TRIAC Progress Report - KEK

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atio), a diffusion coefficient was estimated by comparing with the simulation where one-dimensional Fickian (Gaussian) diffusion was assumed [3-34,-37]. Fig. 3-28. Time spectra of α-particle yields measured at various temperatures for LiIn. The spectra were corrected for removing trivial time dependence and further normalized properly for easy comparison. Fig. 3-29. Temperature-dependence of diffusion coefficients (closed symbols) and electrical resistivity (open symbols) for β-LiGa with 44 at. % Li, and β-LiIn with 48 % at. Li. The diffusion coefficients of Li in β-LiGa and β-LiIn with a near stoichiometeric composition of Li, are displayed in Fig. 3-29 as a function of inverse temperature. For both samples, the diffusion coefficients suddenly change at a certain temperature, following Arrhenius behavior in the region of higher temperature. The sudden change in the value of the diffusion coefficient occurs at the temperature where the anomalous electrical resistivity is observed. The resistivity measurements were carried out using a van der Pauw method as used for β-LiAl [3-38]. This observation is closely related to 82
the thermal properties of the structural defects, already observed as the anomalies in heat capacity [3-39, -40] and nuclear-spin lattice relaxation [3-41] at 233 K near the critical composition of the Li-deficient β-LiGa. It has been suggested that these phenomena are related to order-disorder transformation of the Li vacancies in the compounds. The ordering of the vacancies would produce a sharp drop in the Li diffusion coefficients below the ordering temperature since the vacancies are supposed to be the carriers of Li atom. The observed amount of change, more than two orders of magnitude in the value of diffusion coefficients in the case of β-LiGa, is quite impressive as compared to those observed in the measurement of electrical resistivities where just a small change (at most 1/10) can be seen at the transformation temperature. The transition temperature is known to shift to lower temperature, and the change in the electrical resistivity becomes invisibly smaller with increasing Li composition, where a large fraction of the Li vacancies forms complex defects with anti-structural Li atoms on Ga sublattices [3-42]. Therefore, with higher sensitivity, the present method could be applied for better investigating the characteristics of the transformation that are supposed to be correlated with the concentrations of structural defects strongly depending on the Li compositions. At the lower temperature followed by a sudden change around 234 (±2) K for β-LiGa, the diffusion coefficients are observed as a constant, which is the lower limit of diffusion coefficients accessible by the present method; for diffusion coefficients less than about 10 -10 cm 2 /s, any significant effect in the yields of α-particles due to the diffusing 8 Li could not be observed because of the short life-time of the radiotracer. In Fig. 3-30, the time-dependent normalized α-particle yields are compared for different Li compositions, i.e. 43.6, 50.0 and 53.2 at. % Li. Referring to the time dependence of the α-particle yields, the stoichiometric β-LiGa has the highest diffusivity of Li among three, most quickly rising and falling down. This observation is quite different from those observed for β-LiAl and β-LiIn [3-43] which are iso-structural with the β-LiGa. The abnormal behavior of Li diffusivity in β-LiGa is well identified in Fig.3-31, where the diffusion coefficients in β-LiGa at room temperature are presented as a function of Li composition together with the data for β-LiAl and β-LiIn reported in Ref. 3-43. As shown in Fig. 3-31, the Li diffusion coefficients in β-LiAl and β-LiIn decrease monotonously with increasing Li composition, but the correlation is changing due to the coexistence of vacant Li sites VLi and antistructure Li atoms on the aluminum (or indium) sites LiAl (or LiIn), as discussed earlier in terms of the size effect of constituent 83
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TRIAC Progress Report TRIAC collabo
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i KEK Progress Report 2011-1 June 2
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PREFACE The Tokai Radioactive Ion A
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1. Introduction Following the succe
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maximum available beam power for th
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container of ion source and uranyl
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gaseous and volatile elements (e.g.
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= 10.6 m) were 4.5 %, that for 146
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with different plasma volumes [2-6]
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ECR plasma: We used natural helium
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higher efficiency for gaseous eleme
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The asymmetric component representi
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ut differs from the electron-loss p
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consumption in the cavity is less t
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measured with Faraday cups, FC1, FC
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y turning off the supply of RF powe
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Encouraged by the new finding, as t
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2-4-4. Development of superconducti
Page 40 and 41: accelerating the radioactive ion be
Page 42 and 43: Fig. 2-29. Photos of the pre-bunche
Page 44 and 45: For the proposed experiment, the po
Page 46: a diagonal direction. The monitors
Page 49: charge state of xenon ions by using
Page 52 and 53: electrode as shown in Fig. 2-40) sh
Page 54 and 55: CO2 (10 %) and 16 kPa, respectively
Page 56 and 57: Although the gain shift of THGEM#3
Page 58 and 59: 3. Experiments at the TRIAC Since t
Page 60 and 61: Fig. 3-1. Schematic view of the det
Page 62 and 63: -element abundances up to the third
Page 64: higher reliability of the experimen
Page 67 and 68: GEM-MSTPC among the accumulated dat
Page 69 and 70: upstream of the pre-buncher, avoidi
Page 72 and 73: The process of nuclear polarization
Page 74 and 75: annealed platinum foil (stopper foi
Page 78 and 79: the observed CP-violating phenomena
Page 80 and 81: offline data analysis, about 1-Mega
Page 82 and 83: Secondary 9 Li ions extracted from
Page 84 and 85: Fig.3-24. γ ray energy spectra coi
Page 86 and 87: In the experiments of RNB-J02/03 (S
Page 91 and 92: Although the data for β-LiAl and
Page 93 and 94: In the experiment of RNB-K06 ((Spok
Page 95 and 96: difference spectra, more specifical
Page 97 and 98: Mass, which is one of the most fund
Page 99: gamma rays. 111 In, which decays to
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TRIAC Progress Report - KEK

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