Since the early days of experimental particle physics photomultipliers (PMTs) have played an important role in the detector design. Thanks to their capability of fast photon counting, PMTs are ...extensively used in the new-generation of astroparticle physics experiments, such as air, ice and water Cherenkov detectors. Small size PMTs (\(\leq \) 3 inches diameter) show little sensitivity to the Earth magnetic field, small transit time, stable transit time spread; the price per photocathode area is less comparing to the one for the large area PMTs, typically used so far in such applications. Together with developments and reduced price of multichannel electronics, the use of PMTs of 3-inches or smaller diameter is a promising option even for nowadays large volume detectors. In this paper we report on the design and performance of a new instrument for mass characterisation of PMTs (from 1 inch to 3 inches size), capable to calibrate hundreds of PMTs per day and provide measurements of dark counts, signal amplitude, late-, delayed-, pre- and after-pulses, transit time and transit time spread.
The ANTARES neutrino telescope has an energy threshold of a few tens of GeV. This allows to study the phenomenon of atmospheric muon neutrino disappearance due to neutrino oscillations. In a similar ...way, constraints on the 3+1 neutrino model, which foresees the existence of one sterile neutrino, can be inferred. Using data collected by the ANTARES neutrino telescope from 2007 to 2016, a new measurement of \(\Delta m^2_{32}\) and \(\theta_{23}\) has been performed - which is consistent with world best-fit values - and constraints on the 3+1 neutrino model have been derived.
Behind the mind of the strategist Pellegrino, Kimberly C; Carbo, Jerry A
TQM magazine,
12/2001, Volume:
13, Issue:
6
Journal Article
Delves into the mind of the strategic thinker. The aim of this examination is to establish the conceptual foundations for a new theory of strategic thinking that looks at this process from an ...individual perspective. This will be accomplished by merging two separate strains of strategy research into a single strategic thinking philosophy. The two strains of strategy research that will be utilized include cognitive simplification tools and personal cognitive style. This foundational work opens the door to a new perspective on how strategic thinking is conducted and creates avenues for future empirical investigation into the mind of the strategist.
The activity of
137Cs,
134Cs and
40K in tissues from fish, molluse and shellfish of the Ligurian sea was measured during 1987–1988. The mean annual concentrations in 1987 were 5.92 ± 4.1 Bq/kg (wet ...tissue) for
137Cs and 2.7 ± 1.5 Bq/kg for
134Cs and 2.46 ± 1.82 and 0.33 ± 0.57 Bq/kg respectively in 1988. The mean value of
40K activity was 138.6 ± 22.1 Bq/kg. Contamination was significantly higher in the littoral area up to 1000 m from the coast (8.39 ± 7.6 and 1.74 ± 2.08 Bq/kg respectively versus 2.91 ± 1.87 and 0.58 ± 0.59 Bq/kg respectively in the open sea). The common octopus (
Octopus vulgaris) had the highest radioactivity values and could be utilized as an indicator of radioactivity pollution. There were no significant differences regarding the trophic level, the seafood phylum, or the east and west Ligurian sea areas. Long-term reduction in the sea habitat was estimated at about 200 days for
137Cs and 110 days for
134Cs, reflecting differences in the physical half-life of these radionuclides. These values were lower than those found in terrestrial foodstuff and could have reflected dilution of the contaminants in the open sea. The effective dose equivalent for the Ligurian population of radiocesium originating from seafood was estimated at 1.3 μSv in 1987 and 0.5 μSv in 1988. These values represent 0.8 and 0.3% respectively of the annual dose (180 μSv/year) due to
40K intake with the diet.
In the past years, the IceCube Collaboration has reported in several analyses the observation of astrophysical high-energy neutrino events. Despite a compelling evidence for the first identification ...of a neutrino source, TXS 0506+056, the origin of the majority of these events is still unknown. In this paper, a possible transient origin of the IceCube astrophysical events is searched for using neutrino events detected by the ANTARES telescope. The arrival time and direction of 6894 track-like and 160 shower-like events detected over 2346 days of livetime are examined to search for coincidences with 54 IceCube high-energy track-like neutrino events, by means of a maximum likelihood method. No significant correlation is observed and upper limits on the one-flavour neutrino fluence from the direction of the IceCube candidates are derived. The non-observation of time and space correlation within the time window of 0.1 days with the two most energetic IceCube events constrains the spectral index of a possible point-like transient neutrino source, to be harder than \(-2.3\) and \(-2.4\) for each event, respectively.
The muon telescopes of the Extreme Energy Events (EEE) Project are made of three Multigap Resistive Plate Chambers (MRPC). The EEE array is composed, so far, of 59 telescopes and is organized in ...clusters and single telescope stations distributed all over the Italian territory. They are installed in High Schools with the aim to join research and teaching activities, by involving researchers, teachers and students in the construction, maintenance, data taking and data analysis. The unconventional working sites, mainly school buildings with non-controlled environmental parameters and heterogeneous maintenance conditions, are a unique test field for checking the robustness, the low-ageing features and the long-lasting performance of the MRPC technology for particle tracking and timing purposes. The measurements performed with the EEE array require excellent performance in terms of time and spatial resolution, efficiency, tracking capability and stability. The data from two recent coordinated data taking periods, named Run 2 and Run 3, have been used to measure these quantities and the results are described, together with a comparison with expectations and with the results from a beam test performed in 2006 at CERN.
The Extreme Energy Events (EEE) experiment is the largest system in the world completely implemented with Multigap Resistive Plate Chambers (MRPCs). Presently, it consists of a network of 59 muon ...telescopes, each made of 3 MRPCs, devoted to the study of secondary cosmic rays. Its stations, sometimes hundreds of kilometers apart, are synchronized at a few nanoseconds level via a clock signal delivered by the Global Positioning System. The data collected during centrally coordinated runs are sent to INFN CNAF, the largest center for scientific computing in Italy, where they are reconstructed and made available for analysis. Thanks to the on-line monitoring and data transmission, EEE operates as a single coordinated system spread over an area of about \(3 \times 10^5\) km\(^2\). In 2017, the EEE collaboration started an important upgrade program, aiming to extend the network with 20 additional stations, with the option to have more in the future. This implies the construction, testing and commissioning of 60 chambers, for a total detector surface of around 80 m\(^2\). In this paper, aspects related to this challenging endeavor are covered, starting from the technological solutions chosen to build these state-of-the-art detectors, to the quality controls and the performance tests carried on.
Multigap Resistive Plate Chambers (MRPC). The EEE network is composed, so far, of 53 telescopes, each made of three MRPC detectors; it is organized in clusters and single telescope stations ...distributed all over the Italian territory and installed in High Schools, covering an area larger than \(3\times10^{5}\) km\(^{2}\). The study of Extensive Air Showers (EAS), that is one of the goal of the project, requires excellent performance in terms of time and spatial resolution, efficiency, tracking capability and long term stability. The data from two recent coordinated data taking periods, named Run 2 and Run 3, have been used to measure these quantities and the results are here reported, together with a comparison with expectations and with the results from a beam test performed in 2006 at CERN.
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