Decay spectroscopy at the two-proton drip line: radioactivity of the new nuclides 160Os and 156W

The radioactivity of 76160Os84 and 74156W82 that lie at the two-proton drip line have been measured in an experiment performed at the Accelerator Laboratory of the University of Jyväskylä. The 160Os nuclei were produced using fusion-evaporation reactions induced by a beam of 310 MeV 58Ni ions bombarding a 106Cd target. The 160Os ions were separated in flight using the recoil separator MARA and implanted into a double-sided silicon strip detector, which was used to measure their decays. The α decays of the ground state of 160Os (Eα = 7092(15) keV, t1/2 = 97−32+97 μs) and its isomeric state (Eα = 8890(10) keV, t1/2 = 41−9+15 μs) were measured, allowing the excitation energy of the isomer to be determined as 1844(18) keV. These α-decay properties and the excitation energy of the isomer are compared with systematics. The α decays were correlated with subsequent decays to investigate the β decays of the ground state of 156W, revealing that unlike its isotones, both low-lying isomers were populated in its daughter nuclide, 156Ta. An improved value for the half-life of the proton-decaying high-spin isomeric state in 73156Ta83 of 333−22+25 ms was obtained in a separate experiment using the same experimental systems with a 102Pd target. This result was employed to improve the precision of the half-life determined for 156W, which was measured as 157−34+57 ms

OECD Environmental Performance Review Programme: accountability (f)or learning?

The growing interest in evaluation as a new form of environmental governance stems from two developments: the movement towards New Public Management, and the search for new policy instruments for managing complexity, uncertainty and plurality of values in the pursuit of sustainable development. The former holds increasing accountability as the main purpose of evaluation, while the latter stresses the importance of learning. These approaches are often considered as mutually exclusive, but recent literature has underlined their complementary roles in policy making. This article examines to what extent the OECD Environmental Performance Review (EPR) programme has succeeded in combining the objectives of learning and accountability within a single evaluation framework. he EPRs have been relatively successful in avoiding the negative side-effects often associated with traditional performance measurement, but have usually ailed to generate broad debate. Focusing on enhancing accountability through social learning would probably contribute to overcoming this problem