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| 2. |
- Asano, H., et al.
(author)
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Spectroscopic study of the Λ(1405) resonance via the d (K-, n) reaction at J-PARC
- 2019
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In: 13th International Conference on Hypernuclear and Strange Particle Physics, HYP 2018. - : AIP Publishing. - 9780735418721 ; 2130
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Conference paper (peer-reviewed)abstract
- The structure of the Λ(1405) hyperon is an important and long-standing issue related to the K̄-nucleus interaction. The J-PARC E31 experiment has been performed to investigate the Λ(1405) spectrum shape. Because it is hard to form the Λ(1405) directly by a K̄N scattering in free space, E31 uses the d(K-, n) reaction with an incident kaon momentum of 1 GeV/c. We will identify three final states - ς-π+, ς+π-, ς0π0-so that the isospin structure of hyperon resonance states produced can be decomposed. The first physics run of the E31 experiment was performed in 2016. To enhance the statistics of the data set, we have performed the second physics run in the beginning of 2018. During the second run of E31, around 3.9×1010 kaons impacted on the deuteron target.
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| 3. |
- Sada, Y., et al.
(author)
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Structure near the K- + p + p threshold in the in-flight 3He(K-, Λp)n reaction
- 2016
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In: Progress of Theoretical and Experimental Physics. - : Oxford University Press (OUP). - 2050-3911. ; 2016:5
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Journal article (peer-reviewed)abstract
- To search for an S = -1 di-baryonic state which decays toΛp, the 3He(K-,Λp)nmissing reaction was studied at 1.0 GeV/c. Unobserved neutrons were kinematically identified from the missing mass MX of the 3He (K-,Λp) X reaction in order to have a large acceptance for the Λpn final state. The observed Λpn events, distributed widely over the kinematically allowed region of the Dalitz plot, establish that the major component comes from a three-nucleon absorption process. A concentration of events at a specific neutron kinetic energy was observed in a region of low momentum transfer to the Λp. To account for the observed peak structure, the simplest S-wave polewas assumed to exist in the reaction channel, having a Breit-Wigner formin energy and with a Gaussian form factor. A minimum X2 method was applied to deduce its mass, MX = 2355+6 -8 (stat.) ±12 (syst.)MeV/c2, and decay width, γX = 110+19 -17 (stat.) ±27 (syst.)MeV/c2, respectively. The form factor parameter QX ∼ 400MeV/c implies that the range of the interaction is about 0.5 fm.
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| 4. |
- Yamaga, Takumi, et al.
(author)
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Study of the elementary (K -, n) reactions to search for the K NN bound state via the 3He (K -, n) reaction at J-PARC
- 2016
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In: XVIth International Conference on Hadron Spectroscopy, Hadron 2015. - : Author(s). - 9780735413894 ; 1735
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Conference paper (peer-reviewed)abstract
- We have searched for the simplest kaonic nuclear state, K̄NN, using the in-flight 3He (K-, n) reaction at the J-PARC hadron experimental facility. In the semi-inclusive neutron missing-mass spectrum at θnlab=0°, an excess of yield was observed just below the K- pp mass-threshold, which cannot be explained by any elementary reactions [PTEP 2015, 061D01]. To understand the missing-mass spectrum of 3He (K-, n) X, we investigated the elementary (K-, n) reactions using hydrogen and deuterium targets. The p (K-, n) X missing-mass spectrum was well described by the charge-exchange reaction. However, in the d (K-, n) X spectrum, we observed an excess of yield just below the K- p mass-threshold, which was similar to that in the 3He (K-, n) X spectrum.
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| 5. |
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| 6. |
- Wang, Q.Z., et al.
(author)
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The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks : analytical and numerical results
- 2004
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In: International Journal of Rock Mechanics And Mining Sciences. - 1365-1609 .- 1873-4545. ; 41:2, s. 245-253
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Journal article (peer-reviewed)abstract
- The flattened Brazilian disc specimen is proposed for determination of the elastic modulus E, tensile strength sigma (sub t) and opening mode fracture toughness K (sub IC) for brittle rocks in just one test. This paper is concerned with the theoretical analysis as well as analytical and numerical results for the formulas. According to the results of stress analysis and Griffith's strength criteria, in order to guarantee crack initiation at the centre of the specimen, which is considered to be crucial for the test validity, the loading angle corresponding to the flat end width must be greater than a critical value (2alpha > or =20 degrees ). The analysis shows that, based on the recorded complete load-displacement curve of the specimen (the curve should include the "fluctuation" section after the maximum load), E can be determined by the slope of the section before the maximum load, sigma (sub t) by the maximum load, and K (sub IC) by the local minimum load immediately subsequent to the maximum load. The relevant formulas for the calculation of E, sigma (sub t) , K (sub IC) are obtained, and the key coefficients in these formulas are calibrated by finite-element analysis. In addition, some approximate closed-form formulas based on elasticity are provided, and their accuracy is shown to be adequate by comparison with the finite-element results.
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| 7. |
- Duarte, Margarida Taborda, et al.
(author)
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Microstructural modeling approach applied to rock material
- 2005
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In: Journal of materials engineering and performance (Print). - : Springer Science and Business Media LLC. - 1059-9495 .- 1544-1024 .- 0000-0000. ; 14:1, s. 104-111
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Journal article (peer-reviewed)abstract
- The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover, the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull. It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure. This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling, characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences in the mechanical behavior obtained in testing several specimens.
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| 8. |
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| 9. |
- Hoshino, T., et al.
(author)
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Optimum delay interval design in delay blasting
- 1999
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In: Rock Fragmentation by Blasting. - Johannesburg : South African Institute of Mining and Metallurgy. - 1919783032 ; , s. 145-148
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Conference paper (peer-reviewed)
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| 10. |
- Kou, S-Q, et al.
(author)
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Burden related to blasthole diameter in rock blasting
- 1992
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In: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - : Elsevier BV. - 0148-9062 .- 1879-2073. ; 29:6, s. 543-553
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Journal article (peer-reviewed)abstract
- Since the 1950s, most of the empirical formulas in rock blasting have incorporated a linear relation between burden and blasthole diameter. Recently it has been shown that a non-linear relation is more accurate for blasthole diameters in 40-400 mm range. This relation is different for surface and underground mines. In this paper, a complete relation between burden and either blasthole diameter or specific charge is established. This relation is based on energy conservation in single hole blast and consists of three terms which are related to surface energy for the two side cracks, fragmentation for the rock prism released and energy needed to move the rock. Four approximate formulas describing burden as a power function of the blasthole diameter are derived from the complete relation and dimensional analysis. The exponents of the diameter in the formulas are 2, 1, 5/6 and 2/3 and these decrease with the increasing scale in blasting. The coefficients of the power formulas are expressed as functions of the physical properties of the rock and explosive. The linear relation, derived as a special case with comparatively small blasthole diameters, is in a good agreement with Langefors' well-known formula. The valid ranges of the new formulas depend on the rock properties. The formulas were tested against the regression curves from real values in surface and underground mines and the results were better than those obtained using empirical methods.
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