| Paper | Title | Page |
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| MOPEA013 | Laser-driven Proton Accelerator for Medical Application | 88 |
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The interaction between the high intensity laser and the solid target produces a strong electrostatic proton acceleration field (1 TV/m) with extraordinary small size, contributing to downsizing of the particle accelerator. The proton beam exhibits significant features. having very small source size(~10 um), short pulse duration (~ps) and very low transverse emittance. However it is a diverging beam (half angle of ~10 deg) with wide energy spread of ~100 %. Because of these peculiar characteristics the proton beam attracts many fields for applications including medical applications. To preserve these peculiar characteristics, which are not possessed by those beams from the conventional accelerators, towards the irradiation points, we need to establish a peculiar beam transport line. As the first step, here we report the demonstration of the proto-type laser-driven proton medical accelerator beam line in which we combine the laser-driven proton source with the beam transport technique already established in the conventional accelerator for the purpose of comparison between the data and the particle transport simulation code, PARMILA*. *Harunori Takeda, 2005, Parmila LANL (LA-UR-98-4478). |
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| MOPD071 | Horizontal-Vertical Coupling for Three Dimensional Laser Cooling* | 855 |
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In order to achieve three dimensional crystal beam, laser cooling forces are required not only in the longitudinal direction, but also in the transverse directions. With the resonance coupling method*, transverse temperature is transmitted into longitudinal direction, and we have already demonstrated horizontal laser cooling experimentally **. In the present paper, we describe an approach to extend this result to three dimensional cooling. The vertical cooling requires that the horizontal oscillation couples with the vertical oscillation. For achieving horizontal-vertical coupling, a solenoid in electron beam cooling apparatus is utilized with an experiment (Qx=2.07,Qy=1.07). For various solenoidal magnetic fields from 0 to 40Gauss, horizontal and vertical betatron tunes are measured by beam transfer function. For a certain region of the solenoidal magnetic field, these tunes are mixed up each other. By optimization of such a coupling, we aim to proceed to three dimensional laser cooling. * H. Okamoto Phys. Rev. E 50, 4982 (1994) |
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| MOPD072 | Optical Measurement of Transverse Laser Cooling with Synchro-Betatron Coupling* | 858 |
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Experiments of transverse laser cooling for 24Mg+ beam have been performed at the small ion storage and cooler ring, S-LSR. It is predicted that the longitudinal cooling force is transmitted to the horizontal direction with synchro-betatron coupling at the resonant condition*. The laser system consists of a 532nm pumping laser, a ring dye laser with variable wavelength around 560nm, and a frequency doubler. The horizontal beam size and the longitudinal momentum spread were optically measured by a CCD and a PAT (Post Acceleration Tube) respectively**, ***. The CCD measures the beam size by observing spontaneous emission from the beam and records in sequence of 100ms time windows the development of the beam profile. The time variation of the beam size after beam injection indicates the transverse cooling time. The initial horizontal beam size, which was about 1mm, was decreased by 0.13mm in 1.5s. The longitudinal momentum spread measured by PAT is increased at the resonant condition. This suggests transverse temperature was transferred to longitudinal direction by synchro-betatron coupling. Both measurements denote the horizontal cooling occurred only in the resonant condition ****. * H. Okamoto, Phys. Rev. {E50}, 4982 (1994) |
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| MOPD073 | Transverse Laser Cooling by Synchro-betatron Coupling | 861 |
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Transverse laser cooling with the use of a synchro-betatron coupling is experimentally demonstrated at the ion storage/cooler ring S-LSR. Bunched 40keV 24Mg+ beams are cooled by a co-propagating laser with a wavelength of 280nm. Synchrotron oscillation and horizontal betatron oscillation are coupled by an RF drifttube at a finite dispersive section (D = 1.1m) in order to transmit longitudinal cooling force to the horizontal degree of freedom*. Time evolution of horizontal beam size during laser cooling was measured by a CCD camera**. Horizontal beam sizes were reduced by 0.13mm within 1.5s after injection when the tune values satisfy a difference resonance condition, νs - νh = integer, at the operating tunes of (νh, νv, νs)=(2.067, 1.104, 0.067) and (2.058, 1.101, 0.058). Without resonance condition, the size reduction was negligibly small. The momentum spread was 1.7x10-4 on the resonance otherwise 1.2x10-4. These results show that the horizontal heats are transferred to the longitudinal direction through the synchro-betatron coupling with the resonance condition and are cooled down by a usual longitudinal bunched beam laser cooling. * H. Okamoto, Phys. Rev. E 50, 4982 (1994). |
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| MOPD074 | Beam Lifetime with the Vacuum System in S-LSR | 864 |
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S-LSR is a compact ion storage and cooler ring to inject beam of the 7MeV proton and the 40MeV Mg+. The average vacuum pressure measured by the vacuum gauges without beam was achieved up to about 4x10-9 Pa in 2007. Many experiments have been carried out using the proton and Mg beam, for example the one-dimensional beam ordering of protons utilizing the electron cooler, the extraction tests of the short bunched beam and the laser cooling for the Mg beam had been performed. The beam lifetime can be estimated with the vacuum pressure or the loss-rate of the beam energy. The values of the estimated lifetime are nearly equal to the measured lifetime values. The present status of the proton beam lifetime and the vacuum pressure is reported. |
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| MOPD092 | The Diagnostics System at the Cryogenic Storage Ring CSR | 918 |
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A cryogenic storage ring (CSR) is under construction at MPI für Kernphysik, which will be a unique facility for low velocity phase space cooled ion beams. Among other experiments the cooling and storage of molecular ions in there rotational ground state is planed. To meet this requirement the ring must provide a vacuum with a residual gas density below 10000 molecules/cm3, which will be achieved by cooling the vacuum chamber of the ion beam to 2-10 K. The projected stored beam current will be in the range of 1 nA - 1 μA. The resulting low signal strengths on the beam position pickups, current monitors and Schottky monitor put strong demands on these diagnostics tools. The very low residual gas density of the CSR does not allow using a conventional residual gas monitor to measure the profile of the stored ion beam. Other methods were investigated to measure the profile of a stored ion beam. In the paper an overview of the CSR diagnostics tool and diagnostics procedures will be given. |