About Us
Our Team
For nearly five decades, RAC has been a trusted authority in radiological risk assessment and environmental analysis. Founded by Dr. John Till in 1977, the company’s pioneering work has shaped national understanding of radioactive materials in the environment and their impact on human health.
Today, RAC’s mission continues under a revitalized team dedicated to combining scientific rigor, modern tools, and practical solutions for a new generation of challenges. Guided by Dr. Till’s enduring vision, and led by Dr. Colby Mangini’s technical direction, the RAC team remains committed to delivering clarity, precision, and defensible science in every project.
Leadership
John E. Till, PhD, RADM, USNR (Ret.)
Founder & Senior Advisor
Dr. Till founded RAC in 1977 following his service in the U.S. Navy’s Nuclear Submarine Program, where he retired as a Rear Admiral in the Naval Reserve. A recipient of the Department of Defense Distinguished Service Medal, the L.S. Taylor Medal, and the E.O. Lawrence Award, Dr. Till has devoted his career to advancing radiological science and public understanding.
Under his leadership, RAC conducted landmark dose reconstruction and environmental risk projects at Hanford, Savannah River, Los Alamos, and other major DOE facilities. His contributions to the International Commission on Radiological Protection, the National Council on Radiation Protection and Measurements, and the National Academy of Sciences have shaped international standards for radiological protection.
Dr. Till continues to serve as RAC’s Senior Advisor, guiding the team with insight gained from over 40 years of scientific and public service.
Colby D. Mangini, PhD, CHP
Technical Lead
Dr. Mangini is a board-certified health physicist with over 20 years of experience in radiological analysis, environmental modeling, and regulatory support. A U.S. Navy veteran and former instructor at the Naval Nuclear Power School, he brings a disciplined, problem-solving approach grounded in both scientific rigor and practical application.
At RAC, Dr. Mangini leads technical direction and project execution, specializing in contaminant transport modeling, dose reconstruction, and radiological risk assessment. In parallel with his work at RAC, he serves as a Health Physicist in the Risk and Environmental Assessment Group at Pacific Northwest National Laboratory (PNNL), where he supports federal programs focused on environmental impact evaluation, radiological safety, and nuclear site assessment.
His combined experience in national laboratory research and environmental consulting provides RAC with a unique bridge between applied science and regulatory practice — ensuring the team’s work remains technically robust, transparent, and defensible.
Emily Caffrey, PhD, CHP
Project Lead
Dr. Caffrey is a Certified Health Physicist with a PhD in Radiation Health Physics and Statistics. Her expertise spans ionizing radiation dosimetry, health physics education, and scientific communication.
As Project Lead for RAC, Dr. Caffrey ensures projects are executed efficiently and effectively, bringing structure, coordination, and a results-driven approach to every engagement. In addition to her consulting work, she serves as Program Director and Assistant Professor for the University of Alabama at Birmingham’s Master’s in Health Physics program and as Editor-in-Chief of the Health Physics Society’s Ask the Experts platform.
Dr. Caffrey’s combination of technical insight and organizational leadership ensures RAC continues to deliver clarity, quality, and precision in all its work.