• R. Kuroda, H. Ikeura-Sekiguchi, M. Koike, H. Ogawa, N. Sei, H. Toyokawa, K. Yamada, M.Y. Yasumoto
  AIST, Tsukuba, Ibaraki

Advanced quantum radiation sources such as a laser Compton scattering X-ray source and a coherent THz radiation source have been developed based on an S-band compact electron linac at AIST in Japan. The laser Compton scattering X-ray source using a TW Ti:Sa laser can generate a hard X-ray pulse which has variable energy of 12 keV - 40 keV with narrow bandwidth by changing electron energy and collision angle for medical and biological applications. The coherent THz radiation source based on the electron linac has been also developed instead of a conventional laser based THz source. The designed THz pulse has high peak power more than 1 kW in frequency range between 0.1 - 2 THz. The THz pulse will be generated with coherent radiation such as synchrotron radiation and transition radiation using an ultra-short electron bunch with bunch length of less than 0.5 ps (rms). The coherent synchrotron radiation in the THz region has been already generated and it will be applied to the THz time domain spectroscopy (TDS). In this work shop, we will report present status of our advanced quantum radiation sources.

• H. Ogawa, N. Sei, K. Yamada
  AIST, Tsukuba, Ibaraki

Recently, an FEL in the near-infrared (IR) region was oscillated at a compact storage ring NIJI-IV whose circumference was 29.6 m. We have been developed a device for the storage ring FEL in the IR region with a 3.6-m optical klystron ETLOK-III, and the first lasing at a wavelength of around 1450 nm was achieved at February 2009. The maximum power of the FEL was 0.3 mW per vacuum window and the relative linewidth was 3·10^-4.* Moreover, gamma-ray beam was also produced in the long straight section of NIJI-IV by Compton backscattering of the intra-cavity IR FEL and the stored electron beam with an energy of 310MeV. After the first lasing experiment, we have successfully performed to extend the lasing wavelength region and increase FEL power, and this recent progress will be presented.

* N. Sei, H. Ogawa, K.Yamada, Opt. Lett. 34 (2009) 1843.

• K. Yamada, S. Arai, M.K. Fujimaki, T. Fujinawa, N. Fukunishi, A. Goto, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Kase, M. Komiyama, K. Kumagai, T. Maie, T. Nakagawa, J. Ohnishi, H. Okuno, N. Sakamoto, Y. Sato, K. Suda, H. Watanabe, Y. Watanabe, Y. Yano, S. Yokouchi
  RIKEN Nishina Center, Wako
• H. Fujisawa
  Kyoto ICR, Uji, Kyoto

A new additional injector (RILAC2) is constructed at RIKEN Nishina Center in order to enable the independent operation of the RIBF experiments and super-heavy element synthesis. The RILAC2 consists of a 28 GHz superconducting ECR ion source, a low-energy beam transport with a pre-buncher, a four-rod RFQ linac, a rebuncher, three DTL tanks, and strong Q-magnets between the rf resonators for the transverse focusing. Very heavy ions with m/q of 7 such as ¹³⁶Xe²⁰⁺ and ²³⁸U³⁵⁺ will be accelerated up to the energy of 680 keV/u in the cw mode and be injected to the RIKEN Ring Cyclotron without charge stripping. The RFQ linac, the last tank of the DTL, and the bunchers have been converted from old ones in order to save the cost. Construction of the RILAC2 started at the end of the fiscal 2008. The RFQ and DTLs will be installed in the AVF cyclotron vault and be tested in March 2010. The ECR ion source and low-energy beam transport will be set on the RILAC2 in 2010 summer, and the first beam will be accelerated in 2010 autumn. We will present the details of the linac part of RILAC2 as well as the progress of construction which includes the result of high power test of resonators.

• K. Suda, S. Arai, Y. Chiba, O. Kamigaito, M. Kase, N. Sakamoto, K. Yamada
  RIKEN Nishina Center, Wako

A new injector RILAC2 for RIKEN RI-Beam Factory is under construction. The three Drift Tube Linac (DTL) cavities, located downstream of an RFQ linac, are designed to operate at a fixed RF frequency of 36.5 MHz, and to accelerate very heavy ions such as 136Xe²⁰⁺ and 238U³⁵⁺ from 100 keV/u to 680 keV/u for the injection to the RIKEN Ring Cyclotron. The first two cavities (DTL1 and 2) are newly constructed, and an existing cavity is modified for the last one (DTL3). The structure is based on the quarter-wavelength resonator. The inner diameter ranges from 0.8 to 1.3 m. In order to save the construction cost and space for the equipments, direct coupling scheme has been adopted for the RF amplifier. A capacitive coupler was designed to match the input impedance to 700, which corresponds to the optimum output impedance of a tetrode. Design of the cavities and couplers will be described in detail.