DIPAC2011 - List of Authors (Bloomer, C.)

Paper

Title

Page

An Aperture Backscatter X-ray Beam Position Monitor at Diamond

6

C. Bloomer, G. Rehm, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.

Slides MOOB01 [7.211 MB]

MOPD28

Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation

110

G. Rehm, C. Bloomer, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD78

Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage

227

G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun
Diamond, Oxfordshire, United Kingdom

We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.

Paper	Title	Page
MOOB01	An Aperture Backscatter X-ray Beam Position Monitor at Diamond	6
	C. Bloomer, G. Rehm, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.
	Slides MOOB01 [7.211 MB]

MOPD28	Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation	110
	G. Rehm, C. Bloomer, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD78	Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage	227
	G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun Diamond, Oxfordshire, United Kingdom
	We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.