IBIC2012 - List of Keywords (timing)

Paper	Title	Other Keywords	Page
MOPA20	Development of 3D EO-Sampling System for the Ultimate Temporal Resolution	FEL, laser, electron, feedback	98
	K. Ogawa, H. Tomizawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Matsubara, Y. Okayasu JASRI/SPring-8, Hyogo, Japan
	We have been developing three dimensional bunch charge distribution (3D-BCD) monitor for FEL seeded with high-order harmonic (HH) pulse. 3D-BCD is based on EO-sampling technique with multiple EO crystal detectors in the manner of spectral decoding. Using this 3D-EO sampling technique, the positioning and timing of electron bunch is obtained in real-time with non-destructive measurement. For obtaining the high temporal resolution, an octave broadband probe laser with linear chirp rate of 1 fs/nm is required. We are developing an EO-probe laser pulse with ~10 μJ pulse energy and the bandwidth over 300 nm (FWHM). For meet these bandwidth and pulse energy, this EO-probe pulse is using a supercontinuum generated by photonic crystal fiber (PCF) and amplified with optical parametric amplification (OPA). Especially, for amplification with maintaining octave bandwidth, non-collinear OPA (NOPA) using BBO crystal and a pump source with a wavelength of 450 nm are adopted. The EO-probe pulse energy of 10 μJ provides for high S/N ratio to each detector and the bandwidth of 300 nm with 300 fs pulse duration allows the measurement for the 30 fs electron bunch duration (FWHM).

MOPA36	Development of Bunch Current and Oscillation Recorder for SuperKEKB Accelerator	FPGA, controls, EPICS, damping	138
	M. Tobiyama, J.W. Flanagan KEK, Ibaraki, Japan
	A High-speed digital signal memory has been developed for the bunch current and oscillation recorder for SuperKEKB. The memory consists of an 8-bit ADC and a FPGA daughter card with Spartan6 and DDR2 memories commercially available on a double width VME card. The block-RAM on the FPGA is used to transfer bunch current data with low latency for prompt bunch current measurements, and the large DDR2 memory is used for long-duration position recording, such as post-mortem bunch oscillation recording. The performance of the board, including data transfer rate, will be presented.

MOPA48	Measurement of Temporal Resolution and Detection Efficiency of X-ray Streak Camera by Single Photon Images	photon, experiment, electron, cathode	171
	A. Mochihashi, M. Masaki, H. Ohkuma, S. Takano, K. Tamura JASRI/SPring-8, Hyogo-ken, Japan
	Funding: This work was partly supported by MEXT Grant-in-Aid for Young Scientists (B) Grant number 21740215. In the third generation and the next generation synchrotron radiation light sources, the electron beam bunch length of ps ~ sub-ps is expected to be achieved. An X-ray streak camera (X-SC) can directly measure the temporal width of X-ray synchrotron radiation pulse. The temporal resolution of X-SC depends on the initial velocity distribution of the photoelectrons from a photocathode which converts the X-ray photons to the photoelectrons. To measure the temporal resolution of the X-SC, we have observed 'single photon' streak camera images and measured the temporal spread of the images. By this 'single photon' experiment, we have evaluated the dependence of the temporal resolution and the detection efficiency on the photon energy. We have also tried to evaluate the dependence of the temporal resolution and the detection efficiency on the thickness of the photocathode. For this purpose, we have developed a multi-array type CsI photocathode with 3 different thickness of the photocathode. The experimental setups, and the results of the measurements of the temporal spread and the detection efficiency of the single photon events will be presented.

MOPA49	EO-sampling-based Temporal Overlap Control System for an HH Seeded FEL	laser, FEL, electron, operation	176
	S. Matsubara RIKEN/SPring-8, Hyogo, Japan M. Aoyama JAEA/Kansai, Kyoto, Japan A. Iwasaki, S. Owada The University of Tokyo, Tokyo, Japan K. Ogawa, T. Sato, H. Tomizawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan Y. Okayasu, T. Togashi, T. Watanabe JASRI/SPring-8, Hyogo-ken, Japan E. Takahashi RIKEN, Saitama, Japan
	FELs have greatly interested for the short-wavelength region. However, their temporal profile and frequency spectra have shot-to-shot fluctuation by a SASE process. One of the promising approached for the problems is a seeded FEL scheme by using a full-coherent light source. The seeded FEL has been demonstrated in the EUV region by employ the high-order harmonics (HH) generation from an external laser source at the SCSS test-accelerator in the SPring-8. It is important for the HH-seeded FEL scheme to synchronize and overlap between the seeding laser pulse and the electron bunch. Their timing difference and laser spatial pointing is drifting. Therefore, a timing feedback and non-destructive monitor are necessary to operate seeded FEL continuously. We have constructed the timing monitor based on Electro-Optic (EO) sampling which is measure the timing difference the seeded laser pulse and the electron bunch simultaneously with the seeded FEL process. The probe laser pulse for the EO-sampling system is optically split from the common external HH laser driver for the seeded FEL. The EO-sampling system is able to use timing feedback for continual operation of the HH-seededFEL.

MOPB83	Turn-by-turn Observation of the Injected Beam Profile at the Australian Synchrotron Storage Ring	injection, storage-ring, synchrotron, electron	276
	M.J. Boland ASCo, Clayton, Victoria, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	A fast gated intensified CCD camera was used to observe the beam profile turn-by-turn in the visible light region. Using the visible light from the optical diagnostic beamline on the storage ring at the Australian Synchrotron an optical telescope was constructed to focus an image on the ICCD. The event driven timing system was then used to synchronise the camera with the injected beam. To overcome the problem of dynamic range between the amount of charge in an injected bunch and the stored beam, the beam was dumped by slowly phase flipping the RF by 180 degrees between each one 1 Hz injection cycle. The injection process was verified to be stable enough so that measurements of the different turns could be captured on successive injections and did not need to be captured in single shot. The beam was seen to come in relatively cleanly in a tight beam but would then rapidly decohere due to the strong non-linear fields needed to run the storage ring at high chromaticity. It would take thousands of turns for the beam to damp down again and recohere into a tight beam spot again. This measurement technique will be used to tune the storage ring injection process.

TUPA19	First Tests of a Low Charge MTCA-based Electronics for Button and Strip-line BPM at FLASH	electronics, detector, electron, operation	378
	B. Lorbeer, N. Baboi, F. Schmidt-Föhre DESY, Hamburg, Germany
	Current FEL based light sources foresee operation with very short electron bunches. These can be obtained with charges of 100pC and lower. The specified charge range for FLASH, DESY, Hamburg goes from 100pC up to 1nC. The electronics currently installed at button and stripline BPMs of FLASH have been designed for best performance at higher charges and have reached their limits. Currently a new type of electronics is being developed at DESY to overcome these limitations. These electronics is/are conforming with the uTCA for physics standard(ref). This paper describes the next generation of FLASH BPM electronics suitable for button and stripline BPM. Furthermore the first measurement results taken with beam at FLASH, DESY are presented here.

TUPA44	Status of the LCLS Experiment Timing System	laser, experiment, electron, feedback	453
	J.C. Frisch, C. Bostedt, R.N. Coffee, A.R. Fry, N. Hartmann, J. May, D.J. Nicholson, S. Schorb, S.R. Smith SLAC, Menlo Park, California, USA
	Funding: Work Supported by Department of Energy Contract DE AC03 76SF00515 X-ray / optical laser pump - probe experiments are used for a significant fraction of the scientific work performed at LCLS. The experimental laser systems are locked to the timing of the electron beam through a combination of RF and optical fiber based systems. The remaining ~100 femtosecond RMS jitter of the X-rays relative to the optical laser is measured shot-to-shot by both a RF timing detector, and by direct X-ray to optical cross-correlation, and the result is used to correct the experiment timing to 10s of femtoseconds. We present the present status of the system and plans for future upgrades.

TUPB63	Development of Turn-by-turn Beam Diagnostic System using Undulator Radiation	radiation, diagnostics, injection, undulator	492
	M. Masaki, A. Mochihashi, H. Ohkuma, S. Takano, K. Tamura JASRI/SPring-8, Hyogo-ken, Japan
	At the diagnostic beamline II (BL05SS) of the SPring-8 storage ring, a turn-by-turn beam diagnostic system using undulator radiation has been developed to observe fast phenomena such as stored beam oscillations during the top-up injections, blowups of beam size and energy spread coming from the instabilities of a high current single bunch and so on. The fast diagnostic system observes a spatial profile of the undulator radiation on a selected harmonic number. Especially, the higher harmonic radiations than the 10th-order are sensitive to the energy spread. A fluorescence screen (YAG:Ce) with afterglow of several tens of nano-second converts the radiation profile into visible light image. The imaging optics makes the horizontal and vertical profiles as two line images by one-dimensional focusing using cylindrical lenses. A fast-gated CCD camera with image intensifier simultaneously captures the two line images. The kinetics readout mode of the fast CCD camera is used to register the spatial profiles of several tens of turns in one flame. The principle and experimental setup of the turn-by-turn diagnostic system, and examples of beam observations will be presented.

TUPB72	Injected Beam Profile Measurement during Top-up Operation	injection, operation, storage-ring, background	508
	M.J. Boland ASCo, Clayton, Victoria, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	A coronagraph-like apparatus was constructed on the optical diagnostic beamline on the storage ring to observe the injected beam during top-up operations. An image was created on an intensified CCD that can be gated on a single bunch or on a bunch train for a stronger signal. The bright central stored beam was obscured so the comparatively faint injected beam could be observed. The injected beam comes in at a large enough offset so that it was clearly visible above any diffraction or beam halo signals. The beam profile measured was in good agreement with the observations made of the injected beam only using a telescope apparatus. The measurements were made during user beam in top-up operation mode and can be used to optimise the injection process.

TUPB78	Flying Wire Beam Profile Monitors at the J-PARC MR	injection, proton, background, emittance	527
	S. Igarashi, D.A. Arakawa, Y. Hashimoto, M. Tejima, T. Toyama KEK, Ibaraki, Japan K. Hanamura Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	Transverse beam profiles have been measured using flying wire monitors at the main ring of the Japan Proton Accelerator Research Complex. The wire target should be thin and the wire scan has to be fast for the precise profile measurement. Otherwise the beam distribution would be disturbed and the measured profile would not be accurate. We use carbon fibers of 7 μm in diameter and the scan speed of 10 m/s. The wire is attached with an aluminum flame of 140 mm of the rotation radius and rotated with a DC servomotor. A potentiometer is attached to the wire flame and the angle readout is used for the feedback of the servomotor and the wire position measurement. The secondary particles from the beam-wire scattering are measured with a scintillation counter. Beam profiles are reconstructed by making the scatter plot of the scintillator signal and wire position. Both horizontal and vertical flying wire monitors have been used for the beam commissioning. We have successfully measured the beam profile of up to 1.2×10¹³ protons per bunch.

WECC04	Analysis of the Electro-optical Front End for the New 40 GHz Bunch Arrival Time Monitor System	laser, pick-up, electron, FEL	571
	A. Kuhl, J. Rönsch-Schulenburg, J. Roßbach Uni HH, Hamburg, Germany A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo DESY, Hamburg, Germany S. Schnepp IFH, Zurich, Switzerland T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	The Free electron LASer in Hamburg (FLASH) is currently equipped with four Bunch Arrival time Monitors (BAMs) which achieve a time resolution of less than 10 fs for bunch charges higher than 500 pC (1). In order to achieve single spike FEL pulses at FLASH, electron bunch charges down to 20 pC are of interest. With the current BAMs the required time resolution is not reachable for bunch charges below 500 pC. Therefore new pickups with a bandwidth of up to 40 GHz (2) are designed and manufactured. The signal evaluation takes place with a time-stabilized reference laser pulse train which is modulated with an Electro-Optical intensity Modulator (EOM). The new pickup system also requires a new electro-optical frontend with a 40 GHz EOM. The theoretical limits of the time resolution depending on the RF signal at different bunch charges and on the jitter of the reference laser pulses where analyzed for the new EOM. (1) M. K. Bock et al. in Proceedings of DIPAC 2011, Hamburg, Germany,2011, p. 365 (2) A. Angelovski, A. Kuhl et al. in Proceedings of IPAC 2011, San Sebastian, Spain, 2011, p. 1177 and p. 1186
	Slides WECC04 [12.560 MB]

Paper

Title

Other Keywords

Page

MOPA20

Development of 3D EO-Sampling System for the Ultimate Temporal Resolution

FEL, laser, electron, feedback

98

K. Ogawa, H. Tomizawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Matsubara, Y. Okayasu
JASRI/SPring-8, Hyogo, Japan

We have been developing three dimensional bunch charge distribution (3D-BCD) monitor for FEL seeded with high-order harmonic (HH) pulse. 3D-BCD is based on EO-sampling technique with multiple EO crystal detectors in the manner of spectral decoding. Using this 3D-EO sampling technique, the positioning and timing of electron bunch is obtained in real-time with non-destructive measurement. For obtaining the high temporal resolution, an octave broadband probe laser with linear chirp rate of 1 fs/nm is required. We are developing an EO-probe laser pulse with ~10 μJ pulse energy and the bandwidth over 300 nm (FWHM). For meet these bandwidth and pulse energy, this EO-probe pulse is using a supercontinuum generated by photonic crystal fiber (PCF) and amplified with optical parametric amplification (OPA). Especially, for amplification with maintaining octave bandwidth, non-collinear OPA (NOPA) using BBO crystal and a pump source with a wavelength of 450 nm are adopted. The EO-probe pulse energy of 10 μJ provides for high S/N ratio to each detector and the bandwidth of 300 nm with 300 fs pulse duration allows the measurement for the 30 fs electron bunch duration (FWHM).

MOPA36

Development of Bunch Current and Oscillation Recorder for SuperKEKB Accelerator

FPGA, controls, EPICS, damping

138

M. Tobiyama, J.W. Flanagan
KEK, Ibaraki, Japan

A High-speed digital signal memory has been developed for the bunch current and oscillation recorder for SuperKEKB. The memory consists of an 8-bit ADC and a FPGA daughter card with Spartan6 and DDR2 memories commercially available on a double width VME card. The block-RAM on the FPGA is used to transfer bunch current data with low latency for prompt bunch current measurements, and the large DDR2 memory is used for long-duration position recording, such as post-mortem bunch oscillation recording. The performance of the board, including data transfer rate, will be presented.

MOPA48

Measurement of Temporal Resolution and Detection Efficiency of X-ray Streak Camera by Single Photon Images

photon, experiment, electron, cathode

171

A. Mochihashi, M. Masaki, H. Ohkuma, S. Takano, K. Tamura
JASRI/SPring-8, Hyogo-ken, Japan

Funding: This work was partly supported by MEXT Grant-in-Aid for Young Scientists (B) Grant number 21740215.
In the third generation and the next generation synchrotron radiation light sources, the electron beam bunch length of ps ~ sub-ps is expected to be achieved. An X-ray streak camera (X-SC) can directly measure the temporal width of X-ray synchrotron radiation pulse. The temporal resolution of X-SC depends on the initial velocity distribution of the photoelectrons from a photocathode which converts the X-ray photons to the photoelectrons. To measure the temporal resolution of the X-SC, we have observed 'single photon' streak camera images and measured the temporal spread of the images. By this 'single photon' experiment, we have evaluated the dependence of the temporal resolution and the detection efficiency on the photon energy. We have also tried to evaluate the dependence of the temporal resolution and the detection efficiency on the thickness of the photocathode. For this purpose, we have developed a multi-array type CsI photocathode with 3 different thickness of the photocathode. The experimental setups, and the results of the measurements of the temporal spread and the detection efficiency of the single photon events will be presented.

MOPA49

EO-sampling-based Temporal Overlap Control System for an HH Seeded FEL

laser, FEL, electron, operation

176

S. Matsubara
RIKEN/SPring-8, Hyogo, Japan
M. Aoyama
JAEA/Kansai, Kyoto, Japan
A. Iwasaki, S. Owada
The University of Tokyo, Tokyo, Japan
K. Ogawa, T. Sato, H. Tomizawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
Y. Okayasu, T. Togashi, T. Watanabe
JASRI/SPring-8, Hyogo-ken, Japan
E. Takahashi
RIKEN, Saitama, Japan

FELs have greatly interested for the short-wavelength region. However, their temporal profile and frequency spectra have shot-to-shot fluctuation by a SASE process. One of the promising approached for the problems is a seeded FEL scheme by using a full-coherent light source. The seeded FEL has been demonstrated in the EUV region by employ the high-order harmonics (HH) generation from an external laser source at the SCSS test-accelerator in the SPring-8. It is important for the HH-seeded FEL scheme to synchronize and overlap between the seeding laser pulse and the electron bunch. Their timing difference and laser spatial pointing is drifting. Therefore, a timing feedback and non-destructive monitor are necessary to operate seeded FEL continuously. We have constructed the timing monitor based on Electro-Optic (EO) sampling which is measure the timing difference the seeded laser pulse and the electron bunch simultaneously with the seeded FEL process. The probe laser pulse for the EO-sampling system is optically split from the common external HH laser driver for the seeded FEL. The EO-sampling system is able to use timing feedback for continual operation of the HH-seededFEL.

MOPB83

Turn-by-turn Observation of the Injected Beam Profile at the Australian Synchrotron Storage Ring

injection, storage-ring, synchrotron, electron

276

M.J. Boland
ASCo, Clayton, Victoria, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

A fast gated intensified CCD camera was used to observe the beam profile turn-by-turn in the visible light region. Using the visible light from the optical diagnostic beamline on the storage ring at the Australian Synchrotron an optical telescope was constructed to focus an image on the ICCD. The event driven timing system was then used to synchronise the camera with the injected beam. To overcome the problem of dynamic range between the amount of charge in an injected bunch and the stored beam, the beam was dumped by slowly phase flipping the RF by 180 degrees between each one 1 Hz injection cycle. The injection process was verified to be stable enough so that measurements of the different turns could be captured on successive injections and did not need to be captured in single shot. The beam was seen to come in relatively cleanly in a tight beam but would then rapidly decohere due to the strong non-linear fields needed to run the storage ring at high chromaticity. It would take thousands of turns for the beam to damp down again and recohere into a tight beam spot again. This measurement technique will be used to tune the storage ring injection process.

TUPA19

First Tests of a Low Charge MTCA-based Electronics for Button and Strip-line BPM at FLASH

electronics, detector, electron, operation

378

B. Lorbeer, N. Baboi, F. Schmidt-Föhre
DESY, Hamburg, Germany

Current FEL based light sources foresee operation with very short electron bunches. These can be obtained with charges of 100pC and lower. The specified charge range for FLASH, DESY, Hamburg goes from 100pC up to 1nC. The electronics currently installed at button and stripline BPMs of FLASH have been designed for best performance at higher charges and have reached their limits. Currently a new type of electronics is being developed at DESY to overcome these limitations. These electronics is/are conforming with the uTCA for physics standard(ref). This paper describes the next generation of FLASH BPM electronics suitable for button and stripline BPM. Furthermore the first measurement results taken with beam at FLASH, DESY are presented here.

TUPA44

Status of the LCLS Experiment Timing System

laser, experiment, electron, feedback

453

J.C. Frisch, C. Bostedt, R.N. Coffee, A.R. Fry, N. Hartmann, J. May, D.J. Nicholson, S. Schorb, S.R. Smith
SLAC, Menlo Park, California, USA

Funding: Work Supported by Department of Energy Contract DE AC03 76SF00515
X-ray / optical laser pump - probe experiments are used for a significant fraction of the scientific work performed at LCLS. The experimental laser systems are locked to the timing of the electron beam through a combination of RF and optical fiber based systems. The remaining ~100 femtosecond RMS jitter of the X-rays relative to the optical laser is measured shot-to-shot by both a RF timing detector, and by direct X-ray to optical cross-correlation, and the result is used to correct the experiment timing to 10s of femtoseconds. We present the present status of the system and plans for future upgrades.

TUPB63

Development of Turn-by-turn Beam Diagnostic System using Undulator Radiation

radiation, diagnostics, injection, undulator

492

M. Masaki, A. Mochihashi, H. Ohkuma, S. Takano, K. Tamura
JASRI/SPring-8, Hyogo-ken, Japan

At the diagnostic beamline II (BL05SS) of the SPring-8 storage ring, a turn-by-turn beam diagnostic system using undulator radiation has been developed to observe fast phenomena such as stored beam oscillations during the top-up injections, blowups of beam size and energy spread coming from the instabilities of a high current single bunch and so on. The fast diagnostic system observes a spatial profile of the undulator radiation on a selected harmonic number. Especially, the higher harmonic radiations than the 10th-order are sensitive to the energy spread. A fluorescence screen (YAG:Ce) with afterglow of several tens of nano-second converts the radiation profile into visible light image. The imaging optics makes the horizontal and vertical profiles as two line images by one-dimensional focusing using cylindrical lenses. A fast-gated CCD camera with image intensifier simultaneously captures the two line images. The kinetics readout mode of the fast CCD camera is used to register the spatial profiles of several tens of turns in one flame. The principle and experimental setup of the turn-by-turn diagnostic system, and examples of beam observations will be presented.

TUPB72

Injected Beam Profile Measurement during Top-up Operation

injection, operation, storage-ring, background

508

M.J. Boland
ASCo, Clayton, Victoria, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

A coronagraph-like apparatus was constructed on the optical diagnostic beamline on the storage ring to observe the injected beam during top-up operations. An image was created on an intensified CCD that can be gated on a single bunch or on a bunch train for a stronger signal. The bright central stored beam was obscured so the comparatively faint injected beam could be observed. The injected beam comes in at a large enough offset so that it was clearly visible above any diffraction or beam halo signals. The beam profile measured was in good agreement with the observations made of the injected beam only using a telescope apparatus. The measurements were made during user beam in top-up operation mode and can be used to optimise the injection process.

TUPB78

Flying Wire Beam Profile Monitors at the J-PARC MR

injection, proton, background, emittance

527

S. Igarashi, D.A. Arakawa, Y. Hashimoto, M. Tejima, T. Toyama
KEK, Ibaraki, Japan
K. Hanamura
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

Transverse beam profiles have been measured using flying wire monitors at the main ring of the Japan Proton Accelerator Research Complex. The wire target should be thin and the wire scan has to be fast for the precise profile measurement. Otherwise the beam distribution would be disturbed and the measured profile would not be accurate. We use carbon fibers of 7 μm in diameter and the scan speed of 10 m/s. The wire is attached with an aluminum flame of 140 mm of the rotation radius and rotated with a DC servomotor. A potentiometer is attached to the wire flame and the angle readout is used for the feedback of the servomotor and the wire position measurement. The secondary particles from the beam-wire scattering are measured with a scintillation counter. Beam profiles are reconstructed by making the scatter plot of the scintillator signal and wire position. Both horizontal and vertical flying wire monitors have been used for the beam commissioning. We have successfully measured the beam profile of up to 1.2×10¹³ protons per bunch.

WECC04

Analysis of the Electro-optical Front End for the New 40 GHz Bunch Arrival Time Monitor System

laser, pick-up, electron, FEL

571

A. Kuhl, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
M. Bousonville, M.K. Czwalinna, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
S. Schnepp
IFH, Zurich, Switzerland
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

The Free electron LASer in Hamburg (FLASH) is currently equipped with four Bunch Arrival time Monitors (BAMs) which achieve a time resolution of less than 10 fs for bunch charges higher than 500 pC (1). In order to achieve single spike FEL pulses at FLASH, electron bunch charges down to 20 pC are of interest. With the current BAMs the required time resolution is not reachable for bunch charges below 500 pC. Therefore new pickups with a bandwidth of up to 40 GHz (2) are designed and manufactured. The signal evaluation takes place with a time-stabilized reference laser pulse train which is modulated with an Electro-Optical intensity Modulator (EOM). The new pickup system also requires a new electro-optical frontend with a 40 GHz EOM. The theoretical limits of the time resolution depending on the RF signal at different bunch charges and on the jitter of the reference laser pulses where analyzed for the new EOM.
(1) M. K. Bock et al. in Proceedings of DIPAC 2011, Hamburg, Germany,2011, p. 365
(2) A. Angelovski, A. Kuhl et al. in Proceedings of IPAC 2011, San Sebastian, Spain, 2011, p. 1177 and p. 1186

Slides WECC04 [12.560 MB]