Woodruff School of Mechanical Engineering
NRE 8011/8012 and MP 6011/6012 Seminar
Nuclear & Radiological Engineering and Medical Physics Programs
Detection of Shielded Special Nuclear Material with a Cherenkov-Based Transmission Imaging
Mr. Paul Rose
Thursday, October 22, 2015 at 11:00:00 AM
Boggs Building, Room 3-47
Dr. Anna Erickson
Detection of shielded special nuclear material, SSNM, while in transit, produces unique challenges. Typical cargo imaging systems are Bremsstrahlung-based and cause an abundance of unnecessary signal in the detectors and doses to the cargo contents and surroundings. Active interrogation using low energy nuclear reactions can produce dual monoenergetic photons which can unveil the illicit material when coupled with a high-contrast imaging system. Such a system will impart significantly less dose to the contents than the Bremsstrahlung methods. Cherenkov detectors provide speed, resilience, inherent energy threshold rejection, and other beneficial traits beyond the capability of most scintillators. High energy resolution is not a priority when using two well separated gamma rays, 4.4 and 15.1 MeV, generated from low energy nuclear reactions such as 11B(d,n-γ)12C. These gamma rays provide a measure of the effective atomic number, Z, of the cargo by taking advantage of the large difference in Compton scattering and pair production cross sections. Experimental validation of this system was carried out using a mini-array of Cherenkov detectors. These studies showed the ability to separate high-Z materials from lower and mid-Z materials by transmission spectral analysis while also producing high-contrast images.
Paul worked as an engineering professional in the natural gas industry for five years before he entered Georgia Tech as an undergraduate student in the Nuclear and Radiological Engineering department in 2010. As an undergraduate student at Georgia Tech he conducted over three years of research in atomic physics on the quantum behavior of atom and photon interactions while completing his bachelor’s degree in nuclear engineering. After graduating with a BS in 2013, he is currently a graduate student at Georgia Tech in the Nuclear and Radiological Engineering department where he specializes in active interrogation and detection methods, especially applied to nuclear security.