NONEXPERIMENTAL SCREENING OF THE WATER SOLUBILITY, LIPOPHILICITY, BIOAVAILABILITY, MUTAGENICITY AND TOXICITY OF VARIOUS PESTICIDES WITH QSAR MODELS AID

In our study the dataset containing 489 pesticides and their active substances of different classes of organic compounds was used for analysis. For compounds of analyzed dataset the values of lipophilicity, water solubility, toxicity, bioavailability and mutagenicity were predicted by developed QSAR models. The most environmentally hazardous substances were identified using prediction of QSAR models for pesticides. The satisfactory coincidence between the experimental values of investigated properties and their predicted values by QSAR models was obtained (coefficient of determination in the range 83-94 %)

ZnWO4_4 anisotropic scintillator for Dark Matter investigation with the directionality technique

International audienceThe ZnWO4 crystal scintillator has unique features that make it very promising to realize a pioneering experiment to pursue Dark Matter investigation with the directionality technique. In particular in this detector the light output and the scintillation pulse shape for heavy particles (p, α, nuclear recoils) depend on the direction of the impinging particle with respect to the crystal axes, while the response to γ/β radiation is isotropic. The anisotropy of the light output can be considered to point out the presence in the diurnal counting rate of a Dark Matter signal produced by candidate particle inducing just nuclear recoils. In addition this crystal detector has also other important characteristics for a Dark Matter experiment: high light output, high level of radiopurity. In this paper the present performances of the developed ZnWO4 crystal scintillator will be summarized together with the possible future improvements. Some reachable sensitivities – under given assumptions – in the investigation of DM candidate particles with the directionality technique will also be addressed

Search for naturally occurring seaborgium with radiopure 116^{116}CdWO4_{4} crystal scintillators

International audienceA detector containing two radiopure $^{116}$CdWO$_{4}$ crystal scintillators with total mass of 1.2 kg was operated during 35324 h at the Gran Sasso Underground Laboratory (INFN, Italy) with the main aim to investigate double beta decay of $^{116}$Cd. As a by-product of the experiment, a new upper limit on atomic abundance of hypothetical naturally occurring long-lived seaborgium (eka-tungsten, Z = 106) in tungsten was set at 5.1 10$^{−15}$ atom(Sg)/atom(W) with 90% C.L. (assuming the Sg half-life of 10$^{9}$ yr) by the analysis of the alpha decay events. This limit is better than those obtained with a ZnWO$_{4}$ scintillator and in other types of experiments which used the accelerator mass spectrometry or searched for spontaneous fission of superheavy elements

Search for double beta decay in 106^{106}Cd in the DAMA/CRYS setup

International audienceAn experiment to search for double beta decay in 106Cd is running in the DAMA/CRYS set-up at the Gran Sasso National Laboratory of the INFN (Italy). In this experiment a 106CdWO4 crystal scintillator (215 g) enriched in 106Cd to 66%, used in previous measurements in different configurations, is now in measurement in coincidence with two large volume low background CdWO4 crystal scintillators in close geometry. This further measurement will allow us to reach a sensitivity at the level of the most sensitive double β+ experiments (T1/2 ≃ 1020 −1022 yr) and to explore the region of the theoretical expectations for some decay modes

ZnWO4 anisotropic scintillator for Dark Matter investigation with the directionality technique

The ZnWO4 crystal scintillator has unique features that make it very promising to realize a pioneering experiment to pursue Dark Matter investigation with the directionality technique. In particular in this detector the light output and the scintillation pulse shape for heavy particles (p, α, nuclear recoils) depend on the direction of the impinging particle with respect to the crystal axes, while the response to γ/β radiation is isotropic. The anisotropy of the light output can be considered to point out the presence in the diurnal counting rate of a Dark Matter signal produced by candidate particle inducing just nuclear recoils. In addition this crystal detector has also other important characteristics for a Dark Matter experiment: high light output, high level of radiopurity. In this paper the present performances of the developed ZnWO4 crystal scintillator will be summarized together with the possible future improvements. Some reachable sensitivities – under given assumptions – in the investigation of DM candidate particles with the directionality technique will also be addressed

Search for double beta processes in 106Cd with enriched 106CdWO4 crystal scintillator in coincidence with four crystals HPGe detector

A radiopure cadmium tungstate crystal scintillator, enriched in 106Cd (106CdWO4), was used to search for double beta decay processes in 106Cd in coincidence with an ultra-low background set-up containing four high purity germanium (HPGe) detectors in a single cryostat. The experiment has been completed after 13085 h of data taking. New improved limits on most of the double beta processes in 106Cd have been set on the level of 1020−1021 yr. Tn particular, the half-life limit on the two neutrinoelectron capture with positron emission, T1/2 ≥ 1.8 × 1021 yr, reached the region of theoretical predictions

Search for Double Beta Decay of 106Cd with an Enriched 106CdWO4 Crystal Scintillator in Coincidence with CdWO4 Scintillation Counters

Studies on double beta decay processes in 106Cd were performed by using a cadmium tungstate scintillator enriched in 106Cd at 66% (106CdWO4) with two CdWO4 scintillation counters (with natural Cd composition). No effect was observed in the data that accumulated over 26,033 h. New improved half-life limits were set on the different channels and modes of the 106Cd double beta decay at level of limT1/2∼1020−1022 yr. The limit for the two neutrino electron capture with positron emission in 106Cd to the ground state of 106Pd, T1/22νECβ+≥2.1×1021 yr, was set by the analysis of the 106CdWO4 data in coincidence with the energy release 511 keV in both CdWO4 counters. The sensitivity approaches the theoretical predictions for the decay half-life that are in the range T1/2∼1021−1022 yr. The resonant neutrinoless double-electron capture to the 2718 keV excited state of 106Pd is restricted at the level of T1/20ν2K≥2.9×1021 yr

First results of the experiment to search for 2β decay of

An experiment to search for double beta processes in 106Cd by using cadmium tungstate crystal scintillator enriched in 106Cd (106CdWO4) in coincidence with the four crystals HPGe detector GeMulti is in progress at the STELLA facility of the Gran Sasso underground laboratory of INFN (Italy). The 106CdWO4 scintillator is viewed by a low-background photomultiplier tube through a lead tungstate crystal light-guide produced from deeply purified archaeological lead to suppress γ quanta from the photomultiplier tube. Here we report the first results of the experiment after 3233 hours of the data taking. A few new improved limits on double beta processes in 106Cd are obtained, in particular T1/22νεβ+ ≥ 8.4 × 1020 yr at 90% C.L

Search for α\alpha decay of naturally occurring osmium nuclides accompanied by γ\gamma quanta

International audienceA search for α decay of naturally occurring osmium isotopes to the lowest excited levels of daughter nuclei has been performed by using an ultra-low-background broad-energy germanium γ detector with a volume of 112 cm3 and an ultrapure osmium sample with a mass of 118 g at the Gran Sasso National Laboratory of the INFN (Italy). The isotopic composition of the osmium sample has been measured with high precision using negative thermal ionization mass spectrometry. After 15851 h of data taking with the γ detector, no effect has been detected, and lower limits on the α decays were set at level of limT1/2≈1015–1019 yr. The limits for the α decays of Os184 and Os186 to the first excited levels of daughter nuclei, T1/2(Os184)≥6.8×1015 yr and T1/2(Os186)≥3.3×1017 yr (at 90% C.L.), exceed the present theoretical estimates of the decays' half-lives. For Os189 and Os192 also decays to the ground states of the daughter nuclei were searched for due to the instability of the daughter nuclides relative to β decay

Search for alpha and double alpha decays of natural Nd isotopes accompanied by gamma quanta

International audienceFrom 7 naturally occurring Nd isotopes, 5 are unstable in relation to α decay. If an excited level of the daughter nucleus is populated, or the daughter nucleus is unstable, γ quanta can be emitted. We used an ultra-low background spectrometry system with 4 high purity germanium (HPGe) detectors (about 225 cm$^{3}$ volume each) to search for such decays using a highly purified Nd-containing sample with mass of 2.381 kg. Measurements were performed at the INFN Gran Sasso underground laboratory (with an overburden of about 3600 m w.e.) during 51,237 h. Half-life limits for α decays of $^{143}$Nd and $^{145}$Nd were determined to be T$_{1/2}$($^{143}$Nd) > 1.1 × 10$^{20}$ year and T$_{1/2}$($^{145}$Nd) > 2.7 × 10$^{19}$ year at 90% C.L. This is an increase of three and two orders of magnitude, respectively, compared with the most restrictive values currently given in literature. A limit for α decay of $^{144}$Nd to the excited level of $^{140}$Ce with E$_{exc}$ = 1596.2 keV was determined for the first time as T$_{1/2}$($^{144}$Nd → $^{140}$Ce$^{*}$) > 9.3 × 10$^{20}$ year. Restriction for the α decay of $^{146}$Nd to the excited level of $^{142}$Ce with E$_{exc}$ = 641.3 keV was increased by 3 orders of magnitude to T$_{1/2}$($^{146}$Nd → $^{142}$Ce$^{*}$) > 1.4 × 10$^{21}$ year. For α and 2α decays of $^{148}$Nd, first T$_{1/2}$ limits were set as 4.2 × 10$^{18}$ year and 2.1 × 10$^{20}$ year, respectively