Eisuke Minehara

Proposal of Nondestructive Radionuclide Assay Using a High-Flux Gamma-Ray Source and Nuclear Resonance Fluorescence

A nondestructive assay system for radioactive waste management is proposed. The system utilizes nuclear resonance fluorescence triggered by a quasi-monochromatic high-flux gamma ray generated from the Compton scattering of laser photons by relativistic electrons. We employ an energy-recovery linac as an electron source and a mode-locked fiber laser followed by a laser supercavity as a photon source. The combination of these novel technologies realizes a gamma-ray flux much higher than existing sources using electron storage rings. The proposed gamma-ray source produces a quasi-monochromatic gamma ray with a flux of 1010/s/keV, which is high enough for industrial applications such as the nondestructive analysis of radionuclides in nuclear waste and the interrogation of fissile material in cargoes. The nuclear resonance fluorescence triggered by quasi-monochromatic gamma rays provides a versatile method of nondestructive analysis of both radioactive and stable nuclides.

Nondestructive Detection of Heavily Shielded Materials by Using Nuclear Resonance Fluorescence with a Laser-Compton Scattering γ-ray Source

We perform a proof-of-principle experiment for a nondestructive method for detecting the elemental and isotopic composition of materials concealed by heavy shields such as iron plates with a thickness of several centimeters. This method uses nuclear resonance fluorescence (NRF) triggered by an energy-tunable laser-Compton scattering (LCS) γ-ray source. One-dimensional mapping of a lead block hidden behind 1.5-cm-thick iron plates is obtained by measuring an NRF γ-ray of a lead isotope 208Pb. We observe a 5512-keV γ-ray from 208Pb excited by the quasi-monochromatic LCS γ-rays with energies up to 5.7 MeV. The edge position of the lead block is consistent with the exact position within the uncertainty.

mubeam system for study of single event upset of semiconductor devices

Abstract A high energy heavy ion mubeam system has just been installed on a beam line of the 3 MV tandem electrostatic accelerator mainly for analysis of single event upset (SEU) of LSI memories in spacecraft. This system was designed for precise beam positioning at a desired muscopic area of the mucircuit, to experimentally evaluate of actual SEU sensitive area, and also to allow single ion hits for observing a transient charge pulse from an SEU. For these purposes, a fair amount of target beam current is required for beam positioning at the desired area. The system is equipped with two lens systems: one to control the target beam current in a wide range down to an extremely low current without any change of the beam optics, and the other to focus heavy ion beams within a spot size of 1 μm. The final goal is to hit a muscopic target area with a single 15 MeV nickel ion.

First demonstration of energy-recovery operation in the JAERI superconducting linac for a high-power free-electron laser

An energy-recovery linac (ERL) for a high-power free-electron laser (FEL) has been designed and constructed at Japan Atomic Energy Research Institute (JAERI). The construction of the ERL was completed and first energy-recovery operation and first FEL lasing have been demonstrated. We present the design overview and the performance of the JAERI-ERL. Future plans towards a 10-kW FEL are also described.

Highly efficient and high-power industrial FELs driven by a compact, stand-alone and zero-boil-off superconducting RF linac

Abstract In order to realize a tunable, highly efficient, high average power, high peak power and ultra-short pulse free-electron laser (FEL) as a Supertool (Laser, Supertool of the 1980s, Ticker & Fields, New Heaven, CT, 1982) of the 21st century, for all, the JAERI FEL group and I have developed an industrial FEL driven by a compact, stand-alone and zero-boil-off superconducting RF linac (Nucl. Instr. and Meth. 445 (2000)183) with an energy-recovery geometry as a conceptual design. Our discussions on the Supertool will cover market requirements for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil-off cryostat concept, non-stop cooling, and operational experience over these 9 years, and our discovery of the new, highly efficient, high-power, and ultra-short pulse lasing mode (Phys. Rev. Lett. 86 (2001) 5707), and the energy-recovery geometry.

Nondestructive detection of hidden chemical compounds with laser Compton-scattering gamma rays

A nondestructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton-scattering (LCS) gamma-ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C(3)H(6)N(6), shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF gamma-rays of (12)C and (14)N of the melamine are measured by using the LCS gamma-rays of the energies of up to 5.0 MeV. The observed ratio ((12)C/(14)N)(exp)=0.39+/-0.12 is consistent with (C/N)(melamine)=0.5.

Status of the JAERI FEL - beam test for injection system

Abstract The injection system of the JAERI superconducting linac for far infrared FEL oscillation was installed and commissioned. The characteristics of the electron beam measured, so far, are as follows: an electron beam of 100 mA with 4 ns bunch length was extracted from the gun at the accelerating voltage of 180–220 kV. The beam was compressed tentatively to less than 70 ps at the end of the transport line by preliminary operation of both the sub-harmonic buncher and the buncher.

High extraction efficiency observed at the JAERI free-electron laser

Abstract A high power Free-Electron Laser (FEL) has lased at a wavelength of 22 μm at the Japan Atomic Energy Research Institute (JAERI). The maximum power on a macro-pulse average is 1.7 kW , and it corresponds to an FEL energy of 160 μJ / micro -pulse. Extraction efficiency from the electron beam to the FEL radiation was measured to be 5.3% by an energy analyzer, when the maximum FEL power was coupled out. The rms wavelength spread was measured to be 4.6% at the same time. The extraction efficiency, in general, has a maximum value near the zero detuning length of an optical cavity, where (in contrast) the single-pass gain becomes smallest. A high peak current and a long macro-pulse duration are therefore indispensable for realizing high efficiency. The electron beam energy is 16.5 MeV , and the average current is 5.3 mA at a micro-pulse repetition rate of 10.4 MHz . The macro-pulse duration is 500 μs (5000 micro-pulses), long enough to reach saturation near the zero detuning length. The width and the peak current of the electron bunch are 5 ps FWHM and 100 A , respectively, at the undulator.

Ion microprobe system combined with scanning electron microscope for high precision aiming

Abstract An ion microprobe system with high precision for target alignment has been realized by combining a compact scanning electron microscope (SEM) column with a target chamber. The target alignment is done first by imaging sample features with a scanning electron microscope (SEM) and then fine alignment of the sample position with respect to the incident ion beam is accomplished by comparing the secondary electron images of a Si test sample produced by the SEM beam and the ion microbeam. A Si test sample, with a specially designed relief pattern, has been used for both measuring the beam size and for determining the exact incident site of the ion beam on the target. Precision of aiming at present is about 5 μm which is limited mainly by the mechanical precision of the SEM sample holder. A beam spot size of 1.9 × 1.7 μm (FWHM) for 3 MeV He + beam has been achieved. Use of a high precision sample manipulator affords the prospect of an ion alignment precision of about 2 μm.

Design of energy-recovery transport for the JAERI FEL driven by a superconducting linac

Abstract A high-average power free-electron laser driven by a superconducting linac has been developed in Japan Atomic Energy Research Institute (JAERI), and stable laser output over 0.1 kW in infrared region is now available. For further increasing of FEL output power, installing energy-recovery transport has been planned. The lattice design for the energy-recovery transport is discussed in the present paper. It is found that a recirculation transport, which fulfills the requirements for energy acceptance and isochronicity, can be realized by adding another triple-bend arc to the existing beam line.