DIPAC2011 - List of Keywords (dipole)

Paper	Title	Other Keywords	Page
MOPD17	Beam-based HOM Study in Third Harmonic SC Cavities for Beam Alignment at FLASH	HOM, cavity, electron, polarization	77
	P. Zhang, R.M. Jones, I.R.R. Shinton UMAN, Manchester, United Kingdom N. Baboi, B. Lorbeer, P. Zhang DESY, Hamburg, Germany H. Ecklebe, T. Flisgen, H.-W. Glock Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by European Commission under the FP7 Research Infrastructures grant agreement No.227579. An electron beam entering an accelerator cavity excites higher order modes (HOM). These are radiated to HOM couplers, subsequently damped, and can also be used to facilitate beam monitoring. The modes which deflect the beam transversely are the focus of this study and are used to monitor the beam position. Results are presented on the first analysis of beam alignment based on HOM signals from the third harmonic cavities at FLASH. The electrical center of each mode is ascertained by moving the beam to minimize the HOM signal detected. A single electron bunch per RF pulse is used.

MOPD25	Diode Down-mixing of HOM Coupler Signals for Beam Position Determination in 1.3-GHz- and 3.9-GHz-Cavities at FLASH	HOM, cavity, polarization, coupling	101
	H.-W. Glock, H. Ecklebe, T. Flisgen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany N. Baboi, P. Zhang DESY, Hamburg, Germany
	Funding: work supported by BMBF under contract 05K10HRC and by European Commission under the FP7 Research Infrastructures grant agreement No.227579 Beam excited signals available at the HOM coupler ports of superconducting accelerating cavities cover a wide frequency range and carry information about (amongst others) transverse beam position. Down-mixing these signals using detector diodes is a mean to measure with standard and non-specific oscilloscope technology the time dependency of the power leaving the HOM coupler. Experiments undertaken at the accelerator modules ACC1 and ACC39 at FLASH demonstrated the possibility to extract beam position data out of low-frequency signals sampled with such a setup. These experiments as part of an ongoing study are described together with mathematical details of the evaluation scheme.

MOPD61	Vertical Emittance Measurement at the ESRF	emittance, radiation, photon, synchrotron	188
	F. Ewald, P. Elleaume, L. Farvacque, A. Franchi, D. Robinson, K.B. Scheidt, A. Snigirev, I. Snigireva ESRF, Grenoble, France
	In the short term the ESRF aims to reach emittances of less than 2 pm. We review the existing emittance diagnostics – X-ray projection monitors and pinhole cameras – and evaluate their ability to resolve such ultra-small vertical emittances. Even though these devices are reliable and show good agreement between measurements and theoretical predictions down to vertical emittance values of less than 10 pm, they will reach their limit of resolution for emittances decreasing below a few picometers. In addition to the existing emittance diagnostics, a new device was installed that images bending magnet radiation using compound refractive lenses (CRLs).

TUPD03	Beam Profile Measurement during Top-up Injection with a Pulsed Sextupole Magnet	injection, kicker, simulation, quadrupole	305
	R. Takai, K. Harada, T. Honda, Y. Kobayashi, S. Nagahashi, N. Nakamura, T. Obina, A. Ueda KEK, Ibaraki, Japan H. Takaki ISSP/SRL, Chiba, Japan
	A beam injection scheme using a pulsed multipole magnet is suitable for the top-up injection because a disturbance to the stored beam is much smaller than that of the conventional scheme using several kicker magnets. At the Photon Factory storage ring, the top-up injection with a pulsed sextupole magnet (PSM) has been used for the user operation since January 2011. In order to ascertain the effect of the PSM injection, we measured turn-by-turn stored beam profiles following the injection kick by using a fast-gated camera. As a result, it was demonstrated that the PSM injection dramatically decreases not only the coherent dipole oscillation but also the beam profile modulation, as expected from the beam tracking simulation.

TUPD05	Diagnostic Scheme for the HITRAP Decelerator	ion, pick-up, rfq, diagnostics	311
	G. Vorobjev, C.A. Andre, W.A. Barth, E. Berdermann, M.I. Ciobanu, G. Clemente, L.A. Dahl, P. Forck, P. Gerhard, R. Haseitl, F. Herfurth, M. Kaiser, W. Kaufmann, H.J. Kluge, N. Kotovski, C. Kozhuharov, M.T. Maier, W. Quint, A. Reiter, A. Sokolov, T. Stöhlker GSI, Darmstadt, Germany O.K. Kester, J. Pfister, U. Ratzinger, A. Schempp IAP, Frankfurt am Main, Germany
	The HITRAP linear decelerator currently being set up at GSI will provide slow, few keV/u highly charged ions for atomic physics experiments. The expected beam intensity is up to 10⁵ ions per shot. To optimize phase and amplitude of the RF systems intensity, bunch length and kinetic energy of the particles need to be monitored. The bunch length that we need to fit is about 2 ns, which is typically measured by capacitive pickups. However, they do not work for the low beam intensities that we face. We investigated the bunch length with a fast CVD diamond detector working in single particle counting mode. Averaging over 8 shots yields a clear, regular picture of the bunched beam. Energy measurements by capacitive pickups are limited by the presence of intense primary and partially decelerated beam and hence make tuning of the IH-structure impossible. The energy of the decelerated fraction of the beam behind the first deceleration cavity was determined to about 10 % accuracy with a permanent dipole magnet combined with a MCP. Better detector calibration should help reaching the required 1%. Design of the detectors as well as the results of the measurements will be presented.

TUPD40	Analysis of the Post-mortem Events at the TLS	SRF, diagnostics, power-supply, injection	392
	K.H. Hu, Y.-T. Chang, J. Chen, P.C. Chiu, K.T. Hsu, C.H. Kuo, Y.-H. Lin, Y.R. Pan NSRRC, Hsinchu, Taiwan
	Analyzing the reasons of various trip events are basis to improve reliability of a accelerator system. Understand the mechanisms caused trip of the machine will be very helpful to decide what the adequate measures to improve availability. To identify the causes of trips at Taiwan Light Source (TLS), various diagnostics tool were employed. These diagnostic tools can capture beam trips, interlock signals of superconducting RF system, quench and interlock signals of the superconducting insertion device, waveform of the injection kickers, and instability signals of the stored beam for post-mortem analysis. Various functionalities of trip diagnostic are supported. Available tools and experiences will be summarized in this report.

TUPD49	Performance of Parabolic and Diffusive OTR Screens at the CLIC Test Facility 3	linac, diagnostics, alignment, simulation	413
	M. Olvegård, B. Bolzon, E. Bravin, S. Burger, A.E. Dabrowski, T. Lefèvre CERN, Geneva, Switzerland C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the position on the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in a small cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex. The results are presented in this paper.

TUPD55	Performance of the Time Resolved Spectrometer for the 5 MeV Photo-Injector PHIN	vacuum, instrumentation, impedance, electron	431
	D. Egger EPFL, Lausanne, Switzerland A.E. Dabrowski, M. Divall Csatari, S. Döbert, D. Egger, T. Lefèvre, O. Mete, M. Olvegård, M. Petrarca CERN, Geneva, Switzerland
	The PHIN photo-injector test facility is being commissioned at CERN in order to fulfill the beam parameter requirements for the 3rd CLIC Test Facility (CTF3), which includes the production of a 3.5 Amp stable beam, bunched at 1.5 GHz with a relative energy spread of less than 1%. A 90° spectrometer is instrumented with an OTR screen coupled to a gated intensified camera, followed by a segmented beam dump for time resolved energy measurements. The following paper describes the transverse and temporal resolution of the instrumentation with an outlook towards single-bunch energy measurements.
	Poster TUPD55 [0.959 MB]

TUPD71	Combined Approach using Closed-Orbit and Multiturn Data for Model-Independent and Fast Beam Optics Determination in Storage Rings	closed-orbit, betatron, storage-ring, optics	473
	B. Riemann, P. Grete, H. Huck, A. Nowaczyk, T. Weis DELTA, Dortmund, Germany
	Multiturn-capable BPMs have been used successfully for characterization of storage ring beam optics. While their use eases determination of optical parameters (e.g. beta function and phase) by observation of non ring-periodic beam centroid oscillation, the installation of multiturn electronics in all storage ring BPMs causes a high monetary effort. The presented method aims at combining multiturn and closed-orbit measurement methods in a cost-effective way. This is done using a single drift section in the ring, being equipped with two multiturn BPMs at its ends. Measuring the centroid motion in the full transverse phase space, one can completely determine all local beam optics parameters inside the drift space. Then, four additional dipole correctors inside this drift are used to create closed-orbit perturbations along the ring. Because of the known drift optics, it is then possible to extract all data that would be available if all storage ring BPMs were multiturn-capable, by using only closed-orbit BPM data of the mentioned four perturbations (incl. betatron coupling). This fast and model-independent approach may be increased in accuracy by a coupled bunch feedback system.

TUPD90	POMPOMs: Cost-Efficient Polarity Sensors for the MICE Muon Beamline	EPICS, monitoring, radiation, controls	518
	J.J. Nebrensky Brunel University, Middlesex, United Kingdom P.M. Hanlet IIT, Chicago, Illinois, USA
	Funding: STFC (UK) The cooling effect in MICE (Muon Ionisation Cooling Experiment) will be studied with both positive and negative muons, reversing the electrical input to the magnets by physically swapping over the power leads. Ensuring the actual operating polarity of the beamline is correctly recorded is a manual step and at risk of error or omission. We have deployed a simple system for monitoring the operating polarity of the two bending magnets by placing in each dipole bore a Honeywell LOHET-II Hall-effect sensor that operates past saturation at nominal field strengths, and thus return one of two well-defined voltages corresponding to the two possible polarities of the magnet. The environment in the experimental hall is monitored by an AKCP securityProbe 5E system integrated into our EPICS-based controls and monitoring system. We read out the beamline polarity sensors using a voltmeter module, and translate the output voltage into a polarity (or alarm) state within EPICS whence it can be accessed by the operators and stored in the output datastream. Initial test of the LOHET-II sensors indicates they will still be able to indicate beamline polarity after radiation doses of 600 Gy (Co60). We'd like to thank Prof. Peter Hobson and Dr David Smith at Brunel University for performing the sensor irradiation
	Poster TUPD90 [0.627 MB]

Paper

Title

Other Keywords

Page

MOPD17

Beam-based HOM Study in Third Harmonic SC Cavities for Beam Alignment at FLASH

HOM, cavity, electron, polarization

77

P. Zhang, R.M. Jones, I.R.R. Shinton
UMAN, Manchester, United Kingdom
N. Baboi, B. Lorbeer, P. Zhang
DESY, Hamburg, Germany
H. Ecklebe, T. Flisgen, H.-W. Glock
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by European Commission under the FP7 Research Infrastructures grant agreement No.227579.
An electron beam entering an accelerator cavity excites higher order modes (HOM). These are radiated to HOM couplers, subsequently damped, and can also be used to facilitate beam monitoring. The modes which deflect the beam transversely are the focus of this study and are used to monitor the beam position. Results are presented on the first analysis of beam alignment based on HOM signals from the third harmonic cavities at FLASH. The electrical center of each mode is ascertained by moving the beam to minimize the HOM signal detected. A single electron bunch per RF pulse is used.

MOPD25

Diode Down-mixing of HOM Coupler Signals for Beam Position Determination in 1.3-GHz- and 3.9-GHz-Cavities at FLASH

HOM, cavity, polarization, coupling

101

H.-W. Glock, H. Ecklebe, T. Flisgen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
N. Baboi, P. Zhang
DESY, Hamburg, Germany

Funding: work supported by BMBF under contract 05K10HRC and by European Commission under the FP7 Research Infrastructures grant agreement No.227579
Beam excited signals available at the HOM coupler ports of superconducting accelerating cavities cover a wide frequency range and carry information about (amongst others) transverse beam position. Down-mixing these signals using detector diodes is a mean to measure with standard and non-specific oscilloscope technology the time dependency of the power leaving the HOM coupler. Experiments undertaken at the accelerator modules ACC1 and ACC39 at FLASH demonstrated the possibility to extract beam position data out of low-frequency signals sampled with such a setup. These experiments as part of an ongoing study are described together with mathematical details of the evaluation scheme.

MOPD61

Vertical Emittance Measurement at the ESRF

emittance, radiation, photon, synchrotron

188

F. Ewald, P. Elleaume, L. Farvacque, A. Franchi, D. Robinson, K.B. Scheidt, A. Snigirev, I. Snigireva
ESRF, Grenoble, France

In the short term the ESRF aims to reach emittances of less than 2 pm. We review the existing emittance diagnostics – X-ray projection monitors and pinhole cameras – and evaluate their ability to resolve such ultra-small vertical emittances. Even though these devices are reliable and show good agreement between measurements and theoretical predictions down to vertical emittance values of less than 10 pm, they will reach their limit of resolution for emittances decreasing below a few picometers. In addition to the existing emittance diagnostics, a new device was installed that images bending magnet radiation using compound refractive lenses (CRLs).

TUPD03

Beam Profile Measurement during Top-up Injection with a Pulsed Sextupole Magnet

injection, kicker, simulation, quadrupole

305

R. Takai, K. Harada, T. Honda, Y. Kobayashi, S. Nagahashi, N. Nakamura, T. Obina, A. Ueda
KEK, Ibaraki, Japan
H. Takaki
ISSP/SRL, Chiba, Japan

A beam injection scheme using a pulsed multipole magnet is suitable for the top-up injection because a disturbance to the stored beam is much smaller than that of the conventional scheme using several kicker magnets. At the Photon Factory storage ring, the top-up injection with a pulsed sextupole magnet (PSM) has been used for the user operation since January 2011. In order to ascertain the effect of the PSM injection, we measured turn-by-turn stored beam profiles following the injection kick by using a fast-gated camera. As a result, it was demonstrated that the PSM injection dramatically decreases not only the coherent dipole oscillation but also the beam profile modulation, as expected from the beam tracking simulation.

TUPD05

Diagnostic Scheme for the HITRAP Decelerator

ion, pick-up, rfq, diagnostics

311

G. Vorobjev, C.A. Andre, W.A. Barth, E. Berdermann, M.I. Ciobanu, G. Clemente, L.A. Dahl, P. Forck, P. Gerhard, R. Haseitl, F. Herfurth, M. Kaiser, W. Kaufmann, H.J. Kluge, N. Kotovski, C. Kozhuharov, M.T. Maier, W. Quint, A. Reiter, A. Sokolov, T. Stöhlker
GSI, Darmstadt, Germany
O.K. Kester, J. Pfister, U. Ratzinger, A. Schempp
IAP, Frankfurt am Main, Germany

The HITRAP linear decelerator currently being set up at GSI will provide slow, few keV/u highly charged ions for atomic physics experiments. The expected beam intensity is up to 10⁵ ions per shot. To optimize phase and amplitude of the RF systems intensity, bunch length and kinetic energy of the particles need to be monitored. The bunch length that we need to fit is about 2 ns, which is typically measured by capacitive pickups. However, they do not work for the low beam intensities that we face. We investigated the bunch length with a fast CVD diamond detector working in single particle counting mode. Averaging over 8 shots yields a clear, regular picture of the bunched beam. Energy measurements by capacitive pickups are limited by the presence of intense primary and partially decelerated beam and hence make tuning of the IH-structure impossible. The energy of the decelerated fraction of the beam behind the first deceleration cavity was determined to about 10 % accuracy with a permanent dipole magnet combined with a MCP. Better detector calibration should help reaching the required 1%. Design of the detectors as well as the results of the measurements will be presented.

TUPD40

Analysis of the Post-mortem Events at the TLS

SRF, diagnostics, power-supply, injection

392

K.H. Hu, Y.-T. Chang, J. Chen, P.C. Chiu, K.T. Hsu, C.H. Kuo, Y.-H. Lin, Y.R. Pan
NSRRC, Hsinchu, Taiwan

Analyzing the reasons of various trip events are basis to improve reliability of a accelerator system. Understand the mechanisms caused trip of the machine will be very helpful to decide what the adequate measures to improve availability. To identify the causes of trips at Taiwan Light Source (TLS), various diagnostics tool were employed. These diagnostic tools can capture beam trips, interlock signals of superconducting RF system, quench and interlock signals of the superconducting insertion device, waveform of the injection kickers, and instability signals of the stored beam for post-mortem analysis. Various functionalities of trip diagnostic are supported. Available tools and experiences will be summarized in this report.

TUPD49

Performance of Parabolic and Diffusive OTR Screens at the CLIC Test Facility 3

linac, diagnostics, alignment, simulation

413

M. Olvegård, B. Bolzon, E. Bravin, S. Burger, A.E. Dabrowski, T. Lefèvre
CERN, Geneva, Switzerland
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the position on the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in a small cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex. The results are presented in this paper.

TUPD55

Performance of the Time Resolved Spectrometer for the 5 MeV Photo-Injector PHIN

vacuum, instrumentation, impedance, electron

431

D. Egger
EPFL, Lausanne, Switzerland
A.E. Dabrowski, M. Divall Csatari, S. Döbert, D. Egger, T. Lefèvre, O. Mete, M. Olvegård, M. Petrarca
CERN, Geneva, Switzerland

The PHIN photo-injector test facility is being commissioned at CERN in order to fulfill the beam parameter requirements for the 3rd CLIC Test Facility (CTF3), which includes the production of a 3.5 Amp stable beam, bunched at 1.5 GHz with a relative energy spread of less than 1%. A 90° spectrometer is instrumented with an OTR screen coupled to a gated intensified camera, followed by a segmented beam dump for time resolved energy measurements. The following paper describes the transverse and temporal resolution of the instrumentation with an outlook towards single-bunch energy measurements.

Poster TUPD55 [0.959 MB]

TUPD71

Combined Approach using Closed-Orbit and Multiturn Data for Model-Independent and Fast Beam Optics Determination in Storage Rings

closed-orbit, betatron, storage-ring, optics

473

B. Riemann, P. Grete, H. Huck, A. Nowaczyk, T. Weis
DELTA, Dortmund, Germany

Multiturn-capable BPMs have been used successfully for characterization of storage ring beam optics. While their use eases determination of optical parameters (e.g. beta function and phase) by observation of non ring-periodic beam centroid oscillation, the installation of multiturn electronics in all storage ring BPMs causes a high monetary effort. The presented method aims at combining multiturn and closed-orbit measurement methods in a cost-effective way. This is done using a single drift section in the ring, being equipped with two multiturn BPMs at its ends. Measuring the centroid motion in the full transverse phase space, one can completely determine all local beam optics parameters inside the drift space. Then, four additional dipole correctors inside this drift are used to create closed-orbit perturbations along the ring. Because of the known drift optics, it is then possible to extract all data that would be available if all storage ring BPMs were multiturn-capable, by using only closed-orbit BPM data of the mentioned four perturbations (incl. betatron coupling). This fast and model-independent approach may be increased in accuracy by a coupled bunch feedback system.

TUPD90

POMPOMs: Cost-Efficient Polarity Sensors for the MICE Muon Beamline

EPICS, monitoring, radiation, controls

518

J.J. Nebrensky
Brunel University, Middlesex, United Kingdom
P.M. Hanlet
IIT, Chicago, Illinois, USA

Funding: STFC (UK)
The cooling effect in MICE (Muon Ionisation Cooling Experiment) will be studied with both positive and negative muons, reversing the electrical input to the magnets by physically swapping over the power leads. Ensuring the actual operating polarity of the beamline is correctly recorded is a manual step and at risk of error or omission. We have deployed a simple system for monitoring the operating polarity of the two bending magnets by placing in each dipole bore a Honeywell LOHET-II Hall-effect sensor that operates past saturation at nominal field strengths, and thus return one of two well-defined voltages corresponding to the two possible polarities of the magnet. The environment in the experimental hall is monitored by an AKCP securityProbe 5E system integrated into our EPICS-based controls and monitoring system. We read out the beamline polarity sensors using a voltmeter module, and translate the output voltage into a polarity (or alarm) state within EPICS whence it can be accessed by the operators and stored in the output datastream. Initial test of the LOHET-II sensors indicates they will still be able to indicate beamline polarity after radiation doses of 600 Gy (Co60).
We'd like to thank Prof. Peter Hobson and Dr David Smith at Brunel University for performing the sensor irradiation

Poster TUPD90 [0.627 MB]