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Several faculty members and students from the 91����’s��Department of Physics and Astronomy��in the Division of Natural Sciences and Mathematics were among those who took part in the����(APS) Oct. 19 dedication of the laboratories at Echo Lake and Mount��Evans as a Historic Physics Site.

Others from the physics and science community were also on hand for the dedication, which included the placement of a historical plaque near��the site. Representing DU were: Teaching Professor��Steven Iona; Associate Professor and Chair��Davor Balzar; Research Professor��Jonathan Ormes; Research Professor��Robert Amme; Associate Research Professor Emeritus��John Olson; Professor of Physics��; Associate Professor��Mark Siemens; Associate Professor��Jennifer Hoffman; Dean��Andrei Kutateladze;��Vice Provost for Research��Corinne Lengsfeld;��APA President-elect Roger Falconeand;��and students Drew Voitiv, Tristan Wolfe,��Angie Dickinson and Hannah Slay.

A day before the dedication, the department hosted a colloquium that included discussions about cosmic ray and astronomic research, including work done at the labs at Echo Lake. The colloquium featured talks led by Iona, Stencel, Ormes,��, a professor at Colorado State University, and��, professor emeritus of physics at the University of Michigan.

The Historic Physics Site dedication celebrated the field of physics, specifically the study of cosmic rays, which contain high-energy particles, most originating��outside the solar system. It’s a sub-field of study in which DU physics faculty and researchers have become well-known for their contributions.

While APS offers the��, Iona��says it was Jones who recommended the Echo Lake site for dedication. After initiating a discussion, Jones worked with Iona, Ormes and Stencel to develop a proposal that was then sent to the APS for consideration. APS is the world’s largest society of physicists with more than 54,000 members.

Physics professors and researchers from DU have been contributing to the study and understanding of cosmic rays for decades. DU was part of the����that conducted research on cosmic radiation at Echo Lake and on campus. DU also has hosted three international conferences on cosmic rays. These took place in 1949, 1970 and 2014.

“The work helped multiple graduate students earn degrees. The support that the University provided to national and international research groups was widely acknowledged,” Iona said. “The involvement of the DU community, though primarily the physics department, was critical to the success of the other research groups, as DU maintained and developed the research sites.”

Iona adds that the important research conducted at the sites helped provide��evidence that:

• Heavy nuclei in cosmic radiation interact with atmospheric molecules
• Cosmic radiation carries high energy, requiring thick shields of lead, steel, or aluminum to be slowed
• Einstein’s time dilation was true for the mean lifetime of the μ –meson
• Nuclear disintegrations are produced mainly by neutrons, not photons
• Meson and electron intensity vary with altitude and direction
• Neutrons can be produced by high energy protons bombarding heavy metals

The High Altitude Laboratory on top of Mount Evans and a collection of buildings at Echo Lake, Iona says, were home to important work that helped verify early conclusions about cosmic radiation. This included, as noted in the historic site application, that radiation is primarily made of protons, and that the shower of collision products includes electrons, neutrons, positrons, muons and some anti-matter particles.

A group of institutions — among them the University of Chicago, Cornell University, 91����, Massachusetts Institute of Technology, New York University and Princeton University — had once operated the site together. Today, the site is solely operated by DU.

Several DU faculty members were mentioned during the dedication for their contributions to the operation and success of the High Altitude Laboratory:

• Joyce Stearns — former physics faculty and chair. Stearns was responsible for the acquisition and construction of the Mount Evans Laboratory. He left DU to help direct the Manhattan Project through the University of Chicago Metallurgy Lab.
• Byron Cohn — former physics faculty and chair. Cohn served as chair of the Inter-University High Altitude Research Lab governing board. He participated in cosmic ray research through the University.
• Mario Iona — former physics faculty. Iona served as the coordinator of the High Altitude Research Lab for more than 30 years. He participated in cosmic ray research through the University.

Other international physics researchers worked on various projects at the site between 1935 and 1960. They included: Giuseppi Cocconi, Arthur Compton, Ken Greisen, Wayne Hazen, Serge Korff, Bruno Rossi, Marcel Schein and John Wheeler.