| Paper |
Title |
Page |
| TUPB07 |
Electric -In-Air-X-Ray- Detectors for high Resolution Vertical Beam Position Measurement at the ESRF
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69 |
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- K. B. Scheidt
ESRF, Grenoble
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The tiny fraction of the very hard X-rays that fully penetrate the dipole absorber structure and enter the free air space behind it can be detected in different ways to yield precise information on the vertical characteristics of the electron beam. In addition to a system of imaging detectors to measure the emittance, a 2nd detector type was developed that yields a direct electric signal. It consists of a high-Z blade in conjuction with a small In-Air ionization slot that generates a direct strong electric signal allowing for nanometer resolution measurements of vertical beam motion in a spectrum upto 1KHz. The high resolution performance of this detector type is explained by the fact that it touches the heart and center of the beam whereas other devices (X-BPMs or e-BPMs) have to work on the edges or tails of the beam or feel the beam indirectly by wall-current pick-ups. The results obtained with prototypes will be presented together with the prospects of an installation of 8 units in 2007. The intrinsic advantages of this In-Air detector like costs and simplicity, thanks to a total absence of cooling and UHV requirements, will be emphasized.
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| TUPB08 |
Measurement of Vertical Emittance with a system of Six -In-Air-X-Ray- Projection Monitors at the ESRF
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72 |
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- K. B. Scheidt
ESRF, Grenoble
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The ESRF Storage Ring is now equiped with a system of 5 independent imaging monitors that measure the vertical emittance of the electron beam in the middle of the bending magnet through the very hard X-rays that fully traverse the 40mm thick Copper dipole absorbers and enter the free air space behind it. The tiny power that leaks through the absorber, and carried by X-rays of ~160KeV of very narrow vertical divergence, is simply projected onto a scintillator screen at ~1.8m from the source-point and imaged by optics & camera. These inexpensive and compact detectors are fully operated in free air and can be easily installed and maintained without any vacuum intervention. They now work reliably in routine fashion and have demonstrated their high precision and resolution of the ESRF’s vertical emittance. These results will be presented in this paper together with the underlying principles of the projection detector, aswell as the practical design solutions applied to obtain the high spatial resolution, to make the system resistant to the hostile radiation environment behind the absorber, and to reduce its sensitivity to stray signals generated at this point.
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