| Paper | Title | Page |
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| MOPB63 | Emittance Measurement using X-ray Beam Profile Monitor at KEK-ATF | 1 |
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| The X-ray profile monitor (XPM) is used for the beam size measurement in the KEK-ATF damping ring(ATF-DR) at all times. The XPM consists of a crystal monochromator, two Fresnel zone plates(FZPs) and X-ray CCD camera. Two FZPs make the imaging optics. The design resolution of the selected wavelength 3.8nm is less than 1μm, which is sufficiently small for the emittance measurement of the ATF-DR. However, the measured results at the early stage were affected by the mechanical vibration. This paper describes the improvement of the resolution and the measurement results. | ||
| TUCC04 | Measurement of Nanometer Electron Beam Sizes with Laser Interference using IPBSM | 1 |
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| At ATF2, the Local Chromaticity Correction focusing scheme is to be verified through realizing its design vertical e- beam size (σy ) of 37 nm. The 'IPBSM', installed at ATF2's virtual IP, is the only existing beam size monitor capable of measuring σy < 100 nm, making it indispensable for ATF's goals and R&D at future LCs. This owes to a novel technique of colliding e- beam against laser interference fringes. σy is derived from the modulation depth of resulting Compton photons, which is large for small σy. The measurable range from O(10) nm ~ a few μm, is controlled by switching between laser crossing angles θ = 174° , 30°, and 2° - 8° . In early 2011, measuring σy < 300 nm was hindered by an immense earthquake and heavy signal jitters. The ensuing recovery and upgrades stabilized the laser system and improved resolution to 5%. In spring 2012, we commissioned advanced crossing angle modes by consistently measuring σy ≥ 150 nm. Our goals for the autumn 2012 run is to stably measure σy < 50 nm. Major hardware upgrades during the summer aim at more reliable alignment and optimization of specialized functions to suppress bias factors. | ||
TUPA14 |
Development of Cavity-type Beam Position Monitors with High Resolution for ATF2 | |
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| We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. An electronics for Low-Q IP-BPM will be also described. | ||
WECA01 |
Theoretical and Experimental Investigation on Resolution of Optical Transition Radiation Transverse Beam Profile Monitor | |
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| Optical Transition Radiation (OTR) appearing when a charged particle crosses an interface between two media with different dielectric constants has widely been used as a tool for transverse profile measurements of charged particle beams in numerous facilities worldwide. The basic tuning methods and operation of conventional OTR monitors are well established for transverse beam sizes not smaller than 3-5 um. Since the Point Spread Function (PSF) dimension defines the resolution of the conventional monitors, for small electron beam dimensions the PSF form significantly depends on a presence of OTR tails diffraction and aberrations in the optical system. In our experiment we have managed to squeeze the electron beam such that we can practically measure PSF distribution in one direction. The revealed PSF structure is such that the visibility depends on the transverse beam size on micron scale. We developed an empirical calibration technique and successfully overcame the resolution limit of the common OTR monitor reaching sub-micron level. Here we represent the recent developments and upgrades in both setup and data analysis of a sub-micrometer electron beam profile monitor. | ||
MOPB69 |
Development of Four Mirror Pulsed Laser Wire System for ATF-KEK Damping Ring | |
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Funding: Quantum Beam Technology Program of Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). Production and handling of a low emittance beam is one of the key technologies for linear colliders. The Accelerator Test Facility (ATF) was constructed at KEK to study low emittance beam physics and to develop the technologies associated with it. In ATF damping ring, the vertical beam size is less than 10 μm. To measure it precisely, a thin and intense laser beam is required. We utilize a pulsed four mirror optical cavity based on IR laser oscillator to fulfill this requirement. With pulsed green laser oscillator, the beam waist will reduce by factor of 2. Therefore, with green laser oscillator, effective electron-photon collision can be observed. Minimum beam waist is obtained in sagittal plane. Special type of mirror alignment scheme is used to make a compact four mirror optical cavity. With Pulsed laser oscillator the electron beam scanning is very fast as compare to CW Laser wire system. Profile of electron beam can be measured in vertical, horizontal and longitudinal direction within a few second. We report the design studies of such compact resonator and scheme to obtain laser beam size less than 6μm in rms. |
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