IBIC2012 - List of Authors (Matsubara, S.)

Paper

Title

Page

The First Electron Bunch Measurement by means of DAST Organic EO Crystals

29

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

Pilot user experiments via the seeded FEL have been demonstrated at the Prototype Test Accelerator (VUV-FEL), SPring-8 from July, 2012. A precise measurement of the electron bunch charge distribution (BCD) is crucial key to keep spatial and temporal overlaps between high-order harmonic (HH) laser pulses and electron bunches. R&D of the 3D-BCD monitor with a single-shot detection has been extensively promoted at SPring-8. The monitor adopts a spectral decoding based Electro-Optic (EO) sampling technique that is non-destructive and enables real-time reconstruction of the 3D-BCD with a temporal resolution of 30- to 40-fs (FWHM). So far, such EO sampling based BCD monitors have been developed by utilizing inorganic EO crystals such as ZnTe and their temporal resolutions are limited to ~130 fs (FWHM). As a part of this project, the first BCD measurement with an organic EO crystal DAST has been successfully demonstrated at the facility. Signal intensities, temporal resolutions and radiation related issues via both ZnTe and DAST are discussed.

Slides MOCC03 [3.912 MB]

MOIC02

Electron Beam Diagnostic System for the Japanese XFEL, SACLA

38

H. Maesaka, H. Ego, C. Kondo, T. Ohshima, Y. Otake, H. Tomizawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Matsubara, T. Matsumoto, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan

An x-ray free-electron laser (XFEL) based on self-amplified spontaneous emission (SASE) requires a highly brilliant electron beam. The Japanese XFEL facility, SACLA, requires a normalized emittance less than 1 mm mrad and a peak current more than 3 kA. To achieve this high peak current, 1 A beam with 1 ns duration from a thermionic electron gun is compressed down to 30 fs by means of a multi-stage bunch compressor system. Therefore, the beam diagnostic system for SACLA was designed for the measurements of the emittance and bunch length at each compression stage. We developed a high-resolution transverse profile monitor and a temporal bunch structure measurement system with a C-band rf deflector cavity etc. In addition, precise overlapping between an electron beam and radiated x-rays in the undulator section is necessary to ensure the XFEL interaction. Therefore, we employed a C-band sub-micron resolution RF-BPM to fulfill the demanded accuracy of 4 um. The beam diagnostic system surely contributed to the first x-ray lasing at a wavelength of 1.2 Angstrom. We present a design strategy of the whole beam diagnostic system and the achieved performance for each monitor.

Slides MOIC02 [7.861 MB]

MOPA20

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

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).

MOCC04

Improvement of Screen Monitor with Suppression of Coherent-OTR Effect for SACLA

34

S. Matsubara, Y. Otake
RIKEN/SPring-8, Hyogo, Japan
S.I. Inoue
SES, Hyogo-pref., Japan
H. Maesaka
RIKEN Spring-8 Harima, Hyogo, Japan

The construction of SACLA (SPring-8 Angstrom Compact free electron LAser) was already completed and it is under operation. A screen monitor (SCM) system has been developed and was installed in order to obtain a direct image of a transverse beam profile with a spatial resolution of about 10 um, which is required to investigate electron-beam properties, such as a beam emittance. The SCM originally has a stainless steel target as a OTR radiator or a Ce:YAG crystal as a scintillation target. At the beginning of the SACLA operation, strong coherent OTR (COTR), which made an incorrect beam profile, was observed after bunch compressors. In order to suppress the COTR on the SCM, the stainless steel target was replaced to the Ce:YAG scintillation target. Since the COTR was still generated from the Ce:YAG target, a spatial mask was employed. The mask was mounted on the center of the optical line of the SCM, because the COTR light is emitted forward within ~1/γ radian, while the scintillation light has not angular dependence. Clear beam profiles with a diameter of a few tens of micro-meter are observed by means of the SCMs with this simple improvement.

Slides MOCC04 [1.618 MB]

MOPA49

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

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.

Paper	Title	Page
MOCC03	The First Electron Bunch Measurement by means of DAST Organic EO Crystals	29
	Y. Okayasu, S. Matsubara, T. Togashi JASRI/SPring-8, Hyogo-ken, Japan M. Aoyama JAEA/Kansai, Kyoto, Japan A. Iwasaki, S. Owada The University of Tokyo, Tokyo, Japan T. Matsukawa RIKEN ASI, Sendai, Miyagi, Japan H. Minamide RIKEN Advanced Science Insititute, Sendai, Miyagi, Japan K. Ogawa, T. Sato, H. Tomizawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan E. Takahashi RIKEN, Saitama, Japan
	Pilot user experiments via the seeded FEL have been demonstrated at the Prototype Test Accelerator (VUV-FEL), SPring-8 from July, 2012. A precise measurement of the electron bunch charge distribution (BCD) is crucial key to keep spatial and temporal overlaps between high-order harmonic (HH) laser pulses and electron bunches. R&D of the 3D-BCD monitor with a single-shot detection has been extensively promoted at SPring-8. The monitor adopts a spectral decoding based Electro-Optic (EO) sampling technique that is non-destructive and enables real-time reconstruction of the 3D-BCD with a temporal resolution of 30- to 40-fs (FWHM). So far, such EO sampling based BCD monitors have been developed by utilizing inorganic EO crystals such as ZnTe and their temporal resolutions are limited to ~130 fs (FWHM). As a part of this project, the first BCD measurement with an organic EO crystal DAST has been successfully demonstrated at the facility. Signal intensities, temporal resolutions and radiation related issues via both ZnTe and DAST are discussed.
	Slides MOCC03 [3.912 MB]

MOIC02	Electron Beam Diagnostic System for the Japanese XFEL, SACLA	38
	H. Maesaka, H. Ego, C. Kondo, T. Ohshima, Y. Otake, H. Tomizawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Matsubara, T. Matsumoto, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan
	An x-ray free-electron laser (XFEL) based on self-amplified spontaneous emission (SASE) requires a highly brilliant electron beam. The Japanese XFEL facility, SACLA, requires a normalized emittance less than 1 mm mrad and a peak current more than 3 kA. To achieve this high peak current, 1 A beam with 1 ns duration from a thermionic electron gun is compressed down to 30 fs by means of a multi-stage bunch compressor system. Therefore, the beam diagnostic system for SACLA was designed for the measurements of the emittance and bunch length at each compression stage. We developed a high-resolution transverse profile monitor and a temporal bunch structure measurement system with a C-band rf deflector cavity etc. In addition, precise overlapping between an electron beam and radiated x-rays in the undulator section is necessary to ensure the XFEL interaction. Therefore, we employed a C-band sub-micron resolution RF-BPM to fulfill the demanded accuracy of 4 um. The beam diagnostic system surely contributed to the first x-ray lasing at a wavelength of 1.2 Angstrom. We present a design strategy of the whole beam diagnostic system and the achieved performance for each monitor.
	Slides MOIC02 [7.861 MB]

MOPA20	Development of 3D EO-Sampling System for the Ultimate Temporal Resolution	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).

MOCC04	Improvement of Screen Monitor with Suppression of Coherent-OTR Effect for SACLA	34
	S. Matsubara, Y. Otake RIKEN/SPring-8, Hyogo, Japan S.I. Inoue SES, Hyogo-pref., Japan H. Maesaka RIKEN Spring-8 Harima, Hyogo, Japan
	The construction of SACLA (SPring-8 Angstrom Compact free electron LAser) was already completed and it is under operation. A screen monitor (SCM) system has been developed and was installed in order to obtain a direct image of a transverse beam profile with a spatial resolution of about 10 um, which is required to investigate electron-beam properties, such as a beam emittance. The SCM originally has a stainless steel target as a OTR radiator or a Ce:YAG crystal as a scintillation target. At the beginning of the SACLA operation, strong coherent OTR (COTR), which made an incorrect beam profile, was observed after bunch compressors. In order to suppress the COTR on the SCM, the stainless steel target was replaced to the Ce:YAG scintillation target. Since the COTR was still generated from the Ce:YAG target, a spatial mask was employed. The mask was mounted on the center of the optical line of the SCM, because the COTR light is emitted forward within ~1/γ radian, while the scintillation light has not angular dependence. Clear beam profiles with a diameter of a few tens of micro-meter are observed by means of the SCMs with this simple improvement.
	Slides MOCC04 [1.618 MB]

MOPA49	EO-sampling-based Temporal Overlap Control System for an HH Seeded FEL	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.