SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Di Nitto A.) "

Sökning: WFRF:(Di Nitto A.)

  • Resultat 1-40 av 40
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Ballan, M., et al. (författare)
  • Nuclear physics midterm plan at Legnaro National Laboratories (LNL)
  • 2023
  • Ingår i: European Physical Journal Plus. - 2190-5444. ; 138:8, s. 3-26
  • Tidskriftsartikel (refereegranskat)abstract
    • The next years will see the completion of the radioactive ion beam facility SPES (Selective Production of Exotic Species) and the upgrade of the accelerators complex at Istituto Nazionale di Fisica Nucleare – Legnaro National Laboratories (LNL) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics, and applications. The nuclear physics community has organised a workshop to discuss the new physics opportunities that will be possible in the near future by employing state-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.
  •  
2.
  • Edgecock, T. R., et al. (författare)
  • High intensity neutrino oscillation facilities in Europe
  • 2013
  • Ingår i: Physical Review Special Topics - Accelerators and Beams. - : American Physical Society. - 1098-4402. ; 16:2, s. 021002-
  • Tidskriftsartikel (refereegranskat)abstract
    • The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Frejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of mu(+) and mu(-) beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular He-6 and Ne-18, also stored in a ring. The far detector is also the MEMPHYS detector in the Frejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.
  •  
3.
  • Jaworski, G., et al. (författare)
  • The New Neutron Multiplicity Filter NEDA and Its First Physics Campaign with AGATA
  • 2019
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 50:3, s. 585-590
  • Tidskriftsartikel (refereegranskat)abstract
    • A new neutron multiplicity filter NEDA, after a decade of design, R&D and construction, was employed in its first physics campaign with the AGATA spectrometer. Properties and performance of the array are discussed.
  •  
4.
  • Valiente-Dobon, J. J., et al. (författare)
  • NEDA-NEutron Detector Array
  • 2019
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 927, s. 81-86
  • Tidskriftsartikel (refereegranskat)abstract
    • The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.
  •  
5.
  • Forsberg, Ulrika, et al. (författare)
  • Spectroscopic Tools Applied to Element Z = 115 Decay Chains
  • 2014
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X .- 2101-6275. - 9782759811755 - 9782759811762 ; 66, s. 02036-02036
  • Konferensbidrag (refereegranskat)abstract
    • Nuclides that are considered to be isotopes of element Z = 115 were produced in the reaction 48Ca + 243Am at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt. The detector setup TASISpec was used. It was mounted behind the gas-filled separator TASCA. Thirty correlated α-decay chains were found, and the energies of the particles were determined with high precision. Two important spectroscopic aspects of the offline data analysis are discussed in detail: the handling of digitized preamplified signals from the silicon strip detectors, and the energy reconstruction of particles escaping to upstream detectors relying on pixel-by-pixel dead-layer thicknesses.
  •  
6.
  • Khuyagbaatar, J., et al. (författare)
  • 48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr
  • 2014
  • Ingår i: Physical Review Letters. - 1079-7114. ; 112:17
  • Tidskriftsartikel (refereegranskat)abstract
    • The superheavy element with atomic number Z=117 was produced as an evaporation residue in the 48Ca+249Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope 294-117 and its decay products. A hitherto unknown α-decay branch in 270Db (Z=105) was observed, which populated the new isotope 266Lr (Z=103). The identification of the long-lived (T1/2=1.0+1.9−0.4 h) α-emitter 270Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an “island of stability.”
  •  
7.
  • Khuyagbaatar, J., et al. (författare)
  • Fusion reaction 48Ca + 249Bk leading to formation of the element Ts (Z=117)
  • 2019
  • Ingår i: Physical Review C. - 2469-9985. ; 99:5
  • Tidskriftsartikel (refereegranskat)abstract
    • The heaviest currently known nuclei, which have up to 118 protons, have been produced in 48Ca induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing 48Ca with the radioactive target 249Bk, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of 294Ts. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to 293Ts. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.
  •  
8.
  • Khuyagbaatar, J., et al. (författare)
  • Search for elements 119 and 120
  • 2020
  • Ingår i: Physical Review C. - 2469-9985. ; 102:6
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the 50Ti+249Bk and 50Ti+249Cf fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. Over four months of irradiation, the 249Bk target partially decayed into 249Cf, which allowed for a simultaneous search for both elements. Neither was detected at cross-section sensitivity levels of 65 and 200 fb for the 50Ti+249Bk and 50Ti+249Cf reactions, respectively, at a midtarget beam energy of Elab = 281.5 MeV. The nonobservation of elements 119 and 120 is discussed within the concept of fusion-evaporation reactions including various theoretical predictions on the fission-barrier heights of superheavy nuclei in the region of the island of stability.
  •  
9.
  •  
10.
  •  
11.
  • Boso, A., et al. (författare)
  • Neutron Skin Effects in Mirror Energy Differences : The Case of Mg-23-Na-23
  • 2018
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 121:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) "halo" orbit.
  •  
12.
  •  
13.
  • Di Nitto, A., et al. (författare)
  • Study of Non-fusion Products in the 50Ti+249Cf Reaction
  • 2018
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 784, s. 199-205
  • Tidskriftsartikel (refereegranskat)abstract
    • The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.
  •  
14.
  • Gates, J. M., et al. (författare)
  • Decay Spectroscopy of Element 115 Daughters: 280Rg -> 276Mt and 276Mt -> 272Bh
  • 2015
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Forty-six decay chains, assigned to the decay of 288-115, were produced using the 243Am(48Ca,3n)288-115 reaction at the Lawrence Berkeley National Laboratory 88-in. cyclotron. The resulting series of α decays were studied using α-photon and α-x-ray spectroscopies. Multiple α-photon coincidences were observed in the element 115 decay chain members, particularly in the third- and fourth-generation decays (presumed to be 280Rg and 276Mt, respectively). Upon combining these data with those from 22 288-115 decay chains observed in a similar experiment, updated level schemes in 276Mt and 272Bh (populated by the α decay of 280Rg and 276Mt, respectively) are proposed. Photons were observed in the energy range expected for K x rays coincident with the α decay of both 280Rg and 276Mt. However, Compton scattering of higher-energy γ rays and discrete transitions are present in the K x-ray region preventing a definitive Z identification to be made based on observation of characteristic K x-ray energies.
  •  
15.
  • Yakushev, A., et al. (författare)
  • First Study on Nihonium (Nh, Element 113) Chemistry at TASCA
  • 2021
  • Ingår i: Frontiers in Chemistry. - : Frontiers Media SA. - 2296-2646. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Nihonium (Nh, element 113) and flerovium (Fl, element 114) are the first superheavy elements in which the 7p shell is occupied. High volatility and inertness were predicted for Fl due to the strong relativistic stabilization of the closed 7p1/2 sub-shell, which originates from a large spin-orbit splitting between the 7p1/2 and 7p3/2 orbitals. One unpaired electron in the outermost 7p1/2 sub-shell in Nh is expected to give rise to a higher chemical reactivity. Theoretical predictions of Nh reactivity are discussed, along with results of the first experimental attempts to study Nh chemistry in the gas phase. The experimental observations verify a higher chemical reactivity of Nh atoms compared to its neighbor Fl and call for the development of advanced setups. First tests of a newly developed detection device miniCOMPACT with highly reactive Fr isotopes assure that effective chemical studies of Nh are within reach.
  •  
16.
  • Yakushev, A., et al. (författare)
  • On the adsorption and reactivity of element 114, flerovium
  • 2022
  • Ingår i: Frontiers in Chemistry. - : Frontiers Media SA. - 2296-2646. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Flerovium (Fl, element 114) is the heaviest element chemically studied so far. To date, its interaction with gold was investigated in two gas-solid chromatography experiments, which reported two different types of interaction, however, each based on the level of a few registered atoms only. Whereas noble-gas-like properties were suggested from the first experiment, the second one pointed at a volatile-metal-like character. Here, we present further experimental data on adsorption studies of Fl on silicon oxide and gold surfaces, accounting for the inhomogeneous nature of the surface, as it was used in the experiment and analyzed as part of the reported studies. We confirm that Fl is highly volatile and the least reactive member of group 14. Our experimental observations suggest that Fl exhibits lower reactivity towards Au than the volatile metal Hg, but higher reactivity than the noble gas Rn.
  •  
17.
  • Cederwall, Bo, et al. (författare)
  • Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd
  • 2011
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 469:7328, s. 68-71
  • Tidskriftsartikel (refereegranskat)abstract
    • Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
  •  
18.
  • Såmark-Roth, A., et al. (författare)
  • Low-lying states in 219Ra and 215Rn : Sampling microsecond α-decaying nuclei
  • 2018
  • Ingår i: Physical Review C. - 2469-9985. ; 98:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Short-lived α-decaying nuclei "northeast" of 208Pb in the chart of nuclides were studied using the reaction 48Ca+243Am with the decay station TASISpec at TASCA, GSI Darmstadt. Decay energies and times from pile-up events were extracted with a tailor-made pulse-shape analysis routine and specific α-decay chains were identified in a correlation analysis. Decay chains starting with the even-even 220Ra and its odd-A neighbors, 219Fr, and 219,221Ra, with a focus on the 219Ra→215Rn decay, were studied by means of α-γ spectroscopy. A revised α-decay scheme of 219Ra is proposed, including a new decay branch from a previously not considered isomeric state at 17 keV excitation energy. Conclusions on nuclear structure are drawn from the experimental data, aided by Geant4 simulations and a discussion on theoretical calculations.
  •  
19.
  • Boso, A., et al. (författare)
  • ISOSPIN SYMMETRY BREAKING IN MIRROR NUCLEI Mg-23-Na-23
  • 2017
  • Ingår i: Acta Physica Polonica B. - : Jagiellonian University Press. - 0587-4254 .- 1509-5770. ; 48:3, s. 313-318
  • Tidskriftsartikel (refereegranskat)abstract
    • Mirror energy differences (MED) are a direct consequence of isospin symmetry breaking. Moreover, the study of MED has proved to give valuable information of several nuclear structure properties. We present the results of an experiment performed in GANIL to study the MED in mirror nuclei Mg-23-Na-23 up to high spin. The experimental values are compared with state-of-the-art shell model calculations. This permits to enlighten several nuclear structure properties, such as the way in which the nucleons alignment proceeds, the radius variation with J, the role of the spin-orbit interaction and the importance of isospin symmetry breaking terms of nuclear origin.
  •  
20.
  •  
21.
  • Egea Canet, F. J., et al. (författare)
  • A New Front-End High-Resolution Sampling Board for the New-Generation Electronics of EXOGAM2 and NEDA Detectors
  • 2015
  • Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 62:3, s. 1056-1062
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the final design and results of the FADC Mezzanine for the EXOGAM (EXOtic GAMma array spectrometer) and NEDA (Neutron Detector Array) detectors. The measurements performed include those of studying the effective number of bits, the energy resolution using HP-Ge detectors, as well as timing histograms and discrimination performance. Finally, the conclusion shows how a common digitizing device has been integrated in the experimental environment of two very different detectors which combine both low-noise acquisition and fast sampling rates. Not only the integration fulfilled the expected specifications on both systems, but it also showed how a study of synergy between detectors could lead to the reduction of resources and time by applying a common strategy.
  •  
22.
  • Egea Canet, F. J., et al. (författare)
  • Digital Front-End Electronics for the Neutron Detector NEDA
  • 2015
  • Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 62:3, s. 1063-1069
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the design of the NEDA (Neutron Detector Array) electronics, a first attempt to involve the use of digital electronics in large neutron detector arrays. Starting from the front-end modules attached to the PMTs (PhotoMultiplier Tubes) and ending up with the data processing workstations, a comprehensive electronic system capable of dealing with the acquisition and pre-processing of the neutron array is detailed. Among the electronic modules required, we emphasize the front-end analog processing, the digitalization, digital pre-processing and communications firmware, as well as the integration of the GTS (Global Trigger and Synchronization) system, already used successfully in AGATA (Advanced Gamma Tracking Array). The NEDA array will be available for measurements in 2016.
  •  
23.
  • Forsberg, U., et al. (författare)
  • Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am
  • 2016
  • Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 953, s. 117-138
  • Tidskriftsartikel (refereegranskat)abstract
    • Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z=115, two recoil-α-fission and five recoil-α-α-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel 289115 due to the fact that these recoil-α-α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil-α-α-fission decay chains, as well as some of the recoil-α-α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115.
  •  
24.
  • Jaworski, G., et al. (författare)
  • Monte Carlo simulation of a single detector unit for the neutron detector array NEDA
  • 2012
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 673, s. 64-72
  • Tidskriftsartikel (refereegranskat)abstract
    • 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
  •  
25.
  • Luo, X. L., et al. (författare)
  • Pulse pile-up identification and reconstruction for liquid scintillator based neutron detectors
  • 2018
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : ELSEVIER SCIENCE BV. - 0168-9002 .- 1872-9576. ; 897, s. 59-65
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
  •  
26.
  • Rudolph, Dirk, et al. (författare)
  • Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains
  • 2014
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 45, s. 263-272
  • Tidskriftsartikel (refereegranskat)abstract
    • Produced in the reaction 48Ca+243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115.
  •  
27.
  •  
28.
  •  
29.
  • Rudolph, Dirk, et al. (författare)
  • Selected Spectroscopic Results on Element 115 Decay Chains
  • 2015
  • Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 303:2, s. 1185-1190
  • Tidskriftsartikel (refereegranskat)abstract
    • Thirty correlated alpha-decay chains were observed in an experiment studying the fusion-evaporation reaction 48Ca + 243Am at the GSI Helmholtzzentrum f¨ur Schwerionenforschung. The decay characteristics of the majority of these 30 chains are consistent with previous observations and interpretations of such chains to originate from isotopes of element Z = 115. High-resolution alpha-photon coincidence spectroscopy in conjunction with comprehensive Monte-Carlo simulations allow to propose excitation schemes of atomic nuclei of the heaviest elements, thereby probing nuclear structure models near the ‘Island of Stability’ with unprecedented experimental precision.
  •  
30.
  • Rudolph, Dirk, et al. (författare)
  • Spectroscopy of Element 115 Decay Chains
  • 2013
  • Ingår i: Physical Review Letters. - 1079-7114. ; 111:11
  • Tidskriftsartikel (refereegranskat)abstract
    • A high-resolution , X-ray and gamma-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum für Schwerionenforschung. Thirty correlated alpha-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z > 112. Comprehensive Monte-Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.
  •  
31.
  • Zheng, Y., et al. (författare)
  • gamma-ray linear polarization measurements and (g(9/2))(-3) neutron alignment in Ru-91
  • 2013
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society (APS). - 0556-2813 .- 1089-490X. ; 87:4, s. 044328-
  • Tidskriftsartikel (refereegranskat)abstract
    • Linear polarization measurements have been performed for gamma rays in Ru-91 produced with the Ni-58(Ar-36,2p1n gamma)Ru-91 reaction at a beam energy of 111 MeV. The EXOGAM Ge clover array has been used to measure the gamma-gamma coincidences, gamma-ray linear polarization, and gamma-ray angular distributions. The polarization sensitivity of the EXOGAM clover detectors acting as Compton polarimeters has been determined in the energy range 0.3-1.3 MeV. Several transitions have been observed for the first time. Measurements of linear polarization and angular distribution have led to the firm assignments of spin differences and parity of high-spin states in Ru-91. More specifically, calculations using a semiempirical shell model were performed to understand the structures of the first and second (21/2(+)) and (17/2(+)) levels. The results are in good agreement with the experimental data, supporting the interpretation of the nonyrast (21/2(+)) and (17/2(+)) states in terms of the J(max) and J(max) - 2 members of the seniority-three nu(g(9/2))(-3) multiplet.
  •  
32.
  • Ghazi Moradi, Farnaz, 1976-, et al. (författare)
  • Character of particle-hole excitations in Ru-94 deduced from gamma-ray angular correlation and linear polarization measurements
  • 2014
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:1, s. 014301-
  • Tidskriftsartikel (refereegranskat)abstract
    • Linear polarization and angular correlations of gamma-rays depopulating excited states in the neutron-deficient nucleus Ru-94(44)50 have been measured, enabling firm spin-parity assignments for several excited states in this nucleus. The deduced multipolarities of strong transitions in the yrast structure were found to be mostly of stretched M1, E1, and E2 types and, in most cases, in agreement with previous tentative assignments. The deduced multipolarity of the 1869 keV and the connecting 257 and 1641 keV transitions indicates that the state at 6358 keV excitation energy has spin parity 12(1)(-) rather than 12(3)(+) as proposed in previous works. The presence of a 12(1)(-) state is interpreted within the framework of large-scale shell-model calculations as a pure proton-hole state dominated by the pi(p(1/2)(-1)circle times g(9/2)(-5)) and pi(p(3/2)(-1) g(9/2)(-5)) configurations. A new positive-parity state is observed at 6103 keV and is tentatively assigned as 12(2)(+). The 14(1)(-) state proposed earlier is reassigned as 13(4)(-) and is interpreted as being dominated by neutron particle-hole core excitations. The strengths of several E1 transitions have been measured and are found to provide a signature of core-excited configurations.
  •  
33.
  • Ghazi Moradi, Farnaz, et al. (författare)
  • Spectroscopy of the neutron-deficient N=50 nucleus Rh-95
  • 2014
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:4, s. 044310-
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutron-deficient semimagic (neutron number N = 50) Rh-95 nucleus has been produced at high spins using the projectile-target system Ca-40 + Ni-58 at 125 MeV beam energy. The gamma-decays of levels populated by the 3p fusion evaporation reaction channel were studied using gamma-gamma coincidences, and 20 new gamma-ray transitions involving 15 new positive-and negative-parity states were observed. Spin and parity for many of the excited states were firmly deduced for the first time using the combined directional angular correlation and direction-polarization techniques. The observed structures are discussed within the framework of large-scale shell model calculations. E1 transition strengths were deduced and used together with the results of the shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations.
  •  
34.
  • Luo, X. L., et al. (författare)
  • Test of digital neutron-gamma discrimination with four different photomultiplier tubes for the NEutron Detector Array (NEDA)
  • 2014
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 767, s. 83-91
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
  •  
35.
  • Modamio, V., et al. (författare)
  • Digital pulse-timing technique for the neutron detector array NEDA
  • 2015
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 775, s. 71-76
  • Tidskriftsartikel (refereegranskat)abstract
    • A new digital pulse-timing algorithm, to be used with the future neutron detector array NEDA, has been developed and tested. The time resolution of four 5 in diameter photomultiplier tubes (XP4512, R4144, R11833-100, and ET9390-kb), coupled to a cylindrical 5 in by 5 in BC501A liquict scintillator detector was measured by employing digital sampling electronics and a constant fraction discriminator (CFD) algorithm. The zero crossing of the CM algorithm was obtained with a cubic spline interpolation, which was continuous up to the second derivative. The performance of the algorithm was studied at sampling rates of 500 MS/s and 200 MS/s. The time resolution obtained with the digital electronics was compared to the values acquired with a standard analog CFD. The result of this comparison shows that the time resolution from the analog and the digital measurements at 500 MS/s and at 200 MS/s are within 15% for all the tested photomultiplier tubes.
  •  
36.
  • Söderström, Pär-Anders, 1980-, et al. (författare)
  • Neutron detection and gamma-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537
  • 2019
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : ELSEVIER SCIENCE BV. - 0168-9002 .- 1872-9576. ; 916, s. 238-245
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and gamma rays. Special emphasis is put on the application of artificial neural networks. The results show a systematically higher gamma-ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of gamma rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neutrons could be identified in BC-501A using artificial neural networks down to a recoil proton energy of 800 keV compared to a recoil deuteron energy of 1200 keV for BC-537. We conclude that using artificial neural networks it is possible to obtain the same gamma-ray rejection quality from both BC-501A and BC-537 for neutrons above a low-energy threshold. This threshold is, however, lower for BC-501A, which is important for nuclear structure spectroscopy experiments of rare reaction channels where low-energy interactions dominates.
  •  
37.
  •  
38.
  •  
39.
  • Javier Egea, Francisco, et al. (författare)
  • Design and Test of a High-Speed Flash ADC Mezzanine Card for High-Resolution and Timing Performance in Nuclear Structure Experiments
  • 2013
  • Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 60:5, s. 3526-3531
  • Tidskriftsartikel (refereegranskat)abstract
    • This work describes new electronics for the EX-OGAM2 (HP-Ge detector array) and NEDA (BC501A-based neutron detector array). A new digitizing card with high resolution has been designed for gamma-ray and neutron spectroscopy experiments. The higher bandwidth requirement of the NEDA signals, together with the necessity for accuracy, require a high sampling rate in order to preserve the shape for real-time Pulse Shape Analysis (PSA). The PSA is of paramount importance for the NEDA to discriminate between neutrons and gamma-ray signals. Both high resolution and high speed parameters are often difficult to achieve in a single electronic unit. These constraints, together with the need to build new digitizing electronics to improve performance and flexibility of signal analysis in nuclear physics experiments, led to the development a new FADC mezzanine card. In this work, the design and development are described, including the characterization procedure and the preliminary measurement results.
  •  
40.
  • Perez-Palacin, Diego, et al. (författare)
  • A UML Profile for the Design, Quality Assessment and Deployment of Data-intensive Applications
  • 2019
  • Ingår i: Software and Systems Modeling. - : Springer. - 1619-1366 .- 1619-1374. ; 18:6, s. 3577-3614
  • Tidskriftsartikel (refereegranskat)abstract
    • Big Data or Data-Intensive applications (DIAs) seek to mine, manipulate, extract or otherwise exploit the potential intelligence hidden behind Big Data. However, several practitioner surveys remark that DIAs potential is still untapped because of very difficult and costly design, quality assessment and continuous refinement. To address the above shortcoming, we propose the use of a UML domain-specific modeling language or profile specifically tailored to support the design, assessment and continuous deployment of DIAs. This article illustrates our DIA-specific profile and outlines its usage in the context of DIA performance engineering and deployment. For DIA performance engineering, we rely on the Apache Hadoop technology, while for DIA deployment, we leverage the TOSCA language. We conclude that the proposed profile offers a powerful language for data-intensive software and systems modeling, quality evaluation and automated deployment of DIAs on private or public clouds.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-40 av 40

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy