IBIC2012 - List of Authors (Wootton, K.P.)

Paper

Title

Page

Vertical Emittance Measurements using a Vertical Undulator

20

K.P. Wootton, R.P. Rassool, G. Taylor
The University of Melbourne, Melbourne, Australia
M.J. Boland, B.C.C. Cowie, R.T. Dowd, Y.E. Tan
ASCo, Clayton, Victoria, Australia
Y. Papaphilippou
CERN, Geneva, Switzerland

With vertical dimensions of several microns, direct measurement of beam size is approaching diffraction limits of visible light and hard x-ray emittance diagnostics. We report on the development of a new vertical electron beam size measurement and monitoring technique which utilizes a vertical undulator. An APPLE-II type undulator was phased to produce a horizontal magnetic field, deflecting the electron beam in the vertical plane. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. Vertical electron beam emittances of several picometres have been observed at the Australian Synchrotron storage ring. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.

Slides MOCB04 [3.449 MB]

MOPB83

Turn-by-turn Observation of the Injected Beam Profile at the Australian Synchrotron Storage Ring

276

M.J. Boland
ASCo, Clayton, Victoria, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

A fast gated intensified CCD camera was used to observe the beam profile turn-by-turn in the visible light region. Using the visible light from the optical diagnostic beamline on the storage ring at the Australian Synchrotron an optical telescope was constructed to focus an image on the ICCD. The event driven timing system was then used to synchronise the camera with the injected beam. To overcome the problem of dynamic range between the amount of charge in an injected bunch and the stored beam, the beam was dumped by slowly phase flipping the RF by 180 degrees between each one 1 Hz injection cycle. The injection process was verified to be stable enough so that measurements of the different turns could be captured on successive injections and did not need to be captured in single shot. The beam was seen to come in relatively cleanly in a tight beam but would then rapidly decohere due to the strong non-linear fields needed to run the storage ring at high chromaticity. It would take thousands of turns for the beam to damp down again and recohere into a tight beam spot again. This measurement technique will be used to tune the storage ring injection process.

TUPB72

Injected Beam Profile Measurement during Top-up Operation

508

M.J. Boland
ASCo, Clayton, Victoria, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

A coronagraph-like apparatus was constructed on the optical diagnostic beamline on the storage ring to observe the injected beam during top-up operations. An image was created on an intensified CCD that can be gated on a single bunch or on a bunch train for a stronger signal. The bright central stored beam was obscured so the comparatively faint injected beam could be observed. The injected beam comes in at a large enough offset so that it was clearly visible above any diffraction or beam halo signals. The beam profile measured was in good agreement with the observations made of the injected beam only using a telescope apparatus. The measurements were made during user beam in top-up operation mode and can be used to optimise the injection process.

WECC03

Intensity Imbalance Optical Interferometer Beam Size Monitor

566

M.J. Boland
ASCo, Clayton, Victoria, Australia
T.M. Mitsuhashi, T. Naito
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

The technique of measuring the beam size in a particle accelerator with an optical interferometer with the Mitsuhashi apparatus is well established and one of the only direct measurement techniques available. However, one of the limitations of the technique is the dynamic range and noise level of CCD cameras when measuring ultra low emittance beams and hence visibilities close to unity. A new design has been successfully tested to overcome these limitations by introducing a know intensity imbalance in one of the light paths of the interferometer. This modification reduces the visibility in a controlled way and lifts the measured interference pattern out of the noise level of the CCD, thus increasing the dynamic range of the apparatus. Results are presented from tests at the ATF2 at KEK and on the optical diagnostic beamline at the Australian Synchrotron storage ring.

Slides WECC03 [2.383 MB]

Paper	Title	Page
MOCB04	Vertical Emittance Measurements using a Vertical Undulator	20
	K.P. Wootton, R.P. Rassool, G. Taylor The University of Melbourne, Melbourne, Australia M.J. Boland, B.C.C. Cowie, R.T. Dowd, Y.E. Tan ASCo, Clayton, Victoria, Australia Y. Papaphilippou CERN, Geneva, Switzerland
	With vertical dimensions of several microns, direct measurement of beam size is approaching diffraction limits of visible light and hard x-ray emittance diagnostics. We report on the development of a new vertical electron beam size measurement and monitoring technique which utilizes a vertical undulator. An APPLE-II type undulator was phased to produce a horizontal magnetic field, deflecting the electron beam in the vertical plane. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. Vertical electron beam emittances of several picometres have been observed at the Australian Synchrotron storage ring. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.
	Slides MOCB04 [3.449 MB]

MOPB83	Turn-by-turn Observation of the Injected Beam Profile at the Australian Synchrotron Storage Ring	276
	M.J. Boland ASCo, Clayton, Victoria, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	A fast gated intensified CCD camera was used to observe the beam profile turn-by-turn in the visible light region. Using the visible light from the optical diagnostic beamline on the storage ring at the Australian Synchrotron an optical telescope was constructed to focus an image on the ICCD. The event driven timing system was then used to synchronise the camera with the injected beam. To overcome the problem of dynamic range between the amount of charge in an injected bunch and the stored beam, the beam was dumped by slowly phase flipping the RF by 180 degrees between each one 1 Hz injection cycle. The injection process was verified to be stable enough so that measurements of the different turns could be captured on successive injections and did not need to be captured in single shot. The beam was seen to come in relatively cleanly in a tight beam but would then rapidly decohere due to the strong non-linear fields needed to run the storage ring at high chromaticity. It would take thousands of turns for the beam to damp down again and recohere into a tight beam spot again. This measurement technique will be used to tune the storage ring injection process.

TUPB72	Injected Beam Profile Measurement during Top-up Operation	508
	M.J. Boland ASCo, Clayton, Victoria, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	A coronagraph-like apparatus was constructed on the optical diagnostic beamline on the storage ring to observe the injected beam during top-up operations. An image was created on an intensified CCD that can be gated on a single bunch or on a bunch train for a stronger signal. The bright central stored beam was obscured so the comparatively faint injected beam could be observed. The injected beam comes in at a large enough offset so that it was clearly visible above any diffraction or beam halo signals. The beam profile measured was in good agreement with the observations made of the injected beam only using a telescope apparatus. The measurements were made during user beam in top-up operation mode and can be used to optimise the injection process.

WECC03	Intensity Imbalance Optical Interferometer Beam Size Monitor	566
	M.J. Boland ASCo, Clayton, Victoria, Australia T.M. Mitsuhashi, T. Naito KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	The technique of measuring the beam size in a particle accelerator with an optical interferometer with the Mitsuhashi apparatus is well established and one of the only direct measurement techniques available. However, one of the limitations of the technique is the dynamic range and noise level of CCD cameras when measuring ultra low emittance beams and hence visibilities close to unity. A new design has been successfully tested to overcome these limitations by introducing a know intensity imbalance in one of the light paths of the interferometer. This modification reduces the visibility in a controlled way and lifts the measured interference pattern out of the noise level of the CCD, thus increasing the dynamic range of the apparatus. Results are presented from tests at the ATF2 at KEK and on the optical diagnostic beamline at the Australian Synchrotron storage ring.
	Slides WECC03 [2.383 MB]