River inflow and salinity changes in the Caspian Sea during the last 5500 years

Pollen, spores and dinoflagellate cysts have been analysed on three sediment cores (1.8–1.4 m-long) taken from the south and middle basins of the Caspian Sea. A chronology available for one of the cores is based on calibrated radiocarbon dates (ca 5.5–0.8 cal. ka BP). The pollen and spores assemblages indicate fluctuations between steppe and desert. In addition there are some outstanding zones with a bias introduced by strong river inflow. The dinocyst assemblages change between slightly brackish (abundance of Pyxidinopsis psilata and Spiniferites cruciformis) and more brackish (dominance of Impagidinium caspienense) conditions. During the second part of the Holocene, important flow modifications of the Uzboy River and the Volga River as well as salinity changes of the Caspian Sea, causing sea-level fluctuations, have been reconstructed. A major change is suggested at ca 4 cal. ka BP with the end of a high level phase in the south basin. Amongst other hypotheses, this could be caused by the end of a late and abundant flow of the Uzboy River (now defunct), carrying to the Caspian Sea either meltwater from higher latitudes or water from the Amu-Daria. A similar, later clear phase of water inflow has also been observed from 2.1 to 1.7 cal. ka BP in the south basin and probably also in the north of the middle basin

Impact des gisements des phosphates sur la radioactivité dans les échantillons d’eau naturelle et d’air au Marocag

Impact of the phosphate layers on the radioactivity in the natural water samples and air in MoroccoIn this work, we present the results of radioactivity measurements in some samples of phosphate deposits and in samples in interaction with these  phosphate deposits such air and water. In phosphate samples, we have determined with gamma spectrometry using a well NaI(Tl) detector, concentrations of uranium in some samples of unrefined Moroccan phosphates. In air, we have measured, with nuclear solid track detector LR 115 type II,the volumic activity of 222Rn in some dwellings situated in phosphate areas. In water, we have measured activities of uranium and radium radio-isotopes (234U, 238U) with alpha spectrometry and those of radium ( 226Ra, 228Ra) with gamma spectrometry using a 220 cm3 low-background well type gamma ray detector in the aboratoire Souterrain de Modane (LSM-Centre National de la Recherche Scientifique (CNRS/CEA, France).The obtained results in Moroccan  phosphate samples and in samples in interaction with them are comparable to those habitually obtained in the same samples in the world and these activity do not present any risk for public health. Some harmful effects in the longterm could be avoided by simple precautions such ventilation of dwellings and localities of mining treatment

Mesure des activités de l'uranium ( 238U, 234U) et du rapport isotopique 234U/238U dans des échantillons d’eau naturelle au Maroc à l'aide de la spectrométrie alpha

Measurement of the activities of uranium (238U, 234U) and of Isotopic ratio 234U 238U in natural water samples in Morocco using spectrometry alphaIn this work, specific activities of     234U and 238U and isotopic activity ratios have been measured for 68 natural water samples collected from 5 principal sources of water in Morocco: Wells (18 samples), springs (17 hot spring water samples and 7 cold spring water samples), rivers (13 samples), lakes (5 samples) and tap water (8 samples). These samples have been collected in Moroccan regions characterized by various geology, different socio-economical activities. The obtained results have allow us to establish general tendencies of measured parameters repartition in sources of the analysed waters. This tendency is clear for hot springs where activities of  uranium are relatively low and 234&U/238&U activities ratios are important. This is due to temperature and oxydoreduction conditions of waters that are favourable in particularly to 234U solubility. The results so-obtained are comparable to those habitually found in natural waters in different regions of world and show that there is no radioactive pollution in these water

²¹⁰Pb- ²²⁶Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

Here we show the use of the 210Pb- 226Ra excess method to determine the growth rate of two corals from the world's largest known cold-water coral reef, Røst Reef, north of the Arctic circle off Norway. Colonies of each of the two species that build the reef, Lophelia pertusa and Madrepora oculata, were collected alive at 350 m depth using a submersible. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and trace element compositions were studied. 210Pb and 226Ra differ in the way they are incorporated into coral skeletons. Hence, to assess growth rates, we considered the exponential decrease of initially incorporated 210Pb, as well as the increase in 210Pb from the decay of 226Ra and contamination with 210Pb associated with Mn-Fe coatings that we were unable to remove completely from the oldest parts of the skeletons. 226Ra activity was similar in both coral species, so, assuming constant uptake of 210Pb through time, we used the 210Pb- 226Ra chronology to calculate growth rates. The 45.5 cm long branch of M. oculata was 31 yr with an average linear growth rate of 14.4 ± 1.1 mm yr -1 (2.6 polyps per year). Despite cleaning, a correction for Mn-Fe oxide contamination was required for the oldest part of the colony; this correction corroborated our radiocarbon date of 40 yr and a mean growth rate of 2 polyps yr -1. This rate is similar to the one obtained in aquarium experiments under optimal growth conditions. For the 80 cm-long L. pertusa colony, metal-oxide contamination remained in both the middle and basal part of the coral skeleton despite cleaning, inhibiting similar age and growth rate estimates. The youngest part of the colony was free of metal oxides and this 15 cm section had an estimated a growth rate of 8 mm yr -1, with high uncertainty (∼1 polyp every two to three years). We are less certain of this 210Pb growth rate estimate which is within the lowermost ranges of previous growth rate estimates. We show that 210Pb- 226Ra dating can be successfully applied to determine the age and growth rate of framework-forming cold-water corals if Mn-Fe oxide deposits can be removed. Where metal oxides can be removed, large M. oculata and L. pertusa skeletons provide archives for studies of intermediate water masses with an up to annual time resolution and spanning over many decades. © 2012 Author(s)

Study of 2 beta-decay of Mo-100 and Se-82 using the NEMO3 detector

After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of Mo-100 (T-1/2 > 3.1 x 10(23) y, 90% CL) and Se-82 (T-1/2 > 1.4 x 10(23) y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: 1.4 x 10(22) y (90% CL) for Mo-100 and T-1/2 > 1.2 x 10(22) y (90% CL) for Se-82. Corresponding bounds on the Majoron-neutrino coupling constant are < (0.5-0.9) x 10(- 4) and <(0.7-1.6) x 10(- 4). Two-neutrino 2beta-decay half-lives have been measured with a high accuracy, (T1/2Mo)-Mo-100 = [7.68 +/- 0.02(stat) +/- 0.54(syst)] x 10(18) y and (T1/2Se)-Se-82 = [10.3 +/- 0.3(stat) +/- 0.7(syst)] x 10(19) y. (C) 2004 MAIK "Nauka/Interperiodica"

Measurement of double beta decay of ¹⁰⁰Mo to excited states in the NEMO 3 experiment

The double beta decay of ¹⁰⁰Mo to the 0_{1}^{+} and 2_{1}^{+} excited states of ¹⁰⁰Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of ¹⁰⁰Mo to the excited 0_{1}^{+} state is measured to be T_{1/2}^{2v} = [5.7_{-0.9}^{+1.3} (stat.) ± 0.8 (syst.)] x 10²⁰ y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0_{1}^{+} state has been found. The corresponding half-life limit is T_{1/2}^{0v} (0⁺→0_{1}^{+}) > 8.9 x 10²² y (at 90% C.L.). The search for the double beta decay to the 2_{1}^{+} excited state has allowed the determination of limits on the half-life for the two neutrino mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.1 x 10²¹ y (at 90% C.L.) and for the neutrinoless mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.6 x 10²³ y (at 90% C.L.)

Measurement of the 2νββ decay half-life of 150Nd and a search for 0νββ decay processes with the full exposure from the NEMO-3 detector

We present results from a search for neutrinoless double-β (0νββ) decay using 36.6 g of the isotope 150Nd with data corresponding to a live time of 5.25 y recorded with the NEMO-3 detector. We construct a complete background model for this isotope, including a measurement of the two-neutrino double-β decay half-life of T2ν 1=2 ¼ ½9.34 0.22ðstatÞ þ0.62 −0.60 ðsystÞ × 1018 y for the ground state transition, which represents the most precise result to date for this isotope. We perform a multivariate analysis to search for 0νββ decays in order to improve the sensitivity and, in the case of observation, disentangle the possible underlying decay mechanisms. As no evidence for 0νββ decay is observed, we derive lower limits on half-lives for several mechanisms involving physics beyond the standard model. The observed lower limit, assuming light Majorana neutrino exchange mediates the decay, is T0ν 1=2 > 2.0 × 1022 y at the 90% C.L., corresponding to an upper limit on the effective neutrino mass of hmνi < 1.6–5.3 eV

Measurement of the beta beta Decay Half-Life of Te-130 with the NEMO-3 Detector

We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of Te-130 in the form of enriched and natural tellurium foils. The beta beta decay rate of Te-130 is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T-1/2(2v)=[7.0 +/- 0.9(stat) +/- 1: 1(syst)] x 10(20) yr. This represents the most precise measurement of this half- life yet published and the first real-time observation of this decay

Final results on ⁸²Se double beta decay to the ground state of ⁸²Kr from the NEMO-3 experiment

Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ( 2\nu \beta \beta) half-life of ^{82}Se as T_{\smash {1/2}}^{2\nu } \!=\! \left[ 9.39 \pm 0.17\left( \text{ stat }\right) \pm 0.58\left( \text{ syst }\right) \right] \times 10^{19} y under the single-state dominance hypothesis for this nuclear transition. The corresponding nuclear matrix element is \left| M^{2\nu }\right| = 0.0498 \pm 0.0016. In addition, a search for neutrinoless double beta decay ( 0\nu \beta \beta) using 0.93 kg of ^{82}Se observed for a total of 5.25 y has been conducted and no evidence for a signal has been found. The resulting half-life limit of T_{1/2}^{0\nu } > 2.5 \times 10^{23} \,\text{ y } \,(90\%\,\text{ C.L. }) for the light neutrino exchange mechanism leads to a constraint on the effective Majorana neutrino mass of \langle m_{\nu } \rangle < \left( 1.2{-}3.0\right) \,\text{ eV }, where the range reflects 0\nu \beta \beta nuclear matrix element values from different calculations. Furthermore, constraints on lepton number violating parameters for other 0\nu \beta \beta mechanisms, such as right-handed currents, majoron emission and R-parity violating supersymmetry modes have been set

Measurement of the 2 nu beta beta decay half-life and search for the 0 nu beta beta decay of Cd-116 with the NEMO-3 detector

The NEMO-3 experiment measured the half-life of the 2 ν β β decay and searched for the 0 ν β β decay of 116 Cd . Using 410 g of 116 Cd installed in the detector with an exposure of 5.26 y, ( 4968 ± 74 ) events corresponding to the 2 ν β β decay of 116 Cd to the ground state of 116 Sn have been observed with a signal to background ratio of about 12. The half-life of the 2 ν β β decay has been measured to be T 2 ν 1 / 2 = [ 2.74 ± 0.04 ( stat ) ± 0.18 ( syst ) ] × 1 0 19     y . No events have been observed above the expected background while searching for 0 ν β β decay. The corresponding limit on the half-life is determined to be T 0 ν 1 / 2 ≥ 1.0 × 1 0 23     y at the 90% C.L. which corresponds to an upper limit on the effective Majorana neutrino mass of ⟨ m ν ⟩ ≤ 1.4 – 2.5     eV depending on the nuclear matrix elements considered. Limits on other mechanisms generating 0 ν β β decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained