| Paper | Title | Page |
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| TUO1C05 | Measurements and Interpretation of the Betatron Tune Spectra of High Intensity Bunched Beam at SIS-18 | 310 |
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| The paper presents the status of the transverse tune measurements in the synchrotron SIS18 at GSI. Presently, there are two systems for tune measurements in operation in the SIS18, namely TOPOS (Tune, Orbit and POsition measurement System) and BBQ (Base Band tune measurement system). The first one is a digital system where the BPM signal is digitized and the bunch position is calculated numerically. The second system is an analog system, where the transverse bunch motion is detected using peak detector. Band limited noise and chirp excitations were used to excite the betatron oscillations. Measurements of the betatron tune spectra were done at injection energy at medium and high intensities. In the frequency spectra a number of peaks around the position of betatron tune were seen. The peaks can be attributed to different bunch head-tail modes which were observed in time domain. These modes were dependent on the beam intensity. In this paper we compare the tune spectra measured at high beam intensity with the theoretical model for the space charge affected head-tail modes. | ||
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Slides TUO1C05 [1.315 MB] | |
| THO3C01 | Optical Transition Radiation for Non-relativistic Ion Beams | 580 |
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In this contribution, recent results of Optical Transition Radiation (OTR) measurements with a non-relativistic heavy-ion beam will be presented. This feasibility study was prompted by previous measurements [1] and the theoretical estimation of expected signal strengths for the GSI linear accelerator UNILAC. For this experiment, an 11.4 MeV/u Uranium beam was chosen to investigate OTR signal from several target materials and to evaluate the working regime for the used experimental setup. The OTR light was either observed directly with an Image Intensified CCD camera (ICCD) or indirectly via a spectrometer for wavelength resolved data. A moveable stripping foil allowed measurements with two different ion charge states. The theoretical q2 dependency of the OTR process predicts a six-fold increase in light yield which was confirmed experimentally. Obtained OTR beam profiles were compered to SEM-Grid data. Moreover, ICCD gating feature, as well as the emitted light spectrum ruled out contribution of any background sources with longer emission time constant e.g. blackbody radiation.
[1] C. Bal et al., "OTR from Non-relativistic Electrons", Proceedings of DIPAC03, PM04, Mainz Germany. |
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Slides THO3C01 [1.905 MB] | |
| THO3C02 | Momentum Spread Determination of Linac Beams Using Incoherent Components of the Bunch Signals | 583 |
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| Measurements of the momentum spread of the beam particles are of great importance when optimizing linac settings for high current operation with controlled longitudinal phase space occupation. A new method of momentum spread determination was tested at the GSI heavy ion linear accelerator UNILAC. The method is based on an analysis of incoherent components of the bunch signal. A significant enhancement of the signal-to-noise ratio was achieved by means of a resonant pick-up of pill-box shape. Spectra were analyzed on the 36th harmonics of the linac rf-frequency, i.e. at 1.3 GHz. Thus, the contribution of coherent components in the frequency spectrum of the bunched beam, e.g. due to common mode, was significantly damped. Fast digital processing and gating synchronized to the bunch train allowed for a drastic reduction of the measurement time and, additionally, suppressed noise signals in the frequency spectrum. This contribution describes the measurement setup and discusses first results obtained with heavy ion beams. | ||
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Slides THO3C02 [2.131 MB] | |
| THO3C03 | Beam Induced Fluorescence - Profile Monitoring for Targets and Transport | 586 |
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| Online profile diagnostic is preferred to monitor intense hadron beams at the Facility of Antiproton and Ion Research (FAIR). One instrument for beam profile measurement is the gas based Beam Induced Fluorescence (BIF)-monitor. It relies on the optical fluorescence of residual gas, excited by beam particles. In front of production targets for radioactive ion beams or in plasma physics applications, vacuum constraints are less restrictive and allow a sufficient number of fluorescence photons, even at minimum ionizing energies. Unwanted effects like radiation damage and radiation induced background need to be addressed as well. A profile comparison of BIF and Ionization Profile Monitor (IPM) in nitrogen and rare gases is presented. We studied the BIF method from 10-3 to 30 mbar with an imaging spectrograph. Preferable fluorescence transitions and fundamental limitations are discussed. | ||
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Slides THO3C03 [7.371 MB] | |