T. Tajima - Dept. of Physics and Astronomy, University of California, Irvine, CA

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Name
T. Tajima
Affiliation
Dept. of Physics and Astronomy, University of California, Irvine, CA
City
Irvine
Country
United States

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Physics - Plasma Physics (30)
 
Physics - Accelerator Physics (16)
 
Physics - Optics (9)
 
High Energy Physics - Phenomenology (7)
 
Physics - Computational Physics (6)
 
High Energy Astrophysical Phenomena (4)
 
High Energy Physics - Experiment (4)
 
Physics - Space Physics (3)
 
Instrumentation and Methods for Astrophysics (3)
 
Physics - Superconductivity (3)
 
Physics - General Physics (2)
 
General Relativity and Quantum Cosmology (2)
 
Quantum Physics (2)
 
Astrophysics (1)
 
Physics - Materials Science (1)
 
Solar and Stellar Astrophysics (1)
 
Physics - Medical Physics (1)

Publications Authored By T. Tajima

2016Dec
Affiliations: 1NICADD, DeKalb and Fermilab, 2NICADD, DeKalb, 3Fermilab, 4Fermilab, 5Fermilab, 6Shanghai, Inst. Optics, Fine Mech., 7UC, Irvine, 8UC, Irvine, 9UC, Irvine, 10Michigan U. and Palaiseau, Lab. Opt. Appl., 11Michigan U. and Palaiseau, Lab. Opt. Appl.

This paper describes simulation analyses on beam and laser (X-ray)-driven accelerations in effective nanotube models obtained from Vsim and EPOCH codes. Experimental setups to detect wakefields are also outlined with accelerator facilities at Fermilab and NIU. In the FAST facility, the electron beamline was successfully commissioned at 50 MeV and it is being upgraded toward higher energies for electron accelerator R&D. Read More

2015Nov

This report describes the conceptual steps in reaching the design of the AWAKE experiment currently under construction at CERN. We start with an introduction to plasma wakefield acceleration and the motivation for using proton drivers. We then describe the self-modulation instability --- a key to an early realization of the concept. Read More

We developed a polarization modulation unit (PMU) to rotate a waveplate continuously in order to observe solar magnetic fields by spectropolarimetry. The non-uniformity of the PMU rotation may cause errors in the measurement of the degree of linear polarization (scale error) and its angle (crosstalk between Stokes-Q and -U), although it does not cause an artificial linear polarization signal (spurious polarization). We rotated a waveplate with the PMU to obtain a polarization modulation curve and estimated the scale error and crosstalk caused by the rotation non-uniformity. Read More

Anomalous transitions involving photons derived by many-body interaction of the form, $\partial_{\mu} G^{\mu}$, in the standard model are studied. This does not affect the equation of motion in the bulk, but makes wave functions modified, and causes the unusual transition characterized by the time-independent probability. In the transition probability at a time-interval $T$ expressed generally in the form $P=T \Gamma_0 +P^{(d)}$, now with $ P^{(d)} \neq 0 $. Read More

2014Jul
Affiliations: 1Dept. of Physics and Astronomy, University of California, Irvine, CA, 2Dept. of Physics and Astronomy, University of California, Irvine, CA, 3Dept. of Physics and Astronomy, University of California, Irvine, CA, 4Dept. of Physics and Astronomy, University of California, Irvine, CA, 5Dept. of Physics and Astronomy, University of California, Irvine, CA, 6RIKEN, Wako, Saitama, Japan, 7Dept. of Physics and Astronomy, University of California, Irvine, CA

In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the relativistic intensity EM waves are important, they may be overtaken by the PA itself in the extreme high intensity regime when the dimensionless vector potential $a_0$ of the EM waves far exceeds unity. The energy gain by this regime (in 1D) is shown to be (approximately) proportional to $a_0^2$. Read More

2013Oct

This report summarizes the work of the Energy Frontier Higgs Boson working group of the 2013 Community Summer Study (Snowmass). We identify the key elements of a precision Higgs physics program and document the physics potential of future experimental facilities as elucidated during the Snowmass study. We study Higgs couplings to gauge boson and fermion pairs, double Higgs production for the Higgs self-coupling, its quantum numbers and $CP$-mixing in Higgs couplings, the Higgs mass and total width, and prospects for direct searches for additional Higgs bosons in extensions of the Standard Model. Read More

An accreting supermassive blackhole, the central engine of active galactic nucleus (AGN), is capable of exciting extreme amplitude Alfven waves whose wavelength (wave packet) size is characterized by its clumpiness. The pondermotive force and wakefield are driven by these Alfven waves propagating in the AGN (blazar) jet and accelerate protons/nuclei to extreme energies beyond Zetta-electron volt (ZeV$=10^{21}$ eV). Such acceleration is prompt, localized, and does not suffer from the multiple scattering/bending enveloped in the Fermi acceleration that causes excessive synchrotron radiation loss beyond $10^{19}$ eV. Read More

This paper proposes a Higgs factory located in the Tevatron tunnel. It is based on a photon collider by using a recirculating e- linac and fiber laser technology. The design goal is 10,000 Higgs per year. Read More

2013May
Authors: J. H. Adams, S. Ahmad, J. -N. Albert, D. Allard, M. Ambrosio, L. Anchordoqui, A. Anzalone, Y. Arai, C. Aramo, K. Asano, M. Ave, P. Barrillon, T. Batsch, J. Bayer, T. Belenguer, R. Bellotti, A. A. Berlind, M. Bertaina, P. L. Biermann, S. Biktemerova, C. Blaksley, J. Blecki, S. Blin-Bondil, J. Bluemer, P. Bobik, M. Bogomilov, M. Bonamente, M. S. Briggs, S. Briz, A. Bruno, F. Cafagna, D. Campana, J-N. Capdevielle, R. Caruso, M. Casolino, C. Cassardo, G. Castellini, O. Catalano, A. Cellino, M. Chikawa, M. J. Christl, V. Connaughton, J. F. Cortes, H. J. Crawford, R. Cremonini, S. Csorna, J. C. D'Olivo, S. Dagoret-Campagne, A. J. de Castro, C. De Donato, C. de la Taille, L. del Peral, A. Dell'Oro, M. P. De Pascale, M. Di Martino, G. Distratis, M. Dupieux, A. Ebersoldt, T. Ebisuzaki, R. Engel, S. Falk, K. Fang, F. Fenu, I. Fernandez-Gomez, S. Ferrarese, A. Franceschi, J. Fujimoto, P. Galeotti, G. Garipov, J. Geary, U. G. Giaccari, G. Giraudo, M. Gonchar, C. Gonzalez Alvarado, P. Gorodetzky, F. Guarino, A. Guzman, Y. Hachisu, B. Harlov, A. Haungs, J. Hernandez Carretero, K. Higashide, T. Iguchi, H. Ikeda, N. Inoue, S. Inoue, A. Insolia, F. Isgrio, Y. Itow, E. Joven, E. G. Judd, A. Jung, F. Kajino, T. Kajino, I. Kaneko, Y. Karadzhov, J. Karczmarczyk, K. Katahira, K. Kawai, Y. Kawasaki, B. Keilhauer, B. A. Khrenov, Jeong-Sook Kim, Soon-Wook Kim, Sug-Whan Kim, M. Kleifges, P. A. Klimov, S. H. Ko, D. Kolev, I. Kreykenbohm, K. Kudela, Y. Kurihara, E. Kuznetsov, G. La Rosa, J. Lee, J. Licandro, H. Lim, F. Lopez, M. C. Maccarone, K. Mannheim, L. Marcelli, A. Marini, G. Martin-Chassard, O. Martinez, G. Masciantonio, K. Mase, R. Matev, A. Maurissen, G. Medina-Tanco, T. Mernik, H. Miyamoto, Y. Miyazaki, Y. Mizumoto, G. Modestino, D. Monnier-Ragaigne, J. A. Morales de los Rios, B. Mot, T. Murakami, M. Nagano, M. Nagata, S. Nagataki, T. Nakamura, J. W. Nam, S. Nam, K. Nam, T. Napolitano, D. Naumov, A. Neronov, K. Nomoto, T. Ogawa, H. Ohmori, A. V. Olinto, P. Orleanski, G. Osteria, N. Pacheco, M. I. Panasyuk, E. Parizot, I. H. Park, B. Pastircak, T. Patzak, T. Paul, C. Pennypacker, T. Peter, P. Picozza, A. Pollini, H. Prieto, P. Reardon, M. Reina, M. Reyes, M. Ricci, I. Rodriguez, M. D. Rodriguez Frias, F. Ronga, H. Rothkaehl, G. Roudil, I. Rusinov, M. Rybczynski, M. D. Sabau, G. Saez Cano, A. Saito, N. Sakaki, M. Sakata, H. Salazar, S. Sanchez, A. Santangelo, L. Santiago Cruz, M. Sanz Palomino, O. Saprykin, F. Sarazin, H. Sato, M. Sato, T. Schanz, H. Schieler, V. Scotti, M. Scuderi, A. Segreto, S. Selmane, D. Semikoz, M. Serra, S. Sharakin, T. Shibata, H. M. Shimizu, K. Shinozaki, T. Shirahama, G. Siemieniec-Ozieb, H. H. Silva Lopez, J. Sledd, K. Slominska, A. Sobey, T. Sugiyama, D. Supanitsky, M. Suzuki, B. Szabelska, J. Szabelski, F. Tajima, N. Tajima, T. Tajima, Y. Takahashi, H. Takami, M. Takeda, Y. Takizawa, C. Tenzer, O. Tibolla, L. Tkachev, T. Tomida, N. Tone, F. Trillaud, R. Tsenov, K. Tsuno, T. Tymieniecka, Y. Uchihori, O. Vaduvescu, J. F. Valdes-Galicia, P. Vallania, L. Valore, G. Vankova, C. Vigorito, L. Villasenor, P. von Ballmoos, S. Wada, J. Watanabe, S. Watanabe, J. Watts, M. Weber, T. J. Weiler, T. Wibig, L. Wiencke, M. Wille, J. Wilms, Z. Wlodarczyk, T. Yamamoto, Y. Yamamoto, J. Yang, H. Yano, I. V. Yashin, D. Yonetoku, K. Yoshida, S. Yoshida, R. Young, A. Zamora, A. Zuccaro Marchi

We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth's nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. Read More

We report on experimental studies of divergence of proton beams from nanometer thick diamond-like carbon (DLC) foils irradiated by an intense laser with high contrast. Proton beams with extremely small divergence (half angle) of 2 degree are observed in addition with a remarkably well-collimated feature over the whole energy range, showing one order of magnitude reduction of the divergence angle in comparison to the results from micrometer thick targets. We demonstrate that this reduction arises from a steep longitudinal electron density gradient and an exponentially decaying transverse profile at the rear side of the ultrathin foils. Read More

We report the influence of intrinsic superconducting parameters on the vortex dynamics and the critical current densities of a MgB$_2$ thin film. The small magnetic penetration depth of \lambda = 50 nm at T=4 K is related to a clean \pi-band, and transport and magnetization data show an upper critical field similar to those reported in clean single crystals. We find a high self-field critical current density Jc, which is strongly reduced with applied magnetic field, and attribute this to suppression of the superconductivity in the \pi-band. Read More

We introduce a new model of gamma ray burst (GRB) that explains its observed prompt signals, namely, its primary quasi-thermal spectrum and high energy tail. This mechanism can be applied to either assumption of GRB progenitor: coalescence of compact objects or hypernova explosion. The key ingredients of our model are: (1) The initial stage of a GRB is in the form of a relativistic quark-gluon plasma "lava"; (2) The expansion and cooling of this lava results in a QCD phase transition that induces a sudden gravitational stoppage of the condensed non-relativistic baryons and form a hadrosphere; (3) Acoustic shocks and Alfven waves (magnetoquakes) that erupt in episodes from the epicenter efficiently transport the thermal energy to the hadrospheric surface and induce a rapid detachment of leptons and photons from the hadrons; (4) The detached $e^+e^-$ and $\gamma$ form an opaque, relativistically hot leptosphere, which expands and cools to $T \sim mc^2$, or 0. Read More

Over the last Century the method of particle acceleration to high energies has become the prime approach to explore the fundamental nature of matter in laboratory. It appears that the latest search of the contemporary accelerator based on the colliders shows a sign of saturation (or at least a slow-down) in increasing its energy and other necessary parameters to extend this frontier. We suggest two pronged approach enabled by the recent progress in high intensity lasers. Read More

The recent remark by G. Mourou and T. Tajima (Science 331, 41 (2011)) on the intensity of the driver laser pulse and the duration of the created pulse that higher driver beam intensities are needed to reach shorter pulses of radiation remains a conjecture without clear theoretical reasoning so far. Read More

We present an experimental approach using magnetic force microscopy for measurements of the absolute value of the magnetic penetration depth $\lambda$ in superconductors. $\lambda$ is obtained in a simple and robust way without introducing any tip modeling procedure via direct comparison of the Meissner response curves for a material of interest to those measured on a reference sample. Using a well-characterized Nb film as a reference, we determine the absolute value of $\lambda$ in a Ba(Fe$_{0. Read More

2012Apr
Authors: The JEM-EUSO Collaboration, :, J. H. Adams Jr, S. Ahmad, J. -N. Albert, D. Allard, M. Ambrosio, L. Anchordoqui, A. Anzalone, Y. Arai, C. Aramo, K. Asano, P. Barrillon, T. Batsch, J. Bayer, T. Belenguer, R. Bellotti, A. A. Berlind, M. Bertaina, P. L. Biermann, S. Biktemerova, C. Blaksley, J. Blecki, S. Blin-Bondil, J. Bluemer, P. Bobik, M. Bogomilov, M. Bonamente, M. S. Briggs, S. Briz, A. Bruno, F. Cafagna, D. Campana, J-N. Capdevielle, R. Caruso, M. Casolino, C. Cassardo, G. Castellini, O. Catalano, A. Cellino, M. Chikawa, M. J. Christl, V. Connaughton, J. F. Cortes, H. J. Crawford, R. Cremonini, S. Csorna, J. C. D'Olivo, S. Dagoret-Campagne, A. J. de Castro, C. De Donato, C. de la Taille, M. P. De Pascale, L. del Peral, A. Dell'Oro, M. Di Martino, G. Distrati, M. Dupieux, A. Ebersoldt, T. Ebisuzaki, R. Engel, S. Falk, K. Fang, F. Fenu, S. Ferrarese, I. Fernandez-Gomez, A. Franceschi, J. Fujimoto, P. Galeotti, G. Garipov, J. Geary, U. G. Giaccari, G. Giraudo, M. Gonchar, C. Gonzalez Alvarado, P. Gorodetzky, F. Guarino, A. Guzman, Y. Hachisu, B. Harlov, A. Haungs, J. Hernandez Carretero, K. Higashide, T. Iguchi, H. Ikeda, N. Inoue, S. Inoue, A. Insolia, F. Isgro, Y. Itow, E. Joven, E. G. Judd, A. Jung, F. Kajino, T. Kajino, I. Kaneko, Y. Karadzhov, J. Karczmarczyk, K. Katahira, K. Kawai, Y. Kawasaki, B. Keilhauer, B. A. Khrenov, Jeong-Sook Kim, Soon-Wook Kim, Sug-Whan Kim, M. Kleifges, P. A. Klimov, S. H. Ko, D. Kolev, I. Kreykenbohm, K. Kudela, Y. Kurihara, E. Kuznetsov, G. La Rosa, J. Lee, J. Licandro, H. Lim, F. Lopez, M. C. Maccarone, L. Marcelli, A. Marini, G. Martin-Chassard, O. Martinez, G. Masciantonio, K. Mase, R. Matev, A. Maurissen, G. Medina-Tanco, T. Mernik, H. Miyamoto, Y. Miyazaki, Y. Mizumoto, G. Modestino, D. Monnier-Ragaigne, J. A. Morales de los Rıos, B. Mot, T. Murakami, M. Nagano, M. Nagata, S. Nagataki, J. W. Nam, S. Nam, K. Nam, T. Napolitano, D. Naumov, A. Neronov, K. Nomoto, T. Ogawa, H. Ohmori, A. V. Olinto, P. Orleanski, G. Osteria, N. Pacheco, M. I. Panasyuk, E. Parizot, I. H. Park, B. Pastircak, T. Patzak, T. Paul, C. Pennypacker, T. Peter, P. Picozza, A. Pollini, H. Prieto, P. Reardon, M. Reina, M. Reyes, M. Ricci, I. Rodrıguez, M. D. Rodrıguez Frıas, F. Ronga, H. Rothkaehl, G. Roudil, I. Rusinov, M. Rybczynski, M. D. Sabau, G. Saez Cano, A. Saito, N. Sakaki, M. Sakata, H. Salazar, S. Sanchez, A. Santangelo, L. Santiago Cruz, M. Sanz Palomino, O. Saprykin, F. Sarazin, H. Sato, M. Sato, T. Schanz, H. Schieler, V. Scotti, M. Scuderi, A. Segreto, S. Selmane, D. Semikoz, M. Serra, S. Sharakin, T. Shibata, H. M. Shimizu, K. Shinozaki, T. Shirahama, G. Siemieniec-Ozieblo, H. H. Silva Lopez, J. Sledd, K. Slominska, A. Sobey, T. Sugiyama, D. Supanitsky, M. Suzuki, B. Szabelska, J. Szabelski, F. Tajima, N. Tajima, T. Tajima, H. Takami, T. Nakamura, M. Takeda, Y. Takahashi, Y. Takizawa, C. Tenzer, L. Tkachev, T. Tomida, N. Tone, F. Trillaud, R. Tsenov, K. Tsuno, T. Tymieniecka, Y. Uchihori, O. Vaduvescu, J. F. Valdes-Galicia, P. Vallania, L. Valore, G. Vankova, C. Vigorito, L. Villasenor, P. von Ballmoos, S. Wada, J. Watanabe, S. Watanabe, J. Watts Jr, M. Weber, T. J. Weiler, T. Wibig, L. Wiencke, M. Wille, J. Wilms, Z. Wlodarczyk, T. Yamamoto, Y. Yamamoto, J. Yang, H. Yano, I. V. Yashin, D. Yonetoku, K. Yoshida, S. Yoshida, R. Young, A. Zamora, A. Zuccaro Marchi

Contributions of the JEM-EUSO Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011. Read More

We demonstrate a new high-order harmonic generation mechanism reaching the `water window' spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving uJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. Read More

Proton acceleration by ultra-intense laser pulse irradiating a target with cross-section smaller than the laser spot size and connected to a parabolic density channel is investigated. The target splits the laser into two parallel propagating parts, which snowplow the back-side plasma electrons along their paths, creating two adjacent parallel wakes and an intense return current in the gap between them. The radiation-pressure pre-accelerated target protons trapped in the wake fields now undergo acceleration as well as collimation by the quasistatic wake electrostatic and magnetic fields. Read More

A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. Read More

In vacuum high-intensity lasers can cause photon-photon interaction via the process of virtual vacuum polarization which may be measured by the phase velocity shift of photons across intense fields. In the optical frequency domain, the photon-photon interaction is polarization-mediated described by the Euler-Heisenberg effective action. This theory predicts the vacuum birefringence or polarization dependence of the phase velocity shift arising from nonlinear properties in quantum electrodynamics (QED). Read More

The invention of the laser immediately enabled the detection of nonlinear photon-matter interactions, as manifested for example by Franken et al.'s detection of second-harmonic generation. With the recent advancement in high-power, high-energy lasers and the examples of nonlinearity studies of the laser-matter interaction by virtue of properly arranging lasers and detectors, we envision the possibility of probing nonlinearities of the photon interaction in vacuum over substantial space-time scales, compared to the microscopic scale provided by high-energy accelerators. Read More

Snowplow ion acceleration is presented, using an ultra-relativistically intense laser pulse irradi- ating on a combination target, where the relativistic proton beam generated by radiation pressure acceleration can be trapped and accelerated by the laser plasma wakefield. The theory suggests that sub-TeV quasi-monoenergetic proton bunches can be generated by a centimeter-scale laser wakefield accelerator, driven by a circularly polarized (CP) laser pulse with the peak intensity of 10^23W/cm^2 and duration of 116fs. Read More

2010Sep
Affiliations: 1Max-Planck-Institut für Quantenoptik, Garching, Germany, 2Max-Born-Institut, Berlin, Germany, 3Max-Planck-Institut für Quantenoptik, Garching, Germany, 4Max-Planck-Institut für Quantenoptik, Garching, Germany, 5Max-Born-Institut, Berlin, Germany, 6Max-Born-Institut, Berlin, Germany, 7Max-Planck-Institut für Quantenoptik, Garching, Germany, 8Fakultät für Physik, Ludwig-Maximilians-Universität München, Garching, Germany, 9Fakultät für Physik, Ludwig-Maximilians-Universität München, Garching, Germany, 10Max-Planck-Institut für Quantenoptik, Garching, Germany, 11Fakultät für Physik, Ludwig-Maximilians-Universität München, Garching, Germany, 12Max-Planck-Institut für Quantenoptik, Garching, Germany, 132 qnd 4, 14Max-Born-Institut, Berlin, Germany, 15Max-Planck-Institut für Quantenoptik, Garching, Germany, 16Max-Planck-Institut für Quantenoptik, Garching, Germany, 17Max-Born-Institut, Berlin, Germany, 18Max-Planck-Institut für Quantenoptik, Garching, Germany

In this letter we report on an experimental study of high harmonic radiation generated in nanometer-scale foil targets irradiated under normal incidence. The experiments constitute the first unambiguous observation of odd-numbered relativistic harmonics generated by the $\vec{v}\times\vec{B}$ component of the Lorentz force verifying a long predicted property of solid target harmonics. Simultaneously the observed harmonic spectra allow in-situ extraction of the target density in an experimental scenario which is of utmost interest for applications such as ion acceleration by the radiation pressure of an ultraintense laser. Read More

The invention of laser immediately enabled us to detect nonlinearities of photon interaction in matter, as manifested for example by Franken et al.'s detection of second harmonic generation and the excitation of the Brillouin forward scattering process. With the recent advancement in high power high energy laser and the examples of the nonlinearity study of laser-matter interaction by virtue of properly arranging laser and detectors, we envision the possibility of probing nonlinearities of photon interaction in vacuum over substantial spacetime scales compared with the microscopic scale provided by high energy accelerators. Read More

Identified is a set of ballpark parameters for laser, plasma, and accelerator technologies that are defined for accelerated electron energies reaching as high as PeV. These parameters are carved out from the scaling laws that govern the physics of laser acceleration, theoretically suggested and experimentally explored over a wide range in the recent years. We extrapolate this knowledge toward PeV energies. Read More

X-ray devices are far superior to optical ones for providing nanometre spatial and attosecond temporal resolutions. Such resolution is indispensable in biology, medicine, physics, material sciences, and their applications. A bright ultrafast coherent X-ray source is highly desirable, for example, for the diffractive imaging of individual large molecules, viruses, or cells. Read More

Experiments on ion acceleration by irradiation of ultra-thin diamond-like carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with laser pulses of ultra-high contrast and linear polarization, are presented. A maximum energy of 13MeV for protons and 71MeV for carbon ions is observed with a conversion efficiency of > 10%. Two-dimensional particle-in-cell (PIC) simulations reveal that the increase in ion energies can be attributed to a dominantly collective rather than thermal motion of the foil electrons, when the target becomes transparent for the incident laser pulse. Read More

With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. Read More

We present experimental studies on ion acceleration from ultra-thin diamond-like carbon (DLC) foils irradiated by ultra-high contrast laser pulses of energy 0.7 J focussed to peak intensities of 5*10^{19} W/cm^2. A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5. Read More

Bright Ar K-shell x-ray with very little background has been generated using an Ar clustering gas jet target irradiated with an 800 mJ, 30 fs ultra-high contrast laser, with the measured flux of 1.1 x 10^4 photons/mrad^2/pulse. This intense x-ray source critically depends on the laser contrast and the laser energy and the optimization of this source with interaction is addressed. Read More

A theory for laser ion acceleration is presented to evaluate the maximum ion energy in the interaction of ultrahigh contrast (UHC) intense laser with a nanometer-scale foil. In this regime the energy of ions may be directly related to the laser intensity and subsequent electron dynamics. This leads to a simple analytical expression for the ion energy gain under the laser irradiation of thin targets. Read More

We demonstrate generation of 10-20 MeV/u ions with a compact 4 TW laser using a gas target mixed with submicron clusters, corresponding to tenfold increase in the ion energies compared to previous experiments with solid targets. It is inferred that the high energy ions are generated due to formation of a strong dipole vortex structure. The demonstrated method has a potential to construct compact and high repetition rate ion sources for hadron therapy and other applications. Read More

The paper is devoted to the prospects of using the laser radiation interaction with plasmas in the laboratory relativistic astrophysics context. We discuss the dimensionless parameters characterizing the processes in the laser and astrophysical plasmas and emphasize a similarity between the laser and astrophysical plasmas in the ultrarelativistic energy limit. In particular, we address basic mechanisms of the charged particle acceleration, the collisionless shock wave and magnetic reconnection and vortex dynamics properties relevant to the problem of ultrarelativistic particle acceleration. Read More

A set of ballpark parameters for laser, plasma, and accelerator technologies that define for electron energies reaching as high as TeV are identified. These ballpark parameters are carved out from the fundamental scaling laws that govern laser acceleration, theoretically suggested and experimentally explored over a wide range in the recent years. In the density regime on the order of 10^{16} cm^{-3}, the appropriate laser technology, we find, matches well with that of a highly efficient high fluence LD driven Yb ceramic laser. Read More

Laser acceleration promises innovation in particle beam therapy of cancer where an ultra-compact accelerator system for cancer beam therapy can become affordable to a broad range of patients. This is not feasible without the introduction of a technology that is radically different from the conventional accelerator-based approach. The laser acceleration method provides many enhanced capabilities for the radiation oncologist. Read More

Since the advent of chirped pulse amplification1 the peak power of lasers has grown dramatically and opened the new branch of high field science, delivering the focused irradiance, electric fields of which drive electrons into the relativistic regime. In a plasma wake wave generated by such a laser, modulations of the electron density naturally and robustly take the shape of paraboloidal dense shells, separated by evacuated regions, moving almost at the speed of light. When we inject another counter-propagating laser pulse, it is partially reflected from the shells, acting as relativistic flying (semi-transparent) mirrors, producing an extremely time-compressed frequency-multiplied pulse which may be focused tightly to the diffraction limit. Read More

2006Jul
Affiliations: 1Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 2Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 3Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 4Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 5Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 6Advanced Photon Research Center, Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto, Japan, 7Institute of Physics and China Academy of Sciences, Beijing, China, 8Institute of Physics and China Academy of Sciences, Beijing, China, 9Institute of Physics and China Academy of Sciences, Beijing, China, 10Institute of Physics and China Academy of Sciences, Beijing, China, 11Institute of Physics and China Academy of Sciences, Beijing, China

We studied the hard x-ray emission and the K-alpha x-ray conversion efficiency produced by 60 fs high contrast frequency doubled Ti: sapphire laser pulse focused on Cu foil target. Cu K-alpha photon emission obtained with second harmonic laser pulse is more intense than the case of fundamental laser pulse. The Cu K-alpha conversion efficiency shows strong dependence on laser nonlinearly skewed pulse shape and reaches the maximum value 4x10-4 with 100 fs negatively skewed pulse. Read More

A method of slicing of high-energy electron beams following their interaction with the transverse component of the wakefield left in a plasma behind a high intensity ultra short laser pulse is proposed. The transverse component of the wakefield focuses a portion of the electron bunch, which experiences betatron oscillations. The length of the focused part of the electron bunch can be made substantially less than the wakefield wavelength. Read More

We suggest a novel method for injection of electrons into the acceleration phase of particle accelerators, producing low emittance beams appropriate even for the demanding high energy Linear Collider specifications. In this paper we work out the injection into the acceleration phase of the wake field in a plasma behind a high intensity laser pulse, taking advantage of the laser polarization and focusing. With the aid of catastrophe theory we categorize the injection dynamics. Read More

2006May
Affiliations: 1Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 2Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 3Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 4Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 5Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 6Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan, 7Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 8Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 9Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 10Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 11Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 12Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 13Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 14Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 15Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 16Laser Fusion Research Center, China Academy of Engineering Physics, Sichuan, China, 17Accelerator Laboratory of Tsinghua University, Beijing, China, 18Accelerator Laboratory of Tsinghua University, Beijing, China, 19Accelerator Laboratory of Tsinghua University, Beijing, China, 20Accelerator Laboratory of Tsinghua University, Beijing, China

An experiment for studying laser self-guiding has been carried out for the high power ultrashort pulse laser interaction with an underdense plasma slab. Formation of an extremely long plasma channel and its bending are observed when the laser pulse power is much higher than the critical power for relativistic self-focusing. The long self-guiding channel formation is accompanied by electron acceleration with a low transverse emittance and high electric current. Read More

The ion acceleration driven by a laser pulse at intensity $I = 10^{20} - 10^{22} $W/cm$^2\times(\mu$m$/\lambda)^2$ from a double layer target is investigated with multi-parametric Particle-in-Cell (PIC) simulations. For targets with a wide range of thickness $l$ and density $n_e$, at given intensity the highest ion energy gain occurs at certain {\it critical depth} of the target $\sigma = n_e l$, which is proportional to the square root of intensity. In the case of thin targets and optimal laser pulse duration, the ion maximum energy scales as the square root of the laser pulse power. Read More

The electron and positron acceleration in the first cycle of a laser-driven wakefield is investigated. Separatrices between different types of the particle motion (confined, reflected by the wakefield or ponderomotive potential and transient) are demonstrated. The ponderomotive acceleration is negligible for electrons but is substantial for positrons. Read More

The electromagnetic radiation pressure becomes dominant in the interaction of the ultra-intense electromagnetic wave with a solid material, thus the wave energy can be transformed efficiently into the energy of ions representing the material and the high density ultra-short relativistic ion beam is generated. This regime can be seen even with present-day technology, when an exawatt laser will be built. As an application, we suggest the laser-driven heavy ion collider. Read More

A new mechanism is suggested for efficient proton acceleration in the GeV energy range; applications to non-conventional high intensity proton drivers and, hence, to low-energy (10-200 MeV) neutrino sources are discussed. In particular we investigate possible uses to explore subdominant $\bar{\nu}_\mu \to \bar{\nu}_e$ oscillations at the atmospheric scale and their CP conjugate. We emphasize the opportunity to develop these facilities in conjunction with projects for inertial confined nuclear fusion and neutron spallation sources. Read More

Magnesium diboride (MgB2) is attractive for RF cavity application for particle accelerators because it might not show an increase of RF surface losses at high magnetic surface fields, a phenomenon that has prevented high-Tc superconducting materials such as YBCO from being used for this application. We have measured the RF surface resistance (Rs) at 21 GHz of a MgB2 sample fabricated using Hot Isostatic Press (HIP) at 200 MPa and 1000 C. The results show that polishing with 0. Read More

A method to generate ultrahigh intense electromagnetic fields is suggested, based on the laser pulse compression, carrier frequency upshift and focusing by a counter-propagating breaking plasma wave, relativistic flying parabolic mirror. This method allows us to achieve the quantum electrodynamics critical field (Schwinger limit) with present day laser systems. Read More

A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma, where the energy gain per distance of a test particle is Lorentz invariant. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f(e) 1/e^2. Read More

Since its birth, the laser has been extraordinarily effective in the study and applications of laser-matter interaction at the atomic and molecular level and in the nonlinear optics of the bound electron. In its early life, the laser was associated with the physics of electron volts and of the chemical bond. Over the past fifteen years, however, we have seen a surge in our ability to produce high intensities, five to six orders of magnitude higher than was possible before. Read More

We have developed an efficacious algorithm for simulation of the beam-beam interaction in synchrotron colliders based on the nonlinear $\delta f$ method, where $\delta f$ is the much smaller deviation of the beam distribution from the slowly evolving main distribution $f_0$. In the presence of damping and quantum fluctuations of synchrotron radiation it has been shown that the slowly evolving part of the distribution function satisfies a Fokker-Planck equation. Its solution has been obtained in terms of a beam envelope function and an amplitude of the distribution, which satisfy a coupled system of ordinary differential equations. Read More