TRIAC Progress Report - KEK

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In the experiments of RNB-J02/03 (Spokesperson: S.C. Jeong (KEK), H. Sugai / M. Sataka (KEK)), Collaboration: (KEK (8), JAEA (7), Aomori Univ. (2), NIMS (3), Osaka Prefecture Univ. (1), CNS (1)), it has been found that the short-lived radioactive beam of 8 Li at the TRIAC successfully operates as a diffusion tracer in the lithium ionic conductors. This kind of application has been performed for the first time over the world. In the experiment, we measured α-particles, emitted from β-decaying 8 Li, coming out of the sample of interest after implanting RIBs, and have found that the time-dependent yields of α-particle from the diffusing 8 Li primarily implanted is a good measure of the lithium diffusion in the sample. The radiotracer 8 Li decays through β-emission to 8 Be with a half lifetime of 0.84 s, which immediately breaks up into two α-particles with energies continuously distributed around 1.6 MeV with a full width at half maximum (FWHM) of 0.6 MeV [3-35]. Figure 3-26 shows schematically the principle of the measurement: Implanting the beam of 8 Li with a properly adjusted energy into a depth, deeper than the average range of α-particles, we can make a situation where most α-particles stop in the sample. After implantation, since the primary implantation profile is broadening with time by diffusion, the α-particles emitted by 8 Li diffused toward the surface can survive and come out of sample with measurable energies. Then a charged particle detector, located close to the sample surface, could selectively detect α-particles from 8 Li diffusing toward the sample surface, since the implantation-depth is deeper than the average range of α-particles in the present case. Therefore, the temporal evolution of α-particle yields that come out of the sample is supposed to be a measure of the diffusivity of Li. Fig. 3-26. Principle of diffusion measurements by implanting 8 Li-RIBs. 80
Provided by the TRIAC, the radiotracer beam 8 Li of about 4 MeV with an intensity of about 10 4 particles/s was periodically implanted to the sample of interest with a following time sequence; 1.6 s for implantation (beam-on) and of 5.1 s for subsequent diffusion (beam-off). The α particles coming out of the sample were measured as a function of time by an annular solid-state detector (SSD). The SSD with a central hole was installed close to the front surface of the sample as shown in Fig. 3-27. The sequence was repeated to obtain good statistics, where the time-zero was always at the beginning of the implantation. Before starting the measurement, the sample was set at a temperature where the diffusion coefficient was supposed to be measured. It should be noted that the present diffusion time is different from that of the conventional method [3-36] because the tracer in the present method diffuses all the time of the measurement. This is the reason why we call the present method an on-line measurement of diffusion. Fig. 3-27. Experimental set-up. The energetic and pulsed tracer beam of 8 Li are implanted into the sample and the decayed α particles are measured as a function of time by the solid state detector located in front of the sample. The condition of the tracer beam is given, which includes energy, intensity, repetition frequency of the pulsed beam and its duty factor. Figure 3-28 shows time spectra of the yield of α-particles measured at different temperature for the stoichiometric LiIn. Properly normalized for comparison, the spectra are presented by the ratios, i.e. time-dependent yields of α-particles divided by the α radioactivity of 8 Li at the time of interest. In this way was excluded the trivial time-dependency in the yield of α-particles just depending on the lifetime of 8 Li. If 8 Li does not diffuse at all, the values of the ratios should be constant over time. However, the experimental values as shown in Fig. 3-28 show different time structure depending on the temperature, well demonstrating that the time structure is a good measure of the macroscopic diffusivity of 8 Li at the temperature where the measurement has been performed. Based on this relative time-dependency of α-particle yields (time dependent 81
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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
Page 35: 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 88 and 89: atio), a diffusion coefficient was
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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