The decomposition of level-1 irreducible highest weight modules with respect to the level-0 actions of the quantum affine algebra Uq′(sl^n)U'_q(\hat{sl}_n)

We decompose the level-1 irreducible highest weight modules of the quantum affine algebra $U_q(\hat{sl}_n)$ with respect to the level-0 $U'_q (\hat{sl}_n)$--action defined in q-alg/9702024. The decomposition is parameterized by the skew Young diagrams of the border strip type.Comment: 22 pages, AMSLaTe

Synchrobetatron resonant coupling mechanism in a storage ring

A clear synchrobetatron resonant coupling of Mg ion beam was observed experimentally in the horizontal laser beam cooling experiment in small laser equipped storage ring. Synchrotron and horizontal betatron motions were intentionally coupled in a rf cavity. Using the Hamiltonian which is composed of coasting, synchrotron and betatron motions, physical mechanism of the coupling is analyzed to explain the observed horizontal betatron tune jump near the synchrobetatron resonant coupling point. There energy exchange between the synchrotron oscillation and the horizontal betatron oscillation was mediated by coasting particles and the freedom of the horizontal direction is connected with the freedom of the longitudinal direction

Possible observation of transverse laser cooled ultimate cold ion beam in S-LSR

Transverse laser cooling is pursued at an ion storage/cooler ring, S-LSR, Kyoto University. An RF bunched Mg+ beam was cooled transversely through synchro-betatron resonance coupling by a co-propagating laser. We investigated peaks of synchrotron oscillation spectroscopically so that we can observe them stably. Oscillation signals from a parallel-plate pickup were observed by a spectrum analyzer. We also observed the coherent synchrotron modes. As the beam temperature decreases, the ion beam would be in space charge limited region. According to the computer simulation, in the case the beam turns to be space charge limited, the disappearance of peaks of synchrotron oscillation is expected. We would like to propose a capability of detecting space charge limited region by observing such a frozen synchrotron oscillation

Simulation study on transverse laser cooling and crystallization of heavy-ion beams at the cooler storage ring S-LSR

Multi-dimensional laser cooling of heavy-ion beams at the cooler storage ring S-LSR in Kyoto University is studied numerically using the molecular dynamics simulation technique in which the stochastic interaction between ions and laser photons is incorporated. The purpose of the study is to find out how low-temperature we can achieve using actual experimental parameters and to verify the observation result in the experiment. In these proceedings, the characteristics of the ion beam lasercooled in S-LSR are reported. It has been confirmed that, in spite of the limitation in the experimental conditions such as a single laser beam, low power, fixed detuning and short laser-cooling section, the three-dimensionallylow-temperature beam is obtained through resonant coupling at a low intensity of 104 ions in the ring, which is consistent with the experimental result. It is also demonstrated that a string crystalline state of the beam can be formed at a further lower intensity

Latest results of experimental approach to ultra-cold beam at S-LSR

Utilizing S-LSR which has a super-periodicity of 6 and is designed to be tough against resonant perturbation to the circulating beam, we have tried to approach as low as possible temperature with laser cooled 40 keV 24Mg+ ion beam. With the use of theoretically proposed Synchro-Betatron Resonance Coupling scheme, we have experimentally demonstrated the capability of active indirect transverse laser cooling. At first, the achieved transverse cooling efficiency was limited due to heating caused by intra-beam scattering (IBS). For the purpose of reduction of IBS heating, we have established a scheme tocontrol the circulating ion beam intensity down to ~104 by scraping the outskirt of the beam with the use of a horizontally moving scraper, which enabled us to cool down the transverse beam temperatures down to 20 K and 29 K for horizontal and vertical directions, respectively for the operation tune without H-V coupling. They were modified to be 40 K and 11 K by the horizontal and vertical coupling with the difference resonance with an excitation of a solenoid of 22.5 G, which were further improved to 7.0 K and 2.1 K adding deceleration by an induction accelerator of 6 mV/m using a -26 MHz detuned laser