Doube-pulse Laser-induced Breakdown Spectroscopy of Multi-element Sample Containing Low- And High-Z Analytes

Laser-induced breakdown spectroscopy (LIBS) is a portable, remote, non-invasive analytical technique which effectively distinguishes neutral and ionic species for a range of low- to high-Z elements in a multi-element target. Subsequently, LIBS holds potential in special nuclear material (SNM) sensing and nuclear forensics requiring minimal sample preparation and detecting isotopic shifts which allows for differentiation in SNM (namely U) enrichment levels. Feasible applications include not only nonproliferation and homeland security but also nuclear fuel prospecting and industrial safeguard endorsement. Elements of higher mass with complex atomic structures, such as U, however, result in crowded emission spectra with LIBS, and characteristic emission lines are challenging to discern. Preliminary research suggests double-pulse LIBS (DPLIBS) improves signal sensitivity for analytes of lower atomic mass over conventional single-pulse LIBS (SPLIBS). This study investigates signal sensitivity for low- and high-Z analytes in a glass matrix containing U (1.3%) comparing DPLIBS to SPLIBS. DPLIBS involves sequential firing of 1064 Nd: YAG (FWHM 9 ns) pre-pulse and 10.6 µm TEA CO2 (FWHM 50-100 ns) heating pulse in near collinear geometry; SPLIBS entails only the Nd:YAG laser. Optimization of experimental parameters including inter-pulse delay and energy follows identification of characteristic lines for bulk analytes Ca, Na, and Si and trace analyte U for both DPLIBS and SPLIBS. Temporally-integrated excitation temperature and electron density as well as neutral-to-ionic species ratio constitute relative figures of merit for both DPLIBS and SPLIBS plasma characterization. Temporally-resolved studies provide insight into high-Z U analyte persistence and signal enhancement with DPLIBS as compared to low-Z bulk analytes. The study predicts and discusses optimal emission conditions of U lines and relative figures of merit in both SPLIBS and DPLIBS

Is management accounting just what management accountants do? Implicit cost analysis on Britain's railways c.1923-1939

This paper explores how railway companies performed the management accounting function during the first part of the twentieth century. It will be argued that only by understanding the relationship between management techniques and the business process can any judgement as to the quality of management decisions be reached. Through the medium of educational material, the development of train control and railway statistics is explored. It is argued that implicit marginal costing was obtained from non-financial information outside the realm of accounting. This was due to the specific conditions and complexity of operations faced by railway managers. This is then contrasted with the limited, and ultimately unsuccessful, attempts by accountants at the Railway Clearing House to cost services.Management Accounting, Cost Analysis, British Railways, Inter-war Period,