This document describes a project using Raspberry Pis and cameras to view inside the cryostat of a Liquid Argon Time Projection Chamber (LArTPC) detector after transport. The goal is to check the integrity of sensor wires in a cost-effective way without entering the cryostat. A Raspberry Pi was mounted above simulated wire planes in a cryogenic dewar and programmed with a web interface. Testing showed the Pi camera can clearly see broken wires from various distances when illuminated with an RGB LED. This setup could also monitor detector access and equipment status remotely.

1. Viewing Inside a LArTPC Cryostat with a Raspberry Pi
Camera
By: Crystal Patteson
Appalachian State University, 287 Rivers St, Boone, NC 28607, USA
SULI, Department of Energy
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2. • Motivation
• Equipment
• Construction
• Web Interface
• Other Applications
• Conclusion
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3. • Liquid Argon Time Projection Chambers (LArTPCs) are the detector
technology choice for the future neutrino program at Fermilab.
• Great resolution of tracks and electromagnetic showers.
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http://arxiv.org/pdf/1503.01520v1.pdf
Example event displays for SBND

4. • LArTPCs consist of thousands to tens of thousands of stainless steel or
beryllium-copper sense wires, which detect ionization electrons
produced in neutrino collisions inside the detector
• Wires are spaced 3 mm apart
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5. Construction often takes place in an
assembly hall. After which, the detectors
must be moved.
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• Access to the
wires inside
the cryostat is
limited.
• It is important
to verify the
integrity of the
wires after
transport

8. • This project investigates a cost-efficient way to view the integrity of the
wires after moving the detector without going inside the cryostat.
• Raspberry Pis (RPis) and cameras may also be used to monitor detector
access, condensation on signal feed-throughs, and the status of
electronics and LED indicators.
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9. •
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: Credit card-sized
single-board computer and camera
• Values at less than $60
• Mouse, keyboard, and desktop
or laptop
• Linux Operating System
• Used Python as the main
programming language
• Ethernet Cable

10. • Programmed a web interface for the Cam that can be opened on
the Fermilab computing network
• Can be viewed in real time and accessed remotely
• Record still image and video
• Still image and video can be saved on the SD-card
• Download and delete saved video and picture
• Control Pi Cam features such as brightness, contrast, etc.
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13. Can access website through the IP address
www.169.254.0.2
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Cryogenic Dewar
With Lid
Wire-plane
Unistrut
RGB LED
VerticalDistance
* Not to scale
Schematic of RPi setup in Cryogenic Dewar
Testing the Pi : Can we see broken wires in wire-plane?

15. acc
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1. Place Capton tape (electronically
insulating) on surface of aluminum
thin slab.
2. Screw on
3. Attach Lexan plastic sheet.
1. Lexan sheet covers the top
portion of the RPi for protection
2. The bottom is not covered to
allow access to Ethernet port

16. 1. was then mounted to unistrut
2. Legs were assembled to provide support and elevate off of the
ground
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17. • Two wire-planes were placed in the Cryogenic Dewar
• The Cryogenic Dewar was used to simulate the inside of LArTPCs
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18. The was placed in the Cryogenic Dewar above the wire-planes
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19. • Arduino is a credit card-sized microcontroller that is similar to
• Used Arduino and breadboard to Program RGB LED
• Used Arduino to power RGB LED on and off
• Soldered the RGB LED to the end of 2 long wires & then taped to
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20. 1 9/16” from wire-plane RGB LED and the lid on
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Because otherwise it doesn’t
get much better than this
Why use a RGB
LED?

21. 1 9/16” from wire-plane RGB LED and the lid on
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Better resolution!!!
• Can see broken wire
• Can see wires on both
wire-planes

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Much better resolution!!!
• Can still see broken wires
• Can see wires on both
wire-planes
• Much Clearer than before
3 1/16” from wire-plane RGB LED and lid on

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4 9/16” from wire-plane Lid on
1. RGB LED off 2. RGB LED on
2.
But how does it compared
to when the Lid is off and
is fully illuminated?
1. 2.

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12 1/16” from wire-plane RGB LED and lid on
Much better resolution!!!
• Can still see broken wires
• Can see wires on both
wire-planes

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and cameras may also be used to monitor:
• Monitor the platform in
LArTF detector access
• condensation on
signal feed-throughs
• status of electronics
and LED indicators.
• Control rooms
Platform in LArTF

26. • Great resolution at a variety of distances!!!
• Can still see broken wires
• Can see wires on both wire-planes
• Illumination is sufficient with a RGB LED
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• Further testing will be conducted at Luke Materials Test Stand at
Fermilab to see how much O2/H2O contamination the and
camera introduce when they are submerged in LAr

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