| Paper | Title | Page |
|---|---|---|
| TUPTPF061 | Considerations on ODR Beam-Size Monitoring for Gamma 1000 Beams | 253 |
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We have previously experimentally observed and modeled the near-field optical diffraction radiation (ODR) generated by a 3-nC micropulse of a 7-GeV electron beam at the Advanced Photon Source (APS). Due to the high gamma of ~14,000, the scaling factor of γλ/2π was about 1.4 mm for 0.628 um radiation. Thus, a standard CCD camera was sufficient for imaging at an impact parameter of 1.25 mm. The extension of this technique to γ 1000 is challenged by the ·1014 reduction in visible light photon production compared to the APS case. We discuss the feasibility of monitoring at a new Fermilab facility a high average current linac beam of 3000 times more charge in a video frame time and with a more sensitive 12- to 16-bit camera. Numerical integrations of our base model show beam size sensitivity for ±20% level changes at 200- and 400-um base beam sizes. We also evaluated impact parameters of 5 σy and 12 σy for both 800-nm and 10-um observation wavelengths. The latter examples are also related to a proposal to apply the technique to an ~ 0.94 TeV proton beam, but there are trades on photon intensity and beam size sensitivity to be considered at such gammas. |
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| TUPTPF075 | A Solid-State Pinger Tune Measurement System for the Intense Pulsed Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS) | 290 |
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A cw tune measurement system for the IPNS RCS is described. The pinger magnets are energized by a solid-state, transformer-coupled power supply operating at 30 Hz. In its present configuration, the power supply provides a 160-A pulse to a pair of series-connected, single-turn ferrite magnets. The magnet pair drive separately x- and y-plane orbit bumps in the h=1 beam. The dipole oscillations generated in the beam are sensed with pairs of split-can, "pie" electrodes. Raw signals from the H and V electrodes are carried on matched coax-cables to 0/180-degree combiners. The output difference signals are recorded with gated spectrum analyzers. Bunch circulation frequency varies from 2.21 MHz at injection to 5.14 MHz at extraction. With a fixed frequency span of 24 MHz, between 4 and 10 bunch harmonics and sidebands (SBs) are present in the difference spectra. Software has been developed to use the multi-harmonic SBs present over the span to improve the accuracy of the tune measurements. The software first identifies and then fits the multiple SBs to determine the tune. Sweeping the beam across the momentum aperture provides a method for measuring the chromaticity. |
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| TUPTPF078 | An FPGA-based Tune Measurement System for the APS Booster Synchrotron | 303 |
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The Advanced Photon Source (APS) injection booster is a 7-GeV electron synchrotron with a ramping time of 220 ms and a repetition rate of 2 Hz. A real-time tune measurement system is needed in order to monitor and possibly correct tune drift during the 220-ms energy ramp. Such a drift may occur during user beam operations, especially during top-up operations, and results in shot-to-shot charge fluctuations. We designed and developed a new FPGA-based system that pings the beam at variable intervals and measures booster tune. A prototype system has been built and tested, and it has achieved the specified time resolution of 2 ms and a tune resolution of better than 0.002. This report describes the design and main parameters, test results from our preliminary commissioning, and application of such a system in ramping correction. |