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PSS Spring '11

Out of This World

HWS professor and alumnus partner to advance science

by Melissa Sue Sorrells Galley '05

The greatest projects in experimental physics depend on multidisciplinary collaboration: scientists and engineers working together to solve complex problems and move the knowledge of our universe forward.

ASSOCIATE PROFESSOR OF PHYSICS STEVEN PENN AND LEN MOTT '66
DISCUSS OPTICAL COATINGS IN PENN'S LAB IN EATON HALL.

As a member of the Laser Interferometer Gravitational Wave Observatory (LIGO) Scientific Collaboration, Associate Professor of Physics Steven Penn is part of a team of more than 500 scientists, working together to detect and measure cosmic gravitational waves–ripples in the fabric of space and time created by powerful events in the universe.

As president and co-founder of MLD Technologies, Len Mott '66 works with a team of 25 engineers and technicians to conceive, design and produce high-performance optical coatings and other optical components used in medical and aerospace instruments.

Together, Penn and Mott, although seemingly involved in unrelated areas of science and technology, have forged a partnership that is small in scale but galactic in its impact.

"One day about five years ago, I was working at my desk on the Saturday afternoon of Reunion while everyone else was having fun on the Quad, and there was a knock at my door," says Penn. On the other end of that knock was Mott, who was visiting campus for his 40th Reunion. "I introduced myself as the 'M' in MLD Technologies," says Mott.

As it turns out, Mott and Penn have been working together for years, although they'd never met. "My company makes some of the mirror coatings used in Steve's experiments. But, until recently, I didn't know he was an HWS professor, and he had no idea I was a Hobart graduate."

Funded by the National Science Foundation, LIGO is one of the largest and most ambitious science experiments in history. When completed, scientists hope the Observatory will be able to accurately measure space-time oscillations thousands of times smaller than a proton. Those measurements will provide invaluable data about black holes, neutron stars and the birth of our universe. It will provide a window on some of the most energetic events in our universe that cannot be seen any other way.

As with any project of this size, there are a number of challenges to overcome. Penn and his colleagues are particularly focused on the limitations of the thin-film coatings used on LIGO's optical mirrors. "Currently, our ability to 'see' black holes and neutron stars is limited by the optical coatings used on our mirrors," explains Penn.

Mott's company specializes in depositing super-thin multi-layers on optical mirrors using a process called Ion Beam Sputtering. These thin-film coatings control reflection and transmission of light, as required by the design of the LIGO instruments.

In order to maximize the sensitivity of the Observatory, LIGO requires optical components with very low absorption and very low mechanical loss, which will minimize thermal noise. "Thermal energy causes the mirror coatings to vibrate but it makes it appear that the whole mirror is vibrating," explains Penn. "We 'see' gravitational waves by sensing the location of the mirrors. The thermal motion in the coating creates a noise. This motion is tiny, but it is enormous compared to the ripples of space-time we try to observe."

"At the moment, we know we can create low absorption coatings," explains Mott, whose company develops prototype mirrors that have been tested at HWS and in other labs across the country. "Our current focus is on reducing the mechanical loss, which allows Steve and his team to evaluate the thermal noise." Since their initial meeting, Mott and Penn have stayed in contact, and Mott even returned to campus to talk with current physics majors at Penn's invitation. "Our majors loved Len's talk," recalls Penn. "It was like looking into the future at an image of what they could achieve."

Both men are confident that their partnership will bear fruit and move our knowledge of the universe forward. "I've worked on several cutting-edge projects over the past 40 years," says Mott. "But this is a really challenging and exciting one."