1. |
- Pietras, B., et al.
(author)
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First testing of the CALIFA Barrel Demonstrator
- 2016
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 814, s. 56-65
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Journal article (peer-reviewed)abstract
- Advancement of the CALIFA calorimeter project has reached a new milestone with the construction of the first modules of the CALIFA Demonstrator, ultimately to be integrated into the final calorimeter. Aspects and methods of detector optimisation will be discussed, along with characterisation using proton beams of 70
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2. |
- Cabanelas, P., et al.
(author)
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Commissioning of the CALIFA Barrel Calorimeter of the R 3 B Experiment at FAIR
- 2020
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1667:1
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Conference paper (peer-reviewed)abstract
- CALIFA is the high efficiency and energy resolution calorimeter for the R3B experiment at FAIR, intended for detecting high energy charged particles and γ-rays in inverse kinematics direct reactions. It surrounds the reaction target in a segmented configuration of Barrel and Forward End-Cap pieces. The CALIFA Barrel consists of 1952 detection units made of CsI(Tl) long-shaped scintillator crystals, and it is being commissioned during the Phase0 experiments at FAIR. The first setup for the CALIFA Barrel commissioning is presented here. Results of detector performance with γ-rays are obtained, and show that the system fulfills the design requirements.
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3. |
- Cabanelas, P., et al.
(author)
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Performance recovery of long CsI(Tl) scintillator crystals with APD-based readout
- 2020
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 965
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Journal article (peer-reviewed)abstract
- CALIFA is the high efficiency and energy resolution calorimeter for the R3B experiment at FAIR, intended for detecting high energy light charged particles and gamma rays in scattering experiments, and is being commissioned during the Phase-0 experiments at FAIR, between 2018 and 2020. It surrounds the reaction target in a segmented configuration with 2432 detection units made of long CsI(Tl) finger-shaped scintillator crystals. CALIFA has a 10 year intended operational lifetime as the R3B calorimeter, necessitating measures to be taken to ensure enduring performance. In this paper we present a systematic study of two groups of 6 different detection units of the CALIFA detector after more than four years of operation. The energy resolution and light output yield are evaluated under different conditions. Tests cover the aging of the first detector units assembled and investigates recovery procedures for degraded detection units. A possible reason for the observed degradation is given, pointing to the crystal-APD coupling.
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4. |
- Graña-González, A., et al.
(author)
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Quasi-free (p,2p) reactions in inverse kinematics for studying the fission yield dependence on temperature
- 2023
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In: FAIR next generation scientists - 7th Edition Workshop : FAIRness2022 - FAIRness2022. - 1824-8039. ; 419
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Conference paper (peer-reviewed)abstract
- Despite the recent experimental and theoretical progress in the investigation of the nuclear fission process, a complete description still represents a challenge in nuclear physics because it is a very complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. To improve on the existing data on nuclear fission, we produce fission reactions of heavy nuclei in inverse kinematics by using quasi-free (p,2p) scattering, which induce fission through particle-hole excitations that can range from few to ten's of MeV. The measurement of the four-momenta of the two outgoing protons allows to reconstruct the excitation energy of the fissioning compound nucleus and therefore to study the evolution of the fission yields with temperature. The realization of this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and here some preliminary results are presented.
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5. |
- Knyazev, A., et al.
(author)
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Simulations of light collection in long tapered CsI(Tl) scintillators using real crystal surface data and comparisons to measurement
- 2021
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 1003
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Journal article (peer-reviewed)abstract
- Simulation results for light transport in long tapered CsI(Tl) crystals using look-up tables (LUTs) are presented. The LUTs were derived from the topography of a polished and a lapped surface of a CsI(Tl) crystal measured with atomic force microscopy. Simulations with different combinations of polished and lapped surfaces were performed, to extract the non-uniformity of light collection depending on the interaction point, and compared to experimental results. The simulations reproduce the general trend given by the measurements, and show that more homogeneous light collection is attained when all lateral sides of the crystal are lapped. For the lapped crystal the simulation model is most sensitive to the reflectivity of the enhanced specular reflector (ESR) foil surrounding the crystal, which is one of several properties influencing the light transport examined in this study. The sensitivity of the light-output non-uniformity to variations in the absorption length observed in a batch of CsI(Tl) crystals in a previous study is also discussed. Residual differences between the simulation and the measurements can potentially be attributed to the scattering of scintillation photons inside the materials used. Additional measurements to further advance the construction of the simulation model are suggested.
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6. |
- Knyazev, A., et al.
(author)
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Tl concentration and its variation in a CsI(Tl) crystal for the CALIFA detector
- 2020
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 975
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Journal article (peer-reviewed)abstract
- One of the factors that can contribute to the resolution of long, doped inorganic scintillators used for nuclear spectroscopy is the variation of the dopant concentration over the length the detector crystal. In this work an investigation of such potential variations in one of the CsI(Tl) scintillators used in the calorimeter, CALIFA, of the R3B experiment at FAIR, has been performed using particle induced X-ray emission. No statistically significant gradient in doping level was found along the long axis of the investigated sample crystal and the mean value of the Tl concentration was measured to be 0.0839(38)% by weight. This corresponds to a light output of 97.3−1.7 +1.3% relative to the maximum attainable light output according to previously published work. By taking the ±1σ bounds, the 3% statistical spread in the relative light output provides a good reference value of the minimum light-output non-uniformity observed for the CALIFA crystals. If the relative light output is estimated pointwise from a set of Tl concentration measurements a light-output non-uniformity of 4.6(2.4)% results. For a γ-ray energy of 662 keV the deduced variation in Tl concentration contributes with 0.48(6)% to the typical resolution of 7.74(6)% measured with a collimated source along the crystal main axis. The result is of interest for the characterization of the detector system performance and for realistic simulations of the light collection process in detector systems that are used for nuclear spectroscopy and calorimetry.
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7. |
- Kudaibergenova, E., et al.
(author)
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MEASUREMENTS OF THE REACTION CROSS SECTIONS OF NEUTRON-RICH Sn ISOTOPES AT THE R 3 B SETUP
- 2024
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In: Acta Physica Polonica B, Proceedings Supplement. - 1899-2358. ; 17:3
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Journal article (peer-reviewed)abstract
- A fundamental framework to describe nuclear matter as a function of pressure and nuclear isospin asymmetry is the nuclear Equation of State (EoS). Constraining the parameters of the EoS is one of the central issues in nuclear physics, especially since the slope parameter L has not yet been constrained well experimentally. It has been identified that a precise determination of the neutron-removal cross section in neutron-rich nuclei, which correlates with the neutron-skin thickness, would provide a more precise constraint on L. To this end, an experiment was performed at the R3B setup in the GSI Helmholtzzentrum für Schwerionenforschung GmbH as a part of the FAIR Phase-0 program. The reactions are studied in inverse kinematics with neutron-rich tin isotopes in the mass range of A = 124–134 on carbon targets of different thicknesses. The reaction products have been measured at beam energies of 400–900 MeV/u in a kinematically complete manner. In this communication, the analysis of124Sn+12C at 900 MeV/u is presented. The charge-exchange reactions, resulting processes, and their role in the calculation of other reaction cross sections are discussed.
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8. |
- Lihtar, I., et al.
(author)
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RELATIVISTIC COULOMB EXCITATION OF 124 Sn
- 2024
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In: Acta Physica Polonica B, Proceedings Supplement. - 1899-2358. ; 17:3
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Journal article (peer-reviewed)abstract
- The Coulomb excitation of 124, 128, 130, 132, 134Sn isotopes in the electric field of a Pb target have been studied using the R3B setup as a part of the FAIR Phase-0 program. The experiment was motivated by the possibility of using the nuclear dipole response to infer valuable information on the slope of the symmetry energy of the nuclear equation of state. Measurements were performed in inverse kinematics at relativistic energies of 750 MeV/u and 904 MeV/u. The analysis method and preliminary results for the decay channel with a single outgoing neutron for 124Sn are reported.
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9. |
- Ponnath, L., et al.
(author)
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Measurement of nuclear interaction cross sections towards neutron-skin thickness determination
- 2024
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 855
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Journal article (peer-reviewed)abstract
- The accuracy of reaction theories used to extract properties of exotic nuclei from scattering experiments is often unknown or not quantified, but of utmost importance when, e.g., constraining the equation of state of asymmetric nuclear matter from observables as the neutron-skin thickness. In order to test the Glauber multiple-scattering model, the total interaction cross section of [Formula presented] on carbon targets was measured at initial beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The measurements were performed during the first experiment of the newly constructed R3B (Reaction with Relativistic Radioactive Beams) experiment after the start of FAIR Phase-0 at the GSI/FAIR facility with beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The combination of the large-acceptance dipole magnet GLAD and a newly designed and highly efficient Time-of-Flight detector enabled a precise transmission measurement with several target thicknesses for each initial beam energy with an experimental uncertainty of ±0.4%. A comparison with the Glauber model revealed a discrepancy of around 3.1% at higher beam energies, which will serve as a crucial baseline for the model-dependent uncertainty in future fragmentation experiments.
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10. |
- Rodriguez-Sancheza, J. L., et al.
(author)
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Comprehensive investigation of fission yields by using spallation- and (p,2p)induced fission reactions in inverse kinematics
- 2023
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In: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284
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Conference paper (peer-reviewed)abstract
- In the last decades, measurements of spallation, fragmentation and Coulex induced fission reactions in inverse kinematics have provided valuable data to accurately investigate the fission dynamics and nuclear structure at large deformations of a large variety of stable and non -stable heavy nuclei. To go a step further, we propose now to induce fission by the use of quasi -free (p,2p) scattering reactions in inverse kinematics, which allows us to reconstruct the excitation energy of the compound fissioning system by using the four-momenta of the two outgoing protons. Therefore, this new approach might permit to correlate the excitation energy with the charge and mass distributions of the fission fragments and with the fission probabilities, given for the first time direct access to the simultaneous measurement of the fission yield dependence on temperature and fission barrier heights of exotic heavy nuclei, respectively. The first experiment based on this methodology was realized recently at the GM/FAIR facility and a detailed description of the experimental setup is given here.
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11. |
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12. |
- Knyazev, Alexander, et al.
(author)
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Properties of the CsI(Tl) detector elements of the CALIFA detector
- 2019
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In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 940, s. 393-404
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Journal article (peer-reviewed)abstract
- In the R3B experiment at FAIR, charged particles with energies up to 600 MeV and forward boosted γ-rays with energies up to 20 MeV need to be detected in scattering experiments. Calorimeters for nuclear physics experiments of this kind, using relativistic radioactive ion beams, require high energy resolution and high efficiency for simultaneous detection of strongly Doppler shifted γ-rays and high-energy charged particles. A calorimeter design that can meet these requirements, using CsI(Tl) scintillators, results in detector elements that may exhibit light output variations with crystal depth, which can limit the attainable resolution. In this paper we present results from a systematic study of 478 detector modules of CALIFA, the R3B calorimeter, in order to determine and minimize such variations. To facilitate further systematic studies we also present results for the total absorption length of the scintillation light, using spectrophotometry, light crosstalk between adjacent detector modules, and surface topography of the CsI(Tl) crystals from atomic force microscopy.
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15. |
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16. |
- Heil, M., et al.
(author)
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A new Time-of-flight detector for the R 3 B setup
- 2022
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In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 58:12
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Journal article (peer-reviewed)abstract
- We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R3B experimental setup at GSI and FAIR, Darmstadt, Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision σΔE/ ΔE of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.
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17. |
- Gobel, K., et al.
(author)
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Coulomb dissociation of 16O into 4He and 12C
- 2020
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1668:1
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Conference paper (peer-reviewed)abstract
- We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision.
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