Nuclear Data Sheets for A=31

Nuclear spectroscopic information for the known nuclides of mass 31 (F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar) has been evaluated. A useful source of many of the Adopted Levels for P-31 and S-31 is presented in Endt's evaluations (1998En04,1990En08,1978En02,1973EnVA), however all the adopted properties of levels and gamma rays have been re-evaluated in this work. The data sets for reactions and decays, including all available gamma-ray data, are based mostly on the original literature. The Mg-31 nuclide is a prime candidate for the study of 'island-of-inversion' as its ground state and first excited state can only be explained by intruder orbitals in a deformed shell-model approach. 31S is of importance in astrophysics rp-process as a possible 'bottleneck' nuclide. There are no data available for excited states in F-31, Ne-31 and Ar-31. No gamma transitions are known in Cl-31. For Na-31, only one excited state is known. The radioactive decay characteristics of 31F and 31Ne isotopes have not yet been investigated. The 31S and 31Mg nuclei are currently being pursued intensively by various experimental groups, including recent work by Nuclear Astrophysics group at McMaster, the results of which will soon become available. Cutoff Date: Literature available up to February 15, 2013 has been consulted. General Policies and Organization of Material: See the January issue of the Nuclear Data Sheets or http://www.nndc.bnl.gov/nds/NDSPolicies.pdf. General Comments: The statistical analysis of gamma-ray data and deduced level schemes is carried out through computer codes available at NNDC, BNL website: www.nndc.bnl.gov. The direct feedings to excited states in beta- and epsilon decays have generally been computed from I(gamma+ce) intensity balances at each level; the associated log ft values are calculated using LOGFT code. The Q values have been adopted from 2012Wa38, unless otherwise stated.