LarTPC Electronics Meeting
Current Work at MSU

http://www.pa.msu.edu/~edmunds/LArTPC/Talks/Talk_Feb_2010/

Fermilab Dan Edmunds 23-February-2010

History of the MSU LArTPC Electronics Work

- Built a small warm DAQ system for the Bo LArTPC

- Built a warm DAQ system with cold Bias Voltage

distribution for the ArgoNeuT LArTPC

- About one year ago Stephen Pordes ask us to work

on a small multiplexed readout DAQ system that

would operate cold in LArTPC test cryostats

Motivation and Goals of Our Current Work

- Test this DAQ system in the Bo LArTPC

- Provide a DAQ system for the “no pump out”

long drift LAPD LArTPC at Fermi

- Gain experience with multiplexed readout and

cold electronics in a LArTPC DAQ system

- Gain experience with digital signals inside the

LArTPC cryostat

- Work on ideas to reduce the cost of the DAQ

system for a big detector (3 box to 2 box system)

Project Sections of our Current Work:

1. Characterize components at LN2 temperature

2. Inside the cryostat

- Preamplifier

- Filter

- Multiplexer

- Line Driver

- Digital Control of the Multiplexer

3. At the Cryostat Feedthrough

- Passive Noise Filters: power supply, analog common

mode, digital control signal coupling transformers

4. In the DAQ Rack

- Back of the backplane card: power supply regulators,

analog signal receivers, digital control signal drivers

- Firmware for the ADF-2 VME Readout Card

5. DAQ system software

Design Considerations:

- Operate at RT or LN2 temperature without

significant adjustment

- Per readout card have a single twist-flat cable

running inside:

4 differential analog signals

2 differential digital control signals

3 power supplies (6 conductors)

8 grounds (16 conductors)

50 – 100 mV signal levels

- Control electrical noise inside the cryostat

Filter Step Response

Collection Plane Signal

Preamp and Filter

Line Driver and Cable Response

Output from the Chain: Buffer, Multiplexer,

Line Driver, Cable, and VME ADF-2 (ADC) Card

Checking for Crosstalk

2 Channel Preamp-Filter Card

- 4 layer with ground fill on all layers

- double via connections

- relieved ground plane under Hi Z traces

- compromise between size and ease of modification

16 Channel Mother Board

Engineering Comments:

If Fermi is going to be involved with the DAQ system

for a large LArTPC detector (e.g. LBNE) then the

electrical engineering work for that system should

start soon.

- Technical Challenges

- Cost Control

- Remote Assembly and Operation

DAQ system engineering needs to be integrated with the

mechanical and cryogenic engineering.

We should “prove” that a fully thought out warm

electronics system will not work before committing to

put “all” of the electronics inside.

As far as I know the HEP community has no

examples of a large system operating for 10 or

20 years without needing to work on its electronics.

This is a one detector experiment, i.e. it must work.

A thin wall stainless steel vessel will not shield

electrical noise. There is no “ground” inside and

there is no shield inside.

Need a respected “Noise Czar” early (e.g. now).

Lots of room for DAQ design work:

- Filtering of the hit data

Inline Digital and Offline

Slope dependent hit filtering

Raw data beauty vs information content

- Data Compression: Coding, ROI Readout

- Triggering: Beam Spill vs Continuously Alive

Low Temperature Components:

- Some just don't work.

- Subtle problems.

- Circuit implications.

Backup

2010-02-16T11:08:31