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Radiation Detection & Nuclear Sciences Leadership

Daniel Stephens Photo

Technical Group Manager
Radiation Detection and Nuclear Sciences
509.372.6109

Dr. Daniel L. Stephens, Jr. is the Technical Group Manager of the Radiation Detection and Nuclear Sciences (RDNS) group at Pacific Northwest National Laboratory, where he is responsible for the management of over 50 technical and administrative personnel, the safe and secure operation of twelve thousand square feet of world-class laboratory capabilities, including clean rooms and radioactive material use areas, an active post-Doctoral and student program, and research spanning basic high-energy physics to sensitive nuclear security programs.

Dr. Stephens joined PNNL as a research scientist in February 2003. His career at PNNL has focused on the development and deployment of novel radiation detection instruments with an emphasis on national and homeland security applications. Research topics of interest include advanced spectroscopic identification algorithms, sensor networking, novel radiation detector development, field operations, and operational testing and evaluation.

John Orrell Photo

Team Lead
Radiation Detection and Nuclear Sciences
509.375.1899

John L. Orrell is a Team Lead within the Radiation Detection and Nuclear Sciences technical group. Dr. Orrell's main research areas are fundamental physics on neutrinoless double beta decay and dark matter. He is a member the Majorana and CoGeNT collaborations. John earned his Ph.D. in 2004 from the University of Washington. His dissertation with the Sudbury Neutrino Observatory focused on experimentally limiting the possible conversion of 8B solar neutrinos into antineutrinos due to solar magnetic field interactions, a process possible for massive Majorana-type neutrinos with large magnetic moments. As a post-doctoral fellow at Pacific Northwest National Laboratory (2004 – 2006), John developed hands-on experience in the assembly of ultra-low background germanium detectors both with the Majorana Collaboration and for national security applications. In 2008, Dr. Orrell began the development of the CoGeNT dark matter experiment in the Soudan Underground Laboratory.

Majorana
CoGeNT

Martin Keillor Photo

Scientist
Radiation Detection and Nuclear Sciences
509.372.1810

Dr. Martin E. Keillor joined PNNL in fall of 2006 after retiring as a Lieutenant Colonel from a 20-year career in the US Air Force. Dr. Keillor is a nuclear engineer and RDNS Team Lead, currently leading the Particle Release Experiment to examine survey and sampling techniques relevant to CTBTO's On-Site Inspection needs. He recently completed the RNLabs and CASCADES projects to develop a laboratory-based low-background, 14-crystal germanium array and associated analysis code for applications in nuclear test treaty monitoring. Marty also has been the principal investigator on an ultra-low-background germanium gamma spectrometer array, an associated project to develop a multi-detector coincidence analysis code, and as a supporting investigator on low-background gas proportional counter and gas processing system projects. Dr. Keillor earned his PhD from the Oregon State University Department of Nuclear Engineering in September 2000.

During his final 3 years on active duty, Dr. Keillor pursued low background measurement research at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg, Germany. While at MPIK, he worked on the design and construction of three ultra-low background intrinsic germanium gamma spectrometers, and installation of one of these detectors (GeMPI-2) deep underground at the Laboratori Nazionale del Gran Sasso near L'Aquila, Italy. This period afforded him the opportunity to work directly with Gerd Heusser and Stefan Schönert, leaders in ultra-low background germanium detector research and GERDA, the European analogue to the Majorana collaboration pursuing measurement of neutrinoless double beta decay. There he worked on the design and construction of three ultra-low background intrinsic germanium gamma spectrometers. Earlier in his USAF career, Dr. Keillor performed research and operational measurements at the McClellan Central Laboratory, a world class environmental measurement laboratory supporting US nuclear treaty monitoring efforts where he gained experience in radiochemical and nuclear counting laboratory operations for treaty monitoring.

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