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Constance Walter

From 1980 to 1988 Mike Cherry did research on the 4850 Level. At the time, Cherry was an Assistant Professor of Physics at the University of Pennsylvania. He worked alongside Ray Davis, Ken Lande and other scientists from around the world. He rode the Yates cage with miners and technicians. And his laboratory was very different than what exists today.

"The miners would go off to the left and the scientists to the right," said Cherry, the Roy P. Daniels Professor of Physics at Louisiana State University. "They took excellent care of us. They maintained the mine for us and made it a safe place to work."

Cherry will talk about his experiences working nearly a mile underground at a public presentation Thursday, April 16, at the Deadwood Gulch Convention Center. His talk will follow the Lead Deadwood Community Fund's Chili Feed, which runs from 5 to 7 p.m. Dennis Hothem, a Lab Assistant to Ray Davis for 10 years, is looking forward to the visit. "Dr. Cherry was a great guy. Very conscientious and a deep thinker," he said.

While at Homestake, Cherry worked on Davis's solar neutrino experiment, but his research focused on very energetic cosmic rays. Central to his work was the Large Area Scintillation Detector (LASD)—200 one-foot square plastic pipes welded together and stacked around Davis' tank. Each box contained ultra-pure mineral oil (about 6,000 gallons all together) and had sensitive light detectors on each end. In conjunction with an array of air shower detectors on the surface, Cherry hoped to draw a line between cosmic ray events on the surface and underground. 

In a letter to then-Safety Director Norm Bakke, Cherry said, "The line points back into the sky toward the source. We now have a one-mile long cosmic ray telescope with which we can hope to learn the source of these rare, very energetic cosmic events."

Cosmic rays aren't really rays at all. They are particles, made up mostly of protons that travel at nearly the speed of light. High-energy cosmic rays are the rarest form and scientists believe they could come from exploding stars, which may also emit gamma-ray bursts.

Today, Cherry's research focuses on Terrestrial Gamma Flashes (TGFs) and the CALorimetric Electron Telescope (CALET). TGFs are intense bursts of gamma rays and high energy x-rays associated with lightning. The research could help scientists better understand the electron current's role in thunderstorms. Two TGF detector arrays are being built in the Caribbean, where thunderstorm activity is high.

Scientists working with CALET are trying to measure the intensity of very high-energy cosmic ray electrons and nuclei to search for dark matter and cosmic gamma ray bursts. The instrument, built by a Japanese-Italian-U.S. collaboration, will be launched to  the International Space Station later this year.

Cherry hasn't been back to Lead, S.D., since he left in 1988. "It looks like the facility has been upgraded in a major way since I was there last. I'm looking forward to going underground and seeing the new space and experiments."