Data acquisition system for the Baikal-GVD neutrino telescope

Denis KuleshovDenis Kuleshov Valday, February 3, 2015

1. GVD DAQ architecture

2. Basic elements of the telescope: - Optical module and measuring channel - OM Section and String - GVD Cluster - Underwater Cluster network

3. Reliability

Summary

OUTLINE

GVD DAQ architecture

Cluster DAQ center

Section electronic module

Optical module

String electronic module

SE

CT

ION

SE

CT

ION

ST

RIN

G

Basic principles of GVD design:- Simplicity of all elements;- Deployment convenience from the ice cover;- Detector extensibility and configuration

flexibility.

Basic GVD elements-Optical module (OM);

-Section: 12 OM (spaced by 15 m) Section electronic module (12-ch FADC)

-String: 2 or 3 Sections & String electronic module

-Cluster: 8 strings & DAQ center.

R ~ 60 mH

~ 35

0 m

Cluster with 8 two-section strings

Optical module and measuring channel

HV converter: SHV 12-2.0 K 1000 P 0 …+ 2000 VDC, stability 0.05% ripple and noise 8 mVpk-pk

Passive divider: 18 M2-channel amplifier: Output channel and PMT noise monitoring channel.

2 LEDs L7113: 470 nm, 5-7 ns- regulation of intensities in the range 1…~108 photons (100m Baikal water)- LED pulse delay regulation: 0 … 1000 ns

Slow control board: SiLabs C8051F121Control of electronics operation and monitoring of PMT parameters via RS485 interface.

OM electronics

Mu-metal cage

PMT

Optical gel

Glass sphere VETROVEX (17”)

Optical module design: as simple as possible.

OMSEM

PMT: 107 Ampl. ADC Board

90 m coax. cable

GVD Section

12-channel ADC unit: PMTs analog pulse conversion, time synchronization, data processing, local trigger.Data transmission: Two outputs of ADC board: optical output (for future detector extension) and 100 BASE-TX (present stage).shDSL modem: Extending the Ethernet line up to 1 km.Slow control board: OM power on/off and control of OM operation (RS-485).

Flash ADC (AD9430) 12bit, 200 MSPS

FPGA (Xilinx Spartan 6) Enable to on-line data filtration. Cut the pulses from data frame and paste to output data stream. Rejection factor : 50-100

Section electronic module

Optical output

Section (basic DAQ cell) – 12 OM and Section electronics module (SeM).

Functional scheme of one FADC channel

ADC 200 MSPS

Duble-buffered memory,

30 mks WF data

Datatransmitter

Data control

Peak detectorAmplitude analyser

Smoothing2-level

comparator

Inte

rface

Trigger/Stop

Waveform, 5 mks

Histogram

Request builder

Channel request

L

H

Smoothing level 1...8

Accumulation time

Waveform interval

Thresholds

PMTpulse

FPGAFADC (AD9430) 12bit, 200 MSPS FPGA (Xilinx Spartan 6) - Trigger logic: 2-level adjustable digital comparator forms low threshold L and high threshold H channel requests (section trigger is L&H coincidence of neighboring channels). - Data channel (triggered) consists of double-buffered memory and data transmitter.- Monitor channel (non-triggered) includes peak detector and amplitude analyzer.

LED pulse

Noise

Waveform stamp example (5 mks)

Single PE pulses

Monitor histogram examples

Monitor channelData channel

ADC channel

Trigger Commutator: splits for the section acknowledges & combines requests.

Data transmission: DSL line.

Power Commutator: Controls power to the SEM, OMs and peripherals.

String communication module combines 2 or 3 sections.

Functions:

GVD String

Functional scheme of Power Commutator

8

GVD ClusterCluster - a full functional detection system, working both independently and as a part

of the full detector.Cluster – 8 strings and DAQ center. DAQ center: trigger logic, string power supply, communication to shore.Cluster center electronics is located in 3 glass spheres and metallic box for optical cable attachment “optical box”.

Optical boxCluster DAQ center

Cluster DAQ center

9

GVD Cluster

Power Module:300VDC 12-ch manageable commutator.

Optical Box: conversion 1000 BASE-FX to 100 BASE-TX.

Data module:8 DSL-modems for transmission the string data.8-channel COM-server for DSL speed control.

Trigger Module:12-channel ADC unit: 8 string trigger requests, global trigger for 8 strings.

10

Cluster underwater network

Segments of underwater network:1. Section electronics module – String module2. String module – Cluster DAQ center3. Cluster DAQ center – Optical box4. Optical box – Shore DAQ center

100…200 Hz data event rate are expectedfor the basic trigger L×H.

Section Line speed, Кbit/s SNR, dB

String 1 7040 11

String 2 7552 12

String 3 10048 11

String 4 10048 10

String 5 10048 12

Segment Length Data rate

Line speed Technique

1 100…300 m

1 Mbit ~10 Mbit shDSL

2 ~1000 m 3 Mbit ~10 Mbit shDSL

3 3 m 25 Mbit 100 Mbit 100 BaseTX

4 ~6000 m 25 Mbit 1000 Mbit 1000 BaseFX

(1) Slow data transmission (triggered mode):OM coincidences produce a trigger that rejects the

PMT noise.

(2) Fast data transmission*: optical line from ADC module to Shore Center (all data to shore).

Possibility to use two modes of operation:

Data line speed in 2014

1. Optical modules:The OM electronics failure rate: 3 OM / 140 / Year - 1 OM: HV control system. Failure of the OM controller. - 2 OM: not connection via RS485 bus (out of operation at April 2014). Probable reason is transient error of the slow control board (it was modernized in late 2014). 2. Cable communications: 2 cables are out of operation. Reason - old technology of the sealing (cables of 2011). New sealing technology is applied after 2012.3. Network devices a) Industrial devices (Switches, Eternet-RS485 converters, IEX-402 DSL) – no failure b) Non-industrial DSL-modems: - Unreliable connection to 1 string at 2013 and 1 Section at 2014. We plan to use industrial IEX-402 shDSL, that were presented by MOXA firm at 2013.4. ADC boards - no failure.5. Glass sphere and Connectors - no failure.6. Power supply units (300 VDC commutators, DC/DC converters) - no failure

Reliability

(without long-term laboratory tests and stress tests)

Results from 2011 up to end of 2014

Summary

1. DAQ system was tested with 5-strings engineering array and will be applied

for GVD-Baikal full functional Cluster in this year.

2. Baikal-GVD technical design is basically finalized.

3. Next step of the DAQ development is investigation the possibility to use optical

connections with sections. - Optical hybrid cable is designed (connection between Cluster Center and

Shore)- Optical output of ADC board (SEM) is foreseen.- Optical connectors ???

Backup slides

16

FADC (AD9430) 12bit, 200 MSPS FPGA (Xilinx Spartan 6) - Trigger logic: 2-level adjustable digital comparator forms low threshold L and high threshold H channel requests- Data channel (triggered) consists of double-buffered memory and data transmitter.- Monitor channel (non-triggered) includes peak detector and amplitude analyzer.

ADC board12-ch 200 MSPS

ADC

- Trigger logic(L&H coincidence of neighboring channels- Data readout from ADC buffer - Control of OM mode of operation - Connection via local Ethernet to the cluster DAQ center

Triggering and Data Transmission

SECTION CLUSTER

Prototype arrays: 2012: 36 OM, 2013: 72 OM, 2014: 120 OM

A summarized time of the OMs operation is ~170 years

3 OM failures during this period:

- 1 OM: HV control system out of operation (2013).

- 2 OM: not reliable connection via RS485 bus (2014).

The OM electronics failure rate ~2% / year

Repairing possibility: 8% / year for 100 strings installation (GVD Phase 1).

OM reliability

(without stress tests of electronics during prototyping phase )

Results from 2012 to 2014