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| MOO2A01 | Physics And Diagnostics Of Laser-Plasma Accelerators | laser, electron, target, radio-frequency | 11 | ||
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The recent and continuing development of powerful laser systems, which can now deliver light pulses containing a few Joules of energy in pulse durations of a few tens of femto seconds, has permitted the emergence of new approaches for generating energetic particle beams. By focusing these laser pulses onto matter, extremely large electric fields can be generated, reaching the TV/m level. Such fields are 10,000 times greater than those produced in the radio-frequency cavities of conventional accelerators. As a result, the distance over which particles extracted from the target can be accelerated GeV energy range is reduced to distances on the order of millimetres. A few years ago, several experiments have shown that laser-plasma accelerators can produce electron beam with maxwellian-like distribution [1], in 2004 high-quality electron beams, with quasi-mono energetic energy distributions at the 100 MeV level [2] and recently in the GeV range using a capillary discharge [3]. These experiments were performed by focusing a single ultra short and ultra intense laser pulse into an under dense plasma. More recently we produced a high quality electron beam using two counter-propagating
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| WEPB13 | Focusing of Optical Transition and Diffraction Radiation by a Spherical Target | target, electron, radiation, diagnostics | 259 | ||
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During the last few years Transition Radiation (TR) and Diffraction Radiation (DR) have been intensively studied for different applications such as diagnostics of electron beam size, emittance, length, energy spread, etc. For extremely high-energy electrons the broadening of TR (DR) spatial distribution due to “pre-wave” zone effect [*] leads to distortion of the radiation characteristics and decreasing of photon concentration per unit square detector. In papers [**,***] it was shown that using a spherical target one can make TR (DR) distribution in the pre-wave zone identical to a far-field one. To verify our approach we carried out an experiment at KEK-ATF extraction line with electron beam energy of 1.28 GeV using a spherical target to focus optical TR (DR) at the distance of L=440 mm which corresponds to an extreme pre-wave zone. We also measured OTR (ODR) characteristics from a flat target in order to compare them with OTR (ODR) characteristics from the spherical one. We clearly observed that OTR (ODR) angular distribution from the spherical target is narrower than from a flat one and it’s very similar to a far-field zone distribution as it was predicted by the theory.
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* V. A.Verzilov, PLA 273(2000)135** P. V.Karataev, PLA 345(2005)428*** A. P. Potylitsyn and R. O. Rezaev, NIMB 252(2006)44 |
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| WEPC20 | A Real-Time Beam Monitor for Hadrontherapy Applications Based on Thin Foil Secondary Electron Emission and a Back-Thinned Monolithic Pixel Sensor | electron, proton, cyclotron, monitoring | 352 | ||
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A novel, non-disruptive beam profile monitor for low intensity light-ion beams has been constructed and tested. The system is designed for use in medical hadrontherapy centers where real-time monitoring of the beam intensity profile is of great importance for optimization of the accelerator operation, patient safety and dose delivery. The beam monitor is based on the detection of secondary electrons emitted from a submicron thick Al2O3/Al foil placed in the beam at an angle of 45 degrees. The present paper reports the latest results achieved with a customized monolithic active pixel array, which provides the beam intensity and position with a precision of better than 1 mm at a 10 kHz frame rate. The sensor chip is back-thinned to achieve the required sensitivity to short-range secondary electrons focused onto the sensor surface. The monitor performance has been tested with a patterned beam, produced with a multi-hole collimator, with the results indicating that the system performs according to its design specifications.
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