Study of the Beta-Spectra ofC14andS35

Analysis of the atmospheric 14C record spanning the past 50,000 years derived from high-precision 230Th/234U/238U, 231Pa/235U and 14C dates on fossil corals

“…11a and b). The beta spectrum of 14 C has been computed, measured, and re-measured by many investigators because of its importance to many fields of radiochemistry (Cook et al, 1948;Angus et al, 1949;Feldman and Wu, 1949;Warshaw, 1950;Wu and Schwarzschild, 1953;Moljk and Curran, 1954;Pohm et al, 1955;Kuzminov and Osetrova, 2000). Most studies agreed on the end-point energy (the maximum energy observed in the spectrum), but many disagreed on the shape of 14 C beta spectrum.…”

“…Most studies agreed on the end-point energy (the maximum energy observed in the spectrum), but many disagreed on the shape of 14 C beta spectrum. Some evidence suggested that the 14 C beta spectrum deviated from the theoretical ''allowed'' distribution (Cook et al, 1948;Angus et al, 1949;Warshaw, 1950;Kuzminov and Osetrova, 2000), defined as that predicted by Fermi-Kurie theory (Lieser, 2001); while other data suggested the beta spectrum followed the ''allowed'' distribution from its endpoint energy ($156 keV) to a certain low-energy value (Moljk and Curran, 1954;Pohm et al, 1955;Feldman and Wu, 1949;Wu and Schwarzschild, 1953).…”

“…More importantly, any error in estimating the low-energy beta spectrum of 14 C would result in reproducible but biased counting rates in the early half-life measurement using similar gas counters. There have been extensive research and continued debate over the shape of 14 C beta spectrum especially in the low-energy range (Cook et al, 1948;Angus et al, 1949;Feldman and Wu, 1949;Warshaw, 1950;Wu and Schwarzschild, 1953;Moljk and Curran, 1954;Pohm et al, 1955;Kuzminov and Osetrova, 2000), all of which imply potentially large and poorly constrained errors in 14 C half-life values measured using gas counters (Mann et al, 1961;Watt et al, 1961;Bella et al, 1968). Table 1 is a summary of gas-counter measurements of 14 C half-life in the 1960s.…”

“…Post analysis, applied a back correction term based on their adsorption estimation experiment and theoretical considerations. Although these authors conducted the adsorption check experimentally or made post-measurement corrections, gas adsorption in the gas spitting system remained one of the most challenging problems and the largest source of error in these ARTICLE IN PRESS 194619481950195219561958196019641966 (Godwin, 1962) assumed beta energy spectra discarded by the authors Fig. 8.…”

Development of a 4π detection system for the measurement of the shape of β spectra

“…The β spectrum was investigated with different measurement techniques over the past 70 years (see e.g. [38,39,40,41,42,8]). The two most precise studies ( [41,8]) extracted a maximum energy slightly lower than the recommended value, totally dominated by a single high-precision measurement from [43].…”