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Commissioning of the new electronics and
online system for the Super-Kamiokande Experiment S. Yamada1, K. Awai1, Y. Hayato1, K. Kaneyuki1, Y. Kouzuma1, S. Nakayama1, H. Nishino1, K. Okumura1, Y. Obayashi1, Y. Shimizu1, M. Shiozawa1, A. Takeda1, Y. Heng2, B. Yang3, S. Chen2, T. Tanaka4, T. Yokozawa1, Y. Koshio1, S. Moriyama1 for the Super-Kamiokande collaboration, Y. Arai5, K. Ishikawa6, T. Uchida7 , A. Minegishi6 1, Institute for Cosmic Ray Research, University of Tokyo 2, Department of Engineering Physics, Tsinghua University 3, Department of Physics, Seoul National University 4, Solar Terrestrial Environment Laboratory, Nagoya University 5, High Energy Accelerator Research Organization (KEK ) 6, Iwatsu Test Instruments Corporation 7, Department of Physics, University of Tokyo
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Charge and timing information of
1, Super-Kamiokande detector Water Cherenkov detector 13,000 PMTs are equipped in 50,000 tons water tank ν Charge and timing information of PMT hits are recorded ©Scientific American Cherenkov light Obtain Cherenkov Ring images List of physics topics of the SK detector Atomospheric neutrino oscillation : Δm23, θ23 Solar neutrino oscillation : Δm12, θ12 Neutrino from accerelator(T2K) : search for θ13 Search for neutrino from supernova (burst or diffused) Proton decay search 2
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2, Motivation of upgrading DAQ
■ new Front-end Electronics to achieve Good Data Quality - Low Noise, good timing and charge response - Wide Charge Dynamic Range ■ Process all the hits from PMTs in the online system Previous system Exceeds threshold Hardware trigger module counts hit # of PMTs Only Triggered hit data was sent to online system Issue Event Trigger Higher rate Complex trigger New system All the hit data is sent to the online system → event selection is done by software. ・ Lower energy threshold for solar neutrino measurement ・ Use complex trigger to reduce background for Relic Supernova neutrino search → New system needs high transfer rate and data processing speed. 3
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QTC-Based Electronics with Ethernet
3, New Electronics QTC-Based Electronics with Ethernet (QBEE) Ethernet Readout Features 24channel input QTC (custom ASIC) Charge measurement wide dynamic range (>2000pC) multi-hit TDC (AMT3) Data is sent to Online system via Ethernet External 60MHz clock is used for synchronization with other Qbees On-board pulsar for charge calibration Low power consumption ( < 1W/ch ) Network Interface Card PMT signal 60MHz Clock TDC Trigger Calibration Pulser QTC TDC FPGA
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Good charge resolution
Analog performance of QBEE Dynamic Range Charge Resolution 10 1 0.1 QBEE Prev. Electronics QBEE previous Electronics Large Medium ADC count (– Pedestal) (RMS resolution)/(input charge) [%] Small ~600pC input charge (pC) (1p.e.=~ 2 pC) input charge (p.e.) Good charge resolution 1 p.e. < > 3 p.e. No saturation over 2000 pC !!
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Data-readout via Ethernet
QBEE throughput from analog pulsar Input to a readout PC Custom Network Interface Card 12 10 8 6 4 2 MAX : 11.8MB/s (~95Mbps) throughput rate (MB/s) Requirement input data rate (MB/s) Required data transfer speed : (PMT dark noise) 10kHz x 6byte x 24ch = 1.5MB/sec/board Fast enough. Reaches the theoretical limit of 100BASE-TX !! TCP/IP firmware (SiTCP) and interface logic are implemented on FPGA IP address is set by dip switch 32MB SDRAM
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4, New Online System ~ 430MB/s ~ 14MB/s/FEPC ~ 660kB/s/QBee
Event builder 24PMTs 30QBees QBee Front End PC Merger Software trigger QBee Front End PC QBee ~ 14MB/s/FEPC Recorded Data: 9MB/s typical ~ 660kB/s/QBee ~ 4.5kHz/PMT ~ 430MB/s Merger Software trigger . QBee Organizer Front End PC QBee Merger Software trigger Ethernet 1hit cell = 6bytel (ch, T, Q) Disk Sorting Data from 30Qbee 550 QBees 20 Front-end PCs 10 Merger PCs 13,000 PMTs Offline analysis LINUX Multi-threaded softwares are running on Online PCs equipped with 4 CPU cores. From electronics to offline disk, data is transferred using TCP/IP protocol, with commercial Ethernet network equipments. 7
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Performance of Front-end PC
~550 QBs 20 Front End PC 10 1 Orga nizer offline Function To collect data From 30 Qbees and sort the hit cells in time order Performance with dummy data Front-end PC can handle up to 15kHz dark rate ( PMT dark rate = 4 ~ 5kHz ) To make use of multi core CPUs, data in different time blocks are sorted in parallel by multi-threaded functions ↓ effective for the improvement of throughput 8
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Number of Requests at one time
Data flow manager To Distribute load of event building, data flow manager controls data flow between 20 front-end PCs and 40 Merger processes. FEPC Switch Merger PC Data flow manager 3, Received data available data 1, Report 2, Request of sending data Block 1 2 3 Request rate from data flow manager to front-end PCs vs Number of Requests issued at the same time Required rate To avoid network congestion, data flow manager issues plural number of requests at one time. → Effective for distributing the destination of the data and improvement of throughput Number of Requests at one time
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Software trigger for event building
200ns 200ns Merged and Sorted data From front-end PCs Number of hits exceeds the threshold, Send downstream “Software” event “Software” event Several triggers can be applied for each interest in physics. (different threshold and gate width) Trigger type * Super Lowe ( lower threshold, for solar neutrino analysis ) * LowE, HIghE ( higher threshold, for Atmospheric neutrino) T2K trigger ( with beam spill information sent from T2K beam line) * External ( to synchronize a calibration light source) Basic hitsum triggers
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5, Installation and Basic performance
Replacement work was done for 2weeks in the end of Aug After the installation of new DAQ system, it started working since Sep. 6. DAQ system is stable now and 24hrs operation is ongoing. Installed new DAQ system in an elec. Hut Front-end PCs and network switches Qbees Trigger rate for 12hrs
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Charge and timing response of Qbee with the SK detector
Charge and timing responses were measured by putting LED or Laser light source in the SK detector. Single p.e. Distribution Timing Resolution QBEE Previous Electronics QBEE Prev. Electronics Comparable timing resolution with previous one ~2 1 p.e. ~ p.e. - High S/N for single p.e. detection - Good agreement with single p.e. distribution by previous electronics
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Performance of the Online system
~550 QBs 20 Front End PC 10 Mer ger PC 1 Orga nizer PC offline Change the threshold of the software trigger and measure the efficiency of Online DAQ’s data processing. - 12kHz of Event Trigger rate can be processed without data loss, which is much larger than the max. Trigger rate in the previous System (~4kHz ) - Bottleneck is the disk write on the organizer PC ( max. ~50MB/s) process data w/o loss 13
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Distance between earth and SN (kpc)
7, Other performances with new DAQ system Capability of measuring nearby Supernova Burst Light pulser 2 1.2 Flush rate [MHz] 0.2 10(s) 5 1 Nearby-supernova burst → Need to handle very high rate events Pulse light is injected to SK tank to mimic nearby supernova burst (Light pulse rate follows step-like function ). - 6Mevents/10s can be processed w/o losing SN burst data (Bottle neck is online system) 100 times improvement from the prev. system # of events/10s New Prev Distance between earth and SN (kpc)
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Preliminary Neutron source : ( Am/Be source + BGO ) in SK water tank ?
Measurement of Neutron captured events by software “neutron trigger” Neutron source : ( Am/Be source + BGO ) in SK water tank prompt Prompt signal : Scintillation light of 4.4MeV prompt gamma from BGO Delayed signal : 2.2MeV-γ from neutron capture in water ( It cannot be triggered as a prompt signal because its energy is too low.) Delayed (neutron trigger) ? time Neutron capture time in water To search delayed signal, issue “neutron trigger “ after the normal trigger and save the data. Preliminary Condition for neutron trigger: - neutron trigger gate width = 800 us. - Need prompt signal No signal in outer cosmic Muon VETO detector. This trigger will be used to reduce b.g. for relic-supernova neutrino search
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Online trigger monitor at SK
T2K (neutrino beam from Tokai to Kamioka) trigger By using GPS data of SK and Tokai sites, PMT hits within ±500μs are recorded as T2K triggered event ( 1st priority in software trigger ) Every hit data SK-GPS data Tokai-GPS Data From Tokai check HITSUM Triggered data T2K triggered Offline Disk Merger + Software trigger 1st Reduction 2nd Reduction 3rd Reduction In Apr., 1st neutrino beam was produced at J-PARC in Tokai. Still beam is in commissioning status, but in SK DAQ, T2K trigger and reduction are now applied to SK data and being checked. Online trigger monitor at SK Spill information coming from J-PARC
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8, Summary * Newly developed Electronics and online system for Super-Kamiokande was installed and started running. ** With new electronics, larger charge dynamic range, lower power consumption, larger data transfer speed and good charge and timing resolution were achieved. ** Succeed to handle every hit data from the SK detector using Ethernet based online system by distributed data processing. ** DAQ is stable and continues taking data. Physics analysis is now ongoing. 17
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Time from the nickel trigger
Develop a new Calibration source for SK using external trigger We have used gammas from neutron capture by Ni as a calibration source in SK - In a currently developed calibration source, signal from a fission detector is used as a external trigger for non-biased data taking. - Hit data in the following 500us window is selected by the software trigger to obtain neutron-captured gamma data from the source. Qbee (Ni captured) Fission detector Time from the nickel trigger (micro sec) g events g n n Special Cable hit as an external trigger Cf Preliminary Ni+PE+Epoxy ball SK time
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How to process the T2K gps data Transfer route from Tokai to SK
T2K (neutrino beam from Tokai to Kamioka) trigger How to process the T2K gps data Tspill+TOF SK PMT hits PMT hits within ±500μs are recorded as T2K triggered event ( 1st priority in software trigger ) SK -500ms +500ms T Time stamp GPS receiver Store as “T2K DST” Transfer route from Tokai to SK Kamioka Kenkyuto Off-line sw Neutrino ( J-Parc ) Edge sw. Strage DMZ GPS recv. FW Underground VPN in Sinet Magnet control etc Front-end Merger PC Near Detector Beam DAQ SK Switch (routing) Reflective memory GPS recv. 20
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Data flow manager (cont’d)
To avoid network congestion, data flow manager issues plural number of requests at one time. -> effective for distributing the destination of the data and improvement of throughput Example) Request rate from data flow manager to front-end PCs vs Number of Requests issued at the same time Number of entries in request queue = 1 Number of entries in request queue = 3 Required rate Request :destination Request :destination Req10 : MGR0 Req10 : MGR0 Req11 : MGR1 Req11 : MGR1 Req12 : MGR2 time Req12 : MGR2 time Req13 : MGR3 Req13 : MGR3 Req14 : MGR4 Req14 : MGR4 Req15 : MGR5 Req15 : MGR5 20 FEPC send data to the same PC simultaneously. Depending on the progress in each FEPC, destinations are distributed over 3 PCs.
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Specification of QTC Discriminator Self Number of channel 3
Procesing speed About 900nsec / cycle Chage integration gate 400nsec Gain stage and gain 3 (1:7:49) threshold -0.3 ~ -14mV(S range) Dynamic range 0.2 ~ 51pC(S range) ~ 357pC(M range) ~ 2500pC(L range) Charge resolution ~ 0.2pC(S range) linearity Less than ±1% Timing resolution 0.3nsec(2pC input) 0.2nsec以下(>10pC input) Power consumption < 100mW / channel CMOS process 0.35 um package 100pin CQFP
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Custom ASIC QTC Charge Integration Discriminator Gate Generation
QTC Block Diagram Discriminator Gate Generation QTC timing built-in discriminator 400nsec charge gate ~ 1msec / cycle 3 gain stages (ratio 1:7:49) Only the data from the proper gain stage are left by FPGA charge 3ch x 3gain output 3ch input
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QTC performance (Timing measurement)
T : nsec / count Timing Resolution Timing Linearity 3 2 1 QBEE (QTC) ATM 20-inch PMT resolution 20 10 QBEE (QTC) ATM RMS resolution (nsec) residual from linear fit (nsec) input charge (p.e.) hit timing (nsec) Good timing resolution for 20-inch PMT signal Perfect timing linearity !!
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Breakdown of throughput speed
WR speed 180Mb/s (1.3MHz/ch) QTC (x8) TDC (x4) PMT signal DSM (x4) (FPGA) SIC (FPGA) FIFO (1.5Mb) L1 buffer 256W 1.6MHz/ch (simulation) TKO transfer ~15Mb/s (~100kHz/ch) 1.1 MHz/ch (900nsec gate win.) ~300kHz/ch SDRAM 32Mbyte Ethernet (SiTCP) 11.8Mbyte/sec (82kHz/ch) Daughter Board 25
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Data transfer latency
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MCLK output specification
Output [ 2 pairs in 1 UTP cable ] (1,2) pair MHz clock (5,6) pair Trigger bit event # + TDC reset (3,4) and (7,8) pairs (not used, for future unification of CLK/TRG and 100BASE-TX) Spec. of serial signal [ 1 bit = 1 clock, total 38 clocks = 633 nsec ] Start at a negative edge of the clock 60 MHz clock Serial signal Header (always 1) Trigger (Narrow/Wide + Pedestal + Split) Trigger on/off + TDC reset on/off Trigger w/o TDC reset (10) Trigger w/ TDC reset (11) TDC reset only (No Trigger) (01) 32 bit event # (MSB LSB )
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Clock jitter and clock/trigger phase check
yellow : clock blue : trigger Clock jitter measurement Clock/Trigger phase check 16.67nsec ~4.3nsec measure the variation of zero-crossing point trigger here requirement (by AMT) < 30 psec jitter = 26 psec RMS no problem duty cycle : Tlow/Thigh ~ 1.24
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