arXiv subjects

A. Marchionni

Publications and source records attributed to A. Marchionni.

86 records · Page 5Linked to original sources

arXiv2009

Development of wavelength shifter coated reflectors for the ArDM argon dark matter detector

To optimise the design of the light readout in the ArDM 1-ton liquid argon dark matter detector, a range of reflector and WLS coating combinations were investigated in several small setups, where argon scintillation light was generated by radioactive sources in gas at normal temperature and pressure and shifted into the blue region by tetraphenyl butadiene (TPB). Various thicknesses of TPB were deposited by spraying and vacuum evaporation onto specular 3M{\small\texttrademark}-foil and diffuse Tetratex{\small\textregistered} (TTX) substrates. Light yields of each reflector and TPB coating combination were compared. Reflection coefficients of TPB coated reflectors were independently measured using a spectroradiometer in a wavelength range between 200 and 650 nm. WLS coating on the PMT window was also studied. These measurements were used to define the parameters of the light reflectors of the ArDM experiment. Fifteen large $120\times 25$ cm$^2$ TTX sheets were coated and assembled in the detector. Measurements in argon gas are reported providing good evidence of fulfilling the light collection requirements of the experiment.

physics.ins-det↗

arXiv2008

Construction and operation of a Double Phase LAr Large Electron Multiplier Time Projection Chamber

We successfully operated a novel kind of LAr Time Projection Chamber based on a Large Electron Multiplier (LEM) readout system. The prototype, of about 3 liters active volume, is operated in liquid-vapour (double) phase pure Ar. The ionization electrons, after drifting in the LAr volume, are extracted by a set of grids into the gas phase and driven into the holes of a double stage LEM, where charge amplification occurs. Each LEM is a thick macroscopic hole multiplier of 10x10 cm$^2$ manufactured with standard PCB techniques. The electrons signal is readout via two orthogonal coordinates, one using the induced signal on the segmented upper electrode of the LEM itself and the other by collecting the electrons on a segmented anode. Custom-made preamplifiers have been especially developed for this purpose. Cosmic ray tracks have been successfully observed in pure gas at room temperature and in double phase Ar operation. We believe that this proof of principle represents an important milestone in the realization of very large, long drift (cost-effective) LAr detectors for next generation neutrino physics and proton decay experiments, as well as for direct search of Dark Matter with imaging devices.

physics.ins-det↗

arXiv2008

A Possible Future Long Baseline Neutrino and Nucleon Decay Experiment with a 100 kton Liquid Argon TPC at Okinoshima using the J-PARC Neutrino Facility

In this paper, we consider the physics performance of a single far detector composed of a 100 kton next generation Liquid Argon Time Projection Chamber (LAr TPC) possibly located at shallow depth, coupled to the J-PARC neutrino beam facility with a realistic 1.66 MW operation of the Main Ring. The new far detector could be located in the region of Okinoshima islands (baseline $L\sim 658$ km). Our emphasis is based on the measurement of the $θ_{13}$ and $δ_{CP}$ parameters, possibly following indications for a non-vanishing $θ_{13}$ in T2K, and relies on the opportunity offered by the LAr TPC to reconstruct the incoming neutrino energy with high precision compared to other large detector technologies. We mention other possible baselines like for example J-PARC-Kamioka (baseline $L\sim 295$ km), or J-PARC-Eastern Korean coast (baseline $L\sim 1025$ km). Such a detector would also further explore the existence of proton decays.

hep-ph↗

arXiv2007

Detectors and flux instrumentation for future neutrino facilities

This report summarises the conclusions from the detector group of the International Scoping Study of a future Neutrino Factory and Super-Beam neutrino facility. The baseline detector options for each possible neutrino beam are defined as follows: 1. A very massive (Megaton) water Cherenkov detector is the baseline option for a sub-GeV Beta Beam and Super Beam facility. 2. There are a number of possibilities for either a Beta Beam or Super Beam (SB) medium energy facility between 1-5 GeV. These include a totally active scintillating detector (TASD), a liquid argon TPC or a water Cherenkov detector. 3. A 100 kton magnetized iron neutrino detector (MIND) is the baseline to detect the wrong sign muon final states (golden channel) at a high energy (20-50 GeV) neutrino factory from muon decay. A 10 kton hybrid neutrino magnetic emulsion cloud chamber detector for wrong sign tau detection (silver channel) is a possible complement to MIND, if one needs to resolve degeneracies that appear in the $δ$-$θ_{13}$ parameter space.

physics.ins-det↗

arXiv2007

Report of the US long baseline neutrino experiment study

This report provides the results of an extensive and important study of the potential for a U.S. scientific program that will extend our knowledge of neutrino oscillations well beyond what can be anticipated from ongoing and planned experiments worldwide. The program examined here has the potential to provide the U.S. particle physics community with world leading experimental capability in this intensely interesting and active field of fundamental research. Furthermore, this capability could be unique compared to anywhere else in the world because of the available beam intensity and baseline distances. The present study was initially commissioned in April 2006 by top research officers of Brookhaven National Laboratory and Fermi National Accelerator Laboratory and, as the study evolved, it also provided responses to questions formulated and addressed to the study group by the Neutrino Scientific Advisory Committee (NuSAG) of the U.S. DOE and NSF. The participants in the study, its Charge and history, plus the study results and conclusions are provided in this report and its appendices. A summary of the conclusions is provided in the Executive Summary.

hep-ph↗

arXiv2007

Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large-scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatus employ three different and, to some extent, complementary detection techniques: GLACIER (liquid Argon TPC), LENA (liquid scintillator) and MEMPHYS (\WC), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical- and geo-neutrinos and to the possible use of these detectors in future high-intensity neutrino beams.

hep-ph↗

arXiv2006

Beam-Based Alignment of the NuMI Target Station Components at FNAL

The Neutrinos at the Main Injector (NuMI) facility is a conventional horn-focused neutrino beam which produces muon neutrinos from a beam of mesons directed into a long evacuated decay volume. The relative alignment of the primary proton beam, target, and focusing horns affects the neutrino energy spectrum delivered to experiments. This paper describes a check of the alignment of these components using the proton beam.

physics.acc-ph↗

arXiv2006

Secondary Beam Monitors for the NuMI Facility at FNAL

The Neutrinos at the Main Injector (NuMI) facility is a conventional neutrino beam which produces muon neutrinos by focusing a beam of mesons into a long evacuated decay volume. We have built four arrays of ionization chambers to monitor the position and intensity of the hadron and muon beams associated with neutrino production at locations downstream of the decay volume. This article describes the chambers' construction, calibration, and commissioning in the beam.

physics.ins-det↗

arXiv2005

Ion Chamber Arrays for the Numi Beam at Fermilab

The Neutrinos at the Main Injector (NuMI) beamline will deliver an intense muon neutrino beam by focusing a beam of mesons into a long evacuated decay volume. We have built 4 arrays of ionization chambers to monitor the neutrino beam direction and quality. The arrays are located at 4 stations downstream of the decay volume, and measure the remnant hadron beam and tertiary muons produced along with neutrinos in meson decays.

physics.ins-det↗

arXiv2004

Ion Chambers for Monitoring the NuMI Neutrino Beam at FNAL

The Neutrinos at the Main Injector (NuMI) beamline will deliver an intense muon neutrino beam by focusing a beam of mesons into a long evacuated decay volume. The beam must be steered with 1 mRad angular accuracy toward the Soudan Underground Laboratory in northern Minnesota. We have built 4 arrays of ionization chambers to monitor the neutrino beam direction and quality. The arrays are located at 4 stations downstream of the decay volume, and measure the remnant hadron beam and tertiary muons produced along with neutrinos in meson decays. We review how the monitors will be used to make beam quality measurements, and as well we review chamber construction details, radiation damage testing, calibration, and test beam results.

physics.acc-ph↗

arXiv2002

The Hadron Hose: Continuous Toroidal Focusing for Conventional Neutrino Beams

We have developed a new focusing system for conventional neutrino beams. The ``Hadron Hose'' is a wire located in the meson decay volume, downstream of the target and focusing horns. The wire is pulsed with high current to provide a toroidal magnetic field which continuously focuses mesons. The hose increases the neutrino event rate and reduces differences between near-field and far-field neutrino spectra for oscillation experiments. We have studied this device as part of the development of the Neutrinos at the Main Injector (NuMI) project, but it might also be of use for other conventional neutrino beams.

hep-ex↗

arXiv2001

On particle production for high energy neutrino beams

Analytical formulae for the calculation of secondary particle yields in p-A interactions are given. These formulae can be of great practical importance for fast calculations of neutrino fluxes and for designing new neutrino beam-lines. The formulae are based on a parameterization of the inclusive invariant cross sections for secondary particle production measured in p-Be interactions. Data collected in different energy ranges and kinematic regions are used. The accuracy of the fit to the data with the empirical formulae adopted is within the experimental uncertainties. Prescriptions to extrapolate this parameterization to finite targets and to targets of different materials are given. The results obtained are then used as an input for the simulation of neutrino beams. We show that our approach describes well the main characteristics of measured neutrino spectra at CERN. Thus it may be used in fast simulations aiming at the optimisation of the proposed long-baseline neutrino beams at CERN and FNAL. In particular we will show our predictions for the CNGS beam from CERN to Gran Sasso.

hep-ph↗

arXiv1997

Is the solar neutrino deficit energy-dependent?

All existing measurements of the solar neutrino flux are compared with the predictions of the most recent solar model by Bahcall and Pinsonneault, modified by introducing the hypothesis of neutrino oscillations with mass differences large enough to render energy-independent any quantity observable on earth. It is concluded that the data are consistent with this hypothesis and that, at least for the time being, any energy-dependence of the solar neutrino deficit must be regarded as just an attractive theoretical possibility, but not as a compelling reality.

hep-ph↗

arXiv1996

A complete solution to neutrino mixing

Deviations from expectations have been claimed for solar, atmospheric and high energy prompt neutrinos from charm decay. This information, supplemented only by the existing very good upper limits for oscillations of the $ν_μ$ at accelerator energies, is used as input to a phenomenological three-flavour analysis of neutrino mixing. The solution found is unique and completely determines the mass eigenstates as well as the mixing matrix relating mass and flavour eigenstates. Assuming the mass eigenstates to follow the hierarchy $m_{1} \ll m_{2} \ll m_{3}$, their values are found to be $m_{1} \ll 10^{-2}$ eV, $m_{2} = (0.18 \pm 0.06)$ eV, $m_{3} = (19.4 \pm 0.7)$ eV. These masses are in agreement with the leptonic quadratic hierarchy of the see-saw model and large enough to render energy-independent any oscillation-induced phenomenon in solar neutrino physics observable on Earth. This possibility is not excluded by the present knowledge of solar neutrino physics. The mixing angles are determined to be $θ_{12} = 0.55 \pm 0.08$, $θ_{13} = 0.38 \pm 0.06$, $θ_{23} < 0.03$. Small values of $θ_{23}$ are typical of any solution in which $m_{3}$ lies in the cosmological interesting region. The solution found is not in serious contradiction with any of the present limits to the existence of neutrino oscillations. The most relevant implications in particle physics, astrophysics and cosmology are discussed.

hep-ph↗