IBIC2023 - List of Authors (Bobb, L.)

Paper	Title	Page
MO2I02	Fast Orbit Feedback for Diamond-II	1
	I. Kempf, M.G. Abbott, L. Bobb, G.B. Christian DLS, Oxfordshire, United Kingdom S. Duncan University of Oxford, Oxford, United Kingdom G. Rehm HZB, Berlin, Germany
	Funding: Diamond Light Source and Engineering and Physical Sciences Research Council The electron beam stability is critical for 4th generation light sources. As opposed to 10% of beam size up to 140 Hz at Diamond, advances in detector speed and resolution at Diamond-II increase the stability requirements to 3% up to 1 kHz. This paper presents a novel control methodology for the fast orbit feedback at Diamond-II, which will stabilise the beam using two arrays of 252 slow and 144 fast correctors and 252 beam position monitors at 100 kHz. In contrast to existing approaches that separate slow and fast feedback loops, our approach is based on a two-matrix factorisation called the generalised singular value decomposition (GSVD), which decouples the system into 144 two-input modes controlled by slow and fast magnets and 108 modes controlled by slow magnets only. The GSVD-based controller is implemented in the existing Diamond storage ring using a centralised communication architecture, such as planned for Diamond-II. We present results from the Diamond storage ring and simulation, which confirm that the proposed approach meets the target specification for Diamond-II.
	Slides MO2I02 [3.686 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO2I02
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 18 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP031	A Study Into the Long-Term Stability of Front End X-Ray Beam Position Monitor Support Columns at Diamond Light Source	90
	C.E. Houghton, C. Bloomer, L. Bobb, D. Crivelli, J.E. Melton, H. Patel DLS, Oxfordshire, United Kingdom
	Sand-filled steel columns are used at Diamond Light Source to support front end X-ray beam position monitors. This approach is chosen due to the relatively large thermal mass of the sand being considered useful to reduce the rate at which expansion and contraction of the column occurred as the storage ring tunnel temperature varied, particularly during machine start-up. With the higher requirements for mechanical stability for the upcoming Diamond-II upgrade, there is now a need to assess and quantify the current system’s impact on X-ray beam movement. A study of thermal and mechanical stability has been carried out to quantify the stability performance of the front end X-ray beam position monitor’s columns and the impact that column motion may have on the X-ray beam position measurement. Measurements have been made over a range of different timescales, from 250 Hz up to 2 weeks. The measured stability of the support column is presented, showing that it meets our Diamond-II stability requirements. A comparison of the stability of the column with and without a sand filling is presented.
	Poster MOP031 [0.594 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP031
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 17 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP032	One Dimensional Beam Position Monitor Prototype using Incoherent Cherenkov Diffraction Radiation	94
	A.J. Clapp Royal Holloway, University of London, Surrey, United Kingdom L. Bobb, G. Cook DLS, Oxfordshire, United Kingdom P. Karataev JAI, Egham, Surrey, United Kingdom
	This paper proposes a novel advancement in both the studies of Cherenkov diffraction radiation (ChDR) and beam instrumentation. The proposed beam position monitor (BPM) consists of two identical fused Silica prism radiators, with a fibre collimator attached to each one, which in turn are connected to a photodetector via a series of optical fibres. The setup will be implemented into the booster to storage ring transfer line at Diamond Light Source ¿ an electron light source with 3 GeV beam energy. The prototype proposed aims to test the feasibility of a full BPM utilising ChDR. If proven to be fully realisable, optical rather than capacitive BPM pickups could be more widely distributed. The paper will include the complete design and preliminary results of a one-dimensional BPM, utilising the ChDR effect.
	Poster MOP032 [2.516 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP032
About •	Received ※ 26 August 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 27 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP041	Modified Fast Orbit Feedback Controller for Disturbance Attenuation in Long Straights for Diamond-II	119
	S. Banerjee, M.G. Abbott, L. Bobb, I. Kempf DLS, Harwell, United Kingdom I. Kempf University of Oxford, Oxford, United Kingdom
	At Diamond Light Source, the fast orbit feedback (FOFB) uses one array of correctors and the controller is designed using the internal model control (IMC) structure. The Diamond-II upgrade will introduce an additional array of fast correctors and a new controller that is designed using the generalised modal decomposition, increasing the overall closed-loop bandwidth from 140 Hz to 1 kHz. Although simulation results have shown that the resulting beam displacement is within specification in all straights, they have also shown that the performance on long straights is limited, particularly in the vertical plane. In this paper, the controller is tuned in order to increase the FOFB performance in long straights by introducing a mode-by-mode regularisation parameter. The performance of the controller beyond 1 kHz is assessed using new disturbance data and a new measurement noise model, showing that the Diamond-II performance criteria are met, even in the presence of measurement noise.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP041
About •	Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP020	Performance Evaluation of GAGG+ and Tungsten Carbide Blades in an X-ray Pinhole Camera	382
	S.B. Burholt, L. Bobb, N. Vitoratou DLS, Oxfordshire, United Kingdom
	At Diamond Light Source two X-ray pinhole cameras are used to measure the transverse profile of the 3 GeV electron beam. The current pinhole assembly is formed using tungsten blades with chemically etched shims to produce a 25 µm x 25 µm aperture and the imager incorporates a 0.2 mm LuAG:Ce scintillator. Tungsten carbide is a machinable high-Z material which at millimetre thicknesses is opaque to X-rays. With a slight change in pinhole design, similar to that already in place at the ESRF, tungsten carbide blades could offer a well-controlled aperture size for the pinhole camera with simpler assembly. Further to this, improvements to the photon yield of scintillators mean that the new scintillator GAGG+ has an almost two fold increase in yield compared to the current LuAG: Ce scintillator. An evaluation of the tungsten carbide blades and GAGG+ scintillator is presented.
	Poster WEP020 [0.468 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP020
About •	Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 24 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP021	100Hz X-ray Beam Profile Measurements from a Transmissive CVD Diamond Detector	387
	C. Bloomer, L. Bobb DLS, Oxfordshire, United Kingdom M.E. Newton University of Warwick, Coventry, United Kingdom
	A non-destructive CVD diamond X-ray beam imaging monitor has been developed for synchrotron beamlines. The device can be permanently installed in the X-ray beam path and is capable of transmissively imaging the beam profile at 100 frames per second. The response of this transmissive detector at this imaging rate is compared to synchronously acquired images using a destructive fluorescent screen. It is shown that beam position, size, and intensity measurements can be obtained with minimal disturbance to the transmitted X-ray beam. This functionality is beneficial to synchrotron beamlines as it enables them to monitor the X-ray beam focal size and position in real-time, during user experiments. This is a key enabling technology that would enable live beam size feedback, keeping the beamline’s focusing optics optimised at all times. Ground vibrations (10-20Hz) can cause movement of focusing optics and beamline mirrors, which disturb the X-ray beam and reduce the ultimate quality of the sample-point beam. This instrument can detect this beam motion, enabling the source to be more easily determined and mitigations to be put in place.
	Poster WEP021 [1.842 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP021
About •	Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 02 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Fast Orbit Feedback for Diamond-II

1

I. Kempf, M.G. Abbott, L. Bobb, G.B. Christian
DLS, Oxfordshire, United Kingdom
S. Duncan
University of Oxford, Oxford, United Kingdom
G. Rehm
HZB, Berlin, Germany

Funding: Diamond Light Source and Engineering and Physical Sciences Research Council
The electron beam stability is critical for 4th generation light sources. As opposed to 10% of beam size up to 140 Hz at Diamond, advances in detector speed and resolution at Diamond-II increase the stability requirements to 3% up to 1 kHz. This paper presents a novel control methodology for the fast orbit feedback at Diamond-II, which will stabilise the beam using two arrays of 252 slow and 144 fast correctors and 252 beam position monitors at 100 kHz. In contrast to existing approaches that separate slow and fast feedback loops, our approach is based on a two-matrix factorisation called the generalised singular value decomposition (GSVD), which decouples the system into 144 two-input modes controlled by slow and fast magnets and 108 modes controlled by slow magnets only. The GSVD-based controller is implemented in the existing Diamond storage ring using a centralised communication architecture, such as planned for Diamond-II. We present results from the Diamond storage ring and simulation, which confirm that the proposed approach meets the target specification for Diamond-II.

Slides MO2I02 [3.686 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO2I02

About •

Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 18 September 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP031

A Study Into the Long-Term Stability of Front End X-Ray Beam Position Monitor Support Columns at Diamond Light Source

90

C.E. Houghton, C. Bloomer, L. Bobb, D. Crivelli, J.E. Melton, H. Patel
DLS, Oxfordshire, United Kingdom

Sand-filled steel columns are used at Diamond Light Source to support front end X-ray beam position monitors. This approach is chosen due to the relatively large thermal mass of the sand being considered useful to reduce the rate at which expansion and contraction of the column occurred as the storage ring tunnel temperature varied, particularly during machine start-up. With the higher requirements for mechanical stability for the upcoming Diamond-II upgrade, there is now a need to assess and quantify the current system’s impact on X-ray beam movement. A study of thermal and mechanical stability has been carried out to quantify the stability performance of the front end X-ray beam position monitor’s columns and the impact that column motion may have on the X-ray beam position measurement. Measurements have been made over a range of different timescales, from 250 Hz up to 2 weeks. The measured stability of the support column is presented, showing that it meets our Diamond-II stability requirements. A comparison of the stability of the column with and without a sand filling is presented.

Poster MOP031 [0.594 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP031

About •

Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 17 September 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP032

One Dimensional Beam Position Monitor Prototype using Incoherent Cherenkov Diffraction Radiation

94

A.J. Clapp
Royal Holloway, University of London, Surrey, United Kingdom
L. Bobb, G. Cook
DLS, Oxfordshire, United Kingdom
P. Karataev
JAI, Egham, Surrey, United Kingdom

This paper proposes a novel advancement in both the studies of Cherenkov diffraction radiation (ChDR) and beam instrumentation. The proposed beam position monitor (BPM) consists of two identical fused Silica prism radiators, with a fibre collimator attached to each one, which in turn are connected to a photodetector via a series of optical fibres. The setup will be implemented into the booster to storage ring transfer line at Diamond Light Source ¿ an electron light source with 3 GeV beam energy. The prototype proposed aims to test the feasibility of a full BPM utilising ChDR. If proven to be fully realisable, optical rather than capacitive BPM pickups could be more widely distributed. The paper will include the complete design and preliminary results of a one-dimensional BPM, utilising the ChDR effect.

Poster MOP032 [2.516 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP032

About •

Received ※ 26 August 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 27 September 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP041

Modified Fast Orbit Feedback Controller for Disturbance Attenuation in Long Straights for Diamond-II

119

S. Banerjee, M.G. Abbott, L. Bobb, I. Kempf
DLS, Harwell, United Kingdom
I. Kempf
University of Oxford, Oxford, United Kingdom

At Diamond Light Source, the fast orbit feedback (FOFB) uses one array of correctors and the controller is designed using the internal model control (IMC) structure. The Diamond-II upgrade will introduce an additional array of fast correctors and a new controller that is designed using the generalised modal decomposition, increasing the overall closed-loop bandwidth from 140 Hz to 1 kHz. Although simulation results have shown that the resulting beam displacement is within specification in all straights, they have also shown that the performance on long straights is limited, particularly in the vertical plane. In this paper, the controller is tuned in order to increase the FOFB performance in long straights by introducing a mode-by-mode regularisation parameter. The performance of the controller beyond 1 kHz is assessed using new disturbance data and a new measurement noise model, showing that the Diamond-II performance criteria are met, even in the presence of measurement noise.

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP041

About •

Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP020

Performance Evaluation of GAGG+ and Tungsten Carbide Blades in an X-ray Pinhole Camera

382

S.B. Burholt, L. Bobb, N. Vitoratou
DLS, Oxfordshire, United Kingdom

At Diamond Light Source two X-ray pinhole cameras are used to measure the transverse profile of the 3 GeV electron beam. The current pinhole assembly is formed using tungsten blades with chemically etched shims to produce a 25 µm x 25 µm aperture and the imager incorporates a 0.2 mm LuAG:Ce scintillator. Tungsten carbide is a machinable high-Z material which at millimetre thicknesses is opaque to X-rays. With a slight change in pinhole design, similar to that already in place at the ESRF, tungsten carbide blades could offer a well-controlled aperture size for the pinhole camera with simpler assembly. Further to this, improvements to the photon yield of scintillators mean that the new scintillator GAGG+ has an almost two fold increase in yield compared to the current LuAG: Ce scintillator. An evaluation of the tungsten carbide blades and GAGG+ scintillator is presented.

Poster WEP020 [0.468 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP020

About •

Received ※ 07 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 24 September 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP021

100Hz X-ray Beam Profile Measurements from a Transmissive CVD Diamond Detector

387

C. Bloomer, L. Bobb
DLS, Oxfordshire, United Kingdom
M.E. Newton
University of Warwick, Coventry, United Kingdom

A non-destructive CVD diamond X-ray beam imaging monitor has been developed for synchrotron beamlines. The device can be permanently installed in the X-ray beam path and is capable of transmissively imaging the beam profile at 100 frames per second. The response of this transmissive detector at this imaging rate is compared to synchronously acquired images using a destructive fluorescent screen. It is shown that beam position, size, and intensity measurements can be obtained with minimal disturbance to the transmitted X-ray beam. This functionality is beneficial to synchrotron beamlines as it enables them to monitor the X-ray beam focal size and position in real-time, during user experiments. This is a key enabling technology that would enable live beam size feedback, keeping the beamline’s focusing optics optimised at all times. Ground vibrations (10-20Hz) can cause movement of focusing optics and beamline mirrors, which disturb the X-ray beam and reduce the ultimate quality of the sample-point beam. This instrument can detect this beam motion, enabling the source to be more easily determined and mitigations to be put in place.

Poster WEP021 [1.842 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP021

About •

Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 11 September 2023 — Issue date ※ 02 October 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)