7 th 高能物理学会大会, 李小男, 高能物理研究所 1 大亚湾反应堆中微子实验...

7th 高能物理学会大会 , 李小男 , 高能物理研究所 1

大亚湾反应堆中微子实验触发和数据获取系统

李小男 , IHEPOn behalf of触发 :清华大学

DAQ:IHEP


sin22Measurement at

reactors

νe

νe

νe

νe

νe

νe

Distance (L)

Pro

babi

lity

ν e

1.0

1500 meters

Unoscillated flux Unoscillated flux observed hereobserved here

Well understood, isotropic source Well understood, isotropic source of electron anti-neutrinosof electron anti-neutrinos Oscillations observed Oscillations observed

as a deficit of as a deficit of ννee

sinsin2222θθ1313

)4/(sin θ2sin1)νν( ν213

213

2 ELmP ee

νe

νe

νe

νe

νe

νe

Detectors are located Detectors are located underground to shield underground to shield against cosmic rays.against cosmic rays.

ππEEνν /2/2ΔΔmm221313


Dayabay Reactor Neutrino Experiment

900 m

292 m

465 m

810 m 607 m

Total Tunnel length ~ 3000 m


Detecting e

0

0

( >2 =1.022MeV)

Reaction:

Prompt signal:

Delayed signal: ( ~ 8MeV, ~ 28 )

( 2.2MeV, ~ 2

2 '

00 )Delayed signal

'

:

e

ee

e n

e

n

p

E m

G

e

Gd d E s

s

n d

s

E sp

• Inverse -decay in 0.1% Gd-doped liquid scintillator

• Antineutrino signal, algorithm implemented in offline or on online computer farm– Time coincidence

– Energy correlated


Requirements of readout electronics• Readout board designed for all detector systems except RPC.• Neutrino detector:

– Charge measurement• Dynamic range for each PMT: 0 PE -- 500 PE

– 50 p.e is the maximum for a neutrino event– ~500 p.e. for through-going muons

• resolution: <10% @ 1 p.e, 0.025%@ 400 p.e.• Noise < 0.1 p.e.• Digitization time(mainly shaping time) < 1 s

– Timing measurement:• To determine event time and event vertex• dynamic range: 0 ~ 500 ns• resolution: < 500 ps

• Muon detector:– Water pool: Same requirements as neutrino detector – Water Tracker: Hit and/or charge

• RPC: BESIII electronics


Readout board diagram

From PMT

-5V

50

High speedAmp

AD8021

AD9244

14bit/40MSPSFlash ADC

FPGA

To VME bus

CH1

Single ended to

diff.

fast Q sum to trigger

shaping

threshold

start

stop

CH2

Disc.

L1

TDC

Peak Finding

40MHz

charge

time

DATABUFFER

L1VME

interface

Single channel macro in FPGAX 16

RC=300ns

Test input

Over threshold

Hit number or trigger pattern to trigger module

X 2

K

CH3

CH4

CH13

CH14

CH15

CH16

SUM

DAC

DACLVDS x 6

RC2

High speedDAC

Status bits 2 trigger

DLL

80 MHz Clock

Single ended to

diff.

fast Q sum to FADC board

divider

Trigger AlgorithmDaughter Card

On board calibration circuit

16 Channel inputs

TDC algorithm: Gray counters


Trigger requirement• Good background rejection power rate can go to ~KHz rate limited by DAQ capabilities (hopefully < 10 MB/s/module)• Low threshold ( T+3 < 1MeV )

– Record prompt positron signals and delayed signals from the neutrino interactions.

– Record the background to enable background analysis. • High and well known efficiency• Flexibility (to fight backgrounds), same trigger board for different

detector.– FPGA– Daughter card

• Reliability (to reduce systematic errors)• Independency, Separate trigger for each of neutrino module, and e

ach of muon detector, water pool, water cenrenkov module and RPC.

• Redundancy (to measure the trigger efficiency)• Provide a system clock


Algorithms• Central trigger: OR of the following two

– Energy: total charge > 15 PE– Multiplicity: > 15 PMT fired

• Veto trigger: OR of the following two– RPC: > two hits in any plane (Scin. > 1 hits )– Water: > few PMT fired

• Prompt and delayed sub-event triggered and recorded independently, time correlation offline

• Central and veto events triggered and recorded independently, time correlation offline

• No dead-time induced. Trigger rate is limited by electronics recover time and by DAQ bandwidth.

• Trigger type:– Primary physics trigger– LED– Radioactive source– Periodic trigger– Muon trigger


PMT dark current rate

• PMT max. number: 200• PMT dark current rate:50k• Integration windows:100ns


Trigger rate

Detector EventTrigger Rate

Occ. Ch size (bits)DB LA Far

e Module

Cosmic-μ 36x2 22x2 1.2x4100% 224*64

Rad. 50x2 50x2 50x4

Pool Cosmic-μ 250 160 13.6 50% 340(252)*64

Tracker Cosmic-μ 1390 819 57.8 100% 8*64

RPC

Cosmic-μ 260 260 415

10% 7650(5040)*1

Rad.&Noise 186 117 10.5

Site totals kB/s 653 483 419 1555


Trigger board

• One board per module• Same hardware design for central and veto boa

rd• Each trigger board can handle up to 256 PMTs

• Decision time: → Readout event buffer depth

– Multiplicity trigger based on FPGA: ~ 200 ns

– Energy trigger based on total charge : ~ 300 ns ?

• System clock + Local clock


Trigger scheme


Timing• Each site has a master

clock to synchronize the veto and central modules

• A GPS time/1 PPS/10 kHz reference will be delivered to each site for an absolute time stamp

• If GPS can not be used, we can use a local clock, a problem for Supernova studies.

• Precision: GPS time ~ 100 ns. Time-stamp precision level 25ns.

• Each trigger board have a local clock for self trigger and testing.

GP SR e c e ive r

A n ten n a

E le c tro -o p tic a lc o nv e rte r



O p tica l F ib e r2 K m



F a n-o u tF a n-o u t F a n-o u t

to n e a r s ite -12 trigge r b o a rd s

to n e a r s ite -22 trigge r b o a rd s

to fa r s ite4 trigge r b o a rd s

G P S tim e/1 P P S /1 0 K H z

G PS tim e1 PPS1 0 K H z4 0 M C lo ck

O p tic a l-e le c troc o nv e rte r



L V D S L V D S L V D S

Mid-site

DYB LA FAR


DAQ block diagram


Data acquisition & online control• VME based front-end hardware, Motorola PowerPC co

ntroller• RT-Linux RTOS: TimeSys Co. LinuxLink • Back-end Linux PC. Software based on BES-III/Atlas F

ramework• Each detector system and each neutrino module at each

site is readout (trigger) independently.– 8 antineutrino streams and 9 muon streams. Event reassemble

d using timestamp offline.– One neutrino module → One VME crate.– Water pool → One VME crate (near), Two VME crates (far).– Water Cerenkov Module system: TWO VME crates.

• Communication: – Copper between trigger-FEE– Twisted cable between PowerPC and readout computer– Optical between site-site/site-surface.


Data acquisition and online control • Online control

– Local online control in each detector hall: each detector system has its own online control. Detector debugging and commissioning in parallel.

– Global online control in surface room: Operate and monitor all detector system.

• Data storage: – Data throughout: 1.5MB/s. → 0.4TB/day (safety factor of 3).– Local tapes– Local disks

• Data transfer: – Tapes from DYB to IHEP or to Shenzhen Uni.– A data link from Shenzhen Uni. to IHEP via network can be

discussed• A data center at IHEP to be established. Raw data or

processed data tapes will be copied and shipped to other data centers in the world, or distributed via GRID.


One Readout VME crate

Readout Board 16

(VME)

Energy sumReadout Board 1(VME)

Trigger Board(VME)

Energy sum

Clock, Trigger

Fast hit info

Fast hit info

1:16 Fan-out

Clock, Trigger

Clock, Trigger

GPS Receiver

Buffer-full,Rdrqst

TPD0, TPD1, Check

PMT1

PMT16

PMT256

Buffer-full,Rdrqst

Flash ADC Boards


Status

• Simple version of readout boards and trigger board are successfully running on the prototype.

• We are working on the 2nd version of readout board and trigger board

• We finished conceptual design of DAQ

• DAQ group is formed and begin to work on the project

7 th 高能物理学会大会, 李小男, 高能物理研究所 1 大亚湾反应堆中微子实验...

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