| 1. |
- Reifarth, R., et al.
(författare)
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Nuclear astrophysics with radioactive ions at FAIR
- 2016
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 665:1
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Konferensbidrag (refereegranskat)abstract
- The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.
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| 2. |
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| 3. |
- Boretzky, K., et al.
(författare)
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NeuLAND: The high-resolution neutron time-of-flight spectrometer for R 3 B at FAIR
- 2021
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 1014
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Tidskriftsartikel (refereegranskat)abstract
- NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.
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| 4. |
- Blanco, A., et al.
(författare)
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Performance of timing resistive plate chambers with relativistic neutrons from 300 to 1500 MeV
- 2015
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Ingår i: Journal of Instrumentation. - : IOP Publishing. - 1748-0221. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- A prototype composed of four resistive plate chamber layers has been exposed to quasi-monoenergetic neutrons produced from a deuteron beam of varying energy (300 to 1500 AMeV) in experiment S406 at GSI, Darmstad, Germany. Each layer, with an active area of about 2000 × 500 mm2, is made of modules containing the active gaps, all in multigap construction. Each gap is defined by 0.3 mm nylon mono-filaments positioned between 2.85 mm thick float glass electrodes. The modules are operated in avalanche mode with a non-flammable gas mixture composed of 90% C2H2F4 and 10% SF6. The signals are readout by a pick-up electrode formed by 15 copper strips (per layer), spaced at a pitch of 30 mm, connected at both sides to timing front end electronics. Measurements of the time of flight jitter of neutrons, in the mentioned energy range, point to a contribution of the resistive plate chamber in the order of 150 ps, independent of the neutron energy.
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| 5. |
- Machado, J., et al.
(författare)
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Performance of timing Resistive Plate Chambers with protons from 200 to 800 MeV
- 2015
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 10:1, s. C01043-
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Tidskriftsartikel (refereegranskat)abstract
- A prototype composed of four resistive plate chamber layers has been exposed to quasi-monoenergetic protons produced from a deuteron beam of varying energy (200 to 800 AMeV) in experiment S406 at GSI, Darmstadt, Germany. The aim of the experiment is to characterize the response of the prototype to protons in this energy range, which deposit from 1.75 to 6 times more energy than minimum ionizing particles. Each layer, with an active area of about 2000 × 500 mm 2 , is made of modules containing the active gaps, all in multigap construction. Each gap is defined by 0.3 mm nylon mono-filaments positioned between 2.85 mm thick float glass electrodes. The modules are operated in avalanche mode with a non-flammable gas mixture composed of 90% C 2 H 2 F 4 and 10% SF 6 . The signals are readout by a pick-up electrode formed by 15 copper strips (per layer), spaced at a pitch of 30 mm, connected at both sides to timing front end electronics. Results show an uniform efficiency close to 100% along with a timing resolution of around 60 ps on the entire 2000 × 500 mm 2 area.
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| 6. |
- Roeder, M., et al.
(författare)
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Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons
- 2014
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 50:7
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Tidskriftsartikel (refereegranskat)abstract
- Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment.
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| 7. |
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| 8. |
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| 9. |
- Nilsson Sköld, Helen, 1970, et al.
(författare)
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The pattern of cell proliferation during budding in the colonial ascidian Diplosoma listerianum
- 2011
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Ingår i: Biological Bulletin.
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Tidskriftsartikel (refereegranskat)abstract
- Many invertebrates reproduce asexually by budding, but morphogenesis and the role of cell proliferation in this diverse and non-conserved regeneration-like process are generally poorly understood and particularly little investigated in didemnid ascidians. We here analysed cell proliferation patterns and telomerase activity during budding in the colonial didemnid ascidian Diplosoma listerianum, with special focus on the thoracic bud where a new brain develops de novo. To help define developmental stages of the thoracic bud, the distribution of acetylated tubulin was also examined. We found extensive cell proliferation in both the thoracic and abdominal buds of D. listerianum as well as higher telomerase activity in bud tissue compared to adult tissues. In the parent adult, proliferation was found in various tissues, but was especially intense in the adult esophagus and epicardial structures that protrude into the proliferating and developing buds, confirming these tissues as the primary source of the cells that form the buds. The neural complex in the thoracic bud forms from a hollow tube that appears to separate into the neural gland and the cerebral ganglion. While most of the bud undergoes proliferation, including the hollow tube and the neural gland, the cerebral ganglion shows little or no proliferation. Pulse-chase labelling experiments indicate that the ganglion, as well as the myocardium, in adult zooids are instead composed of postmitotic cells.
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| 10. |
- Li, Y., et al.
(författare)
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Complex structural dynamics of nanocatalysts revealed in Operando conditions by correlated imaging and spectroscopy probes
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how heterogeneous catalysts change size, shape and structure during chemical reactions is limited by the paucity of methods for studying catalytic ensembles in working state, that is, in operando conditions. Here by a correlated use of synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy in operando conditions, we quantitatively describe the complex structural dynamics of supported Pt catalysts exhibited during an exemplary catalytic reaction-ethylene hydrogenation. This work exploits a microfabricated catalytic reactor compatible with both probes. The results demonstrate dynamic transformations of the ensemble of Pt clusters that spans a broad size range throughout changing reaction conditions. This method is generalizable to quantitative operando studies of complex systems using a wide variety of X-ray and electron-based experimental probes.
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