Eric Weis

Computational screening of organic polymer dielectrics for novel accelerator technologies

The use of infrared lasers to power accelerating dielectric structures is a developing area of research. Within this technology, the choice of the dielectric material forming the accelerating structures, such as the photonic band gap (PBG) structures, is dictated by a range of interrelated factors including their dielectric and optical properties, amenability to photo-polymerization, thermochemical stability and other target performance metrics of the particle accelerator. In this direction, electronic structure theory aided computational screening and design of dielectric materials can play a key role in identifying potential candidate materials with the targeted functionalities to guide experimental synthetic efforts. In an attempt to systematically understand the role of chemistry in controlling the electronic structure and dielectric properties of organic polymeric materials, here we employ empirical screening and density functional theory (DFT) computations, as a part of our multi-step hierarchal screening strategy. Our DFT based analysis focused on the bandgap, dielectric permittivity, and frequency-dependent dielectric losses due to lattice absorption as key properties to down-select promising polymer motifs. In addition to the specific application of dielectric laser acceleration, the general methodology presented here is deemed to be valuable in the design of new insulators with an attractive combination of dielectric properties.

SAVY-4000 Surveillance and Life Extension Program Fiscal Year 2013 Annual Report

The Packaging Surveillance Program section of the DOE M441.1-1/sup>1, Nuclear Material Packaging Manual (DOE, 2008) requires DOE contractors to “ensure that a surveillance program is established and implemented to ensure the nuclear material storage package continues to meet its design criteria.” In order to ensure continuing safe storage of nuclear material and the maximization of risk reduction, TA-55 has established a Surveillance Program to ensure storage container integrity for operations within its specified design life. The LANL SAVY-4000 Field Surveillance Plan2 defines the near-term field surveillance plan for SAVY-4000 containers as required by the Manual. A long-term surveillance plan will be established based on the results of the first several years of surveillance and the results of the lifetime extension studies as defined in the Accelerated Aging Plan3. This report details progress in positioning the Surveillance Program for successful implementation in FY14 and status of the Design Life Extension Program in terms of its implementation and data collection for FY13.