Further Development of Lightning Detection and Triggering for the TARA Experiment (2016)

Names: Bennett Haase­-Divine, Lawrence Freestate High School

Pierce Giffin, Shawnee Mission East High School

Research Teacher Mentor: James Deane, Ottawa High School, Ottawa, KS

Research Mentor: Prof. Dave Besson, University of Kansas, Lawrence, KS

Purpose:​ The purpose of our project was to accurately detect flashes of lightning as well as determining their approximate position and time of strike so that other devices involved in the TARA project can study and collect data from flashes of lightning while they’re still striking. This research continues and extends research from previous years.

Methods: ​For light detection, we used several photoresistors and an arduino board that read the voltage off of each resistor. The program constantly averages out all reading over a brief period of time. If a single reading spikes up above this average, the program would identify it as a lightning strike. As soon as a flash of lightning is detected, a signal is sent out to alert other devices that lightning has struck. To calculate the angle the strike occurred relative to the device, we see how high the voltages are on each photoresistor relative to one another and weight each voltage with the photoresistor’s assigned angle. After all the data is collected, it is stored on a micro SD card inside of the device with an absolute time stamp from a GPS chip.

Results:​ Almost all of the necessary operations work properly with a simulated strobe machine. The device is capable of detecting nearly 100% of simulated flashes and calculating the correct angle within about 4o. The signal is capable of being sent out to other devices within 5 milliseconds. The device can accurately identify two flashes of lightning within 20 milliseconds of each other. Since a single lightning strike flashes once then flashes again about 30 milliseconds later (and can repeat several more times), the device is capable of detecting a strike of lightning on the first flash then sending out a signal to other devices to collect data on other flashes. With recent testing we believe our device can detect lightning up to 40 km away with a clear line of sight. However, the data extracted during this test may not have been reliable; therefore, our guess to the range of the device may be inaccurate. All of the data is able to be stored on a micro SD card. However, problems arose with opening multiple files; therefore, all the data must be stored on a single file. This is due to issues regarding data types in the code.

Meaning to Larger Project: ​This detector and the directional and ranging data it provides will permit better triggering and data collection for portions of the TARA experiment as well as collect data on the lightning strikes themselves to better correlate the events with cosmic rays.

http://www.telescopearray.org/tara/

Future Research: ​The lightning detection device is nearly ready to be implemented. The device still needs further field testing. If a method for calculating the distance of a lightning strike is needed, additional devices may need to be constructed. Additionally, cubic fits were applied to the angular calculation algorithm based off of light simulated from a strobe machine. If the angular reading is deemed to be inaccurate, data from lightning strikes should be used to refit the cubic fits. If quicker and more precise measurements are needed, this project could be redesigned using a time­-to-­digital converter instead of the Arduino Uno currently being used. However, a new code would have to be implemented.

Acknowledgements: We appreciate the assistance and guidance of the following during this project:

● Steven Prochyra, Graduate Student, University of Kansas, Lawrence, KS

● Samantha Conrad, Undergraduate Student, University of Kansas, Lawrence, KS