1. Detecting cosmic rays using CMOS sensors in consumer devices
Matthew Plewa

2. Introduction What is a cosmic ray Stable Typically striped nucli
Charged
What is a secondary?
Gammas, muons, protons, pions and electrons

3. Common Detections Methods
Citizen Scientist
Cloud Chambers
Vapor condenses along the particle path (can visually see)
Scintillator Panels
When excited by ionizing particles they emit photons

4. Common Detection Methods
CMOS Sensors
When light is blocked from the sensor cosmic rays deposit a charge on the sensor. This charge is then interpreted as light in the image.
The sensor must be capturing a frame at the time the cosmic ray enters it.
Small active area

5. DECO (CMOS Sensor)
Funded by American Physical Society Knight Foundation and Simon-Strauss Foundation
Works on android phones (IPhones soonish)
Great learning tool and is becoming a great scientific tool with upcoming upgrades

6. CMOS Sensor Benefits Easily attainable
Most of us have them in our pocket
Easily used
CMOS sensor just needs to have light blocked
Tools are being developed for detection in the frames

7. CMOS Sensors
Due to the small area (~.15 cm^2) livetime is extremely important.
For this reason we had to look at what method would increase livetime
Video mode
Still capture

8. Video vs Still Capture Still capture (8MP) Livetime ~5%
1 out of every 20 events detected
High resolution (Low data rate ~1 a sec)
Video mode (2MP)
~95% livetime
Low resolution (High Data rate ~30 a sec)

9. Video vs Still What would work best for high altitude ballooning?
The more events that can be captured the more analysis that can be done.
Lower resolution means track analysis is less accurate
More events seemed to be the best choice for initial testing

10. Using a GoPro Readily available device
Knew the sensor size (.24 cm^2) so determining how many events that should be seen at ground level was easy.
Fairly reliable hardware

11. Post Flight Processing
Video needed to be decompiled into individual frames
Current method of detecting events is a simple threshold cut of the R, G and B values for each pixel
Altitude data was not recorded so events couldn’t be correlated accordingly

12. Results 66 “events” were detected in 2 hour span
Electron worms and Alpha particles (decay on the surface of the sensor)
Demonstrated the viability of detection using CMOS sensors
Need better filtering parameters

13. Future work Raspberry Pi & Pi cameras Potentially larger surface area.
Higher resolution
Data logging
Temperature
Altitude
GPS

14. Long Duration Exposure
DECO V2 (full resolution)
Android Camera2 api
Able to set ISO
Full exposure control up to 2 seconds
Automatic datalogging
Database collection
Highly recommended for future ballooning

15. Track Analysis
Need to determine how to reduce electron and alpha particle noise
Track traceback and pointing of particle origin (path before entering sensor)
Will be easier with higher resolution

16. Questions?