Physics Outreach recreates hot air balloon cosmic ray experiment

Up in the air with Physics students

Physics senior Chris Kraner and McCutcheon High School senior Stephen Claypool's hot air balloon soaring to 10,000 feet in order to measure cosmic rays.

 

FISHERS, IND. — A small group of physics students and instructors measured cosmic rays at 10,000 feet in the air on the morning of March 30 at the Indianapolis Metropolitan Airfield.

The dizzying heights were required to recreate an experiment by Nobel Prize-winning Austrian physicist Victor Hess, who discovered that cosmic rays came from outer space 101 years ago. The original thought was that radiation came from the Earth.

Sponsored by Physics Outreach, the experiment used modern, sophisticated equipment that Hess could only have dreamed of. The main instrument for collecting data was a cosmic ray detector, which is comprised of scintillation plates and photo multiplier tubes that send readings for a computer to translate. The device measures “counts,” which increase when levels of cosmic radiation are more intense. The cosmic ray detector can give real-time results and draw graphs as soon as the counts come in.

McCutcheon High School senior Stephen Claypool rode in Purdue Physics senior Chris Kraner’s balloon, which traveled to 10,000 feet. Claypool is one of the Tippecanoe County school’s top science students and is adept at Physics as well as technology. In Physics Prof. Matthew Jones’ balloon, which rose to about 6,500 feet, Winamac High School physics teacher Jeremy Wegner was along for the ride. Physics Outreach director David Sederberg rode in a smaller balloon to 10,000 feet. His balloon served as a guide for the larger balloons. 

Wind and haze provided some challenge during the flights, which took to the sky a little after 7:30 a.m., but the scientists were pleased with the data they collected. And they were a bit surprised that they encountered very few problems with equipment.

“The data shows that the rate at which cosmic rays hit our detector almost doubles by the time we reach about 6500 feet altitude,” Jones stated after analyzing his March 30 findings. “In our balloon, the altitude was written in a log book by Jeremy Wegner, the teacher from Winamac High School, while Stephen Claypool, the student from McCutcheon High School, and Chris Kraner, one of the four service learning students taking my Physics 29000 course, recorded altitude in the other balloon using Google's cell-phone app MyTracks. We have yet to get this data out of Google and correlate it with the data recorded in the balloon, but when we do we expect it to extend the measurements up to about 9,000 feet. It will be fun to see how the two data sets line up. We fully expect that the trend will just continue up to 9,000 feet.”

Jones said he had to quickly think on his feet to get the equipment configured in the hot air balloon basket. The detector and laptop has been in airplanes and vehicles before but in the open air with two educators and a balloon pilot, it made for some tight quarters.

“In the end, we piled everything on the bottom of the balloon, put the laptop on a fuel tank, and started everything up,” Jones recalled. “It wasn't pretty, but the initial data looked OK, so we just left everything the way it was. ...  We had to keep moving the laptop to let the pilot check fuel levels, but in the end it wasn't as bad as I had initially feared it would be.”

Jones said the high altitude experiment reminded him of his particle physics work on the ground in world famous labs like CERN and Fermilab.

“Sometimes we have a very short window of opportunity to go into an experimental area and fix something or record data, and you have to learn to keep cool, stay focused, think about what you're doing, use whatever information you have to tell if things are working and try to anticipate anything that could go wrong,” Jones explained. “I expect that Victor Hess had to deal with the same issues: You plan everything carefully, but you always have to be ready to react to the unexpected. From our data, we can clearly see the trend that earned Victor Hess the Nobel Prize in 1936, but without any prior information I can imagine that he and others would have been anxious to repeat the flight because the increase in rate is so dramatic that it must be telling us something really significant. In fact, Victor Hess conducted balloon experiments from 1911 to 1913, so technically we didn't miss the 100th anniversary of at least one of his balloon flights.”

The experience was not without a little drama. Sederberg’s balloon and Kraner and Claypool’s dirigible touched down on farmland a few miles from Greenfield, Ind. Jones’ balloon circled back to Indianapolis Metropolitan Airfield for its landing.

After two hours in the air, Claypool was satisfied with his data as well as the opportunity to be a part of a unique physics experiment.

“Science is something that can be repeated with the same results,” Claypool said. “That’s what makes it science. You can keep testing it over and over with different hypotheses and figure out a result in the end. Then if you go back and try it again, you will most likely get the same result unless there is some discrepancy to begin with.”

That science holds true even a century later. Hess would be proud of these young, aeronautical scientists.

Chris Kraner

Physics senior Chris Kraner installs a cosmic ray detector into the basket of a hot air balloon.

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