Performance evaluation of SiPMʼs for low threshold gamma detection

In the context of the on-line monitoring of short and medium term for radioactive waste repository, a new system has been planned. Such system makes use a new kind of detector, named Silicon Photomultiplier, coupled to scintillating fibres to be positioned around each waste drum in shape of fine grid. The purpose of this design is evaluate the variations of the radioactivity distribution by counting the gamma radiation

Role of interfaces on the stability and electrical properties of Ge2Sb2Te5 crystalline structures

GeSbTe-based materials exhibit multiple crystalline phases, from disordered rocksalt, to rocksalt with ordered vacancy layers, and to the stable trigonal phase. In this paper we investigate the role of the interfaces on the structural and electrical properties of Ge2Sb2Te5. We find that the site of nucleation of the metastable rocksalt phase is crucial in determining the evolution towards vacancy ordering and the stable phase. By properly choosing the substrate and the capping layers, nucleation sites engineering can be obtained, thus promoting or preventing the vacancy ordering in the rocksalt structure or the conversion into the trigonal phase. The vacancy ordering occurs at lower annealing temperatures (170 °C) for films deposited in the amorphous phase on silicon (111), compared to the case of SiO2 substrate (200 °C), or in presence of a capping layer (330 °C). The mechanisms governing the nucleation have been explained in terms of interfacial energies. Resistance variations of about one order of magnitude have been measured upon transition from the disordered to the ordered rocksalt structure and then to the trigonal phase. The possibility to control the formation of the crystalline phases characterized by marked resistivity contrast is of fundamental relevance for the development of multilevel phase change data storage

Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower

The results of the analysis of the data collected with the NEMO Phase-2 tower, deployed at 3500 m depth about 80 km off-shore Capo Passero (Italy), are presented. Cherenkov photons detected with the photomultipliers tubes were used to reconstruct the tracks of atmospheric muons. Their zenith-angle distribution was measured and the results compared with Monte Carlo simulations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is also included. The associated depth intensity relation was evaluated and compared with previous measurements and theoretical predictions. With the present analysis, the muon depth intensity relation has been measured up to 13 km of water equivalent.Comment: submitted to Astroparticle Physic

Cryogenic SiPM arrays for the DUNE photon detection system

In this paper we report on the characterization of SiPM tiles developed for the R & D on the DUNE Photon Detection System. The tiles were produced by Fondazione Bruno Kessler (FBK) employing NUV-HD-SF SiPMs. Special emphasis is given on cryo-reliability of the sensors, i.e. the stability of electric and mechanical properties after thermal cycles at room and 77K temperature. The characterization includes the determination of the I-V curve, a high sensitivity measurement of Dark Count Rate at different overvoltages, and correlated noise. The single p.e. sensitivity is measured as a function of the number of sensors connected to a single electronic channel, after amplification at 77K using a dedicated cold amplifier.Comment: 17 pages, 10 figures, 4 table, submitted to NIM-

The NUMEN project: NUclear Matrix Elements for Neutrinoless double beta decay

The article describes the main achievements of the NUMEN project togetherwith an updated and detailed overview of the related R&D activities andtheoretical developments. NUMEN proposes an innovative technique to access thenuclear matrix elements entering the expression of the lifetime of the doublebeta decay by cross section measurements of heavy-ion induced Double ChargeExchange (DCE) reactions. Despite the two processes, namely neutrinoless doublebeta decay and DCE reactions, are triggered by the weak and strong interactionrespectively, important analogies are suggested. The basic point is thecoincidence of the initial and final state many-body wave-functions in the twotypes of processes and the formal similarity of the transition operators. Firstexperimental results obtained at the INFN-LNS laboratory for the40Ca(18O,18Ne)40Ar reaction at 270 MeV, give encouraging indication on thecapability of the proposed technique to access relevant quantitativeinformation. The two major aspects for this project are the K800Superconducting Cyclotron and MAGNEX spectrometer. The former is used for theacceleration of the required high resolution and low emittance heavy ion beamsand the latter is the large acceptance magnetic spectrometer for the detectionof the ejectiles. The use of the high-order trajectory reconstructiontechnique, implemented in MAGNEX, allows to reach the experimental resolutionand sensitivity required for the accurate measurement of the DCE cross sectionsat forward angles. However, the tiny values of such cross sections and theresolution requirements demand beam intensities much larger than manageablewith the present facility. The on-going upgrade of the INFN-LNS facilities inthis perspective is part of the NUMEN project and will be discussed in thearticle

Gestione e miglioramento di pascoli italiani

Experimental results of trials on pastures management and improvement, conducted by 10 University Institutes within the study team «Characterization of italian pastures» are reported. The trials carried out in different soil and climate conditions, ranging from the Alps to the southern Appennines and to the Islands, in different years, provide some conclusive and generaI considerations. With periodical cuts, the forage availability period becomes longer, while using one cut at flowering yield results are higher. As far as management techniques are concerned, fertilization with the three main nutrients affects positively quanti-qualitative yield, although in real situations the application of one or two elements may be sufficient and more economically convenient, and in relation to the botanical composition. Undersowing determines positive effects both on botanical composition and on pasture utilization. Positive results, furthermore, are obtained by mechanical scrub clearing. Vengono riferiti i risultati sperimentali delle prove sulla gestione e sul miglioramento dei pascoli condotte da dieci Istituti Universitari costituenti il gruppo di studio «Caratterizzazione di pascoli italiani», Dalle prove condotte in ambienti pedoclimatici diversi, dalle alpi all'appennino meridionale ed alle isole, e in annate differenti, sono emerse come generalizzabili alcune considerazioni conclusive. Con sfalci periodici si allunga il periodo di disponibilità di foraggio verde, mentre con quello unico alla fioritura la produzione risulta più elevata. Per gli interventi tecnici, la concimazione con i tre macroelementi influisce favorevolmente sull'entità e sulla qualità della produzione, anche se, nelle situazioni concrete, può essere sufficiente, e più vantaggioso dal lato economico, la somministrazione di uno o due elementi, anche in relazione alla facies floristica. La trasemina determina effetti favorevoli sia sulla composizione floristica sia nella migliore utilizzazione del pascolo. Risultati positivi, infine, si conseguono con il decespugliamento meccanico