Development of methods for the preparation of radiopure 82Se sources for the SuperNEMO neutrinoless double-beta decay experiment

A radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8–54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.

Search for Neutrinoless Quadruple-β Decay of ^{150}Nd with the NEMO-3 Detector

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-β decay of ^{150}Nd using a total exposure of 0.19 kg yr recorded with the NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T_{1/2}>(1.1-3.2)×10^{21}  yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons.

The BiPo-3 detector

The BiPo-3 detector is a low radioactive detector dedicated to measuring ultra-low natural contaminations of ²⁰⁸Tl and ²¹⁴Bi in thin materials, initially developed to measure the radiopurity of the double β decay source foils of the SuperNEMO experiment at the μBq/kg level. The BiPo-3 technique consists in installing the foil of interest between two thin ultra-radiopure scintillators coupled to low radioactive photomultipliers. The design and performances of the detector are presented. In this paper, the final results of the ²⁰⁸Tl and ²¹⁴Bi activity measurements of the first enriched ⁸²Se foils are reported for the first time, showing the capability of the detector to reach sensitivities in the range of some μBq/kg.

REVISION OF THE SUBFAMILY SPHAERIDIINAE OF AMERICA NORTH OF MEXICO (COLEOPTERA: HYDROPHILIDAE)

A revision of the hydrophilid subfamily Sphaeridiinae (Coleoptera) is presented including a historical review, a discussion of diagnostic characters and techniques, and some conclusive remarks, mostly on the zoogeography of this group in North America.Thirteen genera and 62 species are recognized. Three genera, one subgenus, 12 species, and one subspecies are described as new. Sphaeridiolinus Menozzi, 1921, is placed in synonymy with Sphaeridium Fabricius, 1775; Ercycon Rey, 1885, and Paraliocercyon Ganglbauer, 1904, are placed in synonymy with Cercyon Leach, 1817. On the specific level, Phaenonotum dubium Sharp, 1882, is placed in synonymy with Ph. exstriatum (Say, 1837); Sphaeridium quadrimaculatum Herbst, 1783, marginatum Fabricius, 1787, daltoni Stephens, 1829, semistriatum Laporte, 1840, testaceum Heer, 1841, humerale Westhoff, 1881, nigrum Csiki, 1953, and pulchrum Csiki, 1953, with S. bipustulatum Fabricius, 1781; Sphaeridium striolatum Heer, 1841, pictum Ménétries, 1832, marginatum Normand, 1933, nigerrimum Reitter, 1909, inhumerale Csiki, 1953, and confluens EndrÖdy-Younga, 1967, with S. scarabaeoides (Linné, 1758); Cercyon testaceus Blatchley, 1923, with C. praetextatus (Say, 1825); Cercyon fulvipennis Mannerheim, 1852, with C. limbatus Mannerheim, 1843; Cercyon mulsanti Ganglbauer, 1904, with C. quisquilius (Linné, 1761); Cercyon impunctatus Kuwert, 1890, and janssoni Nyholm, 1952, with C. unipunctatus (Linné, 1758); Cercyon incrematus Notman, 1920, with C. lateralis (Marsham, 1802); Cercyon erythropterus Mulsant, 1840, discoidalis J. Sahlberg, 1913, basillaris Notman, 1920, and bifenestratellus EndrÖdy-Younga, 1967, with C. haemorrhoidalis (Fabricius, 1775); Cercyon rufipennis Csiki, 1953, with C. impressus (Sturm, 1807); Cercyon rubripennis Kuwert, 1890, with C. melanocephalus (Linné, 1758); Cercyon separandus Rey, 1885, and pictithorax Gridelli, 1926, with C. terminants (Marsham, 1802); Cercyon binotatus Stephens, 1829, and ruficollis Schilsky, 1888, with C. litoralis (Gyllenhal, 1808); Cercyon falli Winters, 1944 (nomen nudum), with C. analis (Paykull, 1798); Cybocephalus unicolor Motschulsky, 1845, with Cercyon adumbratus Mannerheim, 1843; Cryptopleurum cerei Schwarz, 1899, with C. impressum Sharp, 1882.Neotypes are designated for Cercyon praetextatus (Say), C. occallatus (Say), and C. minusculus Melsh. Lectotypes are designated for Dactylosternum advectum Horn, D. cacti (LeC.), Oosternum costatum Sharp, Cercyon roseni Knisch, C. opacellus Fall, C. pubescens LeC., C. kulzeri Knisch, C. nevadanus Knisch, C. floridanus Horn, C. testaceus Blatch., C. limbatus Mannh., C. fulvipennis Mannh., C. variegatus Sharp, C. indistinctus Horn, C. adumbratus Mannh., C. fimbriatus Mannh., C. luniger Mannh., C. maculatus Melsh., Genyon navicularis (Zimm.), Megasternum posticatum Mannh., Cryptopleurum impressum Sharp, C. cerei Schw., and C. subtile Sharp.Keys to tribes, genera, and species are provided. The tribes and genera are described; each species is described and illustrated, and all available bionomic and distributional data are presented; distributional records are mapped.