TRIAC Progress Report - KEK

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Fig. 2-10. Charge sate distributions of 129 Xe (lower panel) and 138 Ba (upper panel). Indices next to the peaks indicate the charge states. Table 2-3. Charge breeding efficiencies. Upper two rows indicate the gaseous elements, while the lower rows present the non-gaseous elements. See the text for details. Charge breeding efficiencies: The εCB for radioactive ion beams, 92 Kr 1+ and 126 In 1+ , as well as the stable ion beams are summarized in Table 2-3 [2-8]. The efficiencies for gaseous elements are higher by a factor of 3 than those for nongaseous elements. The 14
higher efficiency for gaseous elements is considered partly due to desorption of the injected ions on the surface of the plasma chamber. The desorption of the gaseous ions may lead to the weak dependence of εCB on the ∆V over a rather wider range as shown in Fig. 2-8. On the other hand, the lower value of εCB for the nongaseous elements suggests that the adsorption to the surface is not negligible. The improvement of the beam injection efficiency to the ECR plasma may help increase εCB for the nongaseous elements, if the ionization efficiency of ECRIS is element independent. The εCB was found to be independent of the lifetime for radioactive nuclei with lifetimes of a few seconds, as shown in Table 2-3. This result suggests that the charge breeding time is shorter than the lifetimes of presently studied isotopes, which is consistent with the charge breeding time of about 100 ms measured at the <strong>KEK</strong>CB [2-9]. We suppose that εCB could be dependent on lifetime for RIBs with lifetimes shorter than a few 100 ms. 2-3-3. Element-dependent charge breeding efficiency The charge breeding efficiencies are 7.4 % for Xe 20+ and 2.3 % for In 16+ , which are typical efficiencies for radioactive gaseous and metallic elements with a half-life time of ~ 1 s., as well as for stable ions already shown in Fig. 2-8. The efficiencies for gaseous elements are observed to be higher than those for metallic ones, usually by a factor of three as long as the similar masses of the elements are concerned. Because of the significantly different behavior in the injection, which just depends on if the element is volatile or not at room temperature as discussed above, one can conclude that the lower charge breeding efficiencies for metallic ions could be improved by more careful optimization of the injection. The difference could be attributed to ad- and de-sorption of the ions on the surface of the plasma chamber during the injection; the gaseous elements adsorbed on the surface could be more easily desorbed and recycled for further ionization, as compared to the case of metallic, non-volatile elements that stick to the surface once adsorbed. On the other hand, the element-dependent ionization efficiency cannot be completely excluded. Therefore, in order to identify the direction of the development to obtain higher breeding efficiency, especially for metallic elements, it is of importance to study how the injected ions, but failed to be re-extracted, are distributed on the surface of the plasma chamber. The distribution of the injected ions accumulated on the surface of the plasma chamber would help us to understand when the injected ions are adsorbed, i.e. at the time of injection or in the course of the step-by-step ionization in the ECR plasma after being well captured. We have injected radioactive ions of 111 In into the <strong>KEK</strong>CB and, after charge breeding, measured the residual activity to investigate how ions externally injected 15
Page 1 and 2: TRIAC Progress Report TRIAC collabo
Page 3 and 4: i KEK Progress Report 2011-1 June 2
Page 5 and 6: PREFACE The Tokai Radioactive Ion A
Page 7 and 8: 1. Introduction Following the succe
Page 9 and 10: maximum available beam power for th
Page 11 and 12: container of ion source and uranyl
Page 13 and 14: gaseous and volatile elements (e.g.
Page 15 and 16: = 10.6 m) were 4.5 %, that for 146
Page 17 and 18: with different plasma volumes [2-6]
Page 19: ECR plasma: We used natural helium
Page 23 and 24: The asymmetric component representi
Page 25 and 26: ut differs from the electron-loss p
Page 27 and 28: consumption in the cavity is less t
Page 29 and 30: measured with Faraday cups, FC1, FC
Page 31 and 32: y turning off the supply of RF powe
Page 33 and 34: 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 86 and 87:
In the experiments of RNB-J02/03 (S
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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