A search for double beta decays of tin isotopes with enhanced sensitivity

A search for the various double beta decay modes of 124Sn and 112Sn has been performed on 75 kg.days of data. New half-life limits for excited states in 124Sn have been obtained including a lower limit for the decay into the first excited 2+ state of 124Te of T_half > 0.87e20 yrs (90% CL) and into the first excited 0+ state of T_half > 1.08e20 yrs (90% CL). Ground state and excited state transitions of 112Sn have also been experimentally explored. A limit for the 2 neutrino double electron capture of T_half > 1.8e19 yrs (90% CL) is obtained. The non-observation of de-excitation gammas from the 0+ at 1888.5keV results in a lower half-life limit on the 0 neutrino double electron capture decay of 112Sn of T_half > 0.8e19 yrs (90% CL), despite a possible resonant enhancement of the decay rate due to degenerated states.Comment: 6 pages, 7 figures, updated analysis and tex

Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated 3^3He counters

Ambient neutrons may cause significant background for underground experiments. Therefore, it is necessary to investigate their flux and energy spectrum in order to devise a proper shielding. Here, two sets of altogether ten moderated $^3$He neutron counters are used for a detailed study of the ambient neutron background in tunnel IV of the Felsenkeller facility, underground below 45 meters of rock in Dresden/Germany. One of the moderators is lined with lead and thus sensitive to neutrons of energies higher than 10 MeV. For each $^3$He counter-moderator assembly, the energy dependent neutron sensitivity was calculated with the FLUKA code. The count rates of the ten detectors were then fitted with the MAXED and GRAVEL packages. As a result, both the neutron energy spectrum from 10$^{-9}$ MeV to 300 MeV and the flux integrated over the same energy range were determined experimentally. The data show that at a given depth, both the flux and the spectrum vary significantly depending on local conditions. Energy integrated fluxes of $(0.61 \pm 0.05)$, $(1.96 \pm 0.15)$, and $(4.6 \pm 0.4) \times 10^{-4}$ cm$^{-2}$ s$^{-1}$, respectively, are measured for three sites within Felsenkeller tunnel IV which have similar muon flux but different shielding wall configurations. The integrated neutron flux data and the obtained spectra for the three sites are matched reasonably well by FLUKA Monte Carlo calculations that are based on the known muon flux and composition of the measurement room walls.Comment: 10 figures, 4 tables; to be published in Phys. Rev.

First escaping fast ion mesurements in ITER-like geometry using an activation probe

More research is needed to develop suitable diagnostics for measuring alpha particle confinement in ITER and techniques relevant for fusion reactor conditions need further development. Based on nuclear reactions, the activation probe is a novel concept first tested in JET. It may offer a more robust solution for performing alpha particle measurements in ITER. This paper describes the first escaping fast ion measurements performed at ASDEX Upgrade (AUG) tokamak using an activation probe. A detailed analysis, outside the scope of this contribution, will be published in a journal paper.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412)

The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: 40K, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 234U, 238U, 239Pu, 239+240Pu and 241Am for IAEA-410 and 40K, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 235U, 238U, 239Pu, 240Pu and 239+240Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training