COOL 2007 - Classification:Laser Cooling/

Laser Cooling

Paper	Title	Page
FRM1I01	Present Status and Recent Activity on Laser Cooling at S-LSR	221
	A. Noda, M. Ikegami, T. Ishikawa, M. Nakao, T. Shirai, H. Souda, M. Tanabe, H. Tongu Kyoto ICR, Uji, Kyoto M. Grieser MPI-K, Heidelberg I. N. Meshkov, A. V. Smirnov JINR, Dubna, Moscow Region K. Noda NIRS, Chiba-shi
	Funding: The present work has been supported from Advanced Compact Accelerator Development Project by MEXT of Japan and 21 COE at Kyoto University-Center for Diversity and Universality in Physics. Ion storage and cooler ring, S-LSR, has been designed to enable the investigation of coldest possible ion beams with use of various beam cooling schemes such as an electron beam cooling and the laser cooling. Electron beam cooling of 7 MeV protons and laser cooling of 40 keV Mg ions have been applied up to now.　The first laser cooling applied to ~10⁸ Mg ions with the induction accelerator voltage of ~6 mV reduced the momentum spread (1 σ) from 1.7×10^-3 to 2.9×10^-4, which is considered to be saturated by the momentum transfer from transverse degree of freedom to the longitudinal one due to intra-beam scattering. The laser cooling force has been improved from the above one more than one order of magnitude owing to the precise alignment between the laser and Mg ion beam. Recent measurement with frequency shift of the laser showed the enhancement of the coherent signals in odd harmonics of the revolution frequency picked up with an electrostatic beam monitor and detailed measurements of various harmonics have been performed with changing the resolution bandwidth of the spectrum analyzer, although the origin of such coherency is not yet identified up to now. For the purpose of measurement of lowest possible temperature attainable by the laser cooling, measurement with reducing the ion numbers of Mg is needed, which has been blocked by the difficulty of observing the Schotty signal of such a low intensity beam. So as to cope with this situation, development of observing system of emitted light by the transition from the upper level to the ground state with the use of photomultiplier has been performed, which recently succeeded in detection of clear signals coming from the oriented process. Activities above mentioned will be presented together with the forth coming experimental results on laser cooling.
	Slides
FRM1C02	Schottky Noise Signal and Momentum Spread for Laser-Cooled Beams at Relativistic Energies	226
	M. H. Bussmann, D. Habs LMU, München K. Beckert, P. Beller, B. Franzke, C. Kozhuharov, T. Kuehl, W. Noertershaeuser, F. Nolden, M. Steck GSI, Darmstadt Ch. Geppert, S. Karpuk Johannes Gutenberg University Mainz, Mainz C. Novotny Johannes Gutenberg University Mainz, Institut für Physik, Mainz S. Reinhardt MPI-K, Heidelberg G. Saathoff MPQ, Garching, Munich U. Schramm FZD, Dresden
	We report on the first laser cooling of a bunched beam of C³⁺ ions at the ESR (GSI) at a beam energy of E = 1.47 GeV. Combining laser cooling of the 2S1/2-2P3/2 transition with moderate bunching of the beam lead to a reduction of the longitudinal momentum spread by one order of magnitude if compared to pure electron cooling. If additional electron cooling was applied, thus increasing the coupling between the longitudinal and transverse degree of freedom, three-dimensional cold beams with a plasma parameter of unity could be attained. In a second measurement campaign, a combination of a sweeping-frequency and a fixed-frequency laser beam was succesfully implemented to increase the momentum acceptance of the narrow band laser force. This cooling scheme improved the match of acceptance of the laser force to the momentum spread of the beam and reduced heating due to intra beam scattering. In addition to the interesting beam dynamics observed at low momentum spreads of ∆p / p < 10^-6 precision spectroscopy of 2S1/2-2P1/2 and 2S1/2-2P3/2 transition was performed, both absolute and relative, at a precision challenging the best theoretical models available. The laser cooling schemes used at the ESR can be directly extended to the regime of ultra-relativistic ion energies at the new FAIR facility. There, it becomes possible to cool a large number of ion species using a single laser beam source, exploiting the relativistic Doppler shift of the laser frequency. Finally, the fluorescence photons emitted by these ultra-relativistic laser cooled ion beams can be directly used for precision X-ray spectroscopy of the cooling transitions. The resolution of such measurements would essentially be only limited by the resolution of the X-ray spectrometers available.
	Slides