31 results on '"Morace, A."'
Search Results
2. Optimization of laser-driven quantum beam generation and the applications with artificial intelligence.
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Kuramitsu, Y., Taguchi, T., Nikaido, F., Minami, T., Hihara, T., Suzuki, S., Oda, K., Kuramoto, K., Yasui, T., Abe, Y., Ibano, K., Takabe, H., Chu, C. M., Wu, K. T., Woon, W. Y., Chen, S. H., Jao, C. S., Chen, Y. C., Liu, Y. L., and Morace, A.
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ARTIFICIAL intelligence ,ION beams ,NUCLEAR track detectors ,LASER pulses ,LASER plasmas ,PLASMA turbulence ,CONVOLUTIONAL neural networks - Abstract
We have investigated space and astrophysical phenomena in nonrelativistic laboratory plasmas with long high-power lasers, such as collisionless shocks and magnetic reconnections, and have been exploring relativistic regimes with intense short pulse lasers, such as energetic ion acceleration using large-area suspended graphene. Increasing the intensity and repetition rate of the intense lasers, we have to handle large amounts of data from the experiments as well as the control parameters of laser beamlines. Artificial intelligence (AI) such as machine learning and neural networks may play essential roles in optimizing the laser and target conditions for efficient laser ion acceleration. Implementing AI into the laser system in mind, as the first step, we are introducing machine learning in ion etch pit analyses detected on plastic nuclear track detectors. Convolutional neural networks allow us to analyze big ion etch pit data with high precision and recall. We introduce one of the applications of laser-driven ion beams using AI to reconstruct vector electric and magnetic fields in laser-produced turbulent plasmas in three dimensions. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Guided electromagnetic discharge pulses driven by short intense laser pulses: Characterization and modeling.
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Ehret, M., Bailly-Grandvaux, M., Korneev, Ph., Apiñaniz, J. I., Brabetz, C., Morace, A., Bradford, P., d'Humières, E., Schaumann, G., Bagnoud, V., Malko, S., Matveevskii, K., Roth, M., Volpe, L., Woolsey, N. C., and Santos, J. J.
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ELECTROMAGNETIC pulses ,LASER pulses ,PROTONS - Abstract
Strong electromagnetic pulses (EMPs) are generated from intense laser interactions with solid-density targets and can be guided by the target geometry, specifically through conductive connections to the ground. We present an experimental characterization by time- and spatial-resolved proton deflectometry of guided electromagnetic discharge pulses along wires including a coil, driven by 0.5 ps, 50 J, 10
19 W/cm2 laser pulses. Proton-deflectometry allows us to time-resolve first the EMP due to the laser-driven target charging and then the return EMP from the ground through the conductive target stalk. Both EMPs have a typical duration of tens of ps and correspond to currents in the kA-range with electric-field amplitudes of multiple GV/m. The sub-mm coil in the target rod creates lensing effects on probing protons due to both magnetic- and electric-field contributions. This way, protons of the 10 MeV-energy range are focused over cm-scale distances. Experimental results are supported by analytical modeling and high-resolution numerical particle-in-cell simulations, unraveling the likely presence of a surface plasma, in which parameters define the discharge pulse dispersion in the non-linear propagation regime. [ABSTRACT FROM AUTHOR]- Published
- 2023
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4. Predictive capability of material screening by fast neutron activation analysis using laser-driven neutron sources.
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Abe, Y., Nakao, A., Arikawa, Y., Morace, A., Mori, T., Lan, Z., Wei, T., Asano, S., Minami, T., Kuramitsu, Y., Habara, H., Shiraga, H., Fujioka, S., Nakai, M., and Yogo, A.
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NUCLEAR activation analysis ,FAST neutrons ,NEUTRON sources ,NUCLEAR excitation ,NEUTRON irradiation - Abstract
Bright, short-pulsed neutron beams from laser-driven neutron sources (LANSs) provide a new perspective on material screening via fast neutron activation analysis (FNAA). FNAA is a nondestructive technique for determining material elemental composition based on nuclear excitation by fast neutron bombardment and subsequent spectral analysis of prompt γ-rays emitted by the active nuclei. Our recent experiments and simulations have shown that activation analysis can be used in practice with modest neutron fluences on the order of 10
5 n/cm2 , which is available with current laser technology. In addition, time-resolved γ-ray measurements combined with picosecond neutron probes from LANSs are effective in mitigating the issue of spectral interference between elements, enabling highly accurate screening of complex samples containing many elements. This paper describes the predictive capability of LANS-based activation analysis based on experimental demonstrations and spectral calculations with Monte Carlo simulations. [ABSTRACT FROM AUTHOR]- Published
- 2022
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5. Dosimetric calibration of GafChromic HD-V2, MD-V3, and EBT3 films for dose ranges up to 100 kGy.
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Abe, Y., Morace, A., Arikawa, Y., Mirfayzi, S. R., Golovin, D., Law, K. F. F., Fujioka, S., Yogo, A., and Nakai, M.
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NUCLEAR research , *CALIBRATION , *ABSORBED dose , *OPACITY (Optics) - Abstract
A dosimetric calibration of three types of radiochromic films (GafChromicTM HD-V2, MD-V3, and EBT3) was carried out for absorbed doses (D) ranging up to 100 kGy using a 130 TBq C o 60 γ-ray source. The optical densities (ODs) of the irradiated films were acquired with the transmission-mode flatbed film scanner EPSON GT-X980. The calibration data were cross-checked using the 20-MeV proton beam from the azimuthally varying field cyclotron at the Research Center for Nuclear Physics in Osaka University. These experimental results not only present the measurable dose ranges of the films depending on the readout wavelength, but also show consistency with our hypothesis that the OD response curve [log(OD)–log(D) curve] is determined by the volumetric average of the absorption dose and does not strongly depend on the type of radiation for the excitation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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6. The conceptual design of 1-ps time resolution neutron detector for fusion reaction history measurement at OMEGA and the National Ignition Facility.
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Arikawa, Yasunobu, Ota, Masato, Nakajima, Makoto, Shimizu, Tomoki, Segawa, Sadashi, Khoa Phan, Thanh Nhat, Sakawa, Youichi, Abe, Yuki, Morace, Alessio, Mirfayzi, Seyed Reza, Yogo, Akifumi, Fujioka, Shinsuke, Nakai, Mitsuo, Shiraga, Hiroyuki, Azechi, Hiroshi, Kodama, Ryosuke, Kan, Koichi, Frenje, Johan, Gatu Johnson, Maria, and Bose, Arijit
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INERTIAL confinement fusion ,NUCLEAR fusion ,NEUTRON counters ,CONCEPTUAL design ,SOLID-state lasers ,IMPULSE response - Abstract
The nuclear burn history provides critical information about the dynamics of the hot-spot formation and high-density fuel-shell assembly of an Inertial Confinement Fusion (ICF) implosion, as well as information on the impact of alpha heating, and a multitude of implosion failure mechanisms. Having this information is critical for assessing the energy-confinement time τE and performance of an implosion. As the confinement time of an ICF implosion is a few tens of picoseconds, less than 10-ps time resolution is required for an accurate measurement of the nuclear burn history. In this study, we propose a novel 1-ps time-resolution detection scheme based on the Pockels effect. In particular, a conceptual design for the experiment on the National Ignition Facility and OMEGA are elaborated upon herein. A small organic Pockels crystal "DAST" is designed to be positioned ∼5 mm from the ICF implosion, which is scanned by a chirped pulse generated by a femto-second laser transmitted through a polarization-maintained optical fiber. The originally linearly polarized laser is changed to an elliptically polarized laser by the Pockels crystal when exposed to neutrons, and the modulation of the polarization will be analyzed. Our study using 35-MeV electrons showed that the system impulse response is 0.6 ps. The response time is orders of magnitude shorter than current systems. Through measurements of the nuclear burn history with unprecedented time resolution, this system will help for a better understanding of the dynamics of the hot-spot formation, high-density fuel-shell assembly, and the physics of thermonuclear burn wave propagation. [ABSTRACT FROM AUTHOR]
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- 2020
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7. Laser-driven strong magnetostatic fields with applications to charged beam transport and magnetized high energy-density physics.
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Santos, J. J., Bailly-Grandvaux, M., Ehret, M., Arefiev, A. V., Batani, D., Beg, F. N., Calisti, A., Ferri, S., Florido, R., Forestier-Colleoni, P., Fujioka, S., Gigosos, M. A., Giuffrida, L., Gremillet, L., Honrubia, J. J., Kojima, S., Korneev, Ph., Law, K. F. F., Marquès, J.-R., and Morace, A.
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MAGNETIC fields ,MAGNETIZATION ,ENERGY density ,GLOW discharges ,LASER beams ,NUCLEAR fusion - Abstract
Powerful nanosecond laser-plasma processes are explored to generate discharge currents of a few 100 kA in coil targets, yielding magnetostatic fields (B-fields) in excess of 0.5 kT. The quasi-static currents are provided from hot electron ejection from the laser-irradiated surface. According to our model, which describes the evolution of the discharge current, the major control parameter is the laser irradiance I las λ las 2 . The space-time evolution of the B-fields is experimentally characterized by high-frequency bandwidth B-dot probes and proton-deflectometry measurements. The magnetic pulses, of ns-scale, are long enough to magnetize secondary targets through resistive diffusion. We applied it in experiments of laser-generated relativistic electron transport through solid dielectric targets, yielding an unprecedented 5-fold enhancement of the energy-density flux at 60
μ m depth, compared to unmagnetized transport conditions. These studies pave the ground for magnetized high-energy density physics investigations, related to laser-generated secondary sources of radiation and/or high-energy particles and their transport, to high-gain fusion energy schemes, and to laboratory astrophysics. [ABSTRACT FROM AUTHOR]- Published
- 2018
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8. Production of intense, pulsed, and point-like neutron source from deuterated plastic cavity by mono-directional kilo-joule laser irradiation.
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Abe, Y., Sunahara, A., Lee, S., Yanagawa, T., Zhang, Z., Arikawa, Y., Morace, A., Nagai, T., Ikenouchi, T., Tosaki, S., Kojima, S., Sakata, S., Satoh, N., Watari, T., Nishihara, K., Kawashima, T., Yogo, A., Sakagami, H., Shiraga, H., and Nishimura, H.
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NEUTRON sources ,LASER beams ,LASER ablation ,NEUTRON flux ,NUCLEAR fusion ,NEUTRON radiography - Abstract
This paper reports an experimental investigation of a scheme to produce an intense, pulsed, pointlike, and quasi-monoenergy neutron source. In this scheme, the inner wall of a deuterated plastic spherical cavity is mono-directionally irradiated by a 2.4 kJ laser beam through an open-tip gold cone inserted into the cavity. The whole inner wall of the cavity is illuminated by laser light owing to multiple laser reflections, and the laser-ablated plasma stagnates near the center of the cavity, at which a several keV hot spot is generated. Thermonuclear and beam D-D fusion reactions occur in the hot spot. We have demonstrated the neutron yield exceeding 107 neutrons per pulse from a<100 μm diameter hot spot with the deuterated plastic cavity and mono-directional GEKKO-XII laser irradiation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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9. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field.
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Shinsuke Fujioka, Yasunobu Arikawa, Sadaoki Kojima, Tomoyuki Johzaki, Hideo Nagatomo, Hiroshi Sawada, Seung Ho Lee, Takashi Shiroto, Naofumi Ohnishi, Alessio Morace, Xavier Vaisseau, Shohei Sakata, Yuki Abe, Kazuki Matsuo, King Fai Farley Law, Shota Tosaki, Akifumi Yogo, Keisuke Shigemori, Yoichiro Hironaka, and Zhe Zhang
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LARMOR radius ,PINCH effect (Physics) ,MAGNETIC fields ,ELECTROMAGNETISM ,ELECTROMAGNETIC theory - Abstract
A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKOXII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >10
9 . Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding plasma. Following the above improvements, conversion of 13% of the LFEX laser energy to a low energy portion of the REB, whose slope temperature is 0.7 MeV, which is close to the ponderomotive scaling value, was achieved. To meet the second requirement, the compression of a solid spherical ball with a diameter of 200-μm to form a dense core with an areal density of ~0.07 g/cm2 was induced by a laser-driven spherically converging shock wave. Converging shock compression is more hydrodynamically stable compared to shell implosion, while a hot spot cannot be generated with a solid ball target. Solid ball compression is preferable also for compressing an external magnetic field to collimate the REB to the fuel core, due to the relatively small magnetic Reynolds number of the shock compressed region. To meet the third requirement, we have generated a strong kilo-tesla magnetic field using a laser-driven capacitor- coil target. The strength and time history of the magnetic field were characterized with proton deflectometry and a B-dot probe. Guidance of the REB using a 0.6-kT field in a planar geometry has been demonstrated at the LULI 2000 laser facility. In a realistic FI scenario, a magnetic mirror is formed between the REB generation point and the fuel core. The effects of the strong magnetic field on not only REB transport but also plasma compression were studied using numerical simulations. According to the transport calculations, the heating efficiency can be improved from 0.4% to 4% by the GEKKO and LFEX laser system by meeting the three requirements described above. This efficiency is scalable to 10% of the heating efficiency by increasing the areal density of the fuel core. [ABSTRACT FROM AUTHOR]- Published
- 2016
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10. Direct measurement of kilo-tesla level magnetic field generated with laser-driven capacitor-coil target by proton deflectometry.
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Law, K. F. F., Bailly-Grandvaux, M., Morace, A., Sakata, S., Matsuo, K., Kojima, S., Lee, S., Vaisseau, X., Arikawa, Y., Yogo, A., Kondo, K., Zhang, Z., Bellei, C., Santos, J. J., Fujioka, S., and Azechi, H.
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PLASMA jets ,CAPACITOR testing ,ASTROPHYSICAL jets ,LORENTZ force ,MAGNETIC field measurements ,PROTON beams - Abstract
A kilo-tesla level, quasi-static magnetic field (B-field), which is generated with an intense laser-driven capacitor-coil target, was measured by proton deflectometry with a proper plasma shielding. Proton deflectometry is a direct and reliable method to diagnose strong, mm³-scale laser-produced B-field; however, this was not successful in the previous experiment. A target-normal-sheath-accelerated proton beam is deflected by Lorentz force in the laser-produced magnetic field with the resulting deflection pattern recorded on a radiochromic film stack. A 610630 T of B-field amplitude was inferred by comparing the experimental proton pattern with Monte-Carlo calculations. The amplitude and temporal evolutions of the laser-generated B-field were also measured by a differential magnetic probe, independently confirming the proton deflectometry measurement results. [ABSTRACT FROM AUTHOR]
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- 2016
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11. Monte-Carlo simulation of noise in hard X-ray Transmission Crystal Spectrometers: Identification of contributors to the background noise and shielding optimization.
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Thfoin, I., Reverdin, C., Hulin, S., Szabo, C. I., Bastiani-Ceccotti, S., Batani, D., Brambrink, E., Koenig, M., Duval, A., Leboeuf, X., Lecherbourg, L., Rossé, B., Morace, A., Santos, J. J., Vaisseau, X., Fourment, C., Giuffrida, L., and Nakatsutsumi, M.
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SPECTROMETERS ,MONTE Carlo method ,CRYSTAL structure research ,PLASMA diagnostics ,SPECTRUM analysis - Abstract
Transmission crystal spectrometers (TCS) are used on many laser facilities to record hard X-ray spectra. During experiments, signal recorded on imaging plates is often degraded by a background noise. Monte-Carlo simulations made with the code GEANT4 show that this background noise is mainly generated by diffusion of MeV electrons and very hard X-rays. An experiment, carried out at LULI2000, confirmed that the use of magnets in front of the diagnostic, that bent the electron trajectories, reduces significantly this background. The new spectrometer SPECTIX (Spectromètre PETAL à Cristal en TransmIssion X), built for the LMJ/PETAL facility, will include this optimized shielding. [ABSTRACT FROM AUTHOR]
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- 2014
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12. Development of x-ray radiography for high energy density physics.
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Morace, A., Fedeli, L., Batani, D., Baton, S., Beg, F. N., Hulin, S., Jarrott, L. C., Margarit, A., Nakai, M., Nakatsutsumi, M., Nicolai, P., Piovella, N., Wei, M. S., Vaisseau, X., Volpe, L., and Santos, J. J.
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X-rays , *RADIOGRAPHY , *MECHANICAL shock , *CARBON , *ENERGY density of fuel , *IGNITION temperature , *FLUID velocity measurements - Abstract
We describe an experiment performed at the LULI laser facility using an advanced radiographic technique that allowed obtaining 2D, spatially resolved images of a shocked buried-code-target. The technique is suitable for applications on Fast Ignition as well as Warm Dense Matter research. In our experiment, it allowed to show cone survival up to Mbar pressures and to measure the shock front velocity and the fluid velocity associated to the laser-generated shock. This allowed obtaining one point on the shock polar of porous carbon. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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13. Study of target heating induced by fast electrons in mass limited targets.
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Alessio, Morace, Alexander, Magunov, Dimitri, Batani, Renato, Redaelli, Claude, Fourment, Jorge, Santos Joao, Gerard, Malka, Alain, Boscheron, Alexis, Casner, Wigen, Nazarov, Tommaso, Vinci, Yasuaki, Okano, Yuichi, Inubushi, Hiroaki, Nishimura, Alessandro, Flacco, Chris, Spindloe, and Martin, Tolley
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PLASMA heating , *WAVELENGTHS , *X-rays , *RADIATION , *LASERS - Abstract
We studied the induced plasma heating in three different kind of targets: mass limited, foam targets and large mass targets. The experiment was performed at Alisé laser facility of CEA/CESTA. The laser system emitted a ∼1-ps pulse with ∼10 J energy at a wavelength of ∼1 μm. Mass limited targets had three layers with thickness 10 μm C8H8, 1 μm C8H7Cl, 10 μm C8H8 with size 100 μm×100 μm. Detailed spectroscopic analysis of X-rays emitted from the Cl tracer showed that it was possible to heat up the plasma mass limited targets to a temperature ∼250 eV with density ∼1021 cm-3. The plasma heating is only produced by fast electron transport in the target, being the 10 μm C8H8 overcoating thick enough to prevent any possible direct irradiation of the tracer layer even taking into account mass-ablation due to the pre-pulse. These results demonstrate that with mass limited targets is possible to generate a plasma heated up to several hundreds eV. It is also very important for research concerning high energy density phenomena and for fast ignition (in particular for the study of fast electrons transport and induced heating). [ABSTRACT FROM AUTHOR]
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- 2010
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14. Polarized Heα Radiation by Anisotropic Fast Electron Transport in Ultra-Intense Laser Produced Plasmas.
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Kawamura, T., Kai, T., Koike, F., Nakazaki, S., Nishimura, H., Inubushi, Y., Okano, Y., Nagatomo, H., Batani, D., Morace, A., Redaelli, R., Fourment, C., Santos, J., Malka, G., Boscheron, A., Casner, A., Koenig, M., Fujioka, S., Nakamura, T., and Johzaki, T.
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ELECTRON transport ,ANISOTROPY ,PROPERTIES of matter ,PLASMA gases ,X-ray spectroscopy ,POLARIZATION spectroscopy ,SPECTRUM analysis - Abstract
In fast ignition research, the transport dynamics of fast electrons is one of the critical issues. Fast electrons generated by an intense laser pulse show a highly anisotropic velocity distribution. To gain insight into the anisotropy of the velocity distribution of fast electrons, polarized x-ray spectroscopy has been proposed. The polarization spectroscopy of Cl He
α radiation was experimentally demonstrated at 1017 W/cm2 (∼100 mJ in 130 fs), and a new time-dependent atomic population kinetics code was also developed. It predicts that the high polarization arises only in a low-density region of the target plasma. Additional x-ray polarization measurements were done at 1017 17–18 W/cm2 (∼10 J in ∼1 ps). Polarization was measured as a function of the overcoat thickness of a target. The polarization is negative in the shallow region near the target surface, and becomes near zero at the laser intensity of ∼1018 W/cm2 . At ∼1017 W/cm2 , the polarization varies from negative to positive, and finally zero along with an increase in the overcoat thickness. [ABSTRACT FROM AUTHOR]- Published
- 2009
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15. X-ray polarization spectroscopy to study energy transport in ultra-high intensity laser produced plasmas.
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Nishimura, H., Inubushi, Y., Okano, Y., Fujioka, S., Kai, T., Kawamura, T., Batani, D., Morace, A., Redaelli, R., Fourment, C., Santos, J., Malka, G., Boscheron, A., Casner, A., Koenig, M., Nakamura, T., Johzaki, T., Nagatomo, H., and Mima, K.
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X-ray polarization ,PLASMA gases ,CATHODE rays ,LASER beams ,ELECTRONS - Abstract
X-ray polarization spectroscopy was studied to derive directly the velocity distribution function (VDF) of hot electrons propagating in plasma created with a high intensity laser pulse. Polarization measurement was made at around 10
18 W/cm2 using a laser pulse (∼10 J in ∼1 ps) from Alisé facility at CEA/CESTA. Chlorinated triple-layer targets were irradiated, and Cl Heα line was observed with an x-ray polarization spectrometer. Polarization degrees were measured as a function of the target overcoat thickness, corresponding to the depth along pre-formed plasma. It is found that the polarization is weakly negative for thin coating, but becomes positive, and finally zero for thick coating. This result is consistent with predictions made with a time-dependent atomic kinetics code developed to gain an insight into the generation of polarized Cl Heα radiation. The de-polarization on the surface is attributed to excessive bulk electron temperature and that in the deep region to elastic-scattering processes by the isotropic bulk electrons in dense region. [ABSTRACT FROM AUTHOR]- Published
- 2009
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16. Investigation of relativistic intensity laser generated hot electron dynamics via copper Kα imaging and proton acceleration.
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Willingale, L., Thomas, A. G. R., Maksimchuk, A, Morace, A., Bartal, T., Kim, J., Stephens, R. B., Wei, M. S., Beg, F. N., and Krushelnick, K.
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RELATIVITY (Physics) ,LASER beams ,HOT carriers ,COPPER ,IMAGING systems ,PROTONS ,PARTICLE acceleration ,ELECTRON beams - Abstract
Simultaneous experimental measurements of copper Kα imaging and the maximum target normal sheath acceleration proton energies from the rear target surface are compared for various target thicknesses. For the T-cubed laser (≈4 J, 400 fs) at an intensity of ≈2 × 1019 W cm-2, the hot electron divergence is determined to be θ
HW HM ≈22° using a Kα imaging diagnostic. The maximum proton energies are measured to follow the expected reduction with increasing target thickness. Numerical modeling produces copper Kα trends for both signal level and electron beam divergence that are in good agreement with the experiment. A geometric model describing the electron beam divergence reproduces the maximum proton energy trends observed from the experiment and the fast electron density and the peak electric field observed in the numerical modeling. [ABSTRACT FROM AUTHOR]- Published
- 2013
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17. Improved laser-to-proton conversion efficiency in isolated reduced mass targets.
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Morace, A., Bellei, C., Bartal, T., Willingale, L., Kim, J., Maksimchuk, A., Krushelnick, K., Wei, M. S., Patel, P. K., Batani, D., Piovella, N., Stephens, R. B., and Beg, F. N.
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LASERS , *PROTONS , *ELECTRONS , *INERTIAL confinement fusion , *PARTICLES - Abstract
We present experimental results of laser-to-proton conversion efficiency as a function of lateral confinement of the refluxing electrons. Experiments were carried out using the T-Cubed laser at the Center for Ultrafast Optical Science, University of Michigan. We demonstrate that the laser-to-proton conversion efficiency increases by 50% with increased confinement of the target from surroundings with respect to a flat target of the same thickness. Three-dimensional hybrid particle-in-cell simulations using LSP code agree with the experimental data. The adopted target design is suitable for high repetition rate operation as well as for Inertial Confinement Fusion applications. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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18. Comparisons of angularly and spectrally resolved Bremsstrahlung measurements to two-dimensional multi-stage simulations of short-pulse laser-plasma interactions.
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Chen, C. D., Kemp, A. J., Pérez, F., Link, A., Beg, F. N., Chawla, S., Key, M. H., McLean, H., Morace, A., Ping, Y., Sorokovikova, A., Stephens, R. B., Streeter, M., Westover, B., and Patel, P. K.
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LASER-plasma interactions ,ANGULAR distribution (Nuclear physics) ,ELECTRON distribution ,SIMULATION methods & models ,BREMSSTRAHLUNG ,COMPARATIVE studies - Abstract
A 2-D multi-stage simulation model incorporating realistic laser conditions and a fully resolved electron distribution handoff has been developed and compared to angularly and spectrally resolved Bremsstrahlung measurements from high-Z planar targets. For near-normal incidence and 0.5-1 × 1020 W/cm2 intensity, particle-in-cell (PIC) simulations predict the existence of a high energy electron component consistently directed away from the laser axis, in contrast with previous expectations for oblique irradiation. Measurements of the angular distribution are consistent with a high energy component when directed along the PIC predicted direction, as opposed to between the target normal and laser axis as previously measured. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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19. Proton radiography of laser-driven imploding target in cylindrical geometry.
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Volpe, L., Batani, D., Vauzour, B., Nicolai, Ph., Santos, J. J., Regan, C., Morace, A., Dorchies, F., Fourment, C., Hulin, S., Perez, F., Baton, S., Lancaster, K., Galimberti, M., Heathcote, R., Tolley, M., Spindloe, Ch., Koester, P., Labate, L., and Gizzi, L. A.
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PROTON beams ,RADIOGRAPHY ,PHYSICS laboratories ,PARTICLE acceleration ,SYMMETRY (Physics) ,NUMERICAL analysis ,SIMULATION methods & models ,PLASMA gases ,MULTIPLE scattering (Physics) - Abstract
An experiment was done at the Rutherford Appleton Laboratory (Vulcan laser petawatt laser) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European high power laser energy research facility project). In the experiment, protons accelerated by a picosecond-laser pulse were used to radiograph a 220 μm diameter cylinder (20 μm wall, filled with low density foam), imploded with ∼200 J of green laser light in four symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Results are also compared to those from hard x-ray radiography. Detailed comparison with two-dimensional numerical hydrosimulations has been done using a Monte Carlo code adapted to describe multiple scattering and plasma effects. Finally we develop a simple analytical model to estimate the performance of proton radiography for given implosion conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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20. Study of plasma heating induced by fast electrons.
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Morace, A., Magunov, A., Batani, D., Redaelli, R., Fourment, C., Santos, J. J., Malka, G., Boscheron, A., Casner, A., Nazarov, W., Vinci, T., Okano, Y., Inubushi, Y., Nishimura, H., Flacco, A., Spindloe, C., and Tolley, M.
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- *
CONTROLLED fusion , *PLASMA heating , *PARTICLES (Nuclear physics) , *ELECTRON transport , *NUCLEAR physics - Abstract
We studied the induced plasma heating in three different kinds of targets: mass limited, foam targets, and large mass targets. The experiment was performed at Alisé Laser Facility of CEA/CESTA. The laser system emitted a ∼1 ps pulse with ∼10 J energy at a wavelength of ∼1 μm. Mass limited targets had three layers with thicknesses of 10 μm C8H8, 1 μm C8H7Cl, and 10 μm C8H8 with size of 100×100 μm2. Detailed spectroscopic analysis of x rays emitted from the Cl tracer showed that it was possible to heat up the plasma from mass limited targets to a temperature of ∼250 eV with density of ∼1021 cm-3. The plasma heating is only produced by fast electron transport in the target, being the 10 μm C8H8 overcoating thick enough to prevent any possible direct irradiation of the tracer layer even taking into account mass-ablation due to the prepulse. These results demonstrate that with mass limited targets, it is possible to generate a plasma heated up to several hundreds eV. It is also very important for research concerning high energy density phenomena and for fast ignition (in particular for the study of fast electrons transport and induced heating). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
21. Temperature profiles derived from transverse optical shadowgraphy in ultraintense laser plasma interactions at 6×1020 W cm-2.
- Author
-
Lancaster, K. L., Pasley, J., Green, J. S., Batani, D., Baton, S., Evans, R. G., Gizzi, L., Heathcote, R., Hernandez Gomez, C., Koenig, M., Koester, P., Morace, A., Musgrave, I., Norreys, P. A., Perez, F., Waugh, J. N., and Woolsey, N. C.
- Subjects
LASER plasmas ,HYDRODYNAMICS ,SHADOWGRAPH photography ,OPTICAL measurements ,ELECTRON distribution - Abstract
A variety of targets with different dimensions and materials was irradiated using the VULCAN PW laser [C. N. Danson et al., Nucl. Fusion 44, S239 (2004)]. Using transverse optical shadowgraphy in conjunction with a one-dimensional radiation hydrodynamics code it was possible to determine a longitudinal temperature gradient. It was demonstrated for thick targets with a low Z substrate and a thin higher Z tracer layer at the rear that the boundary between the two materials was Rayleigh–Taylor unstable. By including a simple bubble growth model into the calculations it was possible to correct for the associated behavior with regard to temperature. The resulting temperature gradient was in good agreement with the previously published data using two different methods of determining the temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
22. Inhibition of fast electron energy deposition due to preplasma filling of cone-attached targets.
- Author
-
Baton, S. D., Koenig, M., Fuchs, J., Benuzzi-Mounaix, A., Guillou, P., Loupias, B., Vinci, T., Gremillet, L., Rousseaux, C., Drouin, M., Lefebvre, E., Dorchies, F., Fourment, C., Santos, J. J., Batani, D., Morace, A., Redaelli, R., Nakatsutsumi, M., Kodama, R., and Nishida, A.
- Subjects
ELECTRONS ,LASER beams ,ELECTRON distribution ,CATHODE rays ,ELECTRON energy loss spectroscopy - Abstract
We present experimental and numerical results on the propagation and energy deposition of laser-generated fast electrons into conical targets. The first part reports on experimental measurements performed in various configurations in order to assess the predicted benefit of conical targets over standard planar ones. For the conditions investigated here, the fast electron-induced heating is found to be much weaker in cone-guided targets irradiated at a laser wavelength of 1.057 μm, whereas frequency doubling of the laser pulse permits us to bridge the disparity between conical and planar targets. This result underscores the prejudicial role of the prepulse-generated plasma, whose confinement is enhanced in conical geometry. The second part is mostly devoted to the particle-in-cell modeling of the laser-cone interaction. In qualitative agreement with the experimental data, the calculations show that the presence of a large preplasma leads to a significant decrease in the fast electron density and energy flux near the target rear side. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
23. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch.
- Author
-
Sadaoki Kojima, Yasunobu Arikawa, Yasuhiko Nishimura, Hiromi Togawa, Zhe Zhang, Takahito Ikenouchi, Tetsuo Ozaki, Alessio Morace, Takahiro Nagai, Yuki Abe, Shouhei Sakata, Hiroaki Inoue, Masaru Utsugi, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Ryukou Kato, Shinsuke Fujioka, and Hiroshi Azechi
- Subjects
X-ray spectrometers ,COMPTON scattering ,SPECTRAL energy distribution ,BREMSSTRAHLUNG ,FUSED silica ,LINEAR accelerators ,PARTICLE interactions ,MONTE Carlo method - Abstract
A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons' energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5MeV for 6.0 MeV electrons. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
24. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV.
- Author
-
Sakata, S., Arikawa, Y., Kojima, S., Ikenouchi, T., Nagai, T., Abe, Y., Inoue, H., Morace, A., Utsugi, M., Kato, R., Nishimura, H., Nakai, M., Shiraga, H., Fujioka, S., and Azechi, H.
- Subjects
X-ray spectrometer design & construction ,PHOTONUCLEAR reactions ,LASER-plasma interactions ,NEUTRONS ,LINEAR accelerators ,MONTE Carlo method ,QUANTUM efficiency - Abstract
A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (N
e = 1.0 x 10-6 C, Ee = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%-70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10-7 , 10-4 , 10-5 , respectively, for 2-10, 11-15, and 15-25 MeV of photon energy ranges. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
25. Propagation of a short-pulse laser-driven electron beam in matter.
- Author
-
Volpe, L., Batani, D., Birindelli, G., Morace, A., Carpeggiani, P., Xu, M. H., Liu, F., Zhang, Y., Zhang, Z., Lin, X. X., Wang, S. J., Zhu, P. F., Meng, L. M., Wang, Z. H., Li, Y. T., Sheng, Z. M., Wei, Z. Y., Zhang, J., Santos, J. J., and Spindloe, C.
- Subjects
CATHODE rays ,ELECTRONS ,ELECTRIC conductivity ,ELECTRON beams ,GEOMETRY - Abstract
We studied the transport of an intense electron beam produced by high intensity laser pulses through metals and insulators. Targets were irradiated at two different intensities, 1017 W/cm2 and 1019 W/cm2, at the laser facility Xtreme Light XL-III in Beijing, a Ti:Sa laser source emitting 40 fs pulses at 800 nm. The main diagnostic was Cu-K
α fluorescence imaging. Images of Kα spots have been collected for those two laser intensities, for different target thickness, and for different materials. Experimental results are analyzed taking into account both collisional and collective effects as well as refluxing at the edge of the target. The target temperature is evaluated to be Tc ∼ 6 eV for intensity I = 1017 W/cm2 (for all the tested materials: plastic, aluminium, and copper), and Tc ∼ 60 eV in aluminium and 120 eV in titanium for intensity I = 1019 W/cm2. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF
26. Collisional and collective effects in two dimensional model for fast-electron transport in refluxing regime.
- Author
-
Volpe, L., Batani, D., Morace, A., and Santos, J. J.
- Subjects
COLLISIONS (Physics) ,ELECTRON transport ,RELATIVITY (Physics) ,PHYSICS experiments ,CURRENT density (Electromagnetism) ,ELECTROMAGNETISM ,PREDICTION models - Abstract
The relativistic laser-driven electron transport in partially or fully ionized matter has been investigated in many recent experiments. The high laser intensity achievable today (up to 10
20 W/cm2 ) allows to generate electron current density above 1011 A/cm2 . In this regime, electromagnetic effects start to be dominant over collisional ones. In this context, we have developed a simple 2D model for the fast electron transport accounting for (1) electric effects on the electron penetration range and (2) the electron refluxing in thin foils. We compare our model with those existing in literature and with some recent experimental results on fast electron transport in matter. The model predicts a maximum value for the electron penetration range in the region where the collisional and the resistive effects are comparable. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF
27. Temperature profiles derived from transverse optical shadowgraphy in ultraintense laser plasma interactions at 6×1020 W cm-2.
- Author
-
Lancaster, K. L., Pasley, J., Green, J. S., Batani, D., Baton, S., Evans, R. G., Gizzi, L., Heathcote, R., Hernandez Gomez, C., Koenig, M., Koester, P., Morace, A., Musgrave, I., Norreys, P. A., Perez, F., Waugh, J. N., and Woolsey, N. C.
- Subjects
- *
LASER plasmas , *HYDRODYNAMICS , *SHADOWGRAPH photography , *OPTICAL measurements , *ELECTRON distribution - Abstract
A variety of targets with different dimensions and materials was irradiated using the VULCAN PW laser [C. N. Danson et al., Nucl. Fusion 44, S239 (2004)]. Using transverse optical shadowgraphy in conjunction with a one-dimensional radiation hydrodynamics code it was possible to determine a longitudinal temperature gradient. It was demonstrated for thick targets with a low Z substrate and a thin higher Z tracer layer at the rear that the boundary between the two materials was Rayleigh–Taylor unstable. By including a simple bubble growth model into the calculations it was possible to correct for the associated behavior with regard to temperature. The resulting temperature gradient was in good agreement with the previously published data using two different methods of determining the temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
28. Comparative Application of Capacity Models for Seismic Vulnerability Evaluation of Existing RC Structures
- Author
-
FAELLA, CIRO, NIGRO, EMIDIO, C. LIMA, E. MARTINELLI, A. Santini, N. Morace, Faella, Ciro, C., Lima, E., Martinelli, and Nigro, Emidio
- Published
- 2008
29. A large-aperture high-sensitivity avalanche image intensifier panel.
- Author
-
Arikawa Y, Matsubara S, Kishimoto H, Abe Y, Sakata S, Morace A, Mizutani R, Nishibata J, Yogo A, Nakai M, Shiraga H, Nishimura H, Fujioka S, and Kodama R
- Abstract
A large-aperture high-sensitivity image intensifier panel that consists of an avalanche photodiode array and a light-emitting diode array is presented. The device has 40% quantum efficiency, over 10
4 optical gain, and 80-ns time resolution. The aperture size of the device is 20 cm, and with the current manufacturing process, it can be scaled to arbitrarily larger sizes. The device can intensify the light from a single particle scintillation emission to an eye-visible bright flash. The image resolution of the device is currently limited by the size of the avalanche photodiode that is 2 mm, although it can be scaled to smaller sizes in the near future. The image intensifier is operated at a small voltage, typically +57 V. The device can be applied to various applications, such as scintillation imaging, night vision cameras, and an image converter from non-visible light (such as infrared or ultraviolet) to visible light.- Published
- 2018
- Full Text
- View/download PDF
30. Publisher's Note: "Monte-Carlo simulation of noise in hard X-ray Transmission Crystal Spectrometers: Identification of contributors to the background noise and shielding optimization" [Rev. Sci. Instrum. 85, 11D615 (2014)].
- Author
-
Thfoin I, Reverdin C, Hulin S, Szabo CI, Bastiani-Ceccotti S, Batani D, Brambrink E, Koenig M, Duval A, Leboeuf X, Lecherbourg L, Rossé B, Morace A, Santos JJ, Vaisseau X, Fourment C, Giuffrida L, and Nakatsutsumi M
- Published
- 2015
- Full Text
- View/download PDF
31. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch.
- Author
-
Kojima S, Arikawa Y, Nishimura Y, Togawa H, Zhang Z, Ikenouchi T, Ozaki T, Morace A, Nagai T, Abe Y, Sakata S, Inoue H, Utsugi M, Nakai M, Nishimura H, Shiraga H, Kato R, Fujioka S, and Azechi H
- Abstract
A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons' energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9 MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5 MeV for 6.0 MeV electrons.
- Published
- 2014
- Full Text
- View/download PDF
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