DIPAC2011 - List of Authors (Kube, G.)

Paper

Title

Page

Bunch Length Measurement for PETRA III Light Source Storage Ring

113

H.-C. Schröder, A. Affeldt, H.P. Gausepohl, G. Kube, G. Priebe
DESY, Hamburg, Germany

To fulfill the demand for a very high brilliance synchrotron light source, it is required, that the individual particle bunches, used to create the synchrotron light in special undulator sections, do not exceed certain limits in linear dimension and divergence during the storage time. The bunch length measurement in the visible region of the spectrum is the sole system to measure the longitudinal beam parameter needed for a complete description of the behavior of the PETRAIII positron beam. A detailed description of the dipole magnet visible synchrotron light extraction, the light transport and the analysis by means of a Streak Camera System (SCS) in the context of the PETRAIII storage ring is given. The influence of the custom designed apochromatic refractive optics transport line on the time resolution of the bunch length measurement is discussed and values are given. The final time resolution of the whole system transport optics and Streak camera is shown to be not bigger than 4 ps. Several measurements from PETRAIII runs are presented and results of the bunch length measurements are shown. The typical bunch length measured is about 40 ps.

Poster MOPD30 [6.402 MB]

TUPD21

Frontend Measurements and Optimizations at Libera Brilliance BPM Electronics during Commissioning of the Petra III Synchrotron Light Source

350

F. Schmidt-Föhre, G. Kube, J.M. Maass, K. Wittenburg
DESY, Hamburg, Germany

New 3rd generation synchrotron light sources like Petra III utilize high-accuracy beam position measurement (BPM) systems to achieve the desired precision for beam position measurement and control, as needed for electron/positron beam stability and brilliance of the delivered photon beam. To reach the design goals, specifically adapted and parameterized commercial-of-the-shelf (COTS) Libera Brilliance BPM processor electronics are used within the Petra III BPM system. Quality of the acquired position measurement and orbit control data is highly dependent on the properties and setup of the analog and digital frontend of such BPM electronics. This paper shows influences and optimizations at the BPM system frontend of the Petra III light-source in reference to corresponding measurements done during the accelerator commissioning phase.

TUPD33

Coherent Resonant Diffraction Radiation from Inclined Grating as a Tool for Bunch Length Diagnostics

377

L.G. Sukhikh, G. Kube
DESY, Hamburg, Germany
A. Potylitsyn
Tomsk Polytechnic University, Tomsk, Russia
V. Schlott
PSI, Villigen, Switzerland

There exists considerable interest in studying new types of non-invasive bunch length diagnostics for sub-picosecond bunches. In this context coherent Smith-Purcell radiation (CSPR) is a good candidate because the use of grating causes wavelength dispersive radiation emission, i.e. a CSPR based monitor does not require any additional spectrometer. In contrast to existing CSPR monitors a new scheme is proposed with two detectors placed at fixed positions, and a wavelength scan is performed by scanning the tilt angle between grating surface and beam axis. In this scheme the information of both detectors, positioned opposite to each other and perpendicular to the beam axis, can be combined by taking the intensity ratio of the signals from both detectors. The advantage of such diagnostics scheme is that one has not to rely on absolute values of the radiation yield, avoiding the need to know the sensitivity of each detector with high accuracy. In contrast to CSPR which is emitted from a grating oriented parallel to the beam, the effect is termed coherent resonant diffraction radiation when the grating is tilted. In the report we present simulation results and detailed experimental plan.

TUPD59

Suppression of Coherent Optical Transition Radiation in Transverse Beam Diagnostics by Utilising a Scintillation Screen with a Fast Gated CCD Camera

440

M. Yan
Uni HH, Hamburg, Germany
C. Behrens, C. Gerth, G. Kube, B. Schmidt, S. Wesch
DESY, Hamburg, Germany

Micro-bunching instabilities in high-brightness beams of linac-driven FELs can lead to coherence effects in the emission of optical transition radiation (OTR) used for standard transverse profile diagnostics, thus rendering it impossible to observe a direct image of the particle beam. By using a scintillation screen in combination with a fast gated CCD camera, coherence effects can be suppressed as OTR is created in an instantaneous process while scintillation light has a certain decay time. In addition, the emission of the scintillation light is a statistical process from many atoms which is completely insensitive to the longitudinal bunch structure and does not produce coherence effects. Gating the camera during the passage of the electron bunch should eliminate any influence of the coherent OTR (COTR). First experiments using this method have been performed successfully at FLASH as a proof-of-principle. In this paper, we study the applicability of scintillation screens for high-energy electron beams under operation conditions for which COTR is emitted. Experimental results together with simulations are presented and discussed in view of COTR suppression and spatial resolution.

WEOA02

Experimental Investigations of Backward Transition Radiation from Flat Target in Extreme Ultraviolet Region

544

L.G. Sukhikh, G. Kube
DESY, Hamburg, Germany
D. Krambrich, W. Lauth
IKP, Mainz, Germany
Yu.A. Popov, A. Potylitsyn
Tomsk Polytechnic University, Tomsk, Russia

Forward transition radiation in X-ray range and backward transition radiation (BTR) in optical spectral region are investigated in details due to their use for purposes of particle and beam diagnostics. In order to improve diagnostics tools we proposed to use BTR in extreme ultraviolet (EUV) region [*,**], where theoretical models are existing only. We performed experimental investigations of BTR characteristics in EUV spectral region generated by a molybdenum target at 855 MeV electron beam of the MAMI-B (Mainz, Germany). Angular patterns and intensities of BTR both in optical and EUV regions for different observation angles were investigated. The measured intensity of optical BTR agrees with a theory with reasonable accuracy but one in EUV region is more intense than theoretically predicted. Our experimental estimation of the experimental BTR yield in EUV region is (2.4/3.6)•10⁻⁴ photons/electron and this is more than 4 / 6 times higher than the theoretical value.
* L.G. Sukhikh, S.Yu.Gogolev and A.P.Potylitsyn, Nucl. Instrum. Methods Phys. Res., Sect. A 623, 567 (2010)
** L.G. Sukhikh, S.Yu.Gogolev and A.P.Potylitsyn, J. Phys.: Conf. Ser. 236, 012011 (2010).

Slides WEOA02 [6.967 MB]

WEOB01

Scintillating Screen Applications in Beam Diagnostics

553

B. Walasek-Höhne
GSI, Darmstadt, Germany
G. Kube
DESY, Hamburg, Germany

Scintillation screens are widely used for transverse beam profile diagnostics at particle accelerators. The monitor principle relies on the fact that a charged particle crossing the screen material will deposit a part of its energy which is converted to visible light. The resulting light spot is a direct image of the two-dimensional beam distribution and can be measured with standard optical techniques. Scintillating screen monitors were mainly deployed in hadron and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. The experience from modern linac based light sources showed that OTR diagnostics might fail even for high energetic electron beams, thus making the use of scintillators again very attractive. This contribution summarizes results and trends from "Scintillating Screen Applications in Beam Diagnostics" workshop recently held in Darmstadt. In the first part an introduction to the scintillation mechanism will be given, including demands and limitations as e.g. the dynamic range and saturation. Thereafter a brief overview on actual screen monitor applications at electron and hadron accelerators will be presented.

Slides WEOB01 [14.721 MB]

Paper	Title	Page
MOPD30	Bunch Length Measurement for PETRA III Light Source Storage Ring	113
	H.-C. Schröder, A. Affeldt, H.P. Gausepohl, G. Kube, G. Priebe DESY, Hamburg, Germany
	To fulfill the demand for a very high brilliance synchrotron light source, it is required, that the individual particle bunches, used to create the synchrotron light in special undulator sections, do not exceed certain limits in linear dimension and divergence during the storage time. The bunch length measurement in the visible region of the spectrum is the sole system to measure the longitudinal beam parameter needed for a complete description of the behavior of the PETRAIII positron beam. A detailed description of the dipole magnet visible synchrotron light extraction, the light transport and the analysis by means of a Streak Camera System (SCS) in the context of the PETRAIII storage ring is given. The influence of the custom designed apochromatic refractive optics transport line on the time resolution of the bunch length measurement is discussed and values are given. The final time resolution of the whole system transport optics and Streak camera is shown to be not bigger than 4 ps. Several measurements from PETRAIII runs are presented and results of the bunch length measurements are shown. The typical bunch length measured is about 40 ps.
	Poster MOPD30 [6.402 MB]

TUPD21	Frontend Measurements and Optimizations at Libera Brilliance BPM Electronics during Commissioning of the Petra III Synchrotron Light Source	350
	F. Schmidt-Föhre, G. Kube, J.M. Maass, K. Wittenburg DESY, Hamburg, Germany
	New 3rd generation synchrotron light sources like Petra III utilize high-accuracy beam position measurement (BPM) systems to achieve the desired precision for beam position measurement and control, as needed for electron/positron beam stability and brilliance of the delivered photon beam. To reach the design goals, specifically adapted and parameterized commercial-of-the-shelf (COTS) Libera Brilliance BPM processor electronics are used within the Petra III BPM system. Quality of the acquired position measurement and orbit control data is highly dependent on the properties and setup of the analog and digital frontend of such BPM electronics. This paper shows influences and optimizations at the BPM system frontend of the Petra III light-source in reference to corresponding measurements done during the accelerator commissioning phase.

TUPD33	Coherent Resonant Diffraction Radiation from Inclined Grating as a Tool for Bunch Length Diagnostics	377
	L.G. Sukhikh, G. Kube DESY, Hamburg, Germany A. Potylitsyn Tomsk Polytechnic University, Tomsk, Russia V. Schlott PSI, Villigen, Switzerland
	There exists considerable interest in studying new types of non-invasive bunch length diagnostics for sub-picosecond bunches. In this context coherent Smith-Purcell radiation (CSPR) is a good candidate because the use of grating causes wavelength dispersive radiation emission, i.e. a CSPR based monitor does not require any additional spectrometer. In contrast to existing CSPR monitors a new scheme is proposed with two detectors placed at fixed positions, and a wavelength scan is performed by scanning the tilt angle between grating surface and beam axis. In this scheme the information of both detectors, positioned opposite to each other and perpendicular to the beam axis, can be combined by taking the intensity ratio of the signals from both detectors. The advantage of such diagnostics scheme is that one has not to rely on absolute values of the radiation yield, avoiding the need to know the sensitivity of each detector with high accuracy. In contrast to CSPR which is emitted from a grating oriented parallel to the beam, the effect is termed coherent resonant diffraction radiation when the grating is tilted. In the report we present simulation results and detailed experimental plan.

TUPD59	Suppression of Coherent Optical Transition Radiation in Transverse Beam Diagnostics by Utilising a Scintillation Screen with a Fast Gated CCD Camera	440
	M. Yan Uni HH, Hamburg, Germany C. Behrens, C. Gerth, G. Kube, B. Schmidt, S. Wesch DESY, Hamburg, Germany
	Micro-bunching instabilities in high-brightness beams of linac-driven FELs can lead to coherence effects in the emission of optical transition radiation (OTR) used for standard transverse profile diagnostics, thus rendering it impossible to observe a direct image of the particle beam. By using a scintillation screen in combination with a fast gated CCD camera, coherence effects can be suppressed as OTR is created in an instantaneous process while scintillation light has a certain decay time. In addition, the emission of the scintillation light is a statistical process from many atoms which is completely insensitive to the longitudinal bunch structure and does not produce coherence effects. Gating the camera during the passage of the electron bunch should eliminate any influence of the coherent OTR (COTR). First experiments using this method have been performed successfully at FLASH as a proof-of-principle. In this paper, we study the applicability of scintillation screens for high-energy electron beams under operation conditions for which COTR is emitted. Experimental results together with simulations are presented and discussed in view of COTR suppression and spatial resolution.

WEOA02	Experimental Investigations of Backward Transition Radiation from Flat Target in Extreme Ultraviolet Region	544
	L.G. Sukhikh, G. Kube DESY, Hamburg, Germany D. Krambrich, W. Lauth IKP, Mainz, Germany Yu.A. Popov, A. Potylitsyn Tomsk Polytechnic University, Tomsk, Russia
	Forward transition radiation in X-ray range and backward transition radiation (BTR) in optical spectral region are investigated in details due to their use for purposes of particle and beam diagnostics. In order to improve diagnostics tools we proposed to use BTR in extreme ultraviolet (EUV) region [,], where theoretical models are existing only. We performed experimental investigations of BTR characteristics in EUV spectral region generated by a molybdenum target at 855 MeV electron beam of the MAMI-B (Mainz, Germany). Angular patterns and intensities of BTR both in optical and EUV regions for different observation angles were investigated. The measured intensity of optical BTR agrees with a theory with reasonable accuracy but one in EUV region is more intense than theoretically predicted. Our experimental estimation of the experimental BTR yield in EUV region is (2.4/3.6)•10⁻⁴ photons/electron and this is more than 4 / 6 times higher than the theoretical value. L.G. Sukhikh, S.Yu.Gogolev and A.P.Potylitsyn, Nucl. Instrum. Methods Phys. Res., Sect. A 623, 567 (2010) ** L.G. Sukhikh, S.Yu.Gogolev and A.P.Potylitsyn, J. Phys.: Conf. Ser. 236, 012011 (2010).
	Slides WEOA02 [6.967 MB]

WEOB01	Scintillating Screen Applications in Beam Diagnostics	553
	B. Walasek-Höhne GSI, Darmstadt, Germany G. Kube DESY, Hamburg, Germany
	Scintillation screens are widely used for transverse beam profile diagnostics at particle accelerators. The monitor principle relies on the fact that a charged particle crossing the screen material will deposit a part of its energy which is converted to visible light. The resulting light spot is a direct image of the two-dimensional beam distribution and can be measured with standard optical techniques. Scintillating screen monitors were mainly deployed in hadron and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. The experience from modern linac based light sources showed that OTR diagnostics might fail even for high energetic electron beams, thus making the use of scintillators again very attractive. This contribution summarizes results and trends from "Scintillating Screen Applications in Beam Diagnostics" workshop recently held in Darmstadt. In the first part an introduction to the scintillation mechanism will be given, including demands and limitations as e.g. the dynamic range and saturation. Thereafter a brief overview on actual screen monitor applications at electron and hadron accelerators will be presented.
	Slides WEOB01 [14.721 MB]