The NEMO (NEutrino Mediterranean Observatory) Collaboration has been carrying out since 1998 an evaluation programme of deep sea sites suitable for the construction of the future Mediterranean km
3 ...Čerenkov neutrino telescope. We investigated the seawater optical and oceanographic properties of several deep sea marine areas close to the Italian Coast. Inherent optical properties (light absorption and attenuation coefficients) have been measured as a function of depth using an experimental apparatus equipped with standard oceanographic probes and the commercial transmissometer AC9 manufactured by WETLabs. This paper reports on the visible light absorption and attenuation coefficients measured in deep seawater of a marine region located in the Southern Ionian Sea, 60–100
km SE of Capo Passero (Sicily). Data show that blue light absorption coefficient is about 0.015
m
−1 (corresponding to an absorption length of 67
m) close to the one of optically pure water and it does not show seasonal variation.
We present a device, based on the concept of associative memory for pattern recognition, dedicated to on-line track finding in high-energy physics experiments. A large pattern bank, describing all ...possible tracks, can be organized into Field Programmable Gate Arrays where all patterns are compared in parallel to data coming from the detector during readout. Patterns, recognized among 2/sup 66/ possible combinations, are output in a few 30 MHz clock cycles. Programmability results in a flexible, simple architecture and it allows to keep up smoothly with technology improvements. A 64 PAM array has been assembled on a prototype VME board and fully tested up to 30 MHz.
In 2007 the NA62 experiment at CERN collected a large sample of charged kaon decays with a highly efficient trigger selecting events with electrons in the final state. The kaon beam represents a rich ...source of tagged neutral pion decays in vacuum. The electromagnetic transition form factor slope of the π0 in the time-like region has been measured from about 106 fully reconstructed π0 Dalitz decays collected in 2007. The preliminary result a = (3.68 ± 0.51stat ± 0.25syst) × 10-2 is the most precise to date. This value is compatible with theoretical expectations and consistent with the previous measurements.
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay mu super(+) arrow right e super(+) gamma by using one of ...the most intense continuous mu super(+) beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
An associative memory full-custom CMOS VLSI chip (AMchip), to be used in fast trigger systems for pattern recognition, has been designed and is being tested. The AMchip is a full-custom associative ...memory IC developed for high energy physics. It contains about 140000 MOS transistors, has been realized in 1.5- mu m, double-metal, silicon gate CMOS technology, and is housed in a 120-pin package. The AMchip has been designed to be used with any kind of detector which provides in the output the hit coordinates. Some preliminary tests have been done on the 55 prototypes received from the ES2 (European silicon structures) foundry. The performance test, limited by the equipment used, has shown that the AMchip can work with a 20-MHz clock.< >
The selection of the photomultiplier plays a crucial role in the R&D activity related to a large-scale underwater neutrino telescope. This paper illustrates the main procedures and facilities used to ...characterize the performances of 72 large area photomultipliers, Hamamatsu model R7081 sel. The voltage to achieve a gain of 5×10
7, dark count rate and single photoelectron time and charge properties of the overall response were measured with a properly attenuated 410
nm pulsed laser. A dedicated study of the spurious pulses was also performed. The results prove that the photomultipliers comply with the general requirements imposed by the project.
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay μ.sup.+ → e.sup.+γ by using one of the most intense ...continuous μ.sup.+ beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a super-conducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
The upper Albian Amadeus Segment, which falls within Oceanic Anoxic Event 1c, exhibits cyclical alternations of marls/black shales and carbonate-rich beds that record evidence of orbital climate and ...sedimentary dynamics. A combined micropalaeontological (planktic and benthic foraminifera, and palynomorphs) and geochemical (stable isotopes, clay mineralogy, and major element distribution) investigation allowed recognition of a remarkable influence of continental material within the black shales. Moreover, the palaeoproductivity record is characterised by a non-linear response to the orbital forcing. The micropalaeontological and geochemical record suggests that upper Albian bedded cycles in the Marne a Fucoidi Formation resulted from interplay of changes in atmospheric and hydrological parameters of the western Tethys and its drainage basin. In particular, deposition of the black shales occurred during precession minima, in times of increased precipitation, enhanced continental runoff and stratification of the upper water column. In this respect, the black shales of the Amadeus Segment share similarities with the Neogene Eastern Mediterranean sapropels.
Recent results and perspectives of the NEMO project Capone, A.; Aiello, S.; Aloisio, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2009, Letnik:
602, Številka:
1
Journal Article
Recenzirano
The latest results and the activities towards the realization of a km
3 Cherenkov neutrino detector carried out by the NEMO Collaboration are described. The realization of a Phase-1 project has ...validated all relevant technologies proposed for the realization of the km
3 detector on a test site at 2000
m depth. The realization of a new infrastructure on the candidate Capo Passero site (for Phase-2 project) will provide the possibility to test detector components at 3500
m depth.
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