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Sökning: WFRF:(Lantz Mattias)

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1.
  • Aksouh, F., et al. (författare)
  • STUDY OF THE O-15(2p,gamma)Ne-17 CROSS SECTION BY COULOMB DISSOCIATION OF Ne-17 FOR THE rp PROCESS OF NUCLEOSYNTHESIS
  • 2014
  • Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 45:2, s. 229-234
  • Tidskriftsartikel (refereegranskat)abstract
    • The O-15(2p, gamma)Ne-17 cross section has been studied by the inverse reaction, the Coulomb dissociation of Ne-17. The experiment has been performed at the GSI. The Ne-17 excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb dissociation cross sections (sigma(Coul)) have been extracted, which provide a photoabsorption (sigma(photo)) and a radiative capture cross section (sigma(cap)). Additionally, important information about the Ne-17 nuclear structure will be obtained. The analysis is in progress.
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2.
  • Lehr, C., et al. (författare)
  • Unveiling the two-proton halo character of 17 Ne: Exclusive measurement of quasi-free proton-knockout reactions
  • 2022
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 827
  • Tidskriftsartikel (refereegranskat)abstract
    • The proton drip-line nucleus 17Ne is investigated experimentally in order to determine its two-proton halo character. A fully exclusive measurement of the 17Ne(p,2p)16F→15⁎O+p quasi-free one-proton knockout reaction has been performed at GSI at around 500 MeV/nucleon beam energy. All particles resulting from the scattering process have been detected. The relevant reconstructed quantities are the angles of the two protons scattered in quasi-elastic kinematics, the decay of 16F into 15O (including γ decays from excited states) and a proton, as well as the 15O+p relative-energy spectrum and the 16F momentum distributions. The latter two quantities allow an independent and consistent determination of the fractions of l=0 and l=2 motion of the valence protons in 17Ne. With a resulting relatively small l=0 component of only around 35(3)%, it is concluded that 17Ne exhibits a rather modest halo character only. The quantitative agreement of the two values deduced from the energy spectrum and the momentum distributions supports the theoretical treatment of the calculation of momentum distributions after quasi-free knockout reactions at high energies by taking into account distortions based on the Glauber theory. Moreover, the experimental data allow the separation of valence-proton knockout and knockout from the 15O core. The latter process contributes with 11.8(3.1) mb around 40% to the total proton-knockout cross section of 30.3(2.3) mb, which explains previously reported contradicting conclusions derived from inclusive cross sections.
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3.
  • Marganiec, J., et al. (författare)
  • Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics
  • 2012
  • Ingår i: Proceedings of Science. - Proceedings of Science : Sissa. - 1824-8039.
  • Konferensbidrag (refereegranskat)abstract
    • By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
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4.
  • Roger, T., et al. (författare)
  • Precise Determination of the Unperturbed B8 Neutrino Spectrum
  • 2012
  • Ingår i: Phys. Rev. Lett.. ; 108:16, s. Art. no. 162502-
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of the final state distribution of the 8B beta decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvaskyla [O. S.Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measuredspectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, theneutrino spectrum is for the first time directly extracted from the measured final state distribution, thusavoiding the uncertainties related to the extrapolation of R-matrix fits. Combined with the IGISOL data,this leads to an improvement of the overall errors and the extension of the neutrino spectrum at highenergy. The new unperturbed neutrino spectrum represents a benchmark for future measurements of thesolar neutrino flux as a function of energy.
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5.
  • Wamers, F., et al. (författare)
  • Diverse mechanisms in proton knockout reactions from the Borromean nucleus Ne-17
  • 2023
  • Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 59
  • Tidskriftsartikel (refereegranskat)abstract
    • Nucleon knockout experiments using beryllium or carbon targets reveal a strong dependence of the quenching factors, i.e., the ratio (Rs) of theoretical to the experimental spectroscopic factors (C2S), on the proton-neutron asymmetry in the nucleus under study. However, this dependence is greatly reduced when a hydrogen target is used. To understand this phenomenon, exclusive H-1(Ne-17, 2p F-16) and inclusive C-12(Ne-17, 2p 1(6)F)X, 1(2)C(Ne-17, F-16)X as well as 1H(Ne-17,(16) F)X(X-denotes undetected reaction products) reactions with F-16 in the ground and excited states were anal- ysed. The longitudinal momentum distribution of F-16 and the correlations between the detached protons were studied. In the case of the carbon target, there is a significant deviation from the predictions of the eikonal model. The eikonal approximation was used to extract spectroscopic factor values (CS)-S-2. The experimental (CS)-S-2 value obtained with C target is markedly lower than that for H target. This is interpreted as rescattering due to simultaneous nucleon knockout from both reaction partners, Ne-17 and C-12.
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6.
  • Wamers, F., et al. (författare)
  • First Observation of the Unbound Nucleus Ne-15
  • 2014
  • Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:13
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first observation of the unbound proton-rich nucleus Ne-15. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u Ne-17. The Ne-15 ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to O-13 with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2(-) and 1(-) states in F-14 is observed. The Ne-15 ground state is shown to have a strong configuration with two protons in the (sd) shell around O-13 with a 63(5)% (1s(1/2))(2) component.
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7.
  • Marganiec, J., et al. (författare)
  • Coulomb and nuclear excitations of narrow resonances in 17Ne
  • 2016
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 759, s. 200-205
  • Tidskriftsartikel (refereegranskat)abstract
    • New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the O15+p+p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.
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8.
  • Marganiec, J., et al. (författare)
  • Studies of continuum states in (16) Ne using three-body correlation techniques
  • 2015
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 51:1, s. 1-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-proton decay of the unbound nucleus Ne-16 , produced in one-neutron knockout from a 500 MeV/u Ne-17 beam, has been studied at GSI. The ground state, at a resonance energy 1.388(15) MeV, ( MeV) above the O-14 +p+p threshold, and two narrow resonances at MeV and 7.57(6) MeV have been investigated. A comparison of the energy difference between the first excited 2(+) state and the 0(+) ground state in Ne-16 with its mirror nucleus C-16 reveals a small Thomas-Ehrman shift (TES) of keV. A trend of the TES for the T = 2 quintet is obtained by completing the known data with a prediction for F-16 obtained from an IMME analysis. The decay mechanisms of the observed three resonances were revealed from an analysis of the energy and angular correlations of the O-14 +p+p decay products. The ground state decay can be considered as a genuine three-body (democratic) mode and the excited states decay sequentially via states in the intermediate nucleus F-15 , the 3.22 MeV state predominantly via the F-15 ground-state resonance, while the 7.57 MeV state decays via the 5/2(+) resonance in F-15 at 2.8 MeV above the O-14 +p+p threshold. Further, from an analysis of angular correlations, the spin-parity of the 7.57 MeV state has been determined as and assigned as the third 2(+) state in Ne-16 based on a comparison with C-16.
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9.
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10.
  • Abou Nada, Fahd Jouda, et al. (författare)
  • Remote temperature sensing on and beneath atmospheric plasma sprayed thermal barrier coatings using thermographic phosphors
  • 2016
  • Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 302, s. 359-367
  • Tidskriftsartikel (refereegranskat)abstract
    • Investigations on remote temperature sensing of yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) at the surface and at the bond-coat/top-coat interface were carried out. Using Y2O3:Eu thermographic phosphor as an embedded temperature sensing layer, sub-surface temperature probing through 300 μm of atmospheric plasma sprayed YSZ is demonstrated. The Y2O3:Eu thermographic phosphor displays a temperature sensitivity ranging between 400 °C up to a maximum of 900 °C when utilizing the luminescence originating from the 611 nm emission band. Dysprosium stabilized zirconia (10 wt.% DySZ), a TBC material, is also investigated and established as a temperature sensor from 400 °C up to a temperature of 1000 °C using both the intensity decay time and emission intensity ratio methods. In addition, the luminescence of presumed optically inactive YSZ materials was spectroscopically investigated in terms of optical interferences caused by impurities. A validation temperature probing measurement through 300 μm of YSZ top-coat was successfully performed in a SGT-800 Siemens burner running at six different operating conditions in an atmospheric combustion rig.
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11.
  • Acciarri, R., et al. (författare)
  • Demonstration of MeV-scale physics in liquid argon time projection chambers using ArgoNeuT
  • 2019
  • Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 99:1
  • Tidskriftsartikel (refereegranskat)abstract
    • MeV-scale energy depositions by low-energy photons produced in neutrino-argon interactions have been identified and reconstructed in ArgoNeuT liquid argon time projection chamber (LArTPC) data. ArgoNeuT data collected on the NuMI beam at Fermilab were analyzed to select isolated low-energy depositions in the TPC volume. The total number, reconstructed energies, and positions of these depositions have been compared to those from simulations of neutrino-argon interactions using the FLUKA Monte Carlo generator. Measured features are consistent with energy depositions from photons produced by deexcitation of the neutrino's target nucleus and by inelastic scattering of primary neutrons produced by neutrino-argon interactions. This study represents a successful reconstruction of physics at the MeV scale in a LArTPC, a capability of crucial importance for detection and reconstruction of supernova and solar neutrino interactions in future large LArTPCs.
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12.
  • Aksyutina, Yu, et al. (författare)
  • Lithium isotopes beyond the drip line
  • 2008
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 666:5, s. 430-434
  • Tidskriftsartikel (refereegranskat)abstract
    • The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in the 14Be ground-state, evidence for a 13Li resonance at 1.47(31) MeV above the threshold with a width around 2 MeV has been found.
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13.
  • Aksyutina, Yuliya, 1983, et al. (författare)
  • Properties of the 7He ground state from 8He neutron knockout
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 679:3, s. 191-196
  • Tidskriftsartikel (refereegranskat)abstract
    • The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+) + n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s-wave component at low energies in the α+n relative energy spectrum. A possible low-lying exited state in 7He observed in neutron knockout data from 8He in a carbon target and tentatively interpreted as a Iπ=1/2− state, could not be observed in the present experiment. Possible explanations of the shape difference between the 7He resonance obtained in the two knockout reactions are discussed in terms of target-dependence or different reaction mechanisms at relativistic energies.
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14.
  • Al-Adili, Ali, et al. (författare)
  • Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234
  • 2016
  • Ingår i: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of U-235(n,f). The second, on the fission fragment properties in the thermal fission of U-234(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on U-235(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called saw-tooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of U-234(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of U-235(nth, f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.
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15.
  • Al-Adili, Ali, et al. (författare)
  • Fission Activities of the Nuclear Reactions Group in Uppsala
  • 2015
  • Ingår i: Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, THEORY-3. - : Elsevier BV. ; , s. 145-149
  • Konferensbidrag (refereegranskat)abstract
    • This paper highlights some of the main activities related to fission of the nuclear reactions group at Uppsala University. The group is involved for instance in fission yield experiments at the IGISOL facility, cross-section measurements at the NFS facility, as well as fission dynamics studies at the IRMM JRC-EC. Moreover, work is ongoing on the Total Monte Carlo (TMC) methodology and on including the GEF fission code into the TALYS nuclear reaction code. Selected results from these projects are discussed.
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16.
  • Al-Adili, Ali, et al. (författare)
  • Ion counting efficiencies at the IGISOL facility
  • 2014
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high precision. Fission fragments from a U target are passing through a Ni foil and entering a gas filled chamber. The collected fragments are guided through a mass separator to a Penning trap where their masses are identified. This simulation work focuses on how different fission fragment properties (mass, charge and energy) affect the stopping efficiency in the gas cell. In addition, different experimental parameters are varied (e. g. U and Ni thickness and He gas pressure) to study their impact on the stopping efficiency. The simulations were performed using the Geant4 package and the SRIM code. The main results suggest a small variation in the stopping efficiency as a function of mass, charge and kinetic energy. It is predicted that heavy fragments are stopped about 9% less efficiently than the light fragments. However it was found that the properties of the U, Ni and the He gas influences this behavior. Hence it could be possible to optimize the efficiency.
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17.
  • Al-Adili, Ali, et al. (författare)
  • Isomer yields in nuclear fission
  • 2021
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 256
  • Tidskriftsartikel (refereegranskat)abstract
    • The generation of angular momentum in the fission process is still an open question. To shed light on this topic, we started a series of measurements at the IGISOL-JYFLTRAP facility in Finland. Highprecision measurements of isomeric yield ratios (IYR) are performed with a Penning trap, partly with the aim to extract average root-mean-square (rms) quantities of fragment spin distributions. The newly installed Phase-Imaging Ion-Cyclotron Resonance (PI-ICR) technique allows the separation of masses down to tens of keV, which is suffcient to disentangle many isomers. In this paper, we first summarize the previous measurements on the neutron and proton-induced fission of uranium and thorium, e.g. the odd cadmium and indium isotopes (119 ≤ A ≤ 127). The measurements revealed systematic trends as function of mass number, which stimulated further exploration. A recent measurement was performed at IGISIOL and several new IYR data will soon be published, for the first time. Secondly, we employ the TALYS nuclear-reaction code to model one of the newly measured isomer yields. Detailed GEF and TALYS calculations are discussed for the fragment angular momentum distribution in 134I.
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18.
  • Al-Adili, Ali, et al. (författare)
  • Neutron-multiplicity experiments for enhanced fission modelling
  • 2017
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 9782759890200
  • Konferensbidrag (refereegranskat)abstract
    • The nuclear de-excitation process of fission fragments (FF) provides fundamental information for the understanding of nuclear fission and nuclear structure in neutron-rich isotopes. The variation of the prompt-neutron multiplicity, ν(A), as a function of the incident neutron energy (En) is one of many open questions. It leads to significantly different treatments in various fission models and implies that experimental data are analyzed based on contradicting assumptions. One critical question is whether the additional excitation energy (Eexc) is manifested through an increase of ν(A) for all fragments or for the heavy ones only. A systematic investigation of ν(A) as a function of En has been initiated. Correlations between prompt-fission neutrons and fission fragments are obtained by using liquid scintillators in conjunction with a Frisch-grid ionization chamber. The proof-of-principle has been achieved on the reaction 235U(nth,f) at the Van De Graff (VdG) accelerator of the JRC-Geel using a fully digital data acquisition system. Neutrons from 252Cf(sf) were measured separately to quantify the neutron-scattering component due to surrounding shielding material and to determine the intrinsic detector efficiency. Prelimenary results on ν(A) and spectrum in correlation with FF properties are presented.
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19.
  • Al-Adili, Ali, et al. (författare)
  • Simulations of the fission-product stopping efficiency in IGISOL
  • 2015
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:59, s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • At the Jyväskylä Ion Guide Isotope Separator On-Line (IGISOL) facility, independent fission yields are measured employing the Penning-trap technique. Fission products are produced, e.g. by impinging protons on a uranium target, and are stopped in a gas-filled chamber. The products are collected by a flow of He gas and guided through a mass separator to a Penning trap, where their masses are identified. This work investigates how fission-product properties, such as mass and energy, affect the ion stopping efficiency in the gas cell. The study was performed using the Geant4 toolkit and the SRIM code. The main results show a nearly mass-independent ion stopping with regard to the wide spread of ion masses and energies, with a proper choice of uranium target thickness. Although small variations were observed, in the order of 5%, the results are within the systematic uncertainties of the simulations. To optimize the stopping efficiency while reducing the systematic errors, different experimental parameters were varied; for instance material thicknesses and He gas pressure. Different parameters influence the mass dependence and could alter the mass dependencies in the ion stopping efficiency.
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20.
  • Al-Adili, Ali, et al. (författare)
  • Studying fission neutrons with 2E-2v and 2E
  • 2018
  • Ingår i: SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4). - : EDP Sciences. - 9782759890316
  • Konferensbidrag (refereegranskat)abstract
    • This work aims at measuring prompt-fission neutrons at different excitation energies of the nucleus. Two independent techniques, the 2E-2v and the 2E techniques, are used to map the characteristics of the mass-dependent prompt fission neutron multiplicity, 7(A), when the excitation energy is increased. The VERDI 2E-2v spectrometer is being developed at JRC-GEEL. The Fission Fragment (FF) energies are measured using two arrays of 16 silicon (Si) detectors each. The FFs velocities are obtained by time-of-flight, measured between micro-channel plates (MCP) and Si detectors. With MCPs placed on both sides of the fission source, VERDI allows for independent timing measurements for both fragments. Cf-252(sf) was measured and the present results revealed particular features of the 2E-2v technique. Dedicated simulations were also performed using the GEF code to study important aspects of the 2E-2v technique. Our simulations show that prompt neutron emission has a non-negligible impact on the deduced fragment data and affects also the shape of 17(A). Geometrical constraints lead to a total-kinetic energy-dependent detection efficiency. The 2E technique utilizes an ionization chamber together with two liquid scintillator detectors. Two measurements have been performed, one of Cf-252(sf) and another one of thermal-neutron induced fission in U-235(n,f). Results from Cf-252(sf) are reported here.
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21.
  • Andersson Sundén, Erik, et al. (författare)
  • Citizen Science and Radioactivity
  • 2019
  • Ingår i: Nuclear Physics News. - : Informa UK Limited. - 1050-6896 .- 1061-9127 .- 1931-7336. ; 29:2, s. 25-28
  • Tidskriftsartikel (populärvet., debatt m.m.)
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22.
  • Ankowski, A., et al. (författare)
  • Energy reconstruction of electromagnetic showers from Ν0 decays with the ICARUS T600 liquid argon TPC
  • 2010
  • Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 41:1, s. 103-125
  • Tidskriftsartikel (refereegranskat)abstract
    • We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of π 0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The (γγ) invariant mass was found to be consistent with the value of the π 0 mass. The resolution of the reconstructed π 0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a π 0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate π 0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with π 0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data.
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23.
  • Ankowski, A, et al. (författare)
  • Energy reconstruction of electromagnetic showers from π0 decays with the ICARUS T600 liquid argon TPC
  • 2010
  • Ingår i: Acta Physica Polonica B. - : Jagellonian University. - 0587-4254 .- 1509-5770. ; 41:1, s. 103-125
  • Tidskriftsartikel (refereegranskat)abstract
    • We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of π0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The (γ,γ) invariant mass was found to be consistent with the value of the π0 mass. The resolution of the reconstructed π0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a π0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate π0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with π0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data.
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24.
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25.
  • Ballarini, F., et al. (författare)
  • The physics of the FLUKA code : Recent developments
  • 2007
  • Ingår i: Advances in Space Research. - Elsevier : Elsevier BV. - 0273-1177 .- 1879-1948. ; 40:9, s. 1339-1349
  • Tidskriftsartikel (refereegranskat)abstract
    • FLUKA is a Monte-Carlo code able to simulate interaction and transport of hadrons, heavy ions and electromagnetic particles from few keV (or thermal neutron) to cosmic ray energies in whichever material. The highest priority in the design and development of the code has always been the implementation and improvement of sound and modern physical models. A summary of the FLUKA physical models is given, while recent developments are described in detail: among the others, extensions of the intermediate energy hadronic interaction generator, refinements in photon cross sections and interaction models, analytical on-line evolution of radio-activation and remnant dose. In particular, new developments in the nucleus-nucleus interaction models are discussed. Comparisons with experimental data and examples of applications of relevance for space radiation are also provided.
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26.
  • Battistoni, Giuseppe, et al. (författare)
  • Applications of FLUKA Monte Carlo code for nuclear and accelerator physics
  • 2011
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 269:24, s. 2850-2856
  • Tidskriftsartikel (refereegranskat)abstract
    • FLUKA is a general purpose Monte Carlo code capable of handling all radiation components from thermal energies (for neutrons) or 1 keV (for all other particles) to cosmic ray energies and can be applied in many different fields. Presently the code is maintained on Linux. The validity of the physical models implemented in FLUKA has been benchmarked against a variety of experimental data over a wide energy range, from accelerator data to cosmic ray showers in the Earth atmosphere. FLUKA is widely used for studies related both to basic research and to applications in particle accelerators, radiation protection and dosimetry, including the specific issue of radiation damage in space missions, radiobiology (including radiotherapy) and cosmic ray calculations.After a short description of the main features that make FLUKA valuable for these topics, the present paper summarizes some of the recent applications of the FLUKA Monte Carlo code in the nuclear as well high energy physics. In particular it addresses such topics as accelerator related applications.
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27.
  • Battistoni, Giuseppe, et al. (författare)
  • FLUKA Capabilities and CERN Applications for the Study of Radiation Damage to Electronics at High-Energy Hadron Accelerators
  • 2011
  • Konferensbidrag (refereegranskat)abstract
    • The assessment of radiation damage to electronics is a complex process and requires a detailed description of the full particle energy spectra, as well as a clear characterization of the quantities used to predict radiation damage. FLUKA, a multi-purpose particle interaction and transport code, is capable of calculating proton-proton and heavy ion collisions at LHC energies and beyond. It correctly describes the entire hadronic and electromagnetic particle cascade initiated by secondary particles from TeV energies down to thermal neutrons, and provides direct scoring capabilities essential to estimate in detail the possible risk of radiation damage to electronics. This paper presents the FLUKA capabilities for applications related to radiation damage to electronics, providing benchmarking examples and showing the practical applications of FLUKA at CERN facilities such as CNGS and LHC. Related applications range from the study of device effects, the detailed characterization of the radiation field and radiation monitor calibration, to the input requirements for important mitigation studies including shielding, relocation or other options.
  •  
28.
  • Battistoni, G, et al. (författare)
  • FLUKA Monte Carlo calculations for hadrontherapy application
  • 2013
  • Ingår i: CERN-Proceedings-2012-002. ; , s. 461-467
  • Konferensbidrag (refereegranskat)abstract
    • Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models for the description of the transport and the interaction of all components of the expected radiation field (ions, hadrons, electrons, positrons and photons). This contribution will address the specific case of the general-purpose particle and interaction code FLUKA. In this work, an application of FLUKA will be presented, i.e. establishing CT (computed tomography)-based calculations of physical and RBE (relative biological effectiveness)-weighted dose distributions in scanned carbon ion beam therapy.
  •  
29.
  • Battistoni, G., et al. (författare)
  • Generator of neutrino-nucleon interactions for the FLUKA based simulation code
  • 2009
  • Ingår i: American Institute of Physics Conference Series. - American Institute of Physics : AIP. ; , s. 343-346
  • Konferensbidrag (refereegranskat)abstract
    • An event generator of neutrino-nucleon and neutrino-nucleus interactions has been developed for the general purpose Monte Carlo code FLUKA. The generator includes options for simulating quasi-elastic interactions, the neutrino-induced resonance production and deep inelastic scattering. Moreover, it shares the hadronization routines developed earlier in the framework of the FLUKA package for simulating hadron-nucleon interactions. The simulation of neutrino-nuclear interactions makes use of the well developed PEANUT event generator implemented in FLUKA for modeling of the interactions between hadrons and nuclei. The generator has been tested in the neutrino energy range from 0 to 10 TeV and it is available in the standard FLUKA distribution. Limitations related to some particular kinematical conditions are discussed. A number of upgrades is foreseen for the generator which will optimize its applications for simulating experiments in the CNGS beam.
  •  
30.
  • Battistoni, G., et al. (författare)
  • Neutrino Interactions with FLUKA
  • 2009
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:9, s. 2491-2505
  • Tidskriftsartikel (refereegranskat)abstract
    • A new neutrino interaction generator has been developed in FLUKA. The package, called NUNDIS (NeUtrino–Nucleon Deep Inelastic Scattering), is specifically built in order to be fully integrated with the hadronization and nuclear models of the FLUKA Monte Carlo code which were already successfully tested in hadronic interactions. This generator thus complements the already existing generator of quasi-elastic neutrino scattering. Here we describe the physics, sampling methods, and other specifics of NUNDIS, as well as the limitations of the code.
  •  
31.
  • Battistoni, G., et al. (författare)
  • Secondary Cosmic Ray Particles due to GCR Interactions in the Earth’s Atmosphere
  • 2008
  • Ingår i: Exotic Nuclei and Nuclear/Particle Astrophysics (II). - American Institute of Physics : AIP. ; , s. 449-454
  • Konferensbidrag (refereegranskat)abstract
    • Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface.Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.
  •  
32.
  • Battistoni, Giuseppe, et al. (författare)
  • The Application of the Monte Carlo Code FLUKA in Radiation Protection Studies for the Large Hadron Collider
  • 2011
  • Konferensbidrag (refereegranskat)abstract
    • The multi-purpose particle interaction and transport code FLUKA is integral part of all radiation protection studies for the design and operation of the Large Hadron Collider (LHC) at CERN. It is one of the very few codes available for this type of calculations which is capable to calculate in one and the same simulation proton-proton and heavy ion collisions at LHC energies as well as the entire hadronic and electromagnetic particle cascade initiated by secondary particles in detectors and beam-line components from TeV energies down to energies of thermal neutrons. The present paper reviews these capabilities of FLUKA in sketching the relevant physics models along with examples ofradiation protection studies for the LHC such as shielding studies for underground areas occupied by personnel during LHC operation and the simulation of induced radioactivity around beam loss points. Integral part of the FLUKA development is a careful benchmarking of specific models as well as the code performance in actual, complex applications which is demonstrated with examples of studies relevant to radiation protection at the LHC.
  •  
33.
  • Battistoni, G., et al. (författare)
  • The FLUKA code and its use in hadron therapy
  • 2008
  • Ingår i: Nuovo Cimento della Societa Italiana di Fisica C. - Italian Physical Society. - 1124-1896. ; 31:1, s. 69-75
  • Tidskriftsartikel (refereegranskat)abstract
    • FLUKA is a multipurpose Monte Carto code describing transport and interaction with matter of a, large variety of particles over a wide energy range ill complex geometries. FLUKA is successfully applied ill several fields, including, but not only particle physics, cosmic-ray physics, dosimetry, radioprotection, hadron therapy. space radiation, accelerator design and neutronics. Here we briefly review recent model developments and provide examples of applications to hadron therapy, including calculation of physical and biological dose for comparison with analytical treatment planning engines as well as beta(+)-activation for therapy monitoring by means of positron emission tomography.
  •  
34.
  • Bock, David, 1976, et al. (författare)
  • Do negative intrusive thoughts at diagnosis predict impaired quality of life, depressed mood and waking up with anxiety 3, 12 and 24 months after radical prostatectomy?–a longitudinal study
  • 2020
  • Ingår i: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1805 .- 2168-1813. ; 54:3, s. 220-226
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To evaluate the effect of intrusive thoughts at diagnosis on quality of life, depressed mood and waking up with anxiety up to two years after radical prostatectomy. Method: The Laparoscopic Prostatectomy Robot Open (LAPPRO) trial was a prospective, longitudinal multicenter study of 4003 patients undergoing radical prostatectomy. Questionnaire data were collected preoperatively, at 3, 12 and 24 months after surgery. Results: The group of patients with intrusive thoughts at diagnosis had a statistically significant higher postoperative prevalence of impaired quality of life, depressed mood and waking up with anxiety as compared with the group of patients with no or minor intrusive thoughts. The highest risk increase for impaired QoL, depressed mood and waking up with anxiety ≥1/week was at 12, 3 and 3 months, respectively, where the three outcomes increased by 38% (RR: 1.38; 95%CI: 1.27–1.49)), 136% (RR: 2.36; 95%CI: 1.74–3.19)) and 165% (RR: 2.65; 95%CI: 2.22–3.17)), respectively. Conclusions: The demonstrated link between intrusive thoughts and quality of life, depressed mood and waking up with anxiety deliver is further evidence to the idea that intrusive thoughts has potential as an endpoint for assessing and predicting psychological distress among men with prostate cancer diagnosis. Trial registration number: ISRCTN06393679 (www.isrctn.com). Date of registration: 07/02/2008. Retrospectively registered. © 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
  •  
35.
  • Carlson, R. F., et al. (författare)
  • A method for measuring light ion reaction cross-sections
  • 2005
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 547:2-3, s. 541-554
  • Tidskriftsartikel (refereegranskat)abstract
    • An experimental procedure for measuring reaction cross-sections of light ions in the energy range 20 50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross-sections for five different sizes of the solid angle in steps from 99.1% to 99.8% of the total solid angle. The final reaction cross-section values are obtained by extrapolation to the full solid angle.
  •  
36.
  • Doornenbal, P., et al. (författare)
  • Spectroscopy of 32Ne and the "œIsland of Inversion"
  • 2009
  • Ingår i: Physical Review Letters. - American Physical Society. - 0031-9007 .- 1079-7114. ; 103:3, s. 032501-1-032501-4
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first spectroscopic study of the N = 22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single γ-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV=u 32Ne beam on a carbon target and proton removal from 33Na at 245 MeV=u. This transition is assigned to the deexcitation of the first Jπ = 2+ state in 32Ne to the 0+ ground state. Interpreted through comparison with state-of-the-art shell-model calculations, the low excitation energy demonstrates that the ‘‘island of inversion’’ extends to at least N = 22 for the Ne isotopes.
  •  
37.
  • Fan, G. W., et al. (författare)
  • Density distribution of 8Li and 8B$ and capture reaction at low energy
  • 2015
  • Ingår i: Phys. Rev. C. ; 91
  • Tidskriftsartikel (refereegranskat)abstract
    • Reaction cross sections of 8Li on stable targets were measured at intermediate energies. With the existing experimental data of interaction cross sections at 790 MeV/nucleon the nucleon density distribution of 8Liwas extracted by the use of the modified Glauber model. Meanwhile, the existing data of 8B have been also reanalyzed. Structures of 8Li and 8B were compared through the density. On the basis of dilute surface densities, the discussion of 7Li(n,γ)8Li and 7Be(p,γ)8B capture reactions was performed within the framework of the direct capture reaction mechanism. The calculations agreed quite well with the experimental data as well as other analyses.
  •  
38.
  • Fukuda, M., et al. (författare)
  • Reaction cross section studies at NIRS and RIBF
  • 2010
  • Ingår i: American Institute of Physics Conference Series. - American Institute of Physics : AIP. ; , s. 270-273
  • Konferensbidrag (refereegranskat)abstract
    • Reaction cross sections for stable nuclei at intermediate energies have been measured precisely and systematically. The data have been found to be reproduced nicely by the optical‐limit approximation of Glauber theory modified to include the nucleon multiple scattering effect and the Fermi‐motion effect. Applying this prescription, the nucleon density distribution of 17Ne has been studied. The surface structure of 8B and 11Be has been also studied using this prescription and hydrogen targets. Using the RIBF that has just started application to studies of exotic nuclei, neutron‐rich Ne isotopes around the Island of Inversion have been investigated through measurements of their interaction cross sections.
  •  
39.
  • Gao, Zhihao, et al. (författare)
  • Applying machine learning methods for the analysis of two-dimensional mass spectra
  • 2023
  • Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 59:169
  • Tidskriftsartikel (refereegranskat)abstract
    • In a measurement of isomeric yield-ratios in fission, the Phase-Imaging Ion-Cyclotron-Resonance technique, which projects the radial motions of ions in the Penning trap (JYFLTRAP) onto a position-sensitive micro-channel plate detector, has been applied. To obtain the yield ratio, that is the relative population of two states of an isomer pair, a novel analysis procedure has been developed to determine the number of detected ions in each state, as well as corrections for the detector efficiency and decay losses. In order to determine the population of the states in cases where their mass difference is too small to reach full separation, a Bayesian Gaussian Mixture model was implemented. The position-dependent efficiency of the micro-channel plate detector was calibrated by mapping it with 133Cs+ ions, and a Gaussian Process was trained with the position data to construct an efficiency function that could be used to correct the recorded distributions. The obtained numbers of counts of excited and ground-state ions were used to derive the isomeric yield ratio, taking into account decay losses as well as feeding from precursors.
  •  
40.
  • Gao, Zhihao, et al. (författare)
  • Benchmark of a multi-physics Monte Carlo simulation of an ionguide for neutron-induced fission products
  • 2022
  • Ingår i: European Physical Journal. - : Springer Nature. - 1286-0042 .- 1286-0050. ; 58:2
  • Tidskriftsartikel (refereegranskat)abstract
    • To enhance the production of medium-heavy,neutron-rich nuclei, and to facilitate measurements of independentyields of neutron-induced fission, a proton-toneutronconverter and a dedicated ion guide for neutroninducedfission have been developed for the IGISOL facilityat the University of Jyväskylä. The ion guide holds thefissionable targets, and the fission products emerging fromthe targets are collected in helium gas and transported to thedownstream experimental stations.Acomputer model, basedon a combination of MCNPX for modeling the neutron production,the fission code GEF, and GEANT4 for the transportof the fission products, was developed. The model willbe used to improve the setup with respect to the productionand collection of fission products. In this paper we benchmarkthe model by comparing simulations to a measurementin which fission products were implanted in foils located atdifferent positions in the ion guide. In addition, the productsfrom neutron activation in the titanium foil and the uraniumtargets are studied. The result suggests that the neutron fluxat the high-energy part of the neutron spectrum is overestimatedby approximately 40%.However, the transportation offission products in the uranium targets agrees with the experimentwithin 10%. Furthermore, the simulated transportationof fission products in the helium gas achieves almost perfectagreement with the measurement. Hence, we conclude thatthe model, after correction for the neutron flux, is well suitedfor optimization studies of future ion guide designs.
  •  
41.
  • Gao, Zhihao, et al. (författare)
  • Fission studies at IGISOL/JYFLTRAP : Simulations of the ion guide for neutron-induced fission and comparison with experimental data
  • 2020
  • Ingår i: ND 2019. - : EDP Sciences. - 9782759891061
  • Konferensbidrag (refereegranskat)abstract
    • For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation.In order to allow fission yield measurements in the low yield regions, towards the tails and in the symmetric part of the mass distribution, the stopping and extraction efficiency of the ion guide has to be significantly improved. This objective can be achieved by increasing the size while introducing electric field guidance using a combination of static electrodes and an RF-carpet. To this end, the GEANT4 model is used to optimise the design of such an ion guide.
  •  
42.
  • Gao, Zhihao (författare)
  • Isomeric yield ratios in nuclear fission
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Isomeric yield ratios (IYR), referring to the relative yield of the high spin states of a nucleus to the total yield of all observed states, is an observable of nuclear fission that has the potential to improve our understanding of the fission dynamics. Apart from that, systematic observations of IYRs can also contribute to other areas, such as the validation of fission models, modelling of the r-process in stellar nucleosynthesis, studies of the antineutrino mixing angle, the safety of present-day nuclear reactors, and the design of advanced reactor systems.With these motivations in mind, an IYR measurement in proton-induced fission was performed at the IGISOL facility in Jyväskylä, Finland. In the measurement, the Penning trap JYFLTRAP was used to separate the excited state from the ground state and to project those onto a position-sensitive MCP detector. The obtained phase images were used to train a Bayesian Gaussian Mixture model to identify the states. After considering corrections for the detector efficiency and radioactive decay, 19 IYRs were obtained.In this thesis, the measurement of IYRs with the IGISOL technique is described, and a systematic study of IYRs in proton-induced fission is presented. Furthermore, the measured ratios are compared with calculations using three different models: the Madland-England (ME) model, the fission model GEF, and the combination of GEF + TALYS. The experimental results show that, in general, the IYR decreases with the spins of measured states. While this, to some degree, confirms the ME model, variations in the IYR between nuclides with the same spin assignments reveal that the model is too simple to predict individual ratios. Furthermore,discrepancies in the IYRs between the measurement and GEF are observed in most cases, indicating a need to optimize the performance of GEF against nuclear data from proton-induced fission. The combination of GEF + TALYS results in an overall under estimation of the observedIYRs, which could be explained by the different assumptions used in GEF and TALYS.To investigate how the angular momenta of the primary fission fragments relate to the IYRs, a surrogate model of GEF has been developed. By reproducing the measured IYR with the calculated ratios from the model, the average angular momentum Jav, is deduced. The Jav for fission products with a mass number greater than 131 show a mass dependency which fits the parameterisation proposed by J. Wilson et al,. For IYRs in the mass region 119 ≤ A < 132, in which no measurements are presented by Wilson, a decrease in the Jav with increasing mass number is observed for the first time.Besides the study of IYRs, a benchmark of a multi-physics simulation model of the ion guide for neutron-induced fission products has been performed using γ-ray spectroscopy data. The results of the benchmark show that the high-energy part of the neutron flux from the simulation with MCNPX is overestimated by about 40 %, while the ion transportation simulated with GEANT4 agrees well with the experimental data. Based on the benchmark, the ion guide can be optimized to achieve high enough intensities of the collected ions to reach reasonable measurement times. In the next step, the addition of electric fields is considered to direct the ions in and to reduce the ion drifting time. However, this task lies outside the scope of this PhD thesis.
  •  
43.
  • Gao, Zhihao, et al. (författare)
  • Isomeric yield ratios in proton-induced fission of 238U
  • 2023
  • Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 108:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Isomeric yield ratios are an important observable in nuclear fission as they can guide model development by providing insight into the angular momentum generation. Furthermore, isomeric yield ratios are important in applications for nuclear energy, as well as in the study of the r-process in stellar nucleosynthesis, and in the antineutrino mixing angle from reactor spectra. In nuclear data evaluations, the Madland-England model is commonly used to estimate isomeric yield ratios that have not been measured.Purpose: To measure isomeric yield ratios in 25-MeV proton-induced fission of 238U, and to compare the result with the values obtained from the Madland-England model and the fission model code GEF. Furthermore, to evaluate whether the predictions of GEF can be improved by coupling it to the nuclear reaction code TALYS.Methods: Isomeric yield ratios in 25-MeV proton-induced fission of 238U have been measured at the Ion GuideIsotope Separate On-Line facility. The excited state and the ground state were separated by mass using the Phase-Imaging Ion-Cyclotron-Resonance technique in the double Penning trap JYFLTRAP. The number of counts of each state was extracted from the phase-images using a Bayesian Gaussian Mixture model and, after corrections fordetector efficiency and decay, the isomeric yield ratios were derived. The experimental values have been compared with the calculated results from the Madland-England model and the GEF code. Furthermore, GEF has been combined with the nuclear reaction code TALYS, in order to take advantage of the latter codes’ implementation of the Hauser-Feshbach formalism, and the results have been compared with the experimental values.Results: From the measurements, 19 new isomeric yield ratios in 25-MeV proton-induced fission of 238U are reported and are, together with another 12 isomeric yield ratios (IYRs) from a previous campaign, compared with the model calculations. It is shown that, though the models manage to capture some of the features observed, there is room for improvement.Conclusions: As predicted by the Madland-England model, a strong correlation between the measured IYRs and the spins of the long-lived states of the fission products is confirmed. However, the IYRs also vary between nuclides with the same spin-parity of the two states, and systematic trends in the IYRs of close-lying isotopes and isotones with similar nuclear configurations are observed.From the comparison of the experimental data with the prediction of GEF it is concluded that more data from proton-induced fission are needed to optimize the internal parameters of GEF. Furthermore, using a combination of GEF and TALYS in most cases results in an underestimation of the yield ratios. This might be explained by an underestimation of the angular momentum on the initial fission fragments by GEF. Altogether, these results highlight the possibility to use measurements of IYRs to improve model predictions and to study the angular momentum generation in nuclear fission.
  •  
44.
  • Gao, Zhihao, et al. (författare)
  • New design and simulation of the ion guide for neutron-induced fission products at the IGISOL facility
  • 2023
  • Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 284
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements of independent fission yield distributions in neutron-induced fission at high neutron energies are important for our fundamental understanding of the fission process, and are also relevant for reactor physics applications. So far, measurements of independent fission yields in proton-induced fission have been performed at the IGISOL facility at the University of Jyväskylä, using the Penning trap as a high resolving-power mass-filter. In order to also facilitate measurements of neutron-induced fission, a dedicated ion guide and a proton-to-neutron converter was developed. However, the first measurement indicates that fewer fission products than expected reach the Penning trap. To explore potential reasons and possible improvements, a simulation model was also developed and benchmarked. The benchmark showed that the model is able to reproduce the performance of the ion guide remarkably well and that the main reason for the low yield of fission products is the low collection efficiency of the ion guide.Based on the benchmark, a new ion guide is being designed. In the new design, the positions of the uranium targets and volume of the ion guide have been changed to increase the collection of fission products. This results in a five-fold increase of the yield. However, the collection efficiency of the new ion guide still needs to be improved in order to achieve intensities of the extracted fission products that are large enough to allow for reasonable measurement times.Because the volume of the ion guide is increased significantly, the extraction time of the ions is expected to be longer than that from the previous ion guide. Therefore, an electric field guidance system that consists of a combination of a stationary electric field and an RF-carpet is considered to be deployed. The stationary field, produced from a set of DC-ring electrodes, accelerates the ions towards the RF-carpet at end plate of the ion guide. The RF-carpet consists of a time-dependent field, produced from a radio-frequent structure of concentric rings, with a DC-component that guides the ions towards the exit hole in the center of the end plate. In this paper we present the current status of the simulations and design of the new ion guide.
  •  
45.
  • Gengelbach, Aila (författare)
  • Collectivity in Neutron-Rich Erbium Isotopes
  • 2021
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Neutron-rich rare-earth nuclei around the maximum of collectivity are predicted to exist with an extremely stable intrinsic configuration in their ground-state structure. Due to the high degree of axial symmetry and large deformation, these nuclei are also excellent candidates for having long-lived high-K isomers. The present work concerns a study of the structure of the yrast bands and a search for isomers in the neutron-rich 68Er isotopes. Excited states of 68Er isotopes were populated via multi-nucleon transfer reactions.A 859 MeV 136Xe-beam was used to bombard a 170Er-target. The experimental setup consisted of the high-resolution γ-ray spectrometer AGATA coupled to the heavy-ion magnetic spectrometer PRISMA. The experiment collected 2 TB of useful data corresponding to 3 days of effective beam time.Beam-like fragments were identified by the PRISMA specrometer placed at the grazing angle of 44 degrees. PRISMA allows for Z, A and q identification as well as TOF and velocity vector determination. This is required for the Doppler correction of the emitted γ rays detected in time coincidence with AGATA. A good Z and very clean A separation has been achieved in PRISMA. Making use of two-body kinematics, Doppler corrected γ-ray spectra for target-like fragments were obtained as well.Due to the novel techniques of PSA and γ-ray tracking, AGATA provided high-quality γ-ray spectra for both beam-like xenon and target-like erbium isotopes. Known yrast bands and isomeric states in neutron-rich erbium isotopes were observed. A candidate for the decay of an isomeric state with Eγ=184 keV  in 173Er, which has no previously known excited states, was identified.
  •  
46.
  •  
47.
  • Gorelov, D., et al. (författare)
  • Developments for neutron-induced fission at IGISOL-4
  • 2016
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584.
  • Tidskriftsartikel (refereegranskat)abstract
    • Abstract At the IGISOL-4 facility, neutron-rich, medium mass nuclei have usually been produced via charged particle-induced fission of natural uranium and thorium. Neutron-induced fission is expected to have a higher production cross section of the most neutron-rich species. Development of a neutron source along with a new ion guide continues to be one of the major goals since the commissioning of IGISOL-4. Neutron intensities at different angles from a beryllium neutron source have been measured in an on-line experiment with a 30 MeV proton beam. Recently, the new ion guide coupled to the neutron source has been tested as well. Details of the neutron source and ion guide design together with preliminary results from the first neutron-induced fission experiment at IGISOL-4 are presented in this report.
  •  
48.
  • Gorelov, D., et al. (författare)
  • Isomeric Yield Ratios of Fission Products Measured with the Jyfltrap
  • 2014
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 45:2, s. 211-216
  • Tidskriftsartikel (refereegranskat)abstract
    • Experimental methods to determine isomeric yield ratios usually apply gamma-spectroscopic techniques. In such methods, ground and isomeric states are distinguished by their decays. In the present work, several isomeric yield ratios of fission products have been measured by utilizing capabilities of the double Penning-trap mass spectrometer JYFLTRAP, where isomeric and ground state were separated by their masses. To verify the new experimental technique, the results were compared to those from gamma-spectroscopy measurements.
  •  
49.
  • Gorelov, D., et al. (författare)
  • Measurement of Isomeric Yield Ratios of Fission Products with the Jyfltrap
  • 2014
  • Ingår i: Fission and Properties of Neutron-Rich Nuclei - Proceedings of the Fifth International Conference on ICFN5. Edited by Hamilton Joseph H &amp; Ramayya Akunuri V. Published by World Scientific Publishing Co. Pte. Ltd., 2014. ISBN #9789814525435, pp. 252-257. - : WORLD SCIENTIFIC. ; , s. 252-257
  • Konferensbidrag (refereegranskat)
  •  
50.
  • Gorelov, D., et al. (författare)
  • Measuring independent yields of fission products using a penning trap
  • 2015
  • Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 79:7, s. 869-871
  • Tidskriftsartikel (refereegranskat)abstract
    • A new method for determining independent fission products is used in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The method combines the chemical universality of the ion guide technique and the unique properties of the Penning trap. A beam of charged particles is formed by stopping fission products in gaseous helium. The Penning trap is employed as a highly accurate filter to identify particles by their mass. The yields of fission products are determined by the ion count downstream of the trap. The setup’s mass resolving power is on the order of 105 with a radio frequency excitation time of 400 ms. Such high mass resolution occasionally allows us not only to separate nuclides but to separate the isomeric and ground states of nuclei as well. Independent yields of fission products are measured in the fission reaction of the 232Th isotope by protons with an energy of 25 MeV. A short description of the method ae nd soexperimental data are supplememnted by the results fro theoretical calculations.
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