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You’re a what?
Neutron instrument engineer

| March 2022

Nancy Hadad

What do you do?

I’ve spent the last 10 years of my career designing and building a neutron scattering instrument called CANDOR: Chromatic Analyzer Neutron Diffractometer or Reflectometer. It’s a huge, complex instrument for materials research that’s in use at NIST (National Institute of Standards and Technology), where I work. I’ve been involved with everything from writing statements of work to project management to design and testing of the instrument.

I’m a mechanical engineer, and I’m fortunate to have been involved in the whole process. A lot of mechanical engineers don’t get to do much pure engineering because they spend a lot of time on support services, such as documentation and reports.

Is there a nontechnical way to explain what a neutron scattering instrument does?

CANDOR, like all neutron scattering instruments, uses neutrons to analyze materials. These neutrons are ejected from a nuclear reactor and travel down long mirrored tubes. CANDOR massages the neutrons before they’re bounced against the material, then analyzes those neutrons and tells you different things about the characteristics of the materials.

Better understanding of materials helps scientists across many fields of study, such as medical research. For example, neutron scattering was used to gain a clearer picture of the lightning-fast molecular dance occurring within the membrane that encloses each cell in our body. Neutron scattering was also used to evaluate synthetic knee meniscus material.

The engineering side is designing the equipment after the scientists specify the instrument on paper, so the engineers work hand in hand with the scientists. Our work is unique in that we’re not a production facility. We create prototypes: we design and make an instrument once.

Now that CANDOR is complete, scientists from around the world apply for time to use it. The process is similar to how researchers and scientists apply for time to use advanced telescopes, like the Hubble Space Telescope.

Tell me about some of your other activities.

Most of my work at NIST has been on CANDOR, but I’ve also worked on many smaller projects. For example, I designed neutron guide shutters, which pneumatically raise and lower shielding material to open and close several neutron beams. I’ve been the author or secondary author on eight publications over the past several years, primarily focused on CANDOR.

Additionally, I’m a founding member of the International Society of Neutron Instrument Engineers (ISNIE): I helped write our charter and develop the website, and I’ve been 1 of 5 officers of ISNIE since its creation in 2017. I was the chair of our international conference and led the team that planned the event.

More recently, I helped start and then became chair of a diversity, equity, and inclusivity group, following an extensive study done by NIST, to help improve the diversity and workplace culture in our lab.

What does a typical day look like for you?

I may spend some time on my designs. For example, I’m currently working on radiation shielding structures for the room that houses the nuclear reactor. I also might analyze the engineering of others’ assignments, lead a design review on a new element of our project, and continue work on our report on diversity efforts at NIST. There’s also the process improvement part of engineering, such as the project and safety checklist I recently created.

What drew you to your occupation?

I was always really good at math, and when I was 12, I was selected to take part in a Johns Hopkins program for advanced math study. By the time I went to college, I had decided to be a math major. I took a preliminary engineering class that summarized all the different types of engineering, and I liked mechanical the best.

My younger brother, who is also a mechanical engineer, loved to take things apart and put them together again when we were kids, so I guess he got me into it. People are drawn to mechanical engineering because they like to conceptualize how things could be designed, work on cars, build things, or are just really good at math, like me.

How did you get started toward this career?

I got my bachelor's degree in mechanical engineering. After college, my first job was as an automation engineer in which I started out designing and acquiring automated assembly equipment. I got into product design and ended up working in a consulting group that helped other companies design their products, manufacturing lines, and more.

After working there for 10 years, I took time off to raise a family. When I re-entered the labor force, I worked for 2 years helping an entrepreneur design a novel solar panel. Then I posted my resume to a couple of websites, and my current manager from NIST called for an interview. I was thrilled! I’d always wanted to work at NIST because it seemed like the coolest place, and the scientists here are brilliant. Some have won Nobel Prizes, and many—including some in my workgroup—have won other prestigious awards.

What’s your advice for someone who wants to work as a neutron instrument or other type of engineer?

Do internships, join clubs, and pursue hobbies related to the field. It can even be a project that you do for fun. Do something to gain experience and show interest.

Don’t hesitate to ask for help and ask questions. You will be a better engineer if you do. The more you inquire, the more you’ll learn. Especially at the beginning of your career, nobody expects you to know a whole lot.

Finally, when you’re working on a project, pick up the phone or call a meeting. If my email correspondence is confusing to me or starts going in circles, I pick up the phone to solve things quickly. Meetings with the critical people present can also help to resolve something.

What’s difficult about your work?

On a project of CANDOR’s size and over a long period, there are a variety of challenges that come up. For example, one year our funding was limited, and we couldn’t purchase anything. There are also difficult engineering questions. However, my manager is a walking engineering textbook, and he immediately grasps the analysis that needs to be done to ensure a successful engineering design. I don’t hesitate to reach out for help if I’m uncertain of something.

Regarding CANDOR itself, the biggest challenge in creating it was its magnitude: it consisted of over 30 subassemblies that each required significant effort to design, install, and align. For example, we needed repetitive, precise stopping positions to rotate CANDOR’s 3-ton detector arm that’s driven by an outboard motor. Solving this problem required contributions from everyone on the team, and we did it!

What do you enjoy most about it?

One thing that gets me excited is learning about completely new areas. You learn so much about materials and areas of science and engineering you never knew about. I love conceptualizing new designs: Coming up with a design for the first time and laying it out is fun.

I also enjoy working and communicating with others in the engineering community. My work as part of the professional society has been a great experience. It’s been exciting to work with and connect people in our small community from all over the world.

Ryan Farrell is an economist in the Office of Occupational Statistics and Employment Projections, BLS. He can be reached at

Suggested citation:

Ryan Farrell, "Neutron instrument engineer," Career Outlook, U.S. Bureau of Labor Statistics, March 2022.

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Nancy Hadad