TRIAC Progress Report - KEK

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annealed platinum foil (stopper foil), which is 10-µm thick and placed at room temperature in the magnetic field of B0 ~ 0.05 T for holding the nuclear polarization. The β-NMR technique was applied to the measurement of the nuclear polarization. Ten carbon foils, each of which is of 10 µg/cm 2 in thickness and distant by ~1 mm from each other, were used with a tilted angle of 70 o in the first experiment. The polarization was observed to be 3.7 ± 1.1 % but it was not saturated with the 10 sheets of foils. Although higher polarization is expected with increasing number of foils, the carbon foils are so thick that the 8 Li beam cannot pass through more than ten foils. Therefore, we developed thinner polystyrene foils (e.g. ~3 µg/cm 2 in thickness). In the second and third experiments, the polarization of 7.3 ± 0.5 % was achieved at the beam energy of 140 keV/nucleon by using 15 foils of polystyrene at the tilted-angle of 70 o . Figure 3-16 shows the polarization as a function of the number of polystyrene foils for various energies of incident 8 Li. (a) (b) (c) RIBs Stacked tilted-foils 20 foils @ 70o 20 foils @ 70o Magnet B 0 Nuclear polarization 68 45 15 Fig. 3-15. Photos of (a) the experimental setup for the polarization of heavy elements, (b) a polystyrene foil and (c) a stack of the polystyrene foils. For the polarization of 8 Li, we used a rather simple configuration because much lower holding field (Bo) was allowed (i.e. a coreless electromagnet was used).
8 Li polarization : PI (%) 10 8 6 4 2 140 keV/A ( 70 deg. ) 178 keV/A ( 70 deg. ) 240 keV/A ( 70 deg. ) 0 0 5 10 15 20 25 30 Number of foils Fig. 3-16. 8 Li polarization as functions of sheet-number of polystyrene foils measured for incident beam energies of 140, 178 and 240 keV/nucleon, respectively. The solid lines were given by fitting the formula for nuclear polarization (PI) to the data. The data points observed with largest number of foils at the beam energy of 140 and 240 keV/nucleon are largely deviated from the general tendency; it might be related to an unintentional geometrical mismatch in the foil system, especially at the exit of the foil (e.g. tilted angle, damped energy and broadened spatial distribution of the beam, etc.). Except for the two data points, the data points seem to be well reproduced with the formula. In the third experiment, we tested a new experimental set-up modified for the polarization of the heavy nuclei around 132 Sn, as shown in Fig. 3-15 (a): The tilted-foil system was modified to reduce the distance between the tilted-foil and stopper for making possible simultaneous implantation of beam of several charge states after passing through the stack of foils. The modified β-NMR system can operate at a high magnetic field B0 ~ 0.5T (Holding field) and a high frequency for RF magnetic field (oscillating transverse field). The operation of the system was confirmed by using the 8 8 Li beam. The polarized Li beam was applied for test of time reversal symmetry using polarized nuclei (K04) described in the next section. The solid lines in Fig. 3-16 show the fitted results using the formula, which is given above for the polarization where the multi-foil effect is taken into account. In fitting, we assumed the atomic spin of J = 1/2 for 8 Li ions, whose values actually govern the dependence of the polarization on the number of foils. For example, the formula becomes saturated with about 10 foils and cannot reproduce the experimental data when the atomic spin of higher than J = 1/2 is assumed. It indicates that 2p ( 2 P1/2) state may dominantly contribute to produce the polarization of 8 Li. In the presently used formula 69
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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
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 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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