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Search Results: 1 - 10 of 461887 matches for " A. Ereditato "
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The Study of Neutrino Oscillations with Emulsion Detectors
A. Ereditato
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/382172
Abstract: Particle detectors based on nuclear emulsions contributed to the history of physics with fundamental discoveries. The experiments benefited from the unsurpassed spatial and angular resolution of the devices in the measurement of ionizing particle tracks and in their identification. Despite the decline of the technique around the 1970’s caused by the development of the modern electronic particle detectors, emulsions are still alive today thanks to the vigorous rebirth of the technique that took place around the beginning of the 1990’s, in particular due to the needs of neutrino experiments. This progress involved both the emulsion detectors themselves and the automatic microscopes needed for their optical scanning. Nuclear emulsions have marked the study of neutrino physics, notably in relation to neutrino oscillation experiments and to the related first detection of tau-neutrinos. Relevant applications in this field are reviewed here with a focus on the main projects. An outlook is also given trying to address the main directions of the R&D effort currently in progress and the challenging applications to various fields. 1. Introduction to Nuclear Emulsions Particle detectors based on the nuclear emulsion technique contributed to the history of particle physics with fundamental discoveries and measurements that profited from their unsurpassed spatial and angular resolution in the measurement of charged elementary particle tracks. Moreover, thanks to specific detector arrangements, accurate momentum and energy measurements were also carried out. Despite the decline of the technique around 1960–1970 due to the development and use of the modern electronic particle detectors, emulsions are still used today, thanks to the vigorous rebirth of the technique that took place around the beginning of the 1990’s, driven by the needs of neutrino experiments. Nuclear emulsions have been effectively used in many particle physics experiments and in particular contributed to neutrino oscillation physics and to the related issue of the detection of tau-neutrinos ( ). Here, focus is on this specific physics subject and will unfortunately exclude the many scientific results that were obtained in other different fields. For those, we recommend the reader to consult existing reviews [1–3]. The reader is also invited to note that the emulsion detection technique is based on two independent aspects that have been synergic throughout their technological development: the emulsion detector itself and the devices (microscopes) necessary for extracting the information stored in the
Nuclear Emulsion Film Detectors for Proton Radiography: Design and Test of the First Prototype
S. Braccini,A. Ereditato,I. Kreslo,U. Moser,C. Pistillo,P. Scampoli,S. Studer
Physics , 2010, DOI: 10.1142/9789814307529_0103
Abstract: Proton therapy is nowadays becoming a wide spread clinical practice in cancer therapy and sophisticated treatment planning systems are routinely used to exploit at best the ballistic properties of charged particles. The information on the quality of the beams and the range of the protons is a key issue for the optimization of the treatment. For this purpose, proton radiography can be used in proton therapy to obtain direct information on the range of the protons, on the average density of the tissues for treatment planning optimization and to perform imaging with negligible dose to the patient. We propose an innovative method based on nuclear emulsion film detectors for proton radiography, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. Nuclear emulsion films interleaved with tissue equivalent absorbers can be fruitfully used to reconstruct proton tracks with very high precision. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam at PSI. The scanning of the emulsions has been performed at LHEP in Bern, where a fully automated microscopic scanning technology has been developed for the OPERA experiment on neutrino oscillations. After track reconstruction, the first promising experimental results have been obtained by imaging a simple phantom made of PMMA with a step of 1 cm. A second phantom with five 5 x 5 mm^2 section aluminum rods located at different distances and embedded in a PMMA structure has been also imaged. Further investigations are in progress to improve the resolution and to image more sophisticated phantoms.
An adjustable focusing system for a 2 MeV H- ion beam line based on permanent magnet quadrupoles
M. Nirkko,S. Braccini,A. Ereditato,I. Kreslo,P. Scampoli,M. Weber
Physics , 2012, DOI: 10.1088/1748-0221/8/02/P02001
Abstract: A compact adjustable focusing system for a 2 MeV H- RFQ Linac is designed, constructed and tested based on four permanent magnet quadrupoles (PMQ). A PMQ model is realised using finite element simulations, providing an integrated field gradient of 2.35 T with a maximal field gradient of 57 T/m. A prototype is constructed and the magnetic field is measured, demonstrating good agreement with the simulation. Particle track simulations provide initial values for the quadrupole positions. Accordingly, four PMQs are constructed and assembled on the beam line, their positions are then tuned to obtain a minimal beam spot size of (1.2 x 2.2) mm^2 on target. This paper describes an adjustable PMQ beam line for an external ion beam. The novel compact design based on commercially available NdFeB magnets allows high flexibility for ion beam applications.
First results on proton radiography with nuclear emulsion detectors
S. Braccini,A. Ereditato,I. Kreslo,U. Moser,C. Pistillo,S. Studer,P. Scampoli,A. Coray,E. Pedroni
Physics , 2010, DOI: 10.1088/1748-0221/5/09/P09001
Abstract: We propose an innovative method for proton radiography based on nuclear emulsion film detectors, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. For this purpose, nuclear emulsion films interleaved with tissue equivalent absorbers can be used to reconstruct proton tracks with very high accuracy. This is performed through a fully automated scanning procedure employing optical microscopy, routinely used in neutrino physics experiments. Proton radiography can be used in proton therapy to obtain direct information on the average tissue density for treatment planning optimization and to perform imaging with very low dose to the patient. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam. The first promising experimental results have been obtained by imaging simple phantoms.
Ionization signals from electrons and alpha-particles in mixtures of liquid Argon and Nitrogen - perspectives on protons for Gamma Resonant Nuclear Absorption applications
M. Zeller,I. Badhrees,S. Delaquis,A. Ereditato,S. Janos,I. Kreslo,M. Messina,U. Moser,B. Rossi
Physics , 2010, DOI: 10.1088/1748-0221/5/10/P10009
Abstract: In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) flled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric feld in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar-N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications.
Pulse-shape discrimination of scintillation from alpha and beta particles with liquid scintillator and Geiger-mode multipixel avalanche diodes
I. Kreslo,I. Badhrees,S. Delaquis,A. Ereditato,S. Janos,M. Messina,U. Moser,B. Rossi,M. Zeller
Physics , 2011, DOI: 10.1088/1748-0221/6/07/P07009
Abstract: A successfull application of Geiger-mode multipixel avalanche diodes (GMAPDs) for pulse-shape discrimination in alpha-beta spectrometry using organic liquid scintillator is described in this paper. Efficient discrimination of alpha and beta components in the emission of radioactive isotopes is achieved for alpha energies above 0.3 MeV. The ultra-compact design of the scintillating detector helps to efficiently suppress cosmic-ray and ambient radiation background. This approach allows construction of hand-held robust devices for monitoring of radioactive contamination in various environmental conditions.
30 kV coaxial vacuum-tight feedthrough for operation at cryogenic temperatures
I. Kreslo,I. Badhrees,S. Delaquis,A. Ereditato,S. Janos,M. Messina,U. Moser,B. Rossi,M. Zeller
Physics , 2010, DOI: 10.1088/1748-0221/5/11/T11002
Abstract: In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon.
A steerable UV laser system for the calibration of liquid argon time projection chambers
A. Ereditato,I. Kreslo,M. Lüthi,C. Rudolf von Rohr,M. Schenk,T. Strauss,M. Weber,M. Zeller
Physics , 2014, DOI: 10.1088/1748-0221/9/11/T11007
Abstract: A number of liquid argon time projection chambers (LAr TPC's) are being build or are proposed for neutrino experiments on long- and short baseline beams. For these detectors a distortion in the drift field due to geometrical or physics reasons can affect the reconstruction of the events. Depending on the TPC geometry and electric drift field intensity this distortion could be of the same magnitude as the drift field itself. Recently, we presented a method to calibrate the drift field and correct for these possible distortions. While straight cosmic ray muon tracks could be used for calibration, multiple coulomb scattering and momentum uncertainties allow only a limited resolution. A UV laser instead can create straight ionization tracks in liquid argon, and allows one to map the drift field along different paths in the TPC inner volume. Here we present a UV laser feed-through design with a steerable UV mirror immersed in liquid argon that can point the laser beam at many locations through the TPC. The straight ionization paths are sensitive to drift field distortions, a fit of these distortion to the linear optical path allows to extract the drift field, by using these laser tracks along the whole TPC volume one can obtain a 3D drift field map. The UV laser feed-through assembly is a prototype of the system that will be used for the MicroBooNE experiment at the Fermi National Accelerator Laboratory (FNAL).
Experimental study of electric breakdowns in liquid argon at centimeter scale
A. Blatter,A. Ereditato,C. -C. Hsu,S. Janos,I. Kreslo,M. Luethi,C. Rudolf von Rohr,M. Schenk,T. Strauss,M. S. Weber,M. Zeller
Physics , 2014, DOI: 10.1088/1748-0221/9/04/P04006
Abstract: In this paper we present results on measurements of the dielectric strength of liquid argon near its boiling point and cathode-anode distances in the range of 0.1 mm to 40 mm with spherical cathode and plane anode. We show that at such distances the applied electric field at which breakdowns occur is as low as 40 kV/cm. Flash-overs across the ribbed dielectric of the high voltage feed-through are observed for a length of 300 mm starting from a voltage of 55 kV. These results contribute to set reference for the breakdown-free design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).
On the Electric Breakdown in Liquid Argon at Centimeter Scale
M. Auger,A. Blatter,A. Ereditato,D. Goeldi,S. Janos,I. Kreslo,M. Luethi,C. Rudolf von Rohr,T. Strauss,M. S. Weber
Physics , 2015,
Abstract: We present a study on the dependence of electric breakdown discharge parameters on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).
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