NIRS, Chiba-shi, Japan
MPI-K, Heidelberg, Germany
FRIB, East Lansing, Michigan, USA
TUB, Beijing, People's Republic of China
Kyoto University, Kyoto, Japan
HU/AdSM, Higashi-Hiroshima, Japan
JINR, Dubna, Moscow Region, Russia
Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan
Kyoto ICR, Uji, Kyoto, Japan
JAEA/TARRI, Gunma-ken, Japan
Doppler laser cooling has been applied to low-energy (40 keV) Mg ions together with the resonant coupling method* at the S-LSR at ICR, Kyoto University,. The S-LSR storage ring has a high super periodicity of 6, which is preferable from the beam dynamical point of view. At S-LSR one dimensional ordering of proton beam was already realized for the first time**. Active three dimensional laser cooling has been experimentally demonstrated for ions with un-negligible velocity (v/c=0.0019, where c is the light velocity) for the first time. Utilizing the above mentioned characteristics of S-LSR, an approach to realize ultralow emittances has been pursuit. To suppress heating effects, due to intra-beam scattering, the circulating ion beam intensity was reduced by scraping and beam emittances of 1.3·10-11 pi m·rad and 8.5·10-12 pi m·rad (normalized) have been realized for the horizontal and vertical directions, respectively with the 40 keV Mg ion beam at a beam intensity of ~104, which is the lowest emittance ever attained by laser cooling. From MD computer simulations, it is predicted that reduction of the ion number to about 103 is needed to realize a crystalline string.
* H. Okamoto, A.M. Sessler, D. Moehl, Phys. Rev. Lett. 72, 397 (1994).
** T. Shirai et. al., Phys. Rev. Lett. 98, 204801 (2007).
JAEA, Ibaraki-ken, Japan
Kyoto ICR, Uji, Kyoto, Japan
KEK, Ibaraki, Japan
We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and gamma-ray sources in academic and industrial applications, we adopt 325-MHz superconducting spoke cavity to electron beam drivers for the LCS sources. The spoke cavity, originally invented for ion and proton acceleration, can be used for electron accelerators, in which we can make best use of features of spoke cavity: relative compactness in comparison with a TM cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, couplers on outer conductor for the better packing in a linac, and so on. In this paper, we present our research plan and results of cavity shape optimization.
Kyoto ICR, Uji, Kyoto, Japan
JAEA, Ibaraki-ken, Japan
KEK, Ibaraki, Japan
Superconducting spoke cavity for laser Compton scattered (LCS) photon sources is under development. The operating frequency is 325-MHz to accelerate electron beam for the LCS sources, where the size of the spoke cavity is less than a elliptical cavities with the same frequency. Because of the complicated shape of the cavity, it may be suffered from a strong multipactor effect. The recent results on the multipactor analysis will be presented.