Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session Y9: Physics of Particle Beams |
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Sponsoring Units: DPB Chair: Peter Zavodsky, National Superconducting Cyclotron Laboratory Room: Hyatt Regency Jacksonville Riverfront City Terrace 5 |
Tuesday, April 17, 2007 1:30PM - 1:42PM |
Y9.00001: Design, construction and commissioning of the SuSI ECR Peter Zavodszky, Ben Arend, Dallas Cole, Jon DeKamp, Guillaume Machicoane, Felix Marti, Peter Miller, Jim Moskalik, William Nurnberger, Jack Ottarson, John Vincent, Xiaoyu Wu, Albert Zeller An ECR ion source was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies and it is planned an upgrade to 24-28 GHz in the second phase of commissioning. A superconducting hexapole coil produces the radial magnetic field; the axial trapping is produced with six superconducting solenoids enclosed in an iron yoke to allow tuning the distance between the plasma electrode and resonant zone in the plasma. The plasma chamber of the ion source can be biased at +30 kV, the beam line at --30 kV. The voltage of the beam line vacuum pipe must be kept constant from the ECRIS to the point of full separation of the beam charge states near the image plane of the analyzing magnet. At this point, an insulator is used to increase the voltage up to zero value. The kinetic energy of the beam is decreased to 30 kV per unit charge after this point, as required for the injection in the Coupled Cyclotron Facility. To decrease the beam divergence, a focusing solenoid is installed after the vacuum pipe break. We report the details of the design, construction and initial commissioning results of this new ECIS. [Preview Abstract] |
Tuesday, April 17, 2007 1:42PM - 1:54PM |
Y9.00002: Spatially resolved X-ray spectroscopy of swift heavy ions -- solid matter interaction S.A. Pikuz Jr., O. Rosmej, A.Ya. Faenov, V.P. Efremov, S. Korostiy, A. Blazevic, A. Fertman, I.Yu. Skobelev, G.E. Norman, D.H.H. Hoffmann K-shell radiation of projectile ions and solid media during its interaction has been investigated. The target media are transparent for radiation applied for diagnostics, which provides the data acquisition directly from the interaction volume. The projectile and target spectra in the energy range of 1.5$^{ }-^{ }$8 keV were registered by spherically bend crystal spectrometers (FSSR) with a high spatial resolution along the beam propagation. The Ni, Ca and Mg ions accelerated in GSI UNILAC facility to the energies of 11.4 MeV/u were slowed down in quartz and aluminum media. Low-density (up to 0.02 g/cc) quartz aerogel targets allowed expanding 100 times the interaction volume and to determine the evolution of ion beam velocity and charge states inside the media. At the same time, the wavelengths and relative intensities of K$_{\alpha }$ satellite lines radiated by Si and Al target ions with different charges were measured. This has been provided us to investigate the excited media of the heavy ion track on a timescale of radiation transitions lifetimes ($\sim $10 fs after excitation). Low beam current of 1 uA allowed us to consider the excitation process as a number of statistically independent acts of single heavy ion energy deposition to the media. Non-stationary radiation kinetics simulations was applied to analyze excited media experimental spectra and to recognize the conditions of initial stage of single ion track formation. [Preview Abstract] |
Tuesday, April 17, 2007 1:54PM - 2:06PM |
Y9.00003: Experimental test of the Chao matrix formalism for spin dynamics. V.S. Morozov, A.W. Chao, A.D. Krisch, M.A. Leonova, R.S. Raymond, D.W. Sivers, V.K. Wong, R. Gebel, A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, A. Schnase, H. Stockhorst, F. Hinterberger, K. Ulbrich We recently started testing Chao's proposed new matrix formalism for describing the spin dynamics due to a single spin resonance in a stored polarized beam. This formalism seems to be the first generalization of the Froissart-Stora equation since it was published in 1960. It allows one to calculate analytically the polarization's behavior inside a resonance, which is not possible using the Froissart-Stora equation. We recently tested some Chao formalism predictions using a 1.85 GeV/c polarized deuteron beam stored in COSY. We swept an rf dipole's frequency through 200 Hz, at different sweep rates, while varying the distance from the sweep's end frequency to an rf-induced spin resonance's central frequency. We compared our experimental data with the predictions of the Chao formalism and the prediction of a phenomenological Froissart-Stora-based two-fluid model. The Froissart-Stora formula itself can make no prediction inside the resonance. The data seem to support the validity of the Chao formalism. (Supported by the German BMBF Science Ministry.) [Preview Abstract] |
Tuesday, April 17, 2007 2:06PM - 2:18PM |
Y9.00004: Unexpected reduction of rf spin resonance strength for stored polarized deuterons. M.A. Leonova, A.D. Krisch, V.S. Morozov, R.S. Raymond, D.W. Sivers, V.K. Wong, R. Gebel, A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, A. Schnase, H. Stockhorst, F. Hinterberger, K. Ulbrich The ratio $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ of the deuteron's measured rf spin resonance's strength, $\varepsilon _{FS }$, obtained by fitting spin-flipping data to the Froissart-Stora equation, to the $^{\ast }\varepsilon _{Bdl}$ calculated from our rf magnet's $\smallint $\textit{Bdl} was about 7 times smaller than predicted. We studied this discrepancy using a 1.85 GeV/c vertically polarized deuteron beam stored in COSY in J\"{u}lich, Germany, by sweeping the frequency of an rf-dipole through an rf-induced spin resonance. We studied the dependence of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ on the beam size, the momentum spread $\Delta p$/$p$, the distance from a 1$^{st}$-order intrinsic spin resonance and the frequency sweep range $\Delta $f. We found no dependence on the beam size, $\Delta p$/$p$ or $\Delta $f. We saw a strong enhancement of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ with a hyperbolic dependence on the distance from the intrinsic resonance. This did not explain the reduction of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ far from the intrinsic resonance. Thus, this small $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ ratio may be due to some unexpected behavior of relativistic spin-1 deuterons in an rf dipole. (Supported by the German BMBF Science Ministry.) [Preview Abstract] |
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