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
= 2 % x = 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
= 2% x = 2.48 .05 S
Width
Wid
th (
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 (
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 a
static 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 resets 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
