Electronics for the DRIFT Detector

Kevin KuwataDr. Jean-Luc Gauvreau & Dr. Dan Snowden-Ifft

July 31, 2013

What is Dark Matter?Matter in the Universe

15%

85%

Dark Matter Matter

What is Dark Matter?

• Does not interact through electromagnetic radiation

• Does interact with gravity

• Theory points towards weak force

DRIFT

Carbon disulfide (CS2)

DRIFT

CS2-

CS2

Cathode

Wires

Current Design:

Pre-Amp Shaper DigitizerDetector

Wire

Current Design Cost• Pre-Amp: CR110

• $155.00

• Shaper: CR200

• $ 155.00

• Digitizer:

• $500

• Per Wire Total: $810 per channel

Grouping Wires1

2

3

4

5

6

7

8

9

10

11

12

Ch. 1Ch. 2

Ch. 3

Ch. 4

... ... ... ...

Problems:

• Grouping increases capacitance, due to large number of wires hooked up to each channel, which increases the noise to an unacceptable level

• No information about location of event

Grouping Wires1

2

3

4

5

6

7

8

9

10

11

12

Ch. 1Ch. 2

Ch. 3

Ch. 4

... ... ... ...

Solution: Multiplex Selection

• Reduce the noise by ungrouping

• Requires inexpensive electronics

Brookhaven National Laboratory (BNL)

• Replaces Pre-Amplifier and Shaper

• Developed the integrated chip (IC) that allows the detector to be sensitive to quantities of charge.

• 16 wires per BNL Chip

• $100 per wire previously, down to $5 per wire

BNL Board

InputOutput Output

BNLControl

BNL details

• Gain

• Peak time

• AC coupling

• Test signal

Programming the BNL Board: Arduino Control Board

• The BNL board can be programmed by sending a series of pulses

• LabJack® initially programming BNL board, now using Arduino Mega2560

Multiplexing

• Multiplexing: process of taking selecting one of several signals

• Allows for the individual wire testing

Multiplexer

Output

Inputs

Multiplexer: Address

• The “Address” of the multiplexer can be thought as a street address of a house

Output

Inputs

S0S1

Address Selection

• S0 and S1 determine the address. S0 and S1 are binary (1,0)

(0,0) (0,1)

(1,0) (1,1)

Output

= 00

= 11

= 2

2

= 3

3

Address Selection

• (S0, S1)

(0,0) (0,1)

(1,0) (1,1)

2

1 3

0

Output

Multiplexing Wires1

2

3

4

5

6

7

8

9

10

11

12

Ch. 1Ch. 2

... ... ... ......

Output

Multiplexing Board

• Multiplexing board uses 17, 8-channel multiplexing integrated circuits to select 1 wire out of a 120.

Multiplexing Board

Multiplexing BoardOutput

Input

Measurements

Height MeasurementsMax Height

Max

Hei

ght (

Volts

)

0.00

0.75

1.50

2.25

3.00

Channel0.0 12.2 24.4 36.6 48.8 61.0 73.2 85.4 97.6 109.8 122.0

• σ = ± 2 %

• x̅ = 2.46 V ± .05

Height MeasurementsMax Height

Volta

ge (V

)

2.3500

2.3875

2.4250

2.4625

2.5000

Wire 0.0 12.2 24.4 36.6 48.8 61.0 73.2 85.4 97.6 109.8 122.0

Width @ 50% Height Measurements

• σ = ± 2%

• x̅ = 2.48 ±.05 µS

Width

Wid

th (µ

S)

0.00

0.65

1.30

1.95

2.60

Channel0 12 24 36 48 60 72 84 96 108 120

Width @ 50% Height Width

Wid

th (µ

S)

2.38

2.43

2.49

2.54

2.60

Channel0 12 24 36 48 60 72 84 96 108 120

Noise Measurements

• noise 3500 electrons, grouping

• noise bnl 600 electrons

• 600 electrons noise after Multiplexer Board

• Boards & Detector Total noise: 750 electron

• ~1 trillion (10^12) electrons in static shock

electrons involved in astatic discharge

Supplementary Slides

Supplementary Slide: Address Selection

• S0 and S1 determine the address. S0 and S1can be either On (1) or Off (0).

(0,0) (0,1)

(1,0) (1,1)

0 1

0

1

Output

= 00

= 11

= 2

2

= 3

3

Supplementary Slide: Address Selection

• S0 and S1 determine the address. S0 and S1can be either On (1) or Off (0).

(0,0) (0,1)

(1,0) (1,1)

0 1

0

1

2

1 3

0

Output

Supplementary Slide: Address Selection

• S0 and S1 determine the address. S0 and S1can be either On (1) or Off (0).

(0,0) (0,1)

(1,0) (1,1)

0 1

0

1

2

1 3

0

Output

Supplementary Slide:

BNL Monitoring

• Arduino monitors “Status” line of the BNL

• Notifies user of a possible error in the BNL parameters

• Automatically reset’s BNL boards if they become un-programmed

BNL Monitoring

Is the Status OK?

No yes

Reset

> 1.0 Resets/Minute?

No yesTurn On Indicator

Light

Multiplexing Wires

Ch. 1

19

17Ch. 2

21018

Ch. 3

81624

Multiplexers (Mux)

In-Field Programming

• Ability to change settings away from computer

• no technical programming required