TRIAC Progress Report - KEK

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failed to be mass-separated, which is possibly due to the decay loss caused by a long release time from the bulk of target material [2-3]. To reduce such decay losses for short-lived isotopes in the target-ion source system, the higher operating temperatures, e.g. around 2300 K just as the case of SI ion sources in Table 2-2, are desirable. Table 2-2. Separation yields and efficiencies for Kr, Rb, Sr, Ag, In, Sn, Xe, Cs and Ba Surface ionization type ion source operated at 2400 K, while FEBIAD-B2 operated at 1800 K. For comparison, the measured separation yield is transformed to that to be obtained with the uranium target thickness of 1 g/cm 2 and the proton beam current of 1 µA. For this reason, a FEBIAD-E type ion source, which can be operated at the temperature of 2000 – 2300 K [2-2], has been newly developed. In this type, as shown in Fig.2-2 (b), the target container is heated by electron bombardment from a couple of tungsten filaments surrounding the target container. The target container has a volume of 0.56 cm 3 (φ = 6 mm, L = 20 mm), and is welded to a connection pipe so as to avoid leaks for vaporized fission products. The length of the target container is twice longer than that of B2 type, while the volume is smaller by 20%. The FEBIAD-E type integrated target–ion source, which was newly fabricated and off-line tested, has been recently on-line tested. In the on-line test, the release properties of the short-lived radioisotopes of 93 Kr (T1/2 = 1.286 s), 129 In (T1/2 = 0.61 s) and 141 Xe (T1/2 = 1.73 s) were investigated [2-4]. The uranium target container with a reduced size in the FEBIAD-E type was heated by electron bombardment from a couple of surrounding tungsten filaments, and successfully operated at 2000 °C. Accordingly, the release time for gaseous and volatile elements was shortened as compared to the previous system (i.e. FEBIAD-B2); 2.6 s for Kr, 1.8 s for In, and 4.6 s for Xe. Using this ion source system, short-lived isotopes of 6
gaseous and volatile elements (e.g. with lifetimes shorter than 1 s) could be provided for decay and in-beam spectroscopy with a reasonable intensity. 2-2-2. SI type ion source For ionization of alkali, alkaline earth and rare earth elements, a surface ionization type ion source was used and shown in Fig. 2-4. A target container of tantalum with a thickness of 0.5 mm was directly attached to the ionizer. With this configuration, target materials can be loaded inside the ion source, which would be very effective to reduce the release time. The inner surface of ionizer was covered by 50 µm-thick rhenium foil, and the target container was loaded by about 650 mg/cm 2 of UCx. The integrated target-ion source is heated by electron bombardment, i.e. electrons emitted from filaments at a potential of typically 450 V relative to the ionizer / target container. The ion source operates continuously for over one week at a temperature of 2400 K (total power input of about 850 W), and can be used repeatedly. With the ion source, the intensities of the mass-separated alkali, alkaline earth isotopes produced by proton-induced fission of uranium were measured and summarized in Table 2-2. 2-2-3. Separation yields of neutron-rich isotopes (uranium fission fragments) Using the FEBIAD-B2 type and SI type ion sources, we have extracted and mass-separated 105 isotopes of 19 elements as ion beams. Figure 2-5 shows the intensities of those isotopes available at the focal plane of the ISOL. Those intensities can be increased by a factor of around 10 with the maximum proton beam power (36 MeV, 3 µA) and the uranium target thickness of 2.6 g/cm 2 . Fig. 2-4. Surface ionization type ion source (U-SIS) and its power supplying scheme for heating. (1) Proton beam, (2) thin foil, (3) uranium target, (4) target container (anode), (5) ionizer (the inner surface is covered by a thin Re foil), (6) filament-1, (7) filament-2, (8) heat shields. 7
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: container of ion source and uranyl
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 and 20: ECR plasma: We used natural helium
Page 21 and 22: higher efficiency for gaseous eleme
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
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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
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offline data analysis, about 1-Mega
Page 82 and 83:
Secondary 9 Li ions extracted from
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Fig.3-24. γ ray energy spectra coi
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In the experiments of RNB-J02/03 (S
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atio), a diffusion coefficient was
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Although the data for β-LiAl and
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In the experiment of RNB-K06 ((Spok
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difference spectra, more specifical
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Mass, which is one of the most fund
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gamma rays. 111 In, which decays to
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TRIAC Progress Report - KEK

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