IPAC2012 - List of Authors (Kirkman, I.W.)

Paper

Title

Page

Computing Bunch Charge, Position, and BPM Resolution in Turn-by-Turn EMMA BPMs

924

A. Kalinin, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.G. Borrell
WareWorks Ltd, Manchester, United Kingdom
G. Cox
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
I.W. Kirkman
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The NS-FFAG electron model ‘EMMA’ and its Injection and Extraction Lines are equipped with a total of 53 EPICS VME BPMs*. In the BPMs, each opposite button signal pair is time-domain-multiplexed into one channel as a pulse doublet. The recording of turn-by-turn data into the BPM memory is triggered by the bunch itself on each of its passages. For each accelerating cycle, the BPMs deliver a snapshot of a turn-by-turn trajectory measured in each of 42 cells. Additional BPMs (two pairs) are used to obtain a Poincare map. We describe the EPICS architecture, and a set of Python data processing algorithms that are used to automatically set a BPM intensity range, to eliminate an error due to tails of the doublet pulses, to calculate the bunch charge and position, and, for a set of injections, to find the BPM resolution. We use three types of button pickup mappings** that allow: to eliminate bunch charge signal dependence on offset, to get a linear offset response, and to eliminate ‘quadrupole’ signal dependence on offset as well (which is used in resolution calculation). We present beam measurement results collected in 2011 runs.
* A. Kalinin et al., Proc. of IPAC’10, MOPE068, p. 1134, (2010.
** I. Kirkman, these proceedings.

MOPPR060

Calibration of the EMMA Beam Position Monitors: Position, Charge and Accuracy

921

I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom
J.S. Berg
BNL, Upton, Long Island, New York, USA
G. Cox
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The accurate determination of transverse beam position is essential to understanding the performance of an accelerator system, and this is particularly the case with non-scaling FFAG machines such as EMMA, where, due to fundamental principles of design, the beam may deviate widely from the central beampipe axis. This paper describes the various modelling approaches taken for the three different button pickup assemblies used in EMMA, and the subsequent methods of calibration (‘mappings’) which allow beam position and charge to be deduced from the processed BPM signals. The use and validity of the modelling and mapping approach adopted is described, and the contributions to positional and bunch charge uncertainty arising from these procedures is discussed.

TUPPD021

Orbit Correction in the EMMA Non-scaling FFAG – Simulation and Experimental Results

1455

D.J. Kelliher, S. Machida, S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J.S. Berg
BNL, Upton, Long Island, New York, USA
J.K. Jones, B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
E. Keil
Honorary CERN Staff Member, Berlin, Germany
I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom

The non-scaling FFAG EMMA (Electron Model for Many Applications) is currently in operation at Daresbury Laboratory, UK. Since the lattice is made up solely of linear elements, the betatron tune varies strongly over the momentum range according to the natural chromaticity. Orbit correction is complicated by the resulting variation in response to corrector magnet settings. We consider a method to optimise correction over a range of fixed momenta and discuss experimental results. Measurements of the closed orbit and response matrix are included.

WEOAB01

New Results from the EMMA Experiment

2134

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.S. Edmonds, K.M. Hock, M.G. Ibison, I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom
J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After demonstration of acceleration in the serpentine channel in April 2011, the beam study with EMMA continues to explore the large transverse and longitudinal acceptance and effects of integer tune crossing with slower rate on the betatron amplitude. Together with a comparison of detailed models based on measured field maps and the experimental mapping of the machine by relating the initial and final phase space coordinates. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

Slides WEOAB01 [2.120 MB]

Paper	Title	Page
MOPPR061	Computing Bunch Charge, Position, and BPM Resolution in Turn-by-Turn EMMA BPMs	924
	A. Kalinin, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.G. Borrell WareWorks Ltd, Manchester, United Kingdom G. Cox STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom I.W. Kirkman Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The NS-FFAG electron model ‘EMMA’ and its Injection and Extraction Lines are equipped with a total of 53 EPICS VME BPMs. In the BPMs, each opposite button signal pair is time-domain-multiplexed into one channel as a pulse doublet. The recording of turn-by-turn data into the BPM memory is triggered by the bunch itself on each of its passages. For each accelerating cycle, the BPMs deliver a snapshot of a turn-by-turn trajectory measured in each of 42 cells. Additional BPMs (two pairs) are used to obtain a Poincare map. We describe the EPICS architecture, and a set of Python data processing algorithms that are used to automatically set a BPM intensity range, to eliminate an error due to tails of the doublet pulses, to calculate the bunch charge and position, and, for a set of injections, to find the BPM resolution. We use three types of button pickup mappings* that allow: to eliminate bunch charge signal dependence on offset, to get a linear offset response, and to eliminate ‘quadrupole’ signal dependence on offset as well (which is used in resolution calculation). We present beam measurement results collected in 2011 runs. * A. Kalinin et al., Proc. of IPAC’10, MOPE068, p. 1134, (2010. ** I. Kirkman, these proceedings.

MOPPR060	Calibration of the EMMA Beam Position Monitors: Position, Charge and Accuracy	921
	I.W. Kirkman The University of Liverpool, Liverpool, United Kingdom J.S. Berg BNL, Upton, Long Island, New York, USA G. Cox STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The accurate determination of transverse beam position is essential to understanding the performance of an accelerator system, and this is particularly the case with non-scaling FFAG machines such as EMMA, where, due to fundamental principles of design, the beam may deviate widely from the central beampipe axis. This paper describes the various modelling approaches taken for the three different button pickup assemblies used in EMMA, and the subsequent methods of calibration (‘mappings’) which allow beam position and charge to be deduced from the processed BPM signals. The use and validity of the modelling and mapping approach adopted is described, and the contributions to positional and bunch charge uncertainty arising from these procedures is discussed.

TUPPD021	Orbit Correction in the EMMA Non-scaling FFAG – Simulation and Experimental Results	1455
	D.J. Kelliher, S. Machida, S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J.S. Berg BNL, Upton, Long Island, New York, USA J.K. Jones, B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom E. Keil Honorary CERN Staff Member, Berlin, Germany I.W. Kirkman The University of Liverpool, Liverpool, United Kingdom
	The non-scaling FFAG EMMA (Electron Model for Many Applications) is currently in operation at Daresbury Laboratory, UK. Since the lattice is made up solely of linear elements, the betatron tune varies strongly over the momentum range according to the natural chromaticity. Orbit correction is complicated by the resulting variation in response to corrector magnet settings. We consider a method to optimise correction over a range of fixed momenta and discuss experimental results. Measurements of the closed orbit and response matrix are included.

WEOAB01	New Results from the EMMA Experiment	2134
	B.D. Muratori, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C.S. Edmonds, K.M. Hock, M.G. Ibison, I.W. Kirkman The University of Liverpool, Liverpool, United Kingdom J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After demonstration of acceleration in the serpentine channel in April 2011, the beam study with EMMA continues to explore the large transverse and longitudinal acceptance and effects of integer tune crossing with slower rate on the betatron amplitude. Together with a comparison of detailed models based on measured field maps and the experimental mapping of the machine by relating the initial and final phase space coordinates. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.
	Slides WEOAB01 [2.120 MB]