Parámetros ambientales y pesqueros de un lago somero de La Pampa, luego de una mortandad masiva de <i>Odontesthes bonariensis</i>

The Bajo Giuliani Lagoon (36 ° 42 ‘20’’ S, 64 ° 16 ‘ 02 ‘’ W) is located south of the city of Santa Rosa, La Pampa, which was stocked with fish during the late 90’s. In this hypertrophic shallow lake, major environmental changes caused mass mortalities of silverside Odontesthes bonariensis, the last one occurred in 2010. In order to know the current state of the environment, in April 2013 surface water samples were collected, several points were georeferenced and major morphometric parameters were estimated. Fish were captured by trawls and gillnets. The lake has an area of 965 ha with an average depth of 2.31 meters, hyposaline, hard and sodium chlorinated water. Captured register 549 specimens of O. bonariensis and 437 of Jenynsia multidentata, showing a low diversity. The captured silverside ranged from 75 to 343 mm standard length and from 4 to 568 grams. The catch per unit effort in number and biomass was 519 fishes/ night and 99.2 kilos / night respectively, and the trophy size (PSD) was 41.6 6 %. The results indicate that PSD was 16% lower than those recorded before mortality in October 2009. Also, CPUE in number and CPUE in weight obtained were lower than that date. Nevertheless, several index showed better current body conditions.Facultad de Ciencias Naturales y Muse

Parámetros ambientales y pesqueros de un lago somero de La Pampa, luego de una mortandad masiva de <i>Odontesthes bonariensis</i>

The Bajo Giuliani Lagoon (36 ° 42 ‘20’’ S, 64 ° 16 ‘ 02 ‘’ W) is located south of the city of Santa Rosa, La Pampa, which was stocked with fish during the late 90’s. In this hypertrophic shallow lake, major environmental changes caused mass mortalities of silverside Odontesthes bonariensis, the last one occurred in 2010. In order to know the current state of the environment, in April 2013 surface water samples were collected, several points were georeferenced and major morphometric parameters were estimated. Fish were captured by trawls and gillnets. The lake has an area of 965 ha with an average depth of 2.31 meters, hyposaline, hard and sodium chlorinated water. Captured register 549 specimens of O. bonariensis and 437 of Jenynsia multidentata, showing a low diversity. The captured silverside ranged from 75 to 343 mm standard length and from 4 to 568 grams. The catch per unit effort in number and biomass was 519 fishes/ night and 99.2 kilos / night respectively, and the trophy size (PSD) was 41.6 6 %. The results indicate that PSD was 16% lower than those recorded before mortality in October 2009. Also, CPUE in number and CPUE in weight obtained were lower than that date. Nevertheless, several index showed better current body conditions.Facultad de Ciencias Naturales y Muse

First direct constraints on Fierz interference in free neutron β\beta decay

Precision measurements of free neutron $\beta$-decay have been used to precisely constrain our understanding of the weak interaction. However the neutron Fierz interference term $b_n$, which is particularly sensitive to Beyond-Standard-Model tensor currents at the TeV scale, has thus far eluded measurement. Here we report the first direct constraints on this term, finding $b_n = 0.067 \pm 0.005_{\text{stat}} {}^{+0.090}_{- 0.061}{}_{\text{sys}}$, consistent with the Standard Model. The uncertainty is dominated by absolute energy reconstruction and the linearity of the beta spectrometer energy response

Search for astronomical neutrinos from blazar TXS 0506+056 in super-kamiokande

We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7–9.3 × 10−10 [erg cm−2 s−1], respectively

First Direct Constraints on Fierz Interference in Free-Neutron \u3cem\u3eβ\u3c/em\u3e Decay

Precision measurements of free-neutron β decay have been used to precisely constrain our understanding of the weak interaction. However, the neutron Fierz interference term bn, which is particularly sensitive to beyond-standard-model tensor currents at the TeV scale, has thus far eluded measurement. Here we report the first direct constraints on this term, finding bn = 0.067 ± 0.005stat+0.090-0.061sys, consistent with the standard model. The uncertainty is dominated by absolute energy reconstruction and the linearity of the β spectrometer energy response

Measurements of and + charged-current cross-sections without detected pions or protons on water and hydrocarbon at a mean anti-neutrino energy of 0.86 GeV

We report measurements of the flux-integrated and + charged-current cross-sections on water and hydrocarbon targets using the T2K anti-neutrino beam with a mean beam energy of 0.86 GeV. The signal is defined as the (anti-)neutrino charged-current interaction with one induced and no detected charged pion or proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton Module. The phase space of muons is restricted to the high-detection efficiency region, 400 and 30 , in the laboratory frame. An absence of pions and protons in the detectable phase spaces of 200, 70 and 600, 70 is required. In this paper, both the; cross-sections and +; cross-sections on water and hydrocarbon targets and their ratios are provided by using the D\u27Agostini unfolding method. The results of the integrated ; cross-section measurements over this phase space are ;\sigma{\rm H{2}O}=(1.082\pm0.068(\rm stat.) {+0.145}{-0.128}(\rm syst.)) \times 10 {-39}\,{\rm cm {2} / nucleon};, ;\sigma{\rm CH}=(1.096\pm0.054(\rm stat.) {+0.132}{-0.117}(\rm syst.)) \times 10 {-39}\,{\rm cm {2} / nucleon};, and ;\sigma{\rm H{2}O}/\sigma{\rm CH} = 0.987\pm0.078(\rm stat.) {+0.093}{-0.090}(\rm syst.);. The +; cross-section is ;\sigma{\rm H{2}O} = (1.155\pm0.064(\rm stat.) {+0.148}{-0.129}(\rm syst.)) \times 10 {-39}\,{\rm cm {2} / nucleon};, ;\sigma{\rm CH}=(1.159\pm0.049(\rm stat.) {+0.129}{-0.115}(\rm syst.)) \times 10 {-39}\,{\rm cm {2} / nucleon};, and ;\sigma{\rm H{2}O}/\sigma{\rm CH}=0.996\pm0.069(\rm stat.) {+0.083}{-0.078}(\rm syst.);

Hyper-Kamiokande Design Report

On the strength of a double Nobel prize winning experiment (Super)Kamiokande and an extremely successful long baseline neutrino programme, the third generation Water Cherenkov detector, Hyper-Kamiokande, is being developed by an international collaboration as a leading worldwide experiment based in Japan. The Hyper-Kamiokande detector will be hosted in the Tochibora mine, about 295 km away from the J-PARC proton accelerator research complex in Tokai, Japan. The currently existing accelerator will be steadily upgraded to reach a MW beam by the start of the experiment. A suite of near detectors will be vital to constrain the beam for neutrino oscillation measurements. A new cavern will be excavated at the Tochibora mine to host the detector. The experiment will be the largest underground water Cherenkov detector in the world and will be instrumented with new technology photosensors, faster and with higher quantum efficiency than the ones in Super-Kamiokande. The science that will be developed will be able to shape the future theoretical framework and generations of experiments. Hyper-Kamiokande will be able to measure with the highest precision the leptonic CP violation that could explain the baryon asymmetry in the Universe. The experiment also has a demonstrated excellent capability to search for proton decay, providing a significant improvement in discovery sensitivity over current searches for the proton lifetime. The atmospheric neutrinos will allow to determine the neutrino mass ordering and, together with the beam, able to precisely test the three-flavour neutrino oscillation paradigm and search for new phenomena. A strong astrophysical programme will be carried out at the experiment that will also allow to measure precisely solar neutrino oscillation

The SOX experiment in the neutrino physics

SOX (Short distance neutrino Oscillations with BoreXino) is a new experiment that takes place at the Laboratori Nazionali del Gran Sasso (LNGS) and it exploits the Borexino detector to study the neutrino oscillations at short distance. In different phases, by using two artificial sources Cr-51 and Ce-144-Pr-144, neutrino and antineutrino fluxes of measured intensity will be detected by Borexino in order to observe possible neutrino oscillations in the sterile state. In this paper an overview of the experiment is given and one of the two calorimeters that will be used to measure the source activity is described. At the end the expected sensitivity to determine the neutrino sterile mass is shown