4,507 research outputs found

    Double-Chooz: a search for Theta13

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    The Double-Chooz experiment goal is to search for a non-vanishing value of the Theta13 neutrino mixing angle. This is the last step to accomplish prior moving towards a new era of precision measurements in the lepton sector. The current best constraint on the third mixing angle comes from the CHOOZ reactor neutrino experiment sin(2θ13)2<0.2\sin(2\theta_{13})^{2}<0.2 (90% C.L., Δmatm2=2.0\Delta m_{atm}^{2}=2.0 eV2^{2}). Double-Chooz will explore the range of sin(2θ13)2\sin(2\theta_{13})^{2} from 0.2 to 0.03-0.02, within three years of data taking. The improvement of the CHOOZ result requires an increase in the statistics, a reduction of the systematic error below one percent, and a careful control of the backgrounds. Therefore, Double-Chooz will use two identical detectors, one at 150 m and another at 1.05 km distance from the Chooz nuclear cores. In addition, we will to use the near detector as a ``state of the art'' prototype to investigate the potential of neutrinos for monitoring the civil nuclear power plants. The plan is to start operation with two detectors in 2008, and to reach a sensitivity sin2^{2}(2θ13)(2\theta_{13}) of 0.05 in 2009, and 0.03-0.02 in 2011.Comment: 3 pages, 1 figure, Proceedings of Nufact'04, July 26 - August 01 2004, Osak

    Future Reactor Neutrino Oscillation Experiments at Krasnoyarsk

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    Recent studies of atmospheric neutrinos and the results from CHOOZ and Palo-Verde experiment call for new and more sensitive searches for neutrino oscillations at reactors. The main goal of the project considered here is to look for very small mixing angle oscillations of electron neutrinos in the atmospheric neutrino mass parameter region around \Delta m^2 ~3 10^-3 eV^2 and to define the element U_{e3} of the neutrino mixing matrix (U_{e3}is the contribution of the mass-3 state to the electron neutrino flavor state). The practical goal of the project is to decrease, relative to the CHOOZ, the statistic and systematic errors as much as possible. To achieve this we plan to use two identical antineutrino detectors each with a ~50-ton liquid scintillator target located at ~1100 m and ~250 m from the underground reactor (~600 mwe). Much attention is given to the detector calibration and monitoring procedures. As a first step we consider two much smaller pilot detectors each of ~ a 3 ton target mass stationed at ~20 m and 35-60 m from the reactor. The goals of this first stage are: (i) to accumulate necessary experience and (ii) to investigate with electron neutrinos the LSND mass parameter region.Comment: LaTeX file, 4 pages and 4 ps figure

    Cabibbo Haze in Lepton Mixing

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    Quark-lepton unification suggests Cabibbo-sized effects in lepton mixings, which we call Cabibbo haze. We give simple examples and explore possible Wolfenstein-like parametrizations of the MNSP matrix which incorporate leptonic Cabibbo shifts. We find that the size of the CHOOZ angle is not always correlated with the observability of CP violation.Comment: 10 page

    Effects and influences on neutrino oscillations due to a thin density layer perturbation added to a matter density profile

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    In this paper, we show the effects on the transition probabilities for neutrino oscillations due to a thin constant density layer perturbation added to an arbitrary matter density profile. In the case of two neutrino flavors, we calculate the effects both analytically and numerically, whereas in the case of three neutrino flavors, we perform the studies purely numerically. As an realistic example we consider the effects of the Earth's atmosphere when added to the Earth's matter density profile on the neutrino oscillation transition probabilities for atmospheric neutrinos.Comment: 9 pages, 6 figures, LaTeX. Final version to be published in Phys. Lett.

    Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine

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    Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near- surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night. Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C. An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.

    Gli Ungulati in Italia: status, gestione e ricerca scientifica

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    Ungulates in Italy: status, management and scientific research. Ungulates in Italy have experienced in the last decade a further increase of their distribution and, possibly, consistence. This trend has been very obvious in the central and northern part of Italy, on the contrary, in south Italy the increase of ungulates populations is quite slow if any. A partial exception is Sardinia where Sardinian red deer (Cervus elaphus corsicanus) has been reintroduced into the four provinces of the island. In this frame the relevance of the increase of ungulates for the increase of wolves (Canis lupus) in Italy must be emphasized. Ungulates management has also experienced a general development in the last decade, even if deep differences between south and central-north Italy still persist. Well conducted reintroductions have allowed to fill many gaps in the species distribution. Ungulates hunting bags size, suggest an increased importance of ungulates in the hunting activities in Italy. Selective hunting with rifles on cervids and bovids was established in wide areas of north and central Italy, mainly as consequence of roe deer (Capreolus capreolus) widespread presence. Wild boar (Sus scrofa) hunting still represents a problem for ungulate management in Italy. Almost 50% of the provinces where wild boar is hunted does not collect hunting bag statistics, and only 35% of them try to roughly estimate the consistence of the populations. The traditional dogs hunting of wild boar has expanded to areas where wild boar was recently and illegally reintroduced, as south Italy and the Alps region, and this is a serious problem for the development of a more rational and correct hunting practices. New possibilities of hunting management of red deer in central Italy, and in the future of alpine ibex (Capra ibex), are to be considered. An increase of the presence of trained wildlife managers in public administrations is suggested, as a further step in the development of a proper management of ungulates and other wildlife. Scientific research on ungulates in Italy was, in the last decade, quite uneven both in the species and in the disciplines chosen. There is a clear opportunistic approach to subjects, that often has no link with the real necessities of wildlife management. The development of long term studies is suggested, together with a more efficient coordination among scientist in the choice of the research subjects. Last but not least a more efficient founding mechanisms is needed in order to avoid money waste and to promote serious research programmes

    NOE: a neutrino experiment for the CERN-Gran Sasso Long Base line project

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    The project of a large underground experiment (NOE) devoted to long baseline neutrino oscillation measurement is presentedComment: 7 pages, 9 figures, Talk at 5th International Workshop on Tau Lepton Physics (TAU98), To be published in Nucl. Phys. B, Proc. Supp

    Quark-Lepton Mass Matrices with U(1)×Z2×Z2U(1)\times Z_2 \times Z_2' Flavor Symmetry

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    The U(1) flavor symmetry explains the large mixing of neutrinos while it leads to the unique texture for the quark mass matrices. It is remarked that U(1) symmetric mass matrices have the phenomenological defects. In the quark sector, the mixing VubV_{ub} is predicted to be large compared with the expected value \l^4 at the GUT scale. In the lepton sector, U(1) charges, which give a large mixing in the neutrino sector, also lead to the large one in the charged lepton sector. In the viewpoint of the flavor symmetry, this is an unpleasant feature because the neutrino mass hierarchy is determined only by unknown coefficients of O(1){\cal O}(1), and the near-maximal flavor mixing is not guaranteed in the case of both large angle rotations. These defects disappear by introducing additional discrete symmetries Z2×Z2Z_2\times Z_2'. The U(1)×Z2×Z2U(1)\times Z_2\times Z_2' quark-lepton mass matrices are presented by taking account of the recent data of atmospheric neutrinos and solar neutrinos.Comment: 19 pages, LaTex file, no figure
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