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Search Results: 1 - 10 of 189879 matches for " G. Gratta "
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Towards Low-Threshold, Real-Time Solar Neutrino Detectors
G. Gratta,Y. F. Wang
Physics , 1999, DOI: 10.1016/S0168-9002(99)00824-4
Abstract: We discuss an alternative approach to the detection of solar neutrinos using a coarsely segmented detector based on inverse-beta decay onto $^{160}$Gd or $^{176}$Yb. While it is know that similar approaches, already discussed in the literature, can in principle provide low-threshold, real-time energy spectroscopy with intrinsic background rejection features, the concepts presented here make this scheme possible with lower background and current technology.
Experimental Study of Acoustic Ultra-High-Energy Neutrino Detection
J. Vandenbroucke,G. Gratta,N. Lehtinen
Physics , 2004, DOI: 10.1086/425336
Abstract: An existing array of underwater, large-bandwidth acoustic sensors has been used to study the detection of ultra-high-energy neutrinos in cosmic rays. Acoustic data from a subset of 7 hydrophones located at a depth of $\sim 1600$ m have been acquired for a total live time of 195 days. For the first time, a large sample of acoustic background events has been studied for the purpose of extracting signals from super-EeV showers. As a test of the technique, an upper limit for the flux of ultra-high-energy neutrinos is presented along with considerations relevant to the design of an acoustic array optimized for neutrino detection.
Nuclear Propelled Vessels and Neutrino Oscillation Experiments
J. Detwiler,G. Gratta,N. Tolich,Y. Uchida
Physics , 2002, DOI: 10.1103/PhysRevLett.89.191802
Abstract: We study the effect of naval nuclear reactors on the study of neutrino oscillations. We find that the presence of naval reactors at unknown locations and times may limit the accuracy of future very long baseline reactor-based neutrino oscillation experiments. At the same time we argue that a nuclear powered surface ship such as a large Russian ice-breaker may provide an ideal source for precision experiments. While the relatively low reactor power would in this case require a larger detector, the source could be conveniently located at essentially any distance from a detector built at an underground location near a shore in a region of the world far away from other nuclear installations. The variable baseline would allow for a precise measurement of backgrounds and greatly reduced systematics from reactor flux and detector efficiency. In addition, once the oscillation measurement is completed, the detector could perform geological neutrino and astrophysical measurements with minimal reactor background.
A New Approach to Background Subtraction in Low-Energy Neutrino Experiments
Y-F. Wang,L. Miller,G. Gratta
Physics , 2000, DOI: 10.1103/PhysRevD.62.013012
Abstract: We discuss a new method to extract neutrino signals in low energy experiments. In this scheme the symmetric nature of most backgrounds allows for direct cancellation from data. The application of this technique to the Palo Verde reactor neutrino oscillation experiment allowed us to reduce the measurement errors on the anti-neutrino flux from $\sim 20$% to $\sim 10$%. We expect this method to substantially improve the data quality in future low background experiments such as KamLAND and LENS.
Neutrino Oscillation Experiments at Nuclear Reactors
Giorgio Gratta
Physics , 1999, DOI: 10.1016/S0920-5632(00)00485-0
Abstract: In this paper I give an overview of the status of neutrino oscillation experiments performed using nuclear reactors as sources of neutrinos. I review the present generation of experiments (Chooz and Palo Verde) with baselines of about 1 km as well as the next generation that will search for oscillations with a baseline of about 100 km. While the present detectors provide essential input towards the understanding of the atmospheric neutrino anomaly, in the future, the KamLAND reactor experiment represents our best opportunity to study very small mass neutrino mixing in laboratory conditions. In addition KamLAND with its very large fiducial mass and low energy threshold, will also be sensitive to a broad range of different physics.
Uncertainties in the Anti-neutrino Production at Nuclear Reactors
Z. Djurcic,J. A. Detwiler,A. Piepke,V. R. Foster Jr.,L. Miller,G. Gratta
Physics , 2008, DOI: 10.1088/0954-3899/36/4/045002
Abstract: Anti-neutrino emission rates from nuclear reactors are determined from thermal power measurements and fission rate calculations. The uncertainties in these quantities for commercial power plants and their impact on the calculated interaction rates in electron anti-neutrino detectors is examined. We discuss reactor-to-reactor correlations between the leading uncertainties and their relevance to reactor anti-neutrino experiments.
Ba-ion extraction from a high pressure Xe gas for double-beta decay studies with EXO
T. Brunner,D. Fudenberg,A. Sabourov,V. L. Varentsov,G. Gratta,D. Sinclair,for the EXO collaboration
Physics , 2013, DOI: 10.1016/j.nimb.2013.05.086
Abstract: An experimental setup is being developed to extract Ba ions from a high-pressure Xe gas environment. It aims to transport Ba ions from 10 bar Xe to vacuum conditions. The setup utilizes a converging-diverging nozzle in combination with a radio-frequency (RF) funnel to move Ba ions into vacuum through the pressure drop of several orders of magnitude. This technique is intended to be used in a future multi-ton detector investigating double-beta decay in $^{136}$Xe. Efficient extraction and detection of Ba ions, the decay product of Xe, would allow for a background-free measurement of the $^{136}$Xe double-beta decay.
Predicting Neutron Production from Cosmic-ray Muons
Y-F. Wang,V. Balic,G. Gratta,A. Fasso',S. Roesler,A. Ferrari
Physics , 2001, DOI: 10.1103/PhysRevD.64.013012
Abstract: Fast neutrons from cosmic-ray muons are an important background to underground low energy experiments. The estimate of such background is often hampered by the difficulty of measuring and calculating neutron production with sufficient accuracy. Indeed substantial disagreement exists between the different analytical calculations performed so far, while data reported by different experiments is not always consistent. We discuss a new unified approach to estimate the neutron yield, the energy spectrum, the multiplicity and the angular distribution from cosmic muons using the Monte Carlo simulation package FLUKA and show that it gives a good description of most of the existing measurements once the appropriate corrections have been applied.
Sensitivity of an underwater acoustic array to ultra-high energy neutrinos
Nikolai G. Lehtinen,Shaffique Adam,Giorgio Gratta,Thomas K. Berger,Michael J. Buckingham
Physics , 2001, DOI: 10.1016/S0927-6505(01)00158-X
Abstract: We investigate the possibility of searching for ultra high energy neutrinos in cosmic rays using acoustic techniques in ocean water. The type of information provided by the acoustic detection is complementary to that of other techniques, and the filtering effect of the atmosphere, imposed by the fact that detection only happens if a shower fully develops in water, would provide a clear neutrino identification. We find that it may be possible to implement this technique with very limited resources using existing high frequency underwater hydrophone arrays. We review the expected acoustic signals produced by neutrino-induced showers in water and develop an optimal filtering algorithm able to suppress statistical noise. The algorithm found is computationally appropriate to be used as a trigger for the signal processors available on existing arrays. We estimate the noise rates for a trigger system on a very large size hydrophone array of the US Navy and find that, while a higher density of hydrophones would be desirable, the existing system may already provide useful data.
Present Status and Future Perspectives for the EXO-200 Experiment
Giorgio Gratta,David Sinclair
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/545431
Abstract: The EXO collaboration has built and operated a 200?kg liquid xenon detector for studies of double beta decay. This paper summarizes the results obtained so far and their significance. The excellent performance of the detector encourages the concept of a much larger detector to obtain improved sensitivity to the possible detection of the neutrinoless decay mode of xenon. 1. Introduction The search for neutrinoless double beta decay is one of the most pressing but also one of the most challenging endeavours in the push to understand the natural world beyond the standard model of particle physics. The standard model has had great success in describing the interactions of the elementary particles and, with the recent observation of a Higgs-like particle, of explaining the mass of all particles except for the neutrinos. In 1937, Majorana [1] suggested that neutrinos might be described as 2-component Weyl spinors rather than the 4 component description of the Dirac model. Shortly after, Furry [2] pointed out that while the Majorana model would not change normal beta decay, it would allow a new form of double beta decay in which no neutrinos were emitted. More than 75 years later, we still have not detected this decay mode or resolved the fundamental difference in the Majorana and Dirac models for the neutrino. The first evidence that rates for either mode of double beta decay that would be very long came from the observation of apparently stable isotopes in nature which were energetically able to decay by this mode. This sets a lower bound on the lifetimes comparable to geological timescales. The limits were extended to higher values by searches for possible daughter elements. For example, in the work of Inghram and Reynolds [3] tellurium bearing ores were analyzed for the presence of xenon isotopes. Limits on decay half-lives in the order of 1019 years were set. Direct searches for double beta decay using counters were also started at about this time. Searches for two electrons being emitted from 124Sn were carried out using coincident electron counters by Fireman [4] and in a bubble chamber by Fireman and Schwarzer [5] gave a lower bound of 1017 years. A motivation for these early searches was the expectation that the neutrinoless decay would be much faster than the two-neutrino decay, if the neutrino was indeed a Majorana particle. This expectation changed dramatically when parity nonconservation in weak interactions was observed and the V-A behavior of the weak interaction established. The first successful detection of the two-neutrino double beta decay
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