1. Baikal-GVD (technical report)
Baikal-GVD (technical report)
Vladimir Aynutdinov DUBNA, Jun 13, 2014

2. OUTLINE 1. DAQ architecture 2. Basic DAQ elements: - Optical module
- Measuring channel
- Section and String
- Cluster
- Networking and Cable communications
3. System reliability
4. Nearest plans
Summary

3. Example of two-section cluster
GVD architecture
Cluster DAQ center
Section electronic module
Optical module
String electronic module
SECTION
STRING
Basic principles:
Simplicity of all elements
Deployment convenience
Configuration flexibility
Basic GVD elements
Optical module (OM)
Section: 12 OM & Section electronic module
String: 3 (±1) Sections & String electronic module
Cluster: up to 8 strings
Cluster DAQ center
Example of two-section cluster

4. Optical module construction
Glass pressure sphere VETROVEX (17”)
1 connector: SubConn LP 5 contacts
2 on-board LED: L7113, 1…108 pe., 470 nm, 5 ns
PMT R : eff. D =220 mm, SBA (QE 0.33…0.35)
OM electronics: Divider,
HV converter, amplifier, controller
Flexible gel
Mu-metal grid

5. Functional scheme of the optical module electronics
PMT R : eff. D =220 mm,
Amplifier:
- spectrometric channel: 14 (A1E ~ 30mV)
- monitor channel: 21
2 LEDs L7113: 470 nm, 5 ns
- dynamic range 1…108 photons (~100 m)
- LED pulses delay: 0 … 1000 ns
Slow control: RS485 (9600, )
Monitoring: PMT count rate, HV value,
temperature, voltages.
Divider: 18 M
2 KV PMT power supply
Traco Power SHV K 1000 P
Power consumption – max 0.3A12V
Functional scheme of the optical module electronics

6. Measuring channel OM Section electronic module
PMT: 107
Amplifier: 12
ADC: ± 2V
90 m coax.cable OM
Section electronic module
Nominal PMT gain: 1107; Amplifier: kamp=12, Amax= 2V;
Cable: 50 , 90 m, non coaxial 5-contact connectors;
PMT Pulse after cable: ~20 ns FWHM, A1E 35…40 mV;
ADC: 12 bit 200 MHz; range ± 2V, waveform stamp up to 5 mks;
Count rate (0.3 PE) 20 … 40 kHz
Waveform stamp example:
(5 mks)
Single PE pulses
Reflected pulse
PMT HV: 1200 – 1600 V
A1E distribution on
all channels
<A1E> = 30 ch
 A1E ~ 10%

7. Section – basic cell of the detector
Section: 12 Optical Modules & Section electronic module
MOXA IEX-402-SHDSL
12 FADC channels: waveform stamps;
Master board: time synchronization, trigger, data processing and
transmission;
Slow control board: OM power on/off and control via RS485.
MASTER
SLOW CONTROL
ADC
Section center

8. Functional scheme of one FADC channel
ADC board
FPGA
4 FADC channels, FPGA logic
FADC (AD9430) 12bit, 200MHz
FPGA (Xilinx Spartan 3 / Spartan 6)
Data channel:
data buffer and data transmitter.
Trigger channel:
smoothing unit (1…8),
2-level adjustable digital comparator
(low threshold L and high threshold H),
amplitude analyzer (monitor histograms)
- Interface on the basis of LVDM bus.
Functional scheme of one FADC channel
0.8 ms
Event t distribution
0.1 ms 8

9. Master board FPGA Xilinx Spartan 6
Trigger logic, data readout from ADC boards, control of the section operation,
connection to the cluster center.
Request analyzer  section local trigger.
Dynamically loading coincidence matrix
(12L12H inputs).
Two basic trigger modes:
Ln - any OMs of the section
L&H – only neighbouring OMs
Event buffer (1000 events)
waveform data for all ADC
global trigger number
Control module
- access to the I/O registers
slow control on the basis
of the RS-485 bus.
Ethernet module (MAC) – connection via local Ethernet to the cluster DAQ center.

10. Section slow control board
A typical single photoelectron spectrum measured with LED (black) and noise spectrum (red)

11. Cluster DAQ center Cluster – up to 8 strings, 192 OM
Cluster center provides trigger logic, string power supply, communication to shore.
Cluster center electronics located in 3 glass sphere and metallic box for optical cable attachment.
Trigger system
2 ADC board (8 channels) and Master board
Inputs: 8 string local trigger
Output: global trigger
Power supply
300 VDC commutator, 8 channels
Networking
- 8 DSL-modems –string data
- Optical Ethernet provides data communication with Shore center.

12. Underwater Cables Acoustic module Optical module Shore cable
Underwater Cables
Twisted pair (120 OM, 0.5 mm2)
9 isolated copper wires 0.15 mm2
Acoustic module
Coaxial cable (50 OM, 0.5 mm2)
9 isolated copper wires 0.15 mm2
Optical module
4 types of cables:
- Optical modules;
- Acoustic module;
- String and section;
- Cluster (shore cable)
Cables specially designed for Baikal
in Pskov factory
3 fiber modules (2 single-mode fiber,
copper sheath 1.8mm2)
3 isolated copper wires 0.75 mm2
Shore cable
2 Coaxial cables (50 OM, 0.5 mm2)
Twisted Pair (120 OM, 0.5 mm2)
TP screen 90×0.1 mm
3 isolated copper wires 0.5 mm2
String, Section
Connectors: SubConn Low Profile
5 contacts (OM) and 9 contacts (String)
600 V  6A
Eternet 100 Mbit

13. Cluster power supply system is divided in two levels
Cluster power supply system is divided in two levels. First level comprises the 12-channel commutator which is used for string power supply and is placed in the cluster DAQ-center. Second level comprises the commutators of strings which are located inside the string communication modules (CoM). They provide independent switch on/off of power supply of the string sections.
Power supply
300 VDC power supply system (450 V at Shore)
1 string power consumption: 0.45A×300V
Basic elements of power supply system:
- 300 VDC commutators (up to 12 channels)
- DC/DC converters (Traco Power firm)
Power commutator was specially designed for Baikal at 2011.
Controlling (on/off) via Ethernet by COM-server and digital output module;
- Monitoring of output voltage;
12- channel 300VDC commutators controlled via Ethernet. They were developed and successfully tested in
The independent switching of the commutator channels is controlled by COM-server and 16-channel digital output module ICP DAS I Monitoring of output voltage is processed by 20-channel analog input module ICP DAS I-7017Z.
Three – level power supply system:
1-st. Cluster center level (300V).
Switch on/off string power supply.
2-nd. String level (300V).
Switch on/off section power (independently ADC and OM).
3-rd. Section level (12V).
Switch on/off OM power.

14. Underwater network In-situ tests of the String data line at 2014
Three segments of underwater net:
Section (Master) – String module
2. String module – Cluster center
3. Cluster center – Shore
Segment
Length
Data rate
Line speed
Techique
Section
100…500 m
1 Mbit
5.6 Mbit
shDSL
String
~1000 m
3 Mbit
7…10 Mbit
Cluster
3 m / 6 km
25 Mbit
100 /1000 Mbit
100 BaseTX
1000 BaseFX
Data collected in section central models are transmitted to shore through three different segments of underwater communication network based on Ethernet. The section communication channels connect each CeM with the corresponding CoM. Given the lengths of these communication channels more than 100 m, the shDSL modems are used as the Ethernet extensions for data transmission from CeM to CoM. In CoM the section communication channels are joined into a single one, which connects each section with the cluster DAQ-center. Data transmission between each CoM and the cluster DAQ-center are also based on shDSL technology.
The data transmission between the cluster DAQ- center and shore station is provided through optical fibre lines extended at about of 6 km. Maximal speed of data transmission to shore is limited by band width of a connection channel between a string CoM and the cluster DAQ-center and is about of 8 Mbit/s.
Sigrand SG-17B-3.3-M SHDSL
String Line
Line speed, Кб/с
SNR, dB
String 1
7040 11
String 2
7552 12
String 3
10048
String 4 10
String 5
Critical points:
DSL modems: only at 2013 the first industrial DSL in Russia.
On-line data processing in the Master FPGA: ~70 Hz maximum data processing rate at software level (processor on the basis of FPGA). Next step – to use hardware level of FPGA for data processing (factor ~3).
MOXA IEX-402-SHDSL
In-situ tests of the String data line at 2014

15. Reliability Results from April 2011 up to Jun 2014
(without long-term laboratory tests and stress tests)
1. Optical modules:
The OM electronics failure rate: 1…3 OM / 180 / Year
- 1 OM: HV control system.
- 2 OM (?): not connection through RS485 bus. They are out of operation at April 2014.
Probable reason is transient error of the slow control board (it will be modernized in 2014).
2. Cable communications:
1 cable is out of operation in April It was mounted in 2011 – old technique of the
connector attachment.
3. Connectors - no failure
4. Power supply (300 VDC commutators, DC/DC converters) - no failure
5. Network devices
a) MOXA devices (Switches, Eternet-RS485 converters, IEX-402 DSL) – no failure
b) DSL-modem Sigrand:
- Out of operation during the detector mounting: 2 cases.
- Unreliable connection for 1 Section at 2014 (after section the mounting).
We plan to use IEX-402 DSL, that were presented by MOXA firm at the end of 2012.
6. Glass sphere – no failure

16. Plans
2014
- On-line data processing: new Master firmware development (the test at 2014).
R&D for the second cluster:
- 1 kV power supply (pilot samples are testing now);
- cluster time synchronization (the in-situ tests at 2015);
Full scale cluster (8 strings)
The organization of Mass production
- Storage space (INR, Dubna, Baikal)
- Manpower and Laboratory stands;
- Long time laboratory tests of electronics, stress tests.

17. Summary GVD technical design is basically finalized.
3 year operation of prototype arrays demonstrate reliable operation all basic elements of the telescope.
3. The nearest tasks ( ) are the organization of mass production and the testing of the electronics.

18. THANK YOU

19. Dependence of measured Npe (ADC) on induced Npe (PMT): 2-LEDs method

20. Оптические модули с ФЭУ XP1807(слева), R8055 (в центре) и R7081HQE (справа).

21. To minimize dead time, the ADC is equipped with two Buffers
To minimize dead time, the ADC is equipped with two Buffers. While one is processing input signals, the other is available for signal capture.
At the nominal PMT gain of 1 x 10^7
Coincidence between nearest neighbors, next-nearest neighbors, and so on