Composition Heterogeneity of Xenoliths of Mantle Peridotites from Alkaline Basalts of the Sverre Volcano, the Svalbard Archipelago

The article presents the results of a study of the composition of xenoliths of mantle peridotites (seven samples), collected from the Quaternary basalts of the Sverre volcano, the Svalbard archipelago. The presence of two big (more than 15 cm in diameter) xenoliths of spinel lherzolite allowed us to consider a change in their composition in the cen- tral, intermediate, and marginal parts of the samples. It is proposed to distinguish three types of xenoliths by the distribution of trace and rare earth elements. Enrich- ment of mantle peridotites with light rare earth elements, as well as high field strength (HFS)  and large-ion lithophile (LIL) elements, is presumably associated with mantlemetasomatism

The relationship of fracture toughness coefficients and geophysical characteristics of rocks of hydrocarbon deposits

This paper contains the results of laboratory tests to determine the fracture toughness coefficient KIC of rocks for terrigenous and carbonate objects by three methods. The tests were carried out by different methods due to the lack of a standard method for determining the fracture toughness characteristics of rocks in Russia. We used the following methods for determining the KIC coefficient: the extension of core specimens with an annular fracture, the action of a concentrated load on a beam specimen with a fracture and the method of bending semi-circular samples with a fracture according to ISRM recommendations. The paper presents the relationship of the fracture toughness coefficients with the P-wave velocity and porosity. The obtained dependencies characterize the general trend of changing for the studied parameter and can be used in the design of hydraulic fracturing in the fields for which tests were conducted

Закономерности изменения адсорбционных свойств глин, активированных давлением и ионами железа

The purpose of the work is to consider the patterns of adsorption of water vapor by clay soils that have been treated with pressure and saturated with iron ions, and also to study the processes of adsorption and desorption of Fe3+ ions by bentonite and kaolin clays. The study of changes in the adsorption properties of clay soils is necessary to understand the processes occurring in soils, both in natural and anthropogenic conditions, especially in the case of soil contamination. As a result of the experiment, it was found that the adsorption capacity of clays in relation to water vapor increases when they are treated with pressure. When clay is treated with pressure and subsequently saturated with iron ions in bentonite clay, the adsorption activity decreases in the range of 0-150 MPa, at higher pressures it changes irregularly. In kaolin, adsorption increases at pressures up to 200 MPa, but it decreases at pressures from 200 to 800 MPa.Цель работы: рассмотреть закономерности адсорбции водяного пара глинистыми грунтами, которые были обработаны под разными давлениями и насыщены ионами железа, а также изучить процессы адсорбции и десорбции ионов Fe3+ бентонитовой и каолиновой глинами. Изучение изменений адсорбционных свойств глинистых грунтов необходимо для понимания процессов, происходящих в грунтах как в природных, так и в антропогенных условиях, особенно в случае загрязнения грунтов. В результате эксперимента было установлено, что адсорбционная способность глин по отношению к водяному пару возрастает при обработке их давлением. При обработке глин давлением и при последующем насыщении их ионами железа в бентонитовой глине адсорбционная активность снижается в диапазоне 0–150 МПа, при более высоких давлениях изменяется незакономерно. В каолине происходит рост адсорбции при давлениях до 200 МПа, но она уменьшается при давлениях от 200 до 800 МПа

Measurement of the velocity of neutrinos from the CNGS beam with the Large Volume Detector

We report the measurement of the time-of-flight of ~17 GeV muon neutrinos on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated to the beam, with a high absolute time accuracy. These events allow to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8 x 10-6 < (v-c)/c < 3.1 x 10-6 (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements

Implication for the core collapse supernova rate from 21 years of data of the Large Volume Detector

The Large Volume Detector (LVD) has been continuously taking data since 1992 at the INFN Gran Sasso National Laboratory. LVD is sensitive to neutrino bursts from gravitational stellar collapses with full detection probability over the Galaxy. We have searched for neutrino bursts in LVD data taken in 7335 days of operation. No evidence of neutrino signals has been found between June 1992 and December 2013. The 90% C.L. upper limit on the rate of core-collapse and failed supernova explosions out to distances of 25 kpc is found to be 0.114/y.Comment: Publishe

NEWSdm Collaboration

Direct Dark Matter searches are nowadays one of the most fervid research topics with many experimental efforts devoted to the search for nuclear recoils induced by the scattering of Weakly Interactive Massive Particles (WIMPs). Detectors able to reconstruct the direction of the nucleus recoiling against the scattering WIMP are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also prove the galactic origin of Dark Matter with an unambiguous signal-to-background separation. Indeed, the angular distribution of recoiled nuclei is centered around the direction of the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we present the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and of optical read-out systems reaching unprecedented nanometric resolution

Determination of a time-shift in the OPERA set-up using high energy horizontal muons in the LVD and OPERA detectors

The purpose of this work is to report the measurement of a time-shift in the OPERA set-up in a totally independent way from Time Of Flight (TOF) measurements of CNGS neutrino events. The LVD and OPERA experiments are both installed in the same laboratory: LNGS. The relative position of the two detectors, separated by an average distance of ~ 160 m, allows the use of very high energy horizontal muons to cross-calibrate the timing systems of the two detectors, using a TOF technique which is totally independent from TOF of CNGS neutrino events. Indeed, the OPERA-LVD direction lies along the so-called "Teramo anomaly", a region in the Gran Sasso massif where LVD has established, many years ago, the existence of an anomaly in the mountain structure, which exhibits a low m. w. e. thickness for horizontal directions. The "abundant" high-energy horizontal muons (nearly 100 per year) going through LVD and OPERA exist because of this anomaly in the mountain orography. The total live time of the data in coincidence correspond to 1200 days from mid 2007 until March 2012. The time coincidence study of LVD and OPERA detectors is based on 306 cosmic horizontal muon events and shows the existence of a negative time shift in the OPERA set-up of the order of deltaT(AB) = - (73 \pm 9) ns when two calendar periods, A and B, are compared. This result shows a systematic effect in the OPERA timing system from August 2008 until December 2011. The size of the effect is comparable with the neutrino velocity excess recently measured by OPERA. It is probably interesting not to forget that with the MRPC technology developed by the ALICE Bologna group the TOF world record accuracy of 20 ps was reached. That technology can be implemented at LNGS for a high precision determination of TOF with the CNGS neutrino beams of an order of magnitude smaller than the value of the OPERA systematic effect

Directional Sensitivity of the NEWSdm Experiment to Cosmic Ray Boosted Dark Matter

We present a study of a directional search for Dark Matter boosted forward when scattered by cosmic-ray nuclei, using a module of the NEWSdm experiment. The boosted Dark Matter flux at the edge of the Earth's atmosphere is expected to be pointing to the Galactic Center, with a flux 15 to 20 times larger than in the transverse direction. The module of the NEWSdm experiment consists of a 10 kg stack of Nano Imaging Trackers, i.e.~newly developed nuclear emulsions with AgBr crystal sizes down to a few tens of nanometers. The module is installed on an equatorial telescope. The relatively long recoil tracks induced by boosted Dark Matter, combined with the nanometric granularity of the emulsion, result in an extremely low background. This makes an installation at the INFN Gran Sasso laboratory, both on the surface and underground, viable. A comparison between the two locations is made. The angular distribution of nuclear recoils induced by boosted Dark Matter in the emulsion films at the surface laboratory is expected to show an excess with a factor of 3.5 in the direction of the Galactic Center. This excess allows for a Dark Matter search with directional sensitivity. The surface laboratory configuration prevents the deterioration of the signal in the rock overburden and it emerges as the most powerful approach for a directional observation of boosted Dark Matter with high sensitivity. We show that, with this approach, a 10 kg module of the NEWSdm experiment exposed for one year at the Gran Sasso surface laboratory can probe Dark Matter masses between 1 keV/c$^2$ and 1 GeV/c$^2$ and cross-section values down to $10^{-30}$~cm$^2$ with a directional sensitive search.Comment: 15 pages, 14 figures, updated references, clarified discussion in intro section. Submitted to JCA

Simulation of a small-size ultra-wideband antenna in the shape of biconical vibrator with ring grooves

The paper is devoted to investigation of a version of solid biconical vibrator having several ring-shaped grooves on its side surface. With the same overall dimensions of such antenna, its lower operation frequency can be decreased by 20% and, if using the grooves with dielectric — even by a larger value