Yazar "de Angelis, G." seçeneğine göre listele

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    AGATA-Advanced GAmma Tracking Array
    (ELSEVIER SCIENCE BV, 2012) Akkoyun, S.; Algora, A.; Alikhani, B.; Ameil, F.; de Angelis, G.; Arnold, L.; Badoer, S.
    The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of gamma-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer. (C) 2011 Elsevier B.V. All rights reserved.
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    Monte Carlo simulation of a single detector unit for the neutron detector array NEDA
    (ELSEVIER SCIENCE BV, 2012) Jaworski, G.; Palacz, M.; Nyberg, J.; de Angelis, G.; de France, G.; Di Nitto, A.; Hueyuek, T.
    A study of the dimensions and performance of a single detector of the future neutron detector array NEDA was performed by means of Monte Carlo simulations, using GEANT4. Two different liquid scintillators were evaluated: the hydrogen based BC501A and the deuterated BC537. The efficiency and the probability that one neutron will trigger a signal in more than one detector were investigated as a function of the detector size. The simulations were validated comparing the results to experimental measurements performed with two existing neutron detectors, with different geometries, based on the liquid scintillator BC501. (C) 2012 Elsevier B.V. All rights reserved.
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    Nuclear structure far from stability at the N=50 shell closure
    (AMER INST PHYSICS, 2008) Sahin, E.; de Angelis, G.; Gadea, A.; Duchene, G.; Faul, T.; Napoli, D. R.; Recchia, F.; Demetriuo, P; Harissopulos, SV
    Medium and high spin states of the nuclei close to the N=50 shell closure are investigated Using deep inelastic and multi-nucleon transfer reactions. New excited states of the nuclei Ga-81, Ge-82 and As-83 at N=50 shell closure have been identified by means of the Se-82+U-238 reaction. Gamma rays have been acquired using the PRISMA-CLARA setup of the Laboratori Nazionali di Legnaro, Italy (LNL).
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    Pulse pile-up identification and reconstruction for liquid scintillator based neutron detectors
    (Elsevier Science Bv, 2018) Luo, X. L.; Modamio, V.; Nyberg, J.; Valiente-Dobon, J. J.; Nishada, Q.; de Angelis, G.; Agramunt, J.
    The issue of pulse pile-up is frequently encountered in nuclear experiments involving high counting rates, which will distort the pulse shapes and the energy spectra. A digital method of off-line processing of pile-up pulses is presented. The pile-up pulses were firstly identified by detecting the downward-going zero-crossings in the first-order derivative of the original signal, and then the constituent pulses were reconstructed based on comparing the pile-up pulse with four models that are generated by combining pairs of neutron and.. standard pulses together with a controllable time interval. The accuracy of this method in resolving the pile-up events was investigated as a function of the time interval between two pulses constituting a pile-up event. The obtained results show that the method is capable of disentangling two pulses with a time interval among them down to 20 ns, as well as classifying them as neutrons or gamma rays. Furthermore, the error of reconstructing pile-up pulses could be kept below 6% when successive peaks were separated by more than 50 ns. By applying the method in a high counting rate of pile-up events measurement of the NEutron Detector Array (NEDA), it was empirically found that this method can reconstruct the pile-up pulses and perform neutron-gamma discrimination quite accurately. It can also significantly correct the distorted pulse height spectrum due to pile-up events.
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    Structure of the N=50 As, Ge, Ga nuclei
    (ELSEVIER SCIENCE BV, 2012) Sahin, E.; de Angelis, G.; Duchene, G.; Faul, T.; Gadea, A.; Lisetskiy, A. F.; Byrski, T.
    The level structures of the N = 50 As-83, Ge-82, and Ga-81 isotones have been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the gamma-ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N = 50 shell closure in the region of Ni-78 (Z = 28). The comparison of the experimental level schemes with the shell-model calculations yields an N = 50 energy gap value of 4.7(3) MeV at Z = 28. This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell model calculations, does not support a weakening of the N = 50 shell gap down to Z = 28. (c) 2012 Elsevier B.V. All rights reserved.
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    Test of digital neutron-gamma discrimination with four different photomultiplier tubes for the NEutron Detector Array (NEDA)
    (ELSEVIER SCIENCE BV, 2014) Luo, X. L.; Modamio, V.; Nyberg, J.; Valiente-Dobon, J. J.; Nishada, Q.; de Angelis, G.; Hueyuek, T.
    A comparative study of the neutron-gamma discrimination performance of a liquid scintillator detector BC501A coupled to four different 5 in photomultiplier tubes (ET9390kb, R11833-100, XP4512 and R4144) was carried out Both the Charge Comparison method and the Integrated Rise-Time method were implemented digitally to discriminate between neutrons and gamma rays emitted by a Cf-252 source. In both methods, the neutron-gamma discrimination capabilities of the four photomultiplier tubes were quantitatively compared by evaluating their figure-of-merit values at different energy regions between 50 keVee and 1000 keVee. Additionally, the results were further verified qualitatively using time-of-flight to distinguish gamma rays and neutrons. The results consistently show that photomultiplier tubes R11833-100 and ET9390kb generally perform best regarding neutron-gamma discrimination with only slight differences in figure-of-merit values. This superiority can be explained by their relatively higher photoelectron yield, which indicates that a scintillator detector coupled to a photomultiplier tube with higher photoelectron yield tends to result in better neutron-gamma discrimination performance. The results of this work will provide reference for the choice of photomultiplier tubes for future neutron detector arrays like NEDA. (C) 2014 Elsevier B.V. All rights reserved.