High-accuracy Geant4 simulation and semi-analytical modeling of nuclear resonance fluorescence

Nuclear resonance fluorescence (NRF) is a photonuclear interaction that enables highly isotope-specific measurements in both pure and applied physics scenarios. High-accuracy design and analysis of NRF measurements in complex geometries is aided by Monte Carlo simulations of photon physics and transport, motivating Jordan and Warren (2007) to develop the G4NRF codebase for NRF simulation in Geant4. In this work, we enhance the physics accuracy of the G4NRF code and perform improved benchmarking simulations. The NRF cross section calculation in G4NRF, previously a Gaussian approximation, has been replaced with a full numerical integration for improved accuracy in thick-target scenarios. A high-accuracy semi-analytical model of expected NRF count rates in a typical NRF measurement is then constructed and compared against G4NRF simulations for both simple homogeneous and more complex heterogeneous geometries. Agreement between rates predicted by the semi-analytical model and G4NRF simulation is found at a level of ${\sim}1\%$ in simple test cases and ${\sim}3\%$ in more realistic scenarios, improving upon the ${\sim}20\%$ level of the initial benchmarking study and establishing a highly-accurate NRF framework for Geant4.Comment: 16 pages, 6 figures, revised for peer revie

Experimental demonstration of an isotope-sensitive warhead verification technique using nuclear resonance fluorescence

Future nuclear arms reduction efforts will require technologies to verify that warheads slated for dismantlement are authentic without revealing any sensitive weapons design information to international inspectors. Despite several decades of research, no technology has met these requirements simultaneously. Recent work by Kemp et al. [Kemp RS, Danagoulian A, Macdonald RR, Vavrek JR (2016) Proc Natl Acad Sci USA 113:8618--8623] has produced a novel physical cryptographic verification protocol that approaches this treaty verification problem by exploiting the isotope-specific nature of nuclear resonance fluorescence (NRF) measurements to verify the authenticity of a warhead. To protect sensitive information, the NRF signal from the warhead is convolved with that of an encryption foil that contains key warhead isotopes in amounts unknown to the inspector. The convolved spectrum from a candidate warhead is statistically compared against that from an authenticated template warhead to determine whether the candidate itself is authentic. Here we report on recent proof-of-concept warhead verification experiments conducted at the Massachusetts Institute of Technology. Using high-purity germanium (HPGe) detectors, we measured NRF spectra from the interrogation of proxy 'genuine' and 'hoax' objects by a 2.52 MeV endpoint bremsstrahlung beam. The observed differences in NRF intensities near 2.2 MeV indicate that the physical cryptographic protocol can distinguish between proxy genuine and hoax objects with high confidence in realistic measurement times.Comment: 38 pages, 19 figures; revised for peer review and copy editing; addition to SI for realistic scenario projections; minor length reduction for journal requirement

An Investigation of the Factors Contributing to Measurement uncertaintly using a Coordinate Measurement Machine

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Engineering & Technology Management by Jayson S. Minix on December 3, 2014

Numerical Study on the Effect of Structural Parameters on the Behavior of BRBF-E

Ductile braced frames are often used to resist lateral earthquake loads in steel buildings. However, the presence of the brace element can interfere with architectural features. Buckling-restrained braced frame in eccentric configuration (BRBF-E) is believed to have combined good performance in resisting earthquake loads and great flexibility for architectural design. Eccentrically braced frames can accommodate architectural openings for doors, windows and hallways. However, every configuration of buckling-restrained braced frame in eccentric configuration has a different seismic response in earthquake loadings. The effect of different parameters to the structural response of BRBF-E was studied such as eccentricity-to-length of bay ratio, cross sectional area of BRB, length of the bay, and location of the braces. Design parameters were investigated to determine its effects to the structural response of different eccentric configurations of BRBF-E with building height of 3, 6 and 9 stories. These parameters of BRBF-Es under seismic loading were analyzed using pushover analysis. The analysis of data was composed of comparison of inter-story drift and percentage failure of members. Comparing the different BRBF-E configurations, the single[1] brace configuration provides the most reduction in inter-story drift and percentage of failure of members. From the numerical experiment results, a design guide for BRBF-E was proposed

Evaluation of Unified Student Financial Assistance System in Tertiary Education (UniFAST) in Addressing Capital Market Imperfection in the Philippines

The importance of investing in higher education cannot be overemphasized. It can affect individuals’ income as well as the nations’ progress in terms of the quality of its labor force. However, the participation rate in the Philippines in higher education over several decades has remained relatively stagnant compared with our neighboring countries like Thailand and Korea. Part of the reason for the low participation rate can be attributed to poverty issues as well as the financing problems of the able students who lack sufficient funds to cover the cost of education. Individuals and even organizations always seek the help of capital markets to address such issues of inadequate funds. However, the capital market is not perfect. One cannot use his/her skill or promise for the rendition of service in the future as a form of collateral in exchange of borrowing funds. This is the very reason why the government enacted the Unified Student Financial Assistance System for Tertiary Education Act (R.A. No. 10687) or UniFAST last May 11, 2016. It aims to allow citizens full access to quality education by providing adequate funding and to increase the participation rate in tertiary education