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Quantum Beam Sci., Volume 3, Issue 3 (September 2019)

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Open AccessArticle
Optimization of Performance, Price, and Background of Long Neutron Guides for European Spallation Source
Quantum Beam Sci. 2019, 3(3), 16; https://doi.org/10.3390/qubs3030016
Received: 14 June 2019 / Revised: 10 July 2019 / Accepted: 15 July 2019 / Published: 18 July 2019
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Abstract
We describe a systematic approach for the design of long, ballistic cold, and thermal neutron guides for the European Spallation Source (ESS). The guides investigated in this work are 170 m long and are required to have a narrowing point with room for [...] Read more.
We describe a systematic approach for the design of long, ballistic cold, and thermal neutron guides for the European Spallation Source (ESS). The guides investigated in this work are 170 m long and are required to have a narrowing point with room for a pulse shaping chopper placed 6 m from the moderator. In addition, most guides avoid line-of-sight from the moderator to the sample. The guides are optimized in order to find a reasonable trade-off between neutronics performance and construction price. The geometries simulated are closely related to the thermal-neutron multi-length-scale diffractometer HEIMDAL and the cold-neutron multi-analyser spectrometer BIFROST. For the cold-neutron guide an inexpensive solution was found that maintains good transport properties, while avoiding line-of-sight. However, for the thermal-neutron guide the losses when avoiding line-of-sight are large and it seems a good choice to stay in line-of-sight, even though this will increase both the shielding costs and fast-neutron background. The results are of general relevance for the understanding of the relation between transport, background, and price of long neutron guides. Full article
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Open AccessArticle
Deformation Mechanisms of Twinning-Induced Plasticity Steel under Shock-Load: Investigated by Synchrotron X-ray Diffraction
Quantum Beam Sci. 2019, 3(3), 15; https://doi.org/10.3390/qubs3030015
Received: 6 May 2018 / Revised: 30 June 2018 / Accepted: 6 June 2019 / Published: 6 July 2019
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Abstract
As an ideal candidate material for automobiles, twinning-induced plasticity (TWIP) steels possess excellent formability, high strength and high energy absorption ability during collision. This is attributed to its deformation mechanism of mechanical twinning, resulting in a high work hardening rate. In the current [...] Read more.
As an ideal candidate material for automobiles, twinning-induced plasticity (TWIP) steels possess excellent formability, high strength and high energy absorption ability during collision. This is attributed to its deformation mechanism of mechanical twinning, resulting in a high work hardening rate. In the current study, deformation mechanisms of low-stacking fault energy TWIP steel, under different strain rates between 0.01/s to 1581/s, were investigated by high-energy X-ray diffraction. After compression, grains with {110}||compression direction became favourable. Higher intensity was observed near brass and A components in the selected orientation distribution function (ODF) section (φ2 = 45°) for all the compressed specimens. The activity of twinning was found to be the highest in the specimens that had been compressed with medium–high strain rates (e.g., 100/s and 10/s), while the texture component related to slip had stronger intensity in the specimen deformed with a quasi-static strain rate (0.01/s). Full article
(This article belongs to the Special Issue Strain, Stress and Texture Analysis with Quantum Beams)
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Open AccessArticle
Molecular Analysis of Carbon Ion-Induced Mutations in DNA Repair-Deficient Strains of Saccharomyces cerevisiae
Quantum Beam Sci. 2019, 3(3), 14; https://doi.org/10.3390/qubs3030014
Received: 16 May 2019 / Revised: 20 June 2019 / Accepted: 26 June 2019 / Published: 2 July 2019
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Abstract
Mutations caused by ion beams have been well-studied in plants, including ornamental flowers, rice, and algae. It has been shown that ion beams have several significantly interesting features, such as a high biological effect and unique mutation spectrum, which is in contrast to [...] Read more.
Mutations caused by ion beams have been well-studied in plants, including ornamental flowers, rice, and algae. It has been shown that ion beams have several significantly interesting features, such as a high biological effect and unique mutation spectrum, which is in contrast to low linear energy transfer (LET) radiation such as gamma rays. In this study, the effects of double strand breaks and 8-oxo-2′-deoxyguanosine (8-oxodG) caused by ion-beam irradiation were examined. We irradiated repair-gene-inactive strains rad52, ogg1, and msh2 using carbon ion beams, analyzed the lethality and mutagenicity, and characterized the mutations. High-LET carbon ion-beam radiation was found to cause oxidative base damage, such as 8-oxodG, which can lead to mutations. The present observations suggested that nucleotide incorporation of oxidative damage gave only a limited effect on cell viability and genome fidelity. The ion-beam mutations occurred predominantly in 5′-ACA-3′ sequences, and we detected a hotspot at around +79 to +98 in URA3 in wild-type and mutant lines, suggesting the presence of a mutation-susceptible region. Full article
(This article belongs to the Special Issue Ion Beams in Biology and Medicine)
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Quantum Beam Sci. EISSN 2412-382X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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