Instrumentation for a Large, Underwater Liquid Scintillator

DetectorGary S. Varner

University of Hawai’iMarch 25, 2007

XxxxXxxx Electronics and Communication, DOANOW March, 2006

Instrumentation Issues1. 3 examples of current developments in detector

readout electronics and communications2. Estimate of data rates for a large liquid

scintillator detector (XxxxXxxx)3. Related developments as proof of principle4. Future possibilities in single photon detection

2XxxxXxxx Electronics and Communication, DOANOW March, 2006

μ / KL detection14/15 lyr. RPC+Fe

Tracking + dE/dxsmall cell + He/C2H5

CsI(Tl) 16X0

Aerogel Cherenkov cnt.n=1.015~1.030

Si vtx. det.3 lyr. DSSD

TOF counter

SC solenoid1.5T

Belle DetectorBelle Detector

8GeV e−

3.5GeV e+

Example 1

3XxxxXxxx Electronics and Communication, DOANOW March, 2006

Belle DAQ Upgrade

At L = 1035 cm-2/s :• Pipelined readout: 128k channels equiv., 40MHz x 2bytes

10 Tera-bytes per second! (~2k DVDs per second)

Global Decision logic trigger: 10kHz• FIFO: 128k channels equiv., 16 bytes

20 Giga-bytes per second! (200 GbE links)

200 Mega-bytes per second!

COPPER, online Farm

(max. data rate to disc)

4XxxxXxxx Electronics and Communication, DOANOW March, 2006

• 32 Quad-Ridge horns and 8 monitor antenna• 2.6 GSa/s• Only a few hundred Giga-Bytes onboard storage• Satellite/LOS only

Another low-rate ν experiment

Example 2

5XxxxXxxx Electronics and Communication, DOANOW March, 2006

Trigger Reduction

Raw Signals

80 RF channels@ 1.5By * 2.6GSa/s

= 312 Gbytes/s

Level-1

Antenna

3-of-8

100-200kHz@ 36kBy/evt

= 3.6-7.2Gby/s

Level-2

Cluster

2-of-5

Few kHz@ 36kBy/evt= 36-72Mby/s

Level-3Phi

2-of-2

5-10Hz@ 36kBy/evt

= 180-360kBy/sTo disk

Prioritizer(+compress)

Few

eve

nts/

min

TD

RSS

Logical segmentation

L2 = 2 of 5

Top cluster

Phi = 0(1 of 16)

Bottom cluster

L2 = 2 of 5

Nadir clusterL2 = 2 of 3

(example Trigger Type = 1 shown)

6XxxxXxxx Electronics and Communication, DOANOW March, 2006

Radio in IceCube (AURA)1-2km

Utilize IC DAQ/Control Infrastructure

Example 3

7XxxxXxxx Electronics and Communication, DOANOW March, 2006

Toantenna

Toantenna

To

antenna

To

surface

ToCalibrationunitTo

antenna

Modified glass sphere 6 Penetrators:4 Antennas1 Surface cable1 Calibration unit

Radio BoardsUHF Sampling, Triggering, Digitizing, data processing, trigger banding, interface to the mb

MB (Main board)Communication, timing, connection to IC DAQ infrastructure,

Digital Radio Module (DRM)

8XxxxXxxx Electronics and Communication, DOANOW March, 2006

TRACR

DOM-MB

Metal Plate

Antennas

DRM electronics

ROBUST

Sealing the DRM

9XxxxXxxx Electronics and Communication, DOANOW March, 2006

AURA Data Rate

Each Node: dedicated communication link

• Each node self-triggers• Event size

– 9 channels/260 sample– ~2kB/event

• Link limitation– About 25 Hz

• Build event at surface– Something like 3σ– 100 nodes 5MB/sec

10XxxxXxxx Electronics and Communication, DOANOW March, 2006

Digital Optical Module (DOM)

11XxxxXxxx Electronics and Communication, DOANOW March, 2006

Strategy for low-E threshold

Possible to record eachPhoton/process at surface?

PMTOutput

10kHz40 kB/s

64-channelProcessor

Board

Dua

l (re

dund

ant)

link

to s

urfa

ce

2.6 MB/s21 Mbit/s

2 MasterNodes

~2k PMTs

32-concentratorNodes

655 Mbit/s

10Gbit/s link~100kHz

12XxxxXxxx Electronics and Communication, DOANOW March, 2006

Existence Proof: Saltdome Shower Array (SalSA) Design studies

1

2

3

4

5

6

7

Depth (km)

Halite (rock salt)• Lα(<1GHz) > 500 m w.e.• Depth to >10km• Diameter: 3-8 km• Veff ~ 50-350 km3 w.e.• No known background• >2π steradians possible

Antenna array

• Rock salt can have extremely low RF loss, as radio-clear as Antarctic ice• ~2.4 times as dense as ice• typical: 50-100 km3 water equivalent in top ~3.5km =>300-600 km3 sr w.e.

13XxxxXxxx Electronics and Communication, DOANOW March, 2006

Basic string architecture

String12 nodes

Node = 12 antennas and center housing

tape

Stainless tube

armor

Insulatedconductors

Fibers

NEMA 3R38" x 21" x17"

14XxxxXxxx Electronics and Communication, DOANOW March, 2006

GEISER Data flow [NIM A554 (2005) 437-443](Giga-bit Ethernet Instrumentation for SalSA Electronics Readout)

Digital Cell system for data collection

Internal FPGA: Logic, Buffer

RF inContinuous

64kb/event16kHz (Gbit

Ethernet)

Trigger packets sent via FM/local

radio

Node/String Time stamps

Event requestFinal Data Transfer

Hold event if >2.4σ

antennas

asic digitizerCentral control &

Global Triggerstation

In salt

15XxxxXxxx Electronics and Communication, DOANOW March, 2006

What I can’t/can show

• HV, Digitizer, Fiber-optic communications board development/testing

• Similar studies for Particle ID studies– Custom ASIC for low power operation

– Using FPGA (programmable logic) as Discriminator, TDC and QDC

Journal of Instrumentation, Volume 1, P07001 (2006)

16XxxxXxxx Electronics and Communication, DOANOW March, 2006

ASICs for good timing/QDC

5-10W<= 0.05WPower/Chan.

8/7.412/9-10Bits/ENOBs

2 GSa/s1-3.7 GSa/sSampling speed

CommercialLABRADOR

17XxxxXxxx Electronics and Communication, DOANOW March, 2006

Similar Solutions

TDCPerformance

~0.37ns

Comparison: STaR vs. CAMAC y = 1.0174x - 1.3038R2 = 0.9996

0

10

20

30

40

50

60

0 10 20 30 40 50 60

CAMAC Charge [pC]

STa

R A

DC

Cha

rge

[pC

]

Run 1Linear (Run 1)

QDCPerformance

Belle TOF upgrade

Focusing DIRC proto

18XxxxXxxx Electronics and Communication, DOANOW March, 2006

Large area single γ detection

• PMT technology has stalled

•• New ideas: compact, small cell array New ideas: compact, small cell array (CRT vs. plasma )(CRT vs. plasma )

• Other recent developments– Large area APD (low gain)

– Augment with GEM structures

– Silicon PMTs (small, high dark count)

Issue is to get cost down

19XxxxXxxx Electronics and Communication, DOANOW March, 2006

Summary

• Similar (more challenging) comparative systems shown– Performance and power measured

– Results published later

• Technologies mature– Building on existing, similar systems

– Can always improve

• Future directions– Improved photo detectors

– Event builder demonstration