IPAC2012 - List of Authors (Washio, M.)

Paper

Title

Page

Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac

37

M. Kumaki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Kuroda, H. Toyokawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.

Slides MOOBA03 [3.342 MB]

TUPPD023

RFQ LINAC Commissioning and Carbon⁴⁺ Acceleration for Ag¹⁵⁺ Acceleration via Direct Plasma Injection Scheme

1458

T. Yamamoto, M. Washio
RISE, Tokyo, Japan
K. Kondo, M. Okamura, M. Sekine
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
High intensity, high charge state, various ion species and small emittance heavy ion beam is required for particle physics, medical uses, inertial fusion, and a simulator of space radiation. Direct Plasma Injection Scheme (DPIS), the way to make laser abrasion plasma developed in the past several years, is used for Heavy Ion beam Accerelation. High density plasma with an initial drift velocity will fly to the entrance of the Radio Frequency Quadropole (RFQ) LINAC; ions will be separated from plasma via high voltage and injected it to RFQ LINAC directly. After RFQ LINAC, ions accepted to the RF buckets are accelerated to a current of over 10mA. Until now, we tried a carbon target using the partial modulation rod of the RFQ LINAC, and succeeded in accelerating carbon⁴⁺, carbon⁵⁺, and carbon⁶⁺ non-bunched beam.* In this instance, we succeeded in commissioning of new full modulation RFQ rod designed for the charge mass ratio(q/A) 1/6. We tested the acceleration of carbon⁴⁺, and it could be catched by the RF bucket and accelerated. After this, we'll try accelerating carbon²⁺ (q/A=1/6) for demonstrating the feasibility of the Ag¹⁵⁺ ion accelerating.
* T. Kanesue, M. Okamura, K. Kondo, J. Tamura, H. Kashiwagi, Z. Zhang, Drift distance survey in direct plasma injection scheme for high current beam production, Rev Sci Instrum. 2010 Feb;81(2):02B723

TUPPD058

Development of an RF Electron Gun for Ultra-Short Bunch Generation

1536

Y. Koshiba, T. Aoki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

At Waseda University, various researches are done using a photocathode rf electron gun with a 1.6 cell cavity. Now we are developing a new rf cavity specialized for producing an ultra-short electron bunch, with the collaboration of High Energy Accelerator Research Organization (KEK). We have used SUPERFISH for designing the new rf cavity and PARMELA for beam tracking. The new rf cavity has an extra cell following the 1.6 cell. The extra cell can chirp the energy of electron bunch so we call it ECC (Energy Chirping Cell). ECC chirp the energy because we shortened the length of iris just before the ECC and also the length of ECC itself. Moreover, electric field in ECC is made to be stronger than others. We have confirmed on PARMELA that ECC rf gun can generate an 100pC electron bunch less than 200fsec with the energy of 4.5MeV at about 2.5m away from the cathode. Such an ultra-short electron bunch enables us to generate a coherent terahertz light using ultra-short electron bunch by synchrotron radiation or transition radiation. In this conference, we would like to introduce the detail of the design of this new ECC rf gun, the present progresses and future prospects.

WEOBB02

Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity

2146

K. Sakaue, T. Aoki, M. Washio
RISE, Tokyo, Japan
M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.

Slides WEOBB02 [4.393 MB]

WEPPD055

Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source

2645

T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
H. Kataoka, T. Kon
Seikei University, Japan
M. Kuriki, T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Tanaka, H. Yoshitama
Hiroshima University, Higashi-Hiroshima, Japan

We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

THPPR049

Study on Electron Microbeam Generation for MRT Based on Photo-cathode RF-Gun

4086

Y. Yoshida, K. Sakaue, M. Washio
RISE, Tokyo, Japan

We have been developing an MRT (Microbeam Radiation Therapy) based on Cs-Te photo cathode RF-Gun at Waseda University. MRT is proposed to treat tumor by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition, evaluation of microbeam specifications and future prospects.

Paper	Title	Page
MOOBA03	Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac	37
	M. Kumaki, K. Sakaue, M. Washio RISE, Tokyo, Japan R. Kuroda, H. Toyokawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.
	Slides MOOBA03 [3.342 MB]

TUPPD023	RFQ LINAC Commissioning and Carbon⁴⁺ Acceleration for Ag¹⁵⁺ Acceleration via Direct Plasma Injection Scheme	1458
	T. Yamamoto, M. Washio RISE, Tokyo, Japan K. Kondo, M. Okamura, M. Sekine BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. High intensity, high charge state, various ion species and small emittance heavy ion beam is required for particle physics, medical uses, inertial fusion, and a simulator of space radiation. Direct Plasma Injection Scheme (DPIS), the way to make laser abrasion plasma developed in the past several years, is used for Heavy Ion beam Accerelation. High density plasma with an initial drift velocity will fly to the entrance of the Radio Frequency Quadropole (RFQ) LINAC; ions will be separated from plasma via high voltage and injected it to RFQ LINAC directly. After RFQ LINAC, ions accepted to the RF buckets are accelerated to a current of over 10mA. Until now, we tried a carbon target using the partial modulation rod of the RFQ LINAC, and succeeded in accelerating carbon⁴⁺, carbon⁵⁺, and carbon⁶⁺ non-bunched beam.* In this instance, we succeeded in commissioning of new full modulation RFQ rod designed for the charge mass ratio(q/A) 1/6. We tested the acceleration of carbon⁴⁺, and it could be catched by the RF bucket and accelerated. After this, we'll try accelerating carbon²⁺ (q/A=1/6) for demonstrating the feasibility of the Ag¹⁵⁺ ion accelerating. * T. Kanesue, M. Okamura, K. Kondo, J. Tamura, H. Kashiwagi, Z. Zhang, Drift distance survey in direct plasma injection scheme for high current beam production, Rev Sci Instrum. 2010 Feb;81(2):02B723

TUPPD058	Development of an RF Electron Gun for Ultra-Short Bunch Generation	1536
	Y. Koshiba, T. Aoki, K. Sakaue, M. Washio RISE, Tokyo, Japan T. Takatomi, J. Urakawa KEK, Ibaraki, Japan
	At Waseda University, various researches are done using a photocathode rf electron gun with a 1.6 cell cavity. Now we are developing a new rf cavity specialized for producing an ultra-short electron bunch, with the collaboration of High Energy Accelerator Research Organization (KEK). We have used SUPERFISH for designing the new rf cavity and PARMELA for beam tracking. The new rf cavity has an extra cell following the 1.6 cell. The extra cell can chirp the energy of electron bunch so we call it ECC (Energy Chirping Cell). ECC chirp the energy because we shortened the length of iris just before the ECC and also the length of ECC itself. Moreover, electric field in ECC is made to be stronger than others. We have confirmed on PARMELA that ECC rf gun can generate an 100pC electron bunch less than 200fsec with the energy of 4.5MeV at about 2.5m away from the cathode. Such an ultra-short electron bunch enables us to generate a coherent terahertz light using ultra-short electron bunch by synchrotron radiation or transition radiation. In this conference, we would like to introduce the detail of the design of this new ECC rf gun, the present progresses and future prospects.

WEOBB02	Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity	2146
	K. Sakaue, T. Aoki, M. Washio RISE, Tokyo, Japan M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.
	Slides WEOBB02 [4.393 MB]

WEPPD055	Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source	2645
	T. Akagi, S. Miyoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan H. Kataoka, T. Kon Seikei University, Japan M. Kuriki, T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan K. Sakaue, M. Washio RISE, Tokyo, Japan R. Tanaka, H. Yoshitama Hiroshima University, Higashi-Hiroshima, Japan
	We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

THPPR049	Study on Electron Microbeam Generation for MRT Based on Photo-cathode RF-Gun	4086
	Y. Yoshida, K. Sakaue, M. Washio RISE, Tokyo, Japan
	We have been developing an MRT (Microbeam Radiation Therapy) based on Cs-Te photo cathode RF-Gun at Waseda University. MRT is proposed to treat tumor by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition, evaluation of microbeam specifications and future prospects.