First measurement of low intensity fast neutron background from rock at the Boulby Underground Laboratory

A technique to measure low intensity fast neutron flux has been developed. The design, calibrations, procedure for data analysis and interpretation of the results are discussed in detail. The technique has been applied to measure the neutron background from rock at the Boulby Underground Laboratory, a site used for dark matter and other experiments, requiring shielding from cosmic ray muons. The experiment was performed using a liquid scintillation detector. A 6.1 litre volume stainless steel cell was filled with an in-house made liquid scintillator loaded with Gd to enhance neutron capture. A two-pulse signature (proton recoils followed by gammas from neutron capture) was used to identify the neutron events from much larger gamma background from PMTs. Suppression of gammas from the rock was achieved by surrounding the detector with high-purity lead and copper. Calibrations of the detector were performed with various gamma and neutron sources. Special care was taken to eliminate PMT afterpulses and correlated background events from the delayed coincidences of two pulses in the Bi-Po decay chain. A four month run revealed a neutron-induced event rate of 1.84 +- 0.65 (stat.) events/day. Monte Carlo simulations based on the GEANT4 toolkit were carried out to estimate the efficiency of the detector and the energy spectra of the expected proton recoils. From comparison of the measured rate with Monte Carlo simulations the flux of fast neutrons from rock was estimated as (1.72 +- 0.61 (stat.) +- 0.38 (syst.))*10^(-6) cm^(-2) s^(-1) above 0.5 MeV.Comment: 37 pages, 24 figures, to be published in Astroparticle Physic

Universal features of fluctuations

Universal scaling laws of fluctuations (the $\Delta$-scaling laws) can be derived for equilibrium and off-equilibrium systems when combined with the finite-size scaling analysis. In any system in which the second-order critical behavior can be identified, the relation between order parameter, criticality and scaling law of fluctuations has been established and the relation between the scaling function and the critical exponents has been found.Comment: 10 pages; TORINO 2000, New Frontiers in Soft Physics and Correlations on the Threshold of the Third Milleniu

First minimum bias physics results at LHCb

We report on the first measurements of the LHCb experiment, as obtained from $pp$ collisions at $\sqrt{s} = 0.9$ TeV and 7 TeV recorded using a minimum bias trigger. In particular measurements of the absolute $K^0_S$ production cross section at $\sqrt{s} = 0.9$ TeV and of the $\bar{\Lambda}/\Lambda$ ratio both at $\sqrt{s} = 0.9$ TeV and 7 TeV are discussed and preliminary results are presented.Comment: To appear in the Proceedings of the 15th International QCD Conference (QCD10) submitted to Nuc. Phys. (Proc. Suppl.

Dissipation, noise and DCC domain formation

We investigate the effect of friction on domain formation in disoriented chiral condensate. We solve the equation of motion of the linear sigma model, in the Hartree approximation, including a friction and a white noise term. For quenched initial condition, we find that even in presence of noise and dissipation domain like structure emerges after a few fermi of evolution. Domain size as large as 5 fm can be formed.Comment: 7 pages, 3 figure

Negative Ion Drift and Diffusion in a TPC near 1 Bar

Drift velocity and longitudinal diffusion measurements are reported for a Negative Ion TPC (NITPC) operating with Helium + carbon disulfide gas mixtures at total pressures from 160 to 700 torr. Longitudinal diffusion at the thermal-limit was observed for drift fields up to at least 700 V/cm in all gas mixtures tested. The results are of particular interest in connection with mechanical simplification of Dark Matter searches such as DRIFT, and for high energy physics experiments in which a low-Z, low density, gaseous tracking detector with no appreciable Lorentz drift is needed for operation in very high magnetic fields.Comment: 7 pages, 3 figure

Prevalencia y características epidemiológicas de parasitosis intestinal en los estudiantes de la escuela Cristiana Verbo de la Ciudad de Puerto Cabezas, Agosto a Noviembre del 2016

Se realizó un estudio descriptivo, no experimental y de corte transversal en 130 escolares de la Escuela Cristiana Verbo en el municipio de Puerto Cabezas, en el período de agosto a noviembre del 2016, con el objetivo de determinar la prevalencia de parasitosis intestinal y sus características epidemiológicas. Se recolectó una muestra de materia fecal a cada escolar las que fueron analizadas mediante método directo en el laboratorio de Microbiología y Parasitología de la Facultad de Ciencias Médicas de la UNAN-Managua. La prevalencia de parasitosis intestinal obtenida fue de 63% (82/130), la mayoría de parásitos identificados fueron protozoos (76%), el 58% fueron protozoos comensales y el 18% patógenos, los helmintos representaron el 24%. En el grupo de protozoos el más frecuente fue Blastocystis hominis (29%), le siguieron, Giardia lamblia 18%, Entamoeba coli 17%, Endolimax nana 9.4% y Chilomastix mesnili 2.6%. Para los helmintos la frecuencia de especies identificadas fue: Áscaris lumbricoides con 12.85%, Trichuris trichiura 6%, Uncinarias especies 0.85% e Hymenolepis nana con 4.3%. El 33% de los escolares se encontraron poliparasitados. El 42.6% (35) de los parasitados fueron masculinos y el 57.4% (47) fueron del sexo femenino. El grupo de edad más afectado fue el de 7 a 10 que representó el 34.6% (45). El 96% (125/130) de los niños refirió al menos un síntoma, el síntoma más frecuente fue el dolor abdominal con el 60% (75/125). En relación a factores epidemiológicos y condiciones higiénicas y sanitarias, el 50% (65%) viven en casas con pisos de madera, solo un 4% viven en piso de tierra, el 42% (55) de los niños presentó hacinamiento, el 63% (82) usa letrina, el 34% (44) usa inodoro y el 3% (4) refirió practicar fecalismo al aire libre, el 96% (125) refirió presencia de vectores en el hogar, el 67% (87) viven con animales domésticos dentro del hogar, el 82% (106) del 6 agua que toman proviene de pozo particular,el 32% (41) no le daba ningún tratamiento al agua de consumo, el 52% (68) presentó inadecuada disposición de la basura. Respecto a los hábitos de higiene, el 29% no siempre lava sus manos después de defecar, el 42% no siempre lava sus manos antes de comer, el 60% se muerde las uñas, el 54% suele andar descalzo

Histopathological analysis and in situ localisation of Australian tiger snake venom in two clinically envenomed domestic animals

Objective: To assess histopathological changes in clinically envenomed tiger snake patients and identify tissue specific localisation of venom toxins using immunohistochemistry. Samples: One feline and one canine patient admitted to the Murdoch Pet Emergency Centre (MPEC), Murdoch University with tiger snake (Notechis sp.) envenoming. Both patients died as a result of envenomation. Non-envenomed tissue was also collected and used for comparison. Methodology: Biopsy samples (heart, lung, kidney andskeletal muscle tissue) were retrieved 1-2 h post death and processed for histopathological examination using Haemotoxylin and Eosin, Martius Scarlet Blue and Periodic Acid Schiff staining. Tissues were examined by light microscopy and tissue sections subjected to immunohistochemical staining using in-house generated monoclonal and polyclonal antibodies against Notechis venoms. Results: Venom-induced pathological changes were observed in the lungs, kidneys and muscle tissue of both patients. Evidence, not previously noted, of procoagulant venom effects were apparent, with formed thrombi in the heart, lungs (small fibrillar aggregates and larger, discrete thrombi) and kidneys. Immunohistochemical assays revealed venom present in the pulmonary tissue, in and around the glomerular capsule and surrounding tubules in renal tissue and scattered throughout the Gastrocnemius muscle tissue. Conclusion: This work has shown pathological evidence of procoagulant venom activity supporting previous suggestions that an initial thrombotic state occurs in envenomed patients. We have shown that venom toxins are able to be localised to specific tissues, in this case, venom was detected in the lung, kidney and muscle tissues of clinically envenomed animals. Future work will examine specific toxin localisation using monoclonal antibodies and identify if antivenom molecules are able to reach their target tissues

Theoretical analysis for the apparent discrepancy between pbarp and pp data in charged particle forward-backward multiplicity correlations

The strength of charged particle forward-backward multiplicity correlation in pbar+p and p+p collisions at s^1/2 = 200 GeV is studied by PYTHIA 6.4 and compared to the UA5 and STAR data correspondingly. It is turned out that a factor of 3-4 apparent discrepancy between UA5 and STAR data can be attributed to the differences in detector acceptances and observing bin interval in both experiments. A mixed event method is introduced and used to calculate the statistical correlation strength and the dynamical correlation strengths stemming from the charge conservation, four- momentum conservation, and decay, respectively. It seems that the statistical correlation is much larger than dynamical one and the charge conservation, four-momentum conservation and decay may account for most part of the dynamical correlation. In addition, we have also calculated the correlation strength by fitting the charged particle multiplicity distribution from PYTHIA to the Negative Binomial Distribution and found that the result agrees well with the correlation strength calculated by mixed events.Comment: 5 pages, 4 figure

Superposition models and the multiplicity fluctuations in heavy ion collisions

A class of simple superposition models based on the Glauber picture of multiple collisions is compared with the data on the centrality dependence of the multiplicity distributions in a central rapidity bin. We show how the results depend on the specific assumptions concerning the distributions in the number of participants and their relations to the distributions of the number of produced hadrons in various phase space bins. None of the versions of the model describes satisfactorily the centrality dependence of the scaled dispersion.Comment: 9 pages, 5 figures, a misprint in formula corrected, accepted for publication in EPJ

Directional detection as a strategy to discover Galactic Dark Matter

Directional detection of Galactic Dark Matter is a promising search strategy for discriminating genuine WIMP events from background ones. Technical progress on gaseous detectors and read-outs has permitted the design and construction of competitive experiments. However, to take full advantage of this powerful detection method, one need to be able to extract information from an observed recoil map to identify a WIMP signal. We present a comprehensive formalism, using a map-based likelihood method allowing to recover the main incoming direction of the signal and its significance, thus proving its galactic origin. This is a blind analysis intended to be used on any directional data. Constraints are deduced in the ($\sigma_n, m_\chi$) plane and systematic studies are presented in order to show that, using this analysis tool, unambiguous dark matter detection can be achieved on a large range of exposures and background levels.Comment: 20 pages, 5 figures Final version to appear in Phys. Lett.