The development of high pulse energy and high repetition rate lasers based on Yb:YAG ceramics is expected to achieve high average power in areas not previously achieved by high energy diode pumped solid state lasers (DPSSL). Such lasers are of interest for advanced materials processing, surface treatments such as laser peening, and pumping ultra-intense lasers for compact radiation and particle sources. The choices of gain media, amplifier geometry, thermal management, and extraction architecture are important aspects for development of a scalable high repetition rate and high energy laser system. We are aiming to develop a pulse energy of 100 J, repetition rate of 100 Hz using conductive-cooled Yb:YAG active-mirror amplifier with a liquid-nitrogen cooling. We report on the status of the development our laser.
We report remote detection of oil using a flash Raman lidar system. The utilization of an expanding laser beam and an intensified CCD camera enabled the wide field-of-view observation, capturing the whole scene simultaneously. The second harmonic of a standard Q-switched Nd:YAG laser (532 nm) provided the illumination of the water and oil samples separately prepared under atmospheric conditions. We demonstrated the possibility of remote flash Raman lidar measurements using the interference filters at the water (649 nm) and oil (623 nm) Raman wavelengths.
Fast neutrons, which are neutrons with energies greater than 1 MeV, are expected to be a source of nondestructive inspection for a large-size infrastructure such as a bridge girder because of their mean free path exceeding the meter. A neutron-imaging device with 10-ns time resolution can discriminate pulsed neutrons from X-rays via time of flight. For this purpose, we require a fast-response neutron imager with large aperture and high image resolution. A neutron-imaging device with time resolution of 10 ns and aperture size of 40 cm × 60 cm was developed. It was filled with fast response liquid scintillator [1] in an aluminum honeycomb plate, which converts neutrons to optical light images. The scintillation light images were relayed using an optical lens and detected using a fast response image intensified CCD. The detector was tested at an electron linear accelerator (LINAC) facility in Osaka University. A short X-ray pulse (30 ps pulse duration) was generated using LINAC, and X-ray radiograph images were obtained with a 10- ns exposure time duration. The radiograph images were well attenuated within 10-ns from the X-ray injection. A high energy X-ray image and a neutron radiograph image of a 30-cm thick concrete block with iron blocks located behind it were successfully observed. This promising technique could facilitate nondestructive inspection of large concrete constructions.
We demonstrate a new ion diagnosis method for high energy ions by utilizing a combination of a single CR-39 detector and plastic plates, which enables to detect high energy ions beyond the detection threshold limit of the CR-39. This detection method coupled with a magnetic spectrometer is applied to identify high energy ions of 50 MeV per nucleon in laser-driven ion acceleration experiments using cluster-gas targets.
Human cancer cells are irradiated by laser-driven quasi-monoenergetic protons. Laser pulse intensities at the
5×1019-W/cm2 level provide the source and acceleration field for protons that are subsequently transported by
four energy-selective dipole magnets. The transport line delivers 2.25 MeV protons with an energy spread of 0.66
MeV and a bunch duration of 20 ns. The survival fraction of in-vitro cells from a human salivary gland tumor
is measured with a colony formation assay following proton irradiation at dose levels up to 8 Gy, for which the
single bunch does rate is 1 × 107 Gy/s and the effective dose rate is 0.2 Gy/s for 1-Hz repetition of irradiation.
Relative biological effectiveness at the 10% survival fraction is measured to be 1.20 ± 0.11 using protons with a
linear energy transfer of 17.1 ± 2.8 keV/μm.
M. Nishiuchi, K. Ogura, A. Pirozhkov, T. Tanimoto, A. Yogo, H. Sakaki, T. Hori, Y. Fukuda, M. Kanasaki, A. Sagisaka, M. Tampo, H. Kiriyama, T. Shimomura, K. Kondo, S. Kawanishi, C. Brenner, D. Neely
KEYWORDS: Aluminum, Laser systems engineering, Skin, Laser therapeutics, Electrons, Ions, Medical laser equipment, Laser applications, Particles, Current controlled current source
This paper presents the experimental investigation of laser-driven proton acceleration using a table top Ti:Sapphire laser system interacting with the thin-foil targets during the course of medical
application of the laser-driven proton beam.
The proton beam with maximum energy of upto 14~MeV is generated in 60 TW mode.
The number of protons at ~10 MeV is estimated to be over 105 proton/sr/MeV/shot with
beam having half divergence angle of 5~degree.
If 10 Hz operation is assumed 2 Gy dose is possible to irradiate during 10 min onto a ~1 mm tumor just under the skin.
In contrast to the previous condition of our apparatus with which we
demonstrated the DNA double-strand breaking by irradiating the laser-driven proton beam onto the
human cancer cells in-vitro test,
the result reported here has significant meaning in the sense that
pre-clinical in-vivo test can be started by irradiating the laser-driven proton beam
onto the skin of the mouse, which is unavoidable step before the real radiation therapy.
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