DIPAC2011 - List of Authors (Thomas, C.A.)

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.

MOPD32

Bunch Length Measurement from Power Fluctuation at Diamond

119

C.A. Thomas, I.P.S. Martin, G. Rehm
Diamond, Oxfordshire, United Kingdom

Bunch length can be measured using the visible light power fluctuation statistics of an individual bunch. This method developed at ALS has been implemented at Diamond with further improvement on the detection method and the speed of the measurement. In this paper, we firstly report on the development and implementation of the method. We will show the performance of several detector diodes used and the limits of the method. Validation of the method will be demonstrated against streak camera measurement with picosecond long bunches. Before concluding, we will discuss about the strengths and weaknesses of the method.

MOPD62

Storage Ring Injector Diagnostics using Synchrotron Radiation

191

A.F.D. Morgan, C.A. Thomas
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

The state of the Diamond injector can be passively monitored using beam profile measurements of synchrotron radiation from bending magnets. This provides us with information on the characteristics of the beam injected into the storage ring. Using a numerical fit we are able to retrieve key parameters like beam position, size and tilt angle from every shot. This enables us to gather longer term trends to monitor for any changes during top-up operation in order to better understand any variability of the injector. We present here the study and the analysis performed with this diagnostic with the results from several months of operation.

Poster MOPD62 [0.451 MB]

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.

MOPD32	Bunch Length Measurement from Power Fluctuation at Diamond	119
	C.A. Thomas, I.P.S. Martin, G. Rehm Diamond, Oxfordshire, United Kingdom
	Bunch length can be measured using the visible light power fluctuation statistics of an individual bunch. This method developed at ALS has been implemented at Diamond with further improvement on the detection method and the speed of the measurement. In this paper, we firstly report on the development and implementation of the method. We will show the performance of several detector diodes used and the limits of the method. Validation of the method will be demonstrated against streak camera measurement with picosecond long bunches. Before concluding, we will discuss about the strengths and weaknesses of the method.

MOPD62	Storage Ring Injector Diagnostics using Synchrotron Radiation	191
	A.F.D. Morgan, C.A. Thomas Diamond, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	The state of the Diamond injector can be passively monitored using beam profile measurements of synchrotron radiation from bending magnets. This provides us with information on the characteristics of the beam injected into the storage ring. Using a numerical fit we are able to retrieve key parameters like beam position, size and tilt angle from every shot. This enables us to gather longer term trends to monitor for any changes during top-up operation in order to better understand any variability of the injector. We present here the study and the analysis performed with this diagnostic with the results from several months of operation.
	Poster MOPD62 [0.451 MB]