e. 2 p.e. Evaluate gain and number of pedestal events 27
Systematic Error Estimate Estimate systematic error from attaching and detaching MPPC to measurement device Measured five times Deviation of relative PDE is about 5% 28
Latching pulse with V over =5.0 V • Pre production • S13081-050CS(X) • S13081-050CS(X1) • June 2014 • Dec. 2014 • Feb. 2015 • Latching • Improved • Rarely 29
Relative PDE Derivation Suppose Poisson distribution Probability that N photons are detected: P(N)=λ N e - λ / N! λ is mean value of detected photon. P(0) = # of pedestal events / # of total entries λ = -ln P(0) 30
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