Coating thermal noise research for LIGO-India

Maya Kinley-Hanlon — an undergraduate student in the Department of Physics at the American University in Washington, DC — tells us more about her group’s work on optical coatings for LIGO-India.

Maya Kinley-Hanlon is a PhD candidate in the Department of Physics at the American University in Washington, DC.

Maya Kinley-Hanlon is an undergraduate student in the Department of Physics at the American University in Washington, DC.

Our CQG paper describes measurements of optical coatings on silica glass substrates to determine if storing the LIGO optics for many years before installing them in India will cause any problems.  The coatings are known to be fairly robust in their optical properties, but as is always the case with LIGO optics, no one has any real idea about the thermal noise properties.  Since thermal noise from the coatings is expected to be a limiting noise source in the LIGO detectors, knowing if storing the optics could cause a problem is an important issue.  I worked on this project after my freshman year as a physics major at American University.

My first introduction to physics research was through this work in the American University Thermal Noise and Gravitation Laboratory.  I did not know what I wanted to do with my physics degree until my professors encouraged me to begin attending conferences and networking events. I had not considered graduate school until my professors mentioned it as a natural next step.

When I set my sights on eventually getting a doctorate, I realized that lab experience would be essential. I consulted with upper class physics majors about their research experiences. Based on their recommendations, one lab intrigued me: Professor Gregory Harry’s lab doing research for the Laser Interferometer Gravitational-wave Observatory (LIGO).  Not only did students in his lab do hands-on work studying mechanical loss in mirror coatings under vacuum conditions, but the lab is also part of the larger LIGO collaboration studying gravitational waves. I found gravitational wave astronomy to be fascinating. I started work the summer of 2015, before the September 14, 2015 detection, so LIGO was not as well-known as it is now. Additionally, I was enthusiastic about working in a hands-on capacity in a physical lab rather than focusing solely on equations. I benefited from the mentoring of Hannah Fair, an upper class physics student who worked in Prof. Harry’s lab, and she helped arrange an initial interview with him. Once I was hired, she continued to provide advice that helped me get started in research. My first assignments primarily consisted of smaller tasks. I ran tests on the silica disks we observed and recorded the results. I also began learning more about LIGO and more broadly about gravitational wave physics.

My work the first summer was measuring optical coating samples that had been measured previously in 2002 to see if they had changed their thermal noise properties.  This was a specific question that our funding agency, the National Science Foundation (NSF), had asked and American University was the lab best suited within LIGO to answer it. This is an important question as we expect coating thermal noise to be the limiting noise in LIGO and the optics to be installed in India will have to be stored for many years. I spent the summer measuring the mechanical loss of these samples, which can be used to predict thermal noise. We determined that the mechanical loss had not noticeably changed, thus the optics for LIGO India should be fine.

schematic drawing of the experimental setup and data readout chain. Figure 1 from our CQG paper. © 2016 IOP Publishing Ltd. All rights reserved.

Schematic drawing of the experimental setup and data readout chain. Figure 1 from our CQG paper. © 2016 IOP Publishing Ltd. All rights reserved.

In my two years as a part of the LIGO collaboration, I have begun to learn what it means to be a scientist. Many LIGO members have worked on gravitational wave physics for most of their professional lives without ever even detecting gravitational waves and it was exciting to see that change in 2016. In my first year with LIGO, I grew to appreciate these efforts and the importance it has for the future of physics. Fundamentally, I learned to follow the results of the lab research and corresponding theory to its scientific conclusion, even in the absence of direct evidence.

It was stimulating to meet other scientists in the collaboration. I found that they appreciated my passion for the field and they were generous in sharing their knowledge and expertise.  Upon LIGO’s announcement of this groundbreaking gravitational wave detection, the collaboration’s scientists generously shared the credit. Following the announcement, I sat at my computer smiling, sharing the memorable moment with friends who had thrown a party to mark the occasion. The joy simply was contagious.

As a recent member of LIGO’s email list-serve, I can count on a daily email reporting the newest five articles produced by the collaboration. Being part of a community that works toward a singular scientific goal, knowing that the wider scientific community is both interested and supportive, makes the dedicated effort and hard work worthwhile.

Read the full article for free* in Classical and Quantum Gravity:
The effect of time on optical coating mechanical loss and implications for LIGO-India
Maya Kinley-Hanlon et al 2016 Class. Quantum Grav. 33 147001

*until 15 September 2016

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