TRIAC Progress Report - KEK

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Although the gain shift of THGEM#3 was suppressed to be within 5 % under the same 4 He injection rate, it became larger (about 8 %) in the case of the 12 C injection rate of 10 5 pps as shown in the left panel of Fig. 2-43. Moreover, the gain shift of THGEM#3 gradually increased in several consecutive measurements with the 4 He injection of 10 4 pps. Actually, the shift was about 1 % at the first measurement, whereas it changed to be 5 % at the third measurement. This phenomenon could be explained as the ‘ageing’ of the electrodes, such as oxidation of the surface of the copper electrode. Hence, we coated the electrode of THGEM#4 with gold. THGEM #4 showed good gain stability as shown in the right panel of Fig. 2-43. The pulse height became stable within 3 % under the 12 C injection rate from 400 to 1.2 x 10 5 pps. The energy resolution under the 12 C injection rate of 10 5 pps was also measured. It was obtained from the distribution of energy-loss signals from the segmented anode pads. The energy resolutions under the injection rate of 400 pps of the two THGEMs of #3 and #4 were almost similar (7% in σ). However, with the higher injection rate, e.g. 10 5 pps, THGEM #4 gave better energy resolution than THGEM #3; 8 % vs. 13 %. The observed gain stability and energy resolution of THGEM #4 under the injection rate of 10 5 pps satisfy experimental requirements. The GEM-MSTPC using THGEM #4 (400-µm thick, 300-µm hole-diameter, Cu electrode coated by Au without rim) was successfully employed to measure the 8 Li(α, n) 11 B reaction cross sections (RNB-K05). References [2-1] S. Ichikawa et al., Nucl. Instr. and Meth. B204 (2003) 372. [2-2] R. Kirchner et al., Nucl. Instr. and Meth. 186 (1981) 295. [2-3] A. Osa et al., Nucl. Instr. and Meth. B266 (2008) 4373. [2-4] Y. Otokawa et al., Rev. Sci. Instrum. 81 (2010) 02A902. [2-5] D. Hitz et al., Rev. Sci. Instrum. 73 (2002) 509. [2-6] N. Angert et al., Proc. of the 14th International Workshop on ECR sources, CERN, Geneva, Switzerland, 1999, p220. [2-7] M. Oyaizu et al., Rev. Sci. Instrum. 73 (2002) 806. [2-8] N. Imai et al., Rev. Sci. Instrum. 79 (2008) 02A906. [2-9] S.C. Jeong et al., Rev. Sci. Instrum. 75 (2004) 1631. [2-10] M. Oyaizu et al., AIP CP1120 (2009) 308. [2-11] S.C. Jeong et al., Rev. Sci. Instrum. 73 (2002) 803. [2-12] S. Arai et al., Nucl. Instr. and Meth. A390 (1997) 9. [2-13] S. Arai et al., KEK preprint 98-99, 1998. 50
[2-14] S. Arai et al., KEK Report 2008-8, 2008. [2-15] S. Yamada, ‘TRACEP’, NIRS HIMAC program manual No. 1, May 1990, Private communication. [2-16] S. Arai et al., KEK Report 2008-1, 2008. [2-17] M. J. Lee et al., ‘MAGNET INSERTION CODE’, NAL TM-447, Oct. 1973. [2-18] H. Kabumoto et al., Nucl. Instr. and Meth. A612 (2010) 221. [2-19] K.W. Shepard, C.H. Scheibelhut, R. Benaroya and L.M. Bollinger, IEEE Trans. Nucl. Sci. NS-24(3) (1977) 1147. [2-20] K. Saito and P. Kneisel, Proc. of the 3rd EPAC, Berlin, Germany, (1992) 1231. [2-21] P. Kneisel, B.Lewis and L. Turlington., Proc. of the 6th Workshop on RF Superconductivity, CEBAF, (1993) 628. [2-22] K. Niki et al., Proc. of the 6th Part. Accel. Soc. Meeting, 2009, Tokai, Japan. [2-23] M. Okada et al., Proc. of the 6th Part. Accel. Soc. Meeting, 2009, Tokai, Japan. [2-24] T. Hashimoto et al., Nucl. Instrum. Methods A 556 (2006) 239. [2-25] C. Shalem et al., Nucl. Instrum. Methods A 558 (2006) 475. [2-26] K. Yamaguchi et al., Nucl. Instrum. Methods A 623 (2010) 135. [2-27] S.K. Das et al., Nucl. Instrum. Methods A 625 (2010) 39. 51
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TRIAC Progress Report TRIAC collabo
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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 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 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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