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Search Results: 1 - 10 of 144420 matches for " F. Calaprice "
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Supernova Neutrino Detection in Borexino
L. Cadonati,F. P. Calaprice,M. C. Chen
Physics , 2000, DOI: 10.1016/S0927-6505(01)00129-3
Abstract: We calculated the expected neutrino signal in Borexino from a typical Type II supernova at a distance of 10 kpc. A burst of around 110 events would appear in Borexino within a time interval of about 10 s. Most of these events would come from the reaction channel $\bar{\nu}_e+p\to e^++n$, while about 30 events would be induced by the interaction of the supernova neutrino flux on $^{12}$C in the liquid scintillator. Borexino can clearly distinguish between the neutral-current excitations $^{12}{C}(\nu,\nu')^{12}{C}^*$(15.11 MeV) and the charged-current reactions $^{12}{C}(\nu_e,e^-)^{12}{N}$ and $^{12}{C}(\bar{\nu}_e,e^+)^{12}{B}$, via their distinctive event signatures. The ratio of the charged-current to neutral-current neutrino event rates and their time profiles with respect to each other can provide a handle on supernova and non-standard neutrino physics (mass and flavor oscillations).
First Large Scale Production of Low Radioactivity Argon From Underground Sources
H. O. Back,F. Calaprice,C. Condon,E. de Haas,R. Ford,C. Galbiati,A. Goretti,T. Hohman,An. Inanni,B. Loer,D. Montanari,A. Nelson,A. Pocar
Physics , 2012,
Abstract: We report on the first large-scale production of low radioactivity argon from underground gas wells. Low radioactivity argon is of general interest, in particular for the construction of large scale WIMP dark matter searches and detectors of reactor neutrinos for non-proliferation efforts. Atmospheric argon has an activity of about 1 Bq/kg from the decays of 39Ar; the concentration of 39Ar in the underground argon we are collecting is at least a factor of 100 lower than this value. The argon is collected from a stream of gas from a CO2 well in southwestern Colorado with a Vacuum Pressure Swing Adsorption (VPSA) plant. The gas from the well contains argon at a concentration of 400-600 ppm, and the VPSA plant produces an output stream with an argon concentration at the level of 30,000-50,000 ppm (3-5%) in a single pass. This gas is sent for further processing to Fermilab where it is purified by cryogenic distillation. The argon production rate is presently 0.5 kg/day.
A Prototype Neutron Veto for Dark Matter Detectors
Shawn Westerdale,Emily Shields,Frank Calaprice
Physics , 2015,
Abstract: Neutrons are a particularly dangerous background for direct WIMP dark matter searches; their nuclear recoils with the target nucleus are often indistinguishable from nuclear recoils produced by WIMP-nuclear collisions. In this study, we explore the concept of a liquid scintillator neutron veto detector that would allow direct dark matter detectors to potentially reject neutrons with greater than 99% efficiency. Here we outline the construction and testing of a small prototype detector and the potential implications of this technology for future dark matter detectors.
A Study of the Residual 39Ar Content in Argon from Underground Sources
J. Xu,F. Calaprice,C. Galbiati,A. Goretti,G. Guray,T. Hohman,D. Holtz,A. Ianni,M. Laubenstein,B. Loer,C. Love,C. J. Martoff,D. Montanari,S. Mukhopadhyay,A. Nelson,S. D. Rountree,R. B. Vogelaar,A. Wright
Physics , 2012,
Abstract: The discovery of argon from underground sources with significantly less 39Ar than atmospheric argon was an important step in the development of direct-detection dark matter experiments using argon as the active target. We report on the design and operation of a low background detector with a single phase liquid argon target that was built to study the 39Ar content of the underground argon. Underground argon from the Kinder Morgan CO2 plant in Cortez, Colorado was determined to have less than 0.65% of the 39Ar activity in atmospheric argon.
Antineutrino Geophysics with Liquid Scintillator Detectors
Casey G. Rothschild,Mark C. Chen,Frank P. Calaprice
Physics , 1997, DOI: 10.1029/98GL50667
Abstract: Detecting the antineutrinos emitted by the decay of radioactive elements in the mantle and crust could provide a direct measurement of the total abundance of uranium and thorium in the Earth. In calculating the antineutrino flux at specific sites, the local geology of the crust and the background from the world's nuclear power reactors are important considerations. Employing a global crustal map, with type and thickness data, and using recent estimates of the uranium and thorium distribution in the Earth, we calculate the antineutrino event rate for two new neutrino detectors. We show that spectral features allow terrestrial antineutrino events to be identified above reactor antineutrino backgrounds and that the uranium and thorium contributions can be separately determined.
A Highly Efficient Neutron Veto for Dark Matter Experiments
Alex Wright,Pablo Mosteiro,Ben Loer,Frank Calaprice
Physics , 2010, DOI: 10.1016/j.nima.2011.04.009
Abstract: We present a conceptual design for an active neutron veto, based on boron-loaded liquid scintillator, for use in direct-detection dark matter experiments. The simulated efficiency of a 1 meter thick veto, after including the effects of neutron captures in the inner detector and inefficiencies due to feed-throughs into the veto, is greater than 99.5% for background events produced by radiogenic neutrons, while the background due to externally produced cosmogenic neutrons is reduced by more than 95%. The ability of the veto to both significantly suppress, and provide in situ measurements of, these two dominant sources of background would make the next generation of dark matter experiments much more robust, and dramatically improve the credibility of a dark matter detection claim based on the observation of a few recoil events. The veto would also allow direct extrapolation between the background-free operation of a small detector and the physics reach of a larger detector of similar construction.
Measurement of the specific activity of Ar-39 in natural argon
P. Benetti,F. Calaprice,E. Calligarich,M. Cambiaghi,F. Carbonara,F. Cavanna,A. G. Cocco,F. Di Pompeo,N. Ferrari,G. Fiorillo,C. Galbiati,L. Grandi,G. Mangano,C. Montanari,L. Pandola,A. Rappoldi,G. L. Raselli,M. Roncadelli,M. Rossella,C. Rubbia,R. Santorelli,A. M. Szelc,C. Vignoli,Y. Zhao
Statistics , 2006, DOI: 10.1016/j.nima.2007.01.106
Abstract: We report on the measurement of the specific activity of Ar-39 in natural argon. The measurement was performed with a 2.3-liter two-phase (liquid and gas) argon drift chamber. The detector was developed by the WARP Collaboration as a prototype detector for WIMP Dark Matter searches with argon as a target. The detector was operated for more than two years at Laboratori Nazionali del Gran Sasso, Italy, at a depth of 3,400 m w.e. The specific activity measured for Ar-39 is 1.01 +/- 0.02(stat) +/- 0.08(syst) Bq per kg of natural Ar.
A Scintillator Purification System for the Borexino Solar Neutrino Detector
J. Benziger,L. Cadonati,F. Calaprice,M. Chen,A. Corsi,F. Dalnoki-Veress,R. Fernholz,R. Ford,C. Galbiati,A. Goretti,E. Harding,Aldo Ianni,Andrea Ianni,S. Kidner,M. Leung,F. Loeser,K. McCarty,D. McKinsey,A. Nelson,A. Pocar,C. Salvo,D. Schimizzi,T. Shutt,A. Sonnenschein
Physics , 2007, DOI: 10.1016/j.nima.2007.12.043
Abstract: Purification of the 278 tons of liquid scintillator and 889 tons of buffer shielding for the Borexino solar neutrino detector was performed with a system that combined distillation, water extraction, gas stripping and filtration. The purification of the scintillator achieved unprecedented low backgrounds for the large scale liquid scintillation detector. This paper describes the principles of operation, design, construction and commissioning of the purification system, and reviews the requirements and methods to achieve system cleanliness and leak-tightness.
The Nylon Scintillator Containment Vessels for the Borexino Solar Neutrino Experiment
J. Benziger,L. Cadonati,F. Calaprice,E. de Haas,R. Fernholz,R. Ford,C. Galbiati,A. Goretti,E. Harding,An. Ianni,S. Kidner,M. Leung,F. Loeser,K. McCarty,A. Nelson,R. Parsells,A. Pocar,T. Shutt,A. Sonnenschein,R. B. Vogelaar
Physics , 2007, DOI: 10.1016/j.nima.2007.08.176
Abstract: Borexino is a solar neutrino experiment designed to observe the 0.86 MeV Be-7 neutrinos emitted in the pp cycle of the sun. Neutrinos will be detected by their elastic scattering on electrons in 100 tons of liquid scintillator. The neutrino event rate in the scintillator is expected to be low (~0.35 events per day per ton), and the signals will be at energies below 1.5 MeV, where background from natural radioactivity is prominent. Scintillation light produced by the recoil electrons is observed by an array of 2240 photomultiplier tubes. Because of the intrinsic radioactive contaminants in these PMTs, the liquid scintillator is shielded from them by a thick barrier of buffer fluid. A spherical vessel made of thin nylon film contains the scintillator, separating it from the surrounding buffer. The buffer region itself is divided into two concentric shells by a second nylon vessel in order to prevent inward diffusion of radon atoms. The radioactive background requirements for Borexino are challenging to meet, especially for the scintillator and these nylon vessels. Besides meeting requirements for low radioactivity, the nylon vessels must also satisfy requirements for mechanical, optical, and chemical properties. The present paper describes the research and development, construction, and installation of the nylon vessels for the Borexino experiment.
Oxygen contamination in liquid Argon: combined effects on ionization electron charge and scintillation light
R. Acciarri,M. Antonello,B. Baibussinov,M. Baldo-Ceolin,P. Benetti,F. Calaprice,E. Calligarich,M. Cambiaghi,N. Canci,F. Carbonara,F. Cavanna,S. Centro,A. G. Cocco,F. Di Pompeo,G. Fiorillo,C. Galbiati,V. Gallo,L. Grandi,G. Meng,I. Modena,C. Montanari,O. Palamara,L. Pandola,F. Pietropaolo,G. L. Raselli,M. Roncadelli,M. Rossella,C. Rubbia,E. Segreto,A. M. Szelc,F. Tortorici,S. Ventura,C. Vignoli
Physics , 2008, DOI: 10.1088/1748-0221/5/05/P05003
Abstract: A dedicated test of the effects of Oxygen contamination in liquid Argon has been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP R&D program. Two detectors have been used: the WArP 2.3 lt prototype and a small (0.7 lt) dedicated detector, coupled with a system for the injection of controlled amounts of gaseous Oxygen. Purpose of the test with the 0.7 lt detector is to detect the reduction of the long-lived component lifetime of the Argon scintillation light emission at increasing O2 concentration. Data from the WArP prototype are used for determining the behavior of both the ionization electron lifetime and the scintillation long-lived component lifetime during the O2-purification process activated in closed loop during the acquisition run. The electron lifetime measurements allow to infer the O2 content of the Argon and correlate it with the long-lived scintillation lifetime data. The effect of Oxygen contamination on the scintillation light has been thus measured over a wide range of O2 concentration, spanning from about 10^-3 ppm up to about 10 ppm. The rate constant of the light quenching process induced by Oxygen in LAr has been found to be k'(O2)=0.54+-0.03 micros^-1 ppm^-1.
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