| 1. |
- Faestermann, T, et al.
(författare)
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Decay studies of N approximate to Z nuclei from Sr-75 to Sn-102
- 2002
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 15:1-2, s. 185-188
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Tidskriftsartikel (refereegranskat)abstract
- Neutron deficient nuclei near Sn-100 have been produced by fragmentation of a 1 (.) A GeV Sn-112 beam. The fragments were separated, identified and stopped in a highly segmented silicon strip detector stack. This detector measured the total energy of emitted beta(+)-particles. gamma-radiation was measured with surrounding detectors. The half-lives for many nuclides have been determined for the first time and give important information for the following topics: For the heaviest particle-stable odd-odd nuclei Rh-90, Ag-94 and In-98 we observed for the first time fast beta-decays, compatible with superallowed Fermi transitions and confirmed such decays for 78y, 82 Nb and Tc. We have also observed 'long-lived T = 0 states in some of these nuclei. We measured the half-lives of all rp-process waiting-point nuclei from _Zr up to addition we find the proton drip line nucleus Y-77 to decay dominantly via beta-decay, To study the Gamov-Teller strength in the beta-decay near the doubly magic Sn-102 we measured the half-life, beta- and gamma-spectrum of Sn-102. We propose a level scheme for the daughter nuclide In-102 and deduce the Qamov-Teller strength (B-GT = 4.0 +/- 0.6). This is one of the largest values known.
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| 2. |
- Kittelmann, Irena, et al.
(författare)
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Geant4 based simulations for novel neutron detector development
- 2014
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Ingår i: 20th International Conference on Computing in High Energy and Nuclear Physics (Chep2013), Parts 1-6. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 513, s. 022017-022017
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Konferensbidrag (refereegranskat)abstract
- A Geant4-based Python/C++ simulation and coding framework, which has been developed and used in order to aid the R&D efforts for thermal neutron detectors at neutron scattering facilities, is described. Built upon configurable geometry and generator modules, it integrates a general purpose object oriented output file format with meta-data, developed to facilitate a faster turn-around time when setting up and analysing simulations. Also discussed are the extensions to Geant4 which have been implemented in order to include the effects of low-energy phenomena such as Bragg diffraction in the polycrystalline support materials of the neutron detectors. Finally, an example application of the framework is briefly shown.
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| 3. |
- Schmidt, Susann, et al.
(författare)
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Boron-10 lined RPCs for sub-millimeter resolution thermal neutron detectors : Feasibility study in a thermal neutron beam
- 2019
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- The results of an experimental feasibility study of a position sensitive thermal neutron detector based on a resistive plate chamber (RPC) are presented. The detector prototype features a thin-gap (0.35 mm) hybrid RPC with an aluminium cathode and a float glass anode. The cathode is lined with a 2 mu m thick (B4C)-B-10 neutron converter enriched in B-10. A detection efficiency of 6.2% is measured at the neutron beam (lambda = 2.5 angstrom) for normal incidence. A spatial resolution better than 0.5 mm FWHM is demonstrated.
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| 4. |
- Stefanescu, I., et al.
(författare)
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A B-10-based neutron detector with stacked MultiWire Proportional Counters and macrostructured cathodes
- 2013
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Ingår i: Journal of Instrumentation. - : Institute of Physics: Hybrid Open Access. - 1748-0221. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of the measurements of the detection efficiency for a 4.7 angstrom neutron beam incident upon a detector incorporating a stack of up to five MultiWire Proportional Counters (MWPC) with Boron-coated cathodes. The cathodes were made of Aluminum and had a surface exhibiting millimeter-deep V-shaped grooves of 45 degrees, upon which the thin Boron film was deposited by DC magnetron sputtering. The incident neutrons interacting with the converter layer deposited on the sidewalls of the grooves have a higher capture probability, owing to the larger effective absorption film thickness. This leads to a higher overall detection efficiency for the grooved cathode when compared to a cathode with a flat surface. Both the experimental results and the predictions of the GEANT4 model suggests that a 5-counter detector stack with coated grooved cathodes has the same efficiency as a 7-counter stack with flat cathodes. The reduction in the number of counters in the stack without altering the detection efficiency will prove highly beneficial for large-area position-sensitive detectors for neutron scattering applications, for which the cost-effective manufacturing of the detector and associated readout electronics is an important objective. The proposed detector concept could be a technological option for one of the new chopper spectrometers and other instruments planned to be built at the future European Spallation Source in Sweden. These results with macrostructured cathodes generally apply not just to MWPCs but to other gaseous detectors as well.
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| 5. |
- Stefanescu, I, et al.
(författare)
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Development of a novel macrostructured cathode for large-area neutron detectors based on the B-10-containing solid converter
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 727, s. 109-125
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel design for a macrostructured cathode that can be coated with a thin layer of the B-10 solid converter and mounted to replace the Boron-lined flat parallel plates of a proportional counter used for slow neutron detection. The proposed design consists of a 3D regular pattern exhibiting millimeter deep grooves with an opening angle of alpha = 45 degrees, which could be created in the substrate material by milling or forming. When a commonly used coating method like magnetron sputtering is employed to deposit the Boron-layer, due to the line-of-sight distribution of the ions, the thickness of the coating on the side of the grooves will be reduced by a factor similar to sin alpha/2 with respect to the thickness of the layer deposited on a flat surface normal to the ion flux. The effective neutron absorption film thickness is in this case similar for the sidewalls of the grooves and a surface at normal incidence, yielding comparable absorption efficiencies. However, the escape efficiency for the reaction products is higher for the sidewalls, owing to the thinner coating. This leads to a higher overall detection efficiency for the grooved cathode when compared to a flat cathode with the same surface area and coated with a Boron layer with roughly the same thickness. In this paper we present and discuss the GEANT4 simulations performed to optimize the geometry of the cathode, the manufacturing and coating by magnetron sputtering, as well as the proof-of-principle measurements carried out in order to assess the performance of the proposed design.
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