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1.
  • Asztalos, S. J., et al. (författare)
  • Isotopic yields of neutron-rich nuclei from deep-inelastic reactions
  • 2000
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 6101:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We follow up on our earlier work involving a light projectile (Ca-48) to populate high spin states in neutron-rich nuclei with results from experiments involving a heavier projectile (Sm-154) fur the purposes of studying isotopic yields. These yields, which in some cases were mensurable down to a level of 0.1 of the total reaction cross section, are presented from three separate reactions. A trend in the isotopic yields towards N/Z equilibration is observed in one experiment having a large disparity in N/Z ratios between the projectile and target. In the two other reactions, where the N/Z driving force is less pronounced, the yields are instead clustered around the projectile and target nuclei. We present correlated projectilelike and targetlike fragment isotopic yields derived from gamma-gamma coincidences, a technique that enables one to partition the yield of an isotope according to the amount of neutron evaporation. Using this method we find that for the zero-neutron evaporation channel transfer occurs predominantly into the light fragment, consistent with the nature of the deep-inelastic mechanism. We further find that multiple-neutron evaporation contributes substantially to the yields of the isotopes.
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2.
  • Blazhev, A., et al. (författare)
  • Observation of a core-excited E4 isomer in Cd-98
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69
  • Tidskriftsartikel (refereegranskat)abstract
    • A core-excited I-pi=(12(+)) spin-gap isomer was identified in Cd-98 in an experiment at EUROBALL IV. It was found to feed the known I-pi=(8(+)) seniority isomer by an E4 transition. Half-lives of T-1/2=0.23 ((+4)(-3)) mus and 0.17 ((+6)(-4)) mus were measured for the two states at E-x=6635 keV and 2428 keV, respectively. From the excitation energy of the core-excited isomer a Sn-100 shell gap of 6.46(15) MeV is inferred. The measured E4 and E2 strengths, Sn-100 core excitations and the origin of empirical polarization charges are discussed in the framework of large-scale shell model calculations. An E2 polarization charge for protons of deltae(pi)
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3.
  • Bäck, Torbjörn, et al. (författare)
  • A TOF-PET system for educational purposes
  • 2002
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 477, s. 82-82
  • Tidskriftsartikel (refereegranskat)abstract
    • A TOF-PET system has been designed and constructed for educational purposes. The aim of this system is to demonstrate the possibilities of positron emission tomography in general and the time-of-flight method in particular to the students of various courses at the Royal Institute of Technology, Stockholm, Sweden. The set-up consists of 48 small BaF2 crystals coupled to fast photomultipliers placed in a ring geometry. The signals of the photomultipliers are fed into fast constant fraction discriminators (CFD). The outputs of these are directed to a specially designed logic VME unit. which combines the CFD signals of 6 neighbouring channels to one signal by adding a different delay to each channel. The logic circuitry produces a prompt pulse for each event that serves as the start pulse for the 8-channel fast TDC. The delayed pulses act as the stop pulses for the TDC. In a computer. the measured times are converted into information about which the photomultipliers fired with the difference in the time of flight. The set-up is described and the results are presented.
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4.
  • Bäck, Torbjörn, et al. (författare)
  • An educational tool for demonstrating the TOF-PET technique
  • 2001
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : AMERICAN PHYSICAL SOC. - 0168-9002 .- 1872-9576. ; 471:1-2, s. 200-204
  • Tidskriftsartikel (refereegranskat)abstract
    • A detector system for positron emission tomography with time-of-flight capability has been built to serve as an educational tool for undergraduate students. The set-up consists of 48 BaF2 scintillator crystals, each coupled to a fast photo-multiplier tube, mounted in a circular geometry. The analogue detector pulses are handled by fast constant fraction discriminators. A dedicated unit reduces the 48 channels to eight channels via delay-fine encoding, and the signals are then fed to an eight channel fast time-to-digital converter. A VME processor sorts the events and sends them to a workstation where the coincident events are extracted. The time resolution of the detectors together with fast VME based electronics allows for time-of-flight measurements to improve on the signal-to-noise ratio in the, reconstructed images. The system can be used for different types of exercises for the students, varying from the fundamentals of scintillator detectors to advanced image reconstruction. The set-up is described and some results are presented. (C) 2001 Elsevier Science B.V. All rights reserved.
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5.
  • Bäck, Torbjörn, et al. (författare)
  • First observation of gamma-rays from the proton emitter Au-171
  • 2003
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 16:4, s. 489-494
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-rays from the alpha- and proton-unstable nuclide Au-171 have been observed for the first time. The gamma-rays were correlated with both a proton- and an alpha-particle decay branch, confirming that the nucleus decays by alpha and proton emission from a single (11/2(-)) state. The measurement confirms the previously determined half-lives for these particle decays but the present values are of higher precision. In addition, a longer half-life than determined in previous work was measured for the proton-unstable tentative ground state. The results are discussed in relation to structures in neighbouring nuclei and compared with a Strutinsky-type TRS calculation.
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6.
  • Bäck, Torbjörn, et al. (författare)
  • Spectroscopy of the neutron-deficient nuclide Pt-171
  • 2003
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 17:1, s. 1-5
  • Tidskriftsartikel (refereegranskat)abstract
    • A number of previously unobserved gamma-rays emitted from the neutron-deficient nuclide Pt-171 have been identified using the recoil decay tagging technique. The level scheme has been updated using information from gamma-gamma coincidences and angular distribution measurements. To further confirm the assignments of the gamma-rays to Pt-171, the events were correlated with the alpha-decay of the daughter nucleus Os-167.
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7.
  • Fahlander, Claes, et al. (författare)
  • Excited States in 103Sn: Neutron Single-particle Energies with Respect to 100Sn
  • 2001
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 63:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray lines from Sn-103 have been identified for the first time using EUROBALL and ancillary detectors. The level scheme of Sn-103 has been established by means of particle-gated gamma gamma coincidences. The energy spacing between the g(7/2) and d(5/2) neutron single-particle orbitals is determined from the excited states in Sn-103.
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8.
  • Gono, Y., et al. (författare)
  • Systematics of high-spin isomers in N=83 isotones and a high-spin isomer beam
  • 2002
  • Ingår i: European Physical Journal A. - 1434-6001 .- 1434-601X. ; 13:02-jan, s. 5-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Isomers in N = 83 isotones of Z = 60 66 were studied systematically. Their spins and parities arc,49/2(+) and 27(+) for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a Z = 64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are [v(f(tau/2)h(9/2)i(13/2)), pi(h(11/2))(2)](49/2+) and [v(f(7/2)h(9/2)i(13/2)), pi(h(11/2))(2)(d(5/2))(-1)](27+) for odd and odd-odd nuclei, respectively. The shape of the yrast status changes suddenly at spin 49/2(odd) and 27(odd-odd) from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also described.
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9.
  • Hadinia, Baharak, et al. (författare)
  • First identification of gamma-ray transitions in 107Te
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:6, s. 064314-1-064314-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray transitions in Te-107 have been identified for the first time. The experiment, which utilized the recoil decay tagging technique, was performed at the accelerator laboratory of the University of Jyvaskyla, Finland. Prompt gamma rays produced in Ni-58(Cr-52,3n)Te-107(*) reactions were detected by the JUROGAM gamma-ray spectrometer. The gamma rays belonging to Te-107 were selected based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. A first excited state at 90 keV, tentatively of g(7/2) character, is proposed.
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10.
  • Ideguchi, E., et al. (författare)
  • Position sensitivity of a segmented planar Ge detector
  • 2003
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 496:03-feb, s. 373-384
  • Tidskriftsartikel (refereegranskat)abstract
    • A method to extract depth of interaction information for gamma-rays in a segmented planar Ge detector is presented. The method is demonstrated on signals from a segmented detector which were stored by a digital oscilloscope event by event and analysed off-line. Event samples were acquired for different interaction points in the detector. A Compton scatter coincidence detection technique ensured that the event samples were highly enriched in single-interaction events. By analysing pulse shapes and the relative timing between anode pulses and the pulses from the irradiated cathode segment, a position sensitivity of 1-2 mm in the depth direction was deduced. A similar transverse position sensitivity was inferred by studying image charge pulses on neighbouring segments.
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11.
  • Ideguchi, Eiji, et al. (författare)
  • Superdeformation in 91Tc
  • 2000
  • Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 492:3-4, s. 245-253
  • Tidskriftsartikel (refereegranskat)abstract
    • A high-spin rotational band with 11 gamma -ray transitions has barn observed in Tc-91. The dynamical moment of inertia as well as the transition quadrupole moment of 8.1(-1.4)(+1.9) eb measured for this band show the characteristics of a superdeformed band. However, the shape is more elongated than in the neighbouring A = 80-90 superdeformed nuclei. Theoretical interpretations of the band within the cranked Strutinsky approach based on two different Woods-Saxon potential parameterisations are presented. Even though an unambiguous configuration assignment proved difficult, both calculations indicate a larger deformation and at least three additional high-N intruder orbitals occupied compared to the lighter SD nuclei. (C) 2000 Elsevier Science B.V. All rights reserved.
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12.
  • Joss, D. T., et al. (författare)
  • Identification of excited states in Os-167 and Os-168 : shape coexistence at extreme neutron deficiency
  • 2001
  • Ingår i: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 689:04-mar, s. 631-654
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the very neutron-deficient isotopes Os-167 and Os-168 have been observed using the reaction Sn-112(Ni-58, 2pxn). The JUROSPHERE gamma -ray spectrometer array was used in conjunction with the RITU gas-filled recoil separator to collect prompt gamma radiation in coincidence with recoils implanted in a silicon strip detector located at the focal plane of RITU. Using a selective recoil decay tagging technique it has been possible to unambiguously assign gamma -ray transitions to Os-167 and Os-168 through the characteristic a radioactivity of these nuclides. The high-spin structure of the bands is discussed in terms of quasiparticle configurations within the framework of the cranked shell model. The role of shape coexistence in Os-168 is examined with phenomenological three-band mixing calculations.
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13.
  • Joss, D. T., et al. (författare)
  • Recoil decay tagging of gamma rays in the extremely neutron-deficient nucleus Os-162
  • 2004
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 70:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The neutron-deficient nucleus Os-162, produced in the Cd-106(Ni-58,2n) reaction, has been studied using the JUROGAM gamma-ray spectrometer in conjunction with the RITU gas-filled separator and the GREAT focal plane spectrometer. gamma-ray transitions in Os-162 have been assigned for the first time through the application of the recoil decay tagging technique. The excitation energy of the 2(+) state and the tentative energy of the 8(+) state are discussed in terms of the systematic energy trends as the N=82 shell gap is approached.
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14.
  • Joss, D. T., et al. (författare)
  • Strongly coupled bands in the neutron-deficient nucleus Re-167
  • 2003
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 68:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the neutron-deficient nucleus Re-167 have been observed in a recoil-tagging experiment performed with the Jurosphere gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator. The low-spin yrast band, based on a proton h(11/2) orbital, comprises a strongly coupled band and exhibits significant signature splitting, indicative of a triaxial shape with gamma<0degrees. At higher spin the rotational alignment of a pair of i(13/2) neutrons induces a transition to an axial prolate shape resulting in a drastic reduction of the signature splitting. Two other strongly coupled bands have been established and their structures are discussed in terms of quasiparticle configurations.
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15.
  • Joss, D. T., et al. (författare)
  • Yrast spectroscopy in the neutron-deficient nucleus Os-169
  • 2002
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the neutron-deficient isotope Os-169 have been identified for the first time in an experiment using the Jurosphere gamma-ray spectrometer in conjunction with the Ritu gas-filled recoil separator. The problems associated with identifying neutron-deficient isotopes produced with low fusion cross sections against a high background of competing channels, including fission, have been overcome by using the recoil-decay tagging technique. The band structures observed in Os-169 are interpreted in the context of the systematics of neighboring nuclei and the predictions of cranked Woods-Saxon calculations. The systematics of the second (i(13/2))(2) neutron alignment in this region are discussed.
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16.
  • Kishida, T., et al. (författare)
  • High-spin isomeric beam line
  • 2002
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 484:03-jan, s. 45-55
  • Tidskriftsartikel (refereegranskat)abstract
    • A high-spin isomeric beam line has been constructed at RIKEN based on the inverse kinematics of fusion-evaporation reactions. The beam line provides high-spin isomers as secondary beams, whose intensity is more than 10(5) sec(-1). The characteristics and the present status of the beam line are described.
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17.
  • Klamra, Wlodzimierz, et al. (författare)
  • High-spin multiparticle-hole excitations in Eu-148
  • 2001
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 10:1, s. 11-12
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies by means of 155 MeV Al-27 bombardment on a Te-130 target revealed in Eu-148 high-spin structures up to spin 31 (n) over tilde, in addition to a cascade extended to the 11088.1 keV excitation. The observed levels are tentatively assigned as complex multiparticle-hole proton and neutron configurations.
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18.
  • Lagergren, K, et al. (författare)
  • Coexistence of superdeformed shapes in Er-154
  • 2001
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 8702:2
  • Tidskriftsartikel (refereegranskat)abstract
    • A new superdeformed rotational band has been observed in Er-154 using the Euroball Ge detector array. The new band and the one previously observed can be understood as based on coexisting superdeformed structures at prolate and triaxial shapes, respectively. The observation resolves long-standing difficulties in the theoretical interpretation of superdeformed states in Er-154.
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19.
  • Lagergren, K, et al. (författare)
  • Evidence for excited states in Ag-95
  • 2002
  • Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 14:4, s. 393-396
  • Tidskriftsartikel (refereegranskat)abstract
    • The first evidence for excited states in Ag-95 is presented. Ag-95 is the heaviest T-z = 1/2 nucleus for which gamma-rays have been identified. The reaction Ca-40(Ni-58, 1p2n)Ag-95 was used in the experiment, which resulted in the assignment of three gamma-rays to Ag-95. A detector system consisting of the detector arrays Euroball, Neutron Wall and Euclides was used to detect gamma-rays, neutrons and charged particles, respectively.
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20.
  • Lagergren, Karin, et al. (författare)
  • Experimental evidence for tunneling in the decay of superdeformed states
  • 2004
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 21:2, s. 175-177
  • Tidskriftsartikel (refereegranskat)abstract
    • A systematic study of the depopulation of superdeformed rotational bands in neutron-deficient A approximate to 80-90 nuclei has been performed. We observed a correlation between the rotational frequency at which the decay out of the superdeformed bands takes place and the difference between the transition quadrupole moments of states in the superdeformed bands and high-lying states with normal deformation. The observation may constitute direct experimental evidence that the commonly adopted tunneling picture for the decay of superdeformed states is valid.
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21.
  • Lagergren, Karin, et al. (författare)
  • Isospectral superdeformed bands in the N=46 nuclei Mo-88 and Tc-89
  • 2004
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 21:3, s. 375-381
  • Tidskriftsartikel (refereegranskat)abstract
    • Superdeformed bands in Mo-88 and Tc-89 were populated Using Ca-40-induced fusion-evaporation reactions on Ni-58 at a beam energy of 185 MeV. Gamma-rays emitted in the reactions were detected using the Gammasphere spectrometer, in coincidence with charged particles detected by the Microball array. A new superdeformed band was assigned to the nucleus Mo-88, leading to a revisit of earlier configuration assignments for superdeformed structures in this nucleus. In particular, the theoretical interpretation of a pair of identical (isospectral) superdeformed bands in Mo-88/Tc-89 is discussed. The configurations that are assigned to the four SD bands belonging to Mo-88 have properties that are predicted to be significantly affected by pair correlations.
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22.
  • Lagergren, Karin, et al. (författare)
  • Shape evolution in the superdeformed A approximate to 80-90 mass region
  • 2003
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 68:6, s. 643091-643095
  • Tidskriftsartikel (refereegranskat)abstract
    • Superdeformed bands in Mo-88, Tc-89, and Tc-91 were populated using a Ca-40 beam with an energy of 185 MeV, impinging on a backed Ni-58 target. gamma rays and charged particles emitted in the reactions were detected using the Gammasphere Ge detector array and the CsI(TI) array Microball. Average transition quadrupole moments Q(t) with significantly improved accuracy compared to earlier work, were deduced for the bands using the residual doppler shift technique. The experimental results were included into a systematic study of the Q(t) values throughout the superdeformed mass 80-90 region. The superdeformed shell gaps are predicted to move towards larger deformations with increasing Z and N in this mass region. This trend is confirmed by the experimental Q(t) values.
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23.
  • Lieder, R. M., et al. (författare)
  • Development of gamma-ray tracking detectors
  • 2001
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 32:9, s. 2395-2401
  • Tidskriftsartikel (refereegranskat)abstract
    • The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy AGATA will consist of gamma -ray tracking detectors. They represent high-fold segmented Ge detectors and a front-end electronics, based on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions on the basis of the Compton-scattering formula.
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24.
  • Lieder, R M, et al. (författare)
  • Gamma-ray tracking arrays
  • 2001
  • Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 46. ; , s. 399-407
  • Konferensbidrag (refereegranskat)abstract
    • The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.
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25.
  • Lieder, R. M., et al. (författare)
  • The TMR network project Development of gamma-ray tracking detectors
  • 2001
  • Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 682, s. 279C-285C
  • Tidskriftsartikel (refereegranskat)abstract
    • The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve gamma -ray tracking detectors. They consist of high-fold segmented Ge detectors and a front-end electronics, based on new digital signal processing techniques, which allows to extract energy, timing and spatial information for a gamma -ray by pulse shape analysis of the Ge detector signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.
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26.
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27.
  • Milechina, L., et al. (författare)
  • Improvements in gamma-ray reconstruction with positive sensitive Ge detectors using the backtracking method
  • 2003
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 508:3, s. 394-403
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma-ray tracking, a new detection technique for nuclear spectroscopy, requires efficient algorithms for reconstructing the interaction paths of multiple gamma rays in a detector volume. In the present work, we discuss the effect of the atomic electron momentum distribution in Ge as well as employment of different types of figure-of-merit within the context of the so called backtracking method.
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28.
  • Milechina, Larissa, et al. (författare)
  • Performance considerations for gamma-ray tracking detectors
  • 2004
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 525:02-jan, s. 208-212
  • Tidskriftsartikel (refereegranskat)abstract
    • The newly developed Ge detector segmentation technology together with state-of-the-art digital signal processing allow to define the locations of gamma-ray interaction points as well as the deposited energies in these points. Using this information, it is possible to reconstruct the paths of gamma-rays that are fully absorbed by a Ge detector array. The sum of the deposited energies of the interaction points along a track gives the initial energy of the gamma-ray, whereas the kinematics of the scattering process provides information about its initial direction. At present a few gamma-ray tracking algorithms are under development. In this work, reconstruction results obtained with the backtracking algorithm are presented. The effect of an energy dependence of the position uncertainty on the reconstruction results is shown. An attempt to recover single photointeraction events is also presented. The influence of the atomic-electron momentum on the reconstruction performance in the backtracking and clusterisation algorithms is furthermore discussed.
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29.
  • Mårtensson, Lars, 1970- (författare)
  • CdTe detectors and the Mössbauer effect in ¹²⁵Te : investigations for an axion search
  • 2001
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The use of CdTe crystals as radiation detectors is hampered by the drift properties of charge carriers in CdTe, that make the response depend on the interaction point in the detector crystal. To remedy these effects a detailed model of the signal formation process in such detectors was developed and fitted to sampled pulse shapes. A new data collection system for sampled pulse-shape data and algorithms for automatic fitting of the pulse-shape model to such data were developed.A CdTe detector was applied in Mössbauer spectroscopy with the 35.5 keV transition in 125Te. The probability of recoilless emission was determined in Mg3TeO6, a material allowing room-temperature Mössbauer measurements with the 125Te transition.These studies were performed as a preparation for an experiment searching for axions using the Mössbauer effect.
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30.
  • Palacz, M., et al. (författare)
  • Investigations of Neutron Deficient Nuclei Close to 100Sn with EUROBALL
  • 2001
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254 .- 1509-5770. ; 32, s. 999-1003
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of nuclei in the vicinity of Sn-100 have been studied using: the EUROBALL detector array. Gamma-ray lines from Sn-103 have been identified for the first time, and a level scheme of low-lying excited states of Sn-103 has been established. New constraints on energies of single particle orbitals with respect to the Sn-100 core are obtained.
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31.
  • Podolyak, Z., et al. (författare)
  • gamma-ray spectroscopy with a He-8 beam
  • 2003
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 511:3, s. 354-359
  • Tidskriftsartikel (refereegranskat)abstract
    • The He-8 + Pb-208 reaction was studied in the first experiment with the EXOGAM germanium detector array using beam delivered by the SPIRAL facility. gamma-rays from direct and fusion-evaporation reactions were observed with high resolution. gamma-gamma coincidence data were obtained at a beam intensity level of 105 8He particles per second. Specially designed absorbers and beam detectors could further reduce the background radiation by orders of magnitude.
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32.
  • Singh, A. K., et al. (författare)
  • Detailed study of magnetic rotation in (196)pb
  • 2002
  • Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 707:02-jan, s. 3-31
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Pb-196 have been populated in two different heavy-ion-induced reactions using thin and Au-backed targets, respectively. Gamma-ray coincidences were measured using the EUROBALL spectrometer array. Five new magnetic-rotational bands have been found. The previously known four bands have been extended and some of their levels have been reordered. With one exception, all the bands have been connected to lower-lying states and excitation energies, spins and parities have been determined. From the systematic properties of the bands and from comparison to tilted-axis cranking calculations, arguments for configuration assignments to the bands are derived. It is suggested that the bands are based on proton 11(-) and 8(+) particle states coupled to various neutron-hole excitations.
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33.
  • Slunga, E., et al. (författare)
  • Scintillation response of BaF2 and YAlO3 : Ce (YAP : Ce) to energetic ions
  • 2001
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 469:1, s. 70-76
  • Tidskriftsartikel (refereegranskat)abstract
    • The scintillation response of BaF2 and YAP: Ce to protons. a particles, O-16 and Si-28 ions in the 5-30 MeV range has been investigated. The ratio between the fast and slow parts of the scintillator signal for BaF2 has been used to separate protons, a particles and heavier ions, and the dependence of this ratio on the particle energy has been studied. The time constants and intensities of the two components of the YAP: Ce signal were measured, as were the time constant and intensity of the weak component of the slow part of the BaF2 signal. Furthermore, the dependence of the light yield on the particle energy has been investigated for both BaF2 and YAP: Ce.
  •  
34.
  • Sohler, Dola, et al. (författare)
  • First identification of excited states in the T-z=1/2 nucleus Pd-93
  • 2004
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 19:2, s. 169-172
  • Tidskriftsartikel (refereegranskat)abstract
    • The first experimental information about excited states in the N=Z+1 nucleus Pd-93 is presented. The experiment was performed using a 205 MeV Ni-58 beam from the Vivitron accelerator at IReS, Strasbourg, impinging on a bismuth-backed Ca-40 target. Gamma-rays, neutrons and charged particles emitted in the reactions were detected using the Ge detector array Euroball, the Neutron Wall liquid-scintillator array and the Euclides Si charged-particle detector system. The experimental level scheme is compared with the results of new shell model calculations which predict a coupling scheme with aligned neutron-proton pairs to greatly influence the level structure of Napproximate toZ nuclei at low excitation energies.
  •  
35.
  • Sohler, D, et al. (författare)
  • Neutron Excitations Across the N=50 Shell Gap in 102In
  • 2002
  • Ingår i: Nuclear Physics, Section A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 708:3-4, s. 181-189
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of In-102 has been investigated by in-beam gamma-spectroscopic methods. Knowledge on the excited states of this nucleus has significantly been extended. Three cascades of transitions were observed to exceed the spin-energy domain spanned by the pig(9/2)(-1)v(d(5/2),g(7/2))(3) configurations. The new high spin states at similar to 4 MeV excitation energy could be assigned to the pig(9/2)(-1)v(d(5/2), g(7/2))(2)h (11/2) configuration, while at least those at 4.733, 5.192 and 5.853 MeV most likely arise from the vg(9/2) --> vd(5/2), g(7/2) one-particle-one-hole excitation across the N = 50 shell closure.
  •  
36.
  • van der Marel, J., et al. (författare)
  • Collimatorless imaging of gamma rays with help of gamma-ray tracking
  • 2001
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 471:02-jan, s. 276-280
  • Tidskriftsartikel (refereegranskat)abstract
    • In many gamma-ray detector systems that are built for imaging purposes Compton scattered photons are suppressed as much as possible. However, the information from photons that scattered inside a detector system can be used to reconstruct the tracks of the photons with help of gamma-ray tracking. Estimates of the incident directions of the photons can be made and an image can be created. Examples of potential applications for this technique are the use as a gamma-camera in medical imaging (e.g. SPECT) or as a detector for PET. Due to the omission of collimators, much higher detection efficiencies can be achieved, reducing the doses required for an image. A gamma-ray tracking method, called backtracking, has been developed for nuclear spectroscopy. The method tracks gamma-rays originating from a point source in the center of a spherical detector system consisting of position-sensitive germanium detectors. This method can also be used as a tracking technique for imaging of an unknown source distribution. With help of Monte Carlo simulations the method has been investigated for simple test cases with one or two planar detectors and one or two point sources. The results-show that the sources can be located accurately in three dimensions.
  •  
37.
  • van der Marel, J., et al. (författare)
  • gamma-ray tracking in germanium : the backtracking method
  • 2002
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 477:03-jan, s. 391-396
  • Tidskriftsartikel (refereegranskat)abstract
    • In the framework of a European TMR network project the concept for a gamma-ray tracking array is being developed for nuclear physics spectroscopy in the energy range of similar to 10 keV up to several MeV. The tracking array will consist of a large number of position-sensitive germanium detectors in a spherical geometry around a target. Due to the high segmentation, a Compton scattered gamma-ray will deposit energy in several different segments. A method has been developed to reconstruct the tracks of multiple coincident gamma-rays and to find their initial energies. By starting from the final point the track can be reconstructed backwards to the origin with the help of the photoelectric and Compton cross-sections and the Compton scatter formula. Every reconstructed track is given a figure of merit, thus allowing suppression of wrongly reconstructed tracks and gamma-rays that have scattered out of the detector system. This so-called backtracking method has been tested on simulated events in a shell-like geometry for germanium and in planar geometries for silicon, germanium and CdTe.
  •  
38.
  • Wang, S. Y., et al. (författare)
  • High-spin level scheme of Cs-126
  • 2004
  • Ingår i: Gaoneng wuli yu he wuli. - 0254-3052. ; 28:5, s. 491-494
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states of Cs-126 have been populated via the Cd-116(N-14, 4n) Cs-126 reaction. The experiment was performed at Niels Bohr Institute in Denmark in 1991. After careful data analysis, most of the previously-known bands have been pushed up to much higher spins and 3 new rotational sequences have been identified. Spin, parity and configuration assignments are tentatively proposed for all of the observed bands.
  •  
39.
  • Wang, S. Y., et al. (författare)
  • Structure of the pi g(7/2) 404 7/2(+) band in odd proton nucleus I-123
  • 2004
  • Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 21:6, s. 1024-1026
  • Tidskriftsartikel (refereegranskat)abstract
    • High spin states of the odd proton nucleus I-123 have been populated in the reaction Cd-116(N-14, 5n2p) at a beam energy of 65 MeV. Two previously known positive-parity DeltaI = 2 sequences have been extended up to 31/2(+) and 41/2(+). In addition, a number of DeltaI = 1 transitions linking the two DeltaI = 2 sequences have been observed. It is suggested that both the DeltaI = 2 sequences are built upon the oblate pi(g) (7/2)[404]7/2(+) Nilsson configuration.
  •  
40.
  • Watanabe, H., et al. (författare)
  • Application of the high-spin isomer beams to the secondary fusion reaction and the measurement of g-factor
  • 2004
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 746, s. 540C-543C
  • Tidskriftsartikel (refereegranskat)abstract
    • A technique for providing high-spin isomers as probes of the fusion reaction and the measurement of g-factor has been worked out at RIKEN. In the study of the fusion reaction C-12(Sm-145m,xn)Er157-x, the gamma rays emitted from the fusion-evaporation residue Er-154 have been successfully observed. The nuclear g-factor of the T-1/2 = 28 ns high-spin isomer in Dy-149 has been measured with the gamma-ray TDPAD method.
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