Atsushi Fukasawa

Time-resolved X-ray diffraction at NERL

For ultrafast material analyses, we constructed the time-resolved X-ray diffraction system utilizing ultrashort X-rays from laser-produced plasma generated by the 12-TW-50-fs laser at the Nuclear Engineering Research Laboratory. Ultrafast transient changes in laser-irradiated GaAs crystals were observed as X-ray diffraction patterns. Experimental results were compared with numerical analyses.

MULTI-BEAM COMPTON SCATTERING MONOCHROMATIC TUNABLE HARD X-RAY SOURCE

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo (UTNS). Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV electron beam and 2.5 J/10 nsec Nd:YAG laser. In order to increase the efficiency of the X-ray yield, we adopt a laser pulse circulation system. In our case, the laser pulse circulation system can increase the X-ray intensity of up to 50 times. Main features of our scheme are to produce monochromatic tunable hard (10-40 keV) X-rays with the intensities of 108-109 photons/sec. In addition, X-ray energy can be changed with rapidly by 40 ms by introducing two different wavelength lasers (YAG fundamental (1064 nm), 2nd harmonic (532 nm)) and optical switch. This quick energy change is indispensable to living specimens and very difficult by a large SR light source and others. We designed a laser pulse circulation system to increase the X-ray yield 10 times higher (up to 108 photons/RF pulse, 109 photons/sec). It can be proved that the laser total increases 10 times higher by principle experiment with lower energy laser (25 mJ/pulse). Dual-energy X-ray CT and subtraction X-ray CT are available to determine 3D distribution of atomicc number density and electron density, and specified atomic distribution, respectively. Here, the construction status of the X-band beam line and the application plan of the hard X-ray will be reported.

MEDICAL APPLICATION OF MULTI-BEAM COMPTON SCATTERING MONOCHROMATIC TUNABLE HARD X-RAY SOURCE

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo. Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV electron beam and 2.5 J/10 nsec Nd:YAG laser. In order to increase the efficiency of the X-ray yield, we adopt a laser pulse circulation system. In our case, the laser pulse circulation system can increase the X-ray intensity of up to 10 times. Main features of our scheme are to produce monochromatic tunable hard (10-40 keV) X-rays with the intensities of 108-109 photons/sec. In addition, X-ray energy can be changed with rapidly by 40 ms by introducing two different wavelength lasers (YAG fundamental (1064 nm), 2nd harmonic (532 nm)) and optical switch. This quick energy change is indispensable to living specimens and very difficult by a large SR light source and others. Dual-energy X-ray CT and subtraction X-ray CT are available to determine 3D distribution of atomic number density and electron density, and specified atomic distribution, respectively. Here, the construction status of the X-band beam line and the application plan of the hard X-ray are described and discussed.

X-Band Linac Beam-Line for Medical Compton Scattering X-Ray Source

Compton scattering hard X-ray source for 10-40 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineer ing Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U. Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-40 keV) X-rays with the intensities of 108-109photons/s (at several stages) and the table-top size. In addition, dual energy monochromatic X-ray source can be realized that generate two monochromatic hard X-ray by turin with high (up to 10 pps) repetition rate by one X-ray source. The X-ray yield by the electron beam and Q-switch Nd: YAG laser of 2.5 J/10 ns is 107photons/RF-pulse (108photons/sec in 10 pps). X-band beam line for the demonstration is under commissioning. We also design to adopt a technique of laser circulation to increase the X-ray yield up to 108photons/pulse (109photons/s).

Low Emittance X-band Thermionic Cathode RF Gun for Medical Application

Abstract Beam loadings in the X-band linac for a compact inverse Compton scattering hard X-ray source is estimated. In the RF gun, 0.14MV beam loading voltage was induced, and in a travelling wave accelerating structure the bunches at the head of the beam gain 2.9MV higher energy than followings. Higher energy part should be compensated since it can be a strong noise source. PACS codes: 29.27.Bd

X-band RF gun and linac for medical Compton scattering X-ray source

Compton scattering hard X‐ray source for 10–80 keV are under construction using the X‐band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X‐ray source. Main advantage is to produce tunable monochromatic hard (10–80 keV) X‐rays with the intensities of 108–1010 photons/s (at several stages) and the table‐top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X‐band (11.424 GHz) traveling‐wave‐type linac for the purpose. Numerica...