The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
O J Luiten - One of the best experts on this subject based on the ideXlab platform.
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compact ultracold Electron Source based on a grating magneto optical trap
Physical review accelerators and beams, 2019Co-Authors: J G H Franssen, T C H De Raadt, M A W Van Ninhuijs, O J LuitenAbstract:The ultrafast and ultracold Electron Source, based on near-threshold photoionization of a laser-cooled and trapped atomic gas, offers a unique combination of low transverse beam emittance and high bunch charge. Its use is however still limited because of the required cold-atom laser-cooling techniques. Here we present a compact ultracold Electron Source based on a grating magneto-optical trap (GMOT), which only requires one trapping laser beam that passes through a transparent accelerator module. This makes the technique more widely accessible and increases its applicability. We show the GMOT can be operated with a hole in the center of the grating and with large electric fields applied across the trapping region, which is required for extracting Electron bunches. The calculated values of the applied electric field were found to agree well with measured Stark shifts of the laser cooling transition. The Electron beams extracted from the GMOT have been characterized. Beam energies up to 10 keV were measured using a time-of-flight method. The normalized root-mean-squared transverse beam emittance was determined using a waist scan method, resulting in ϵ=1.9 nm rad. The root-mean-squared transverse size of the ionization volume is 30 μm or larger, implying an Electron Source temperature in the few-10 K range, 2-3 orders of magnitude lower than conventional Electron Sources, based on photoemission or thermionic emission from solid state surfaces.
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compact ultracold Electron Source based on a grating magneto optical trap
arXiv: Accelerator Physics, 2018Co-Authors: J G H Franssen, T C H De Raadt, M A W Van Ninhuijs, O J LuitenAbstract:The ultrafast and ultracold Electron Source, based on near-threshold photoionisation of a laser-cooled and trapped atomic gas, offers a unique combination of low transverse beam emittance and high bunch charge. Its use is however still limited because of the required cold-atom laser-cooling techniques. Here we present a compact ultracold Electron Source based on a grating magneto-optical trap (GMOT), which only requires one trapping laser beam that passes through a transparent accelerator module. This makes the technique more widely accessible and increases its applicability. We show the GMOT can be operated with a hole in the center of the grating and with large electric fields applied across the trapping region, which is required for extracting Electron bunches. The calculated values of the applied electric field were found to agree well with measured Stark shifts of the laser cooling transition. The Electron beams extracted from the GMOT have been characterised. Beam energies up to 10 keV were measured using a time-of-flight method. The normalised root-mean-squared transverse beam emittance was determined using a waist scan method, resulting in $\epsilon = 1.9 \rm{nm}$. The root-mean-squared transverse size of the ionisation volume is $30 \mu\rm{m}$ or larger, implying an Electron Source temperature in the few-10K range, $2-3$ orders of magnitude lower than conventional Electron Sources, based on photoemission or thermionic emission from solid state surfaces.
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analytical model of an isolated single atom Electron Source
Ultramicroscopy, 2014Co-Authors: W J Engelen, E J D Vredenbregt, O J LuitenAbstract:An analytical model of a single-atom Electron Source is presented, where Electrons are created by near-threshold photoionization of an isolated atom. The model considers the classical dynamics of the Electron just after the photon absorption, i.e. its motion in the potential of a singly charged ion and a uniform electric field used for acceleration. From closed expressions for the asymptotic transverse Electron velocities and trajectories, the effective Source temperature and the virtual Source size can be calculated. The influence of the acceleration field strength and the ionization laser energy on these properties has been studied. With this model, a single-atom Electron Source with the optimum Electron beam properties can be designed. Furthermore, we show that the model is also applicable to ionization of rubidium atoms, and thus also describes the ultracold Electron Source, which is based on photoionization of laser-cooled alkali atoms.
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effective temperature of an ultracold Electron Source based on near threshold photoionization
Ultramicroscopy, 2014Co-Authors: W J Engelen, O J Luiten, E P Smakman, D J Bakker, E J D VredenbregtAbstract:Abstract We present a detailed description of measurements of the effective temperature of a pulsed Electron Source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by Electron beam waist scans, Source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the Source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14±3 K were found; for femtosecond photoionization, 30±5 K is possible. With a typical Source size of 25 μ m , this results in Electron bunches with a relative transverse coherence length in the 10−4 range and an emittance of a few nm rad.
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ultracold Electron Source
Physical Review Letters, 2005Co-Authors: Bert Claessens, E J D Vredenbregt, S B Van Der Geer, G Taban, O J LuitenAbstract:We propose a technique for producing Electron bunches that has the potential for advancing the state-of-the-art in brightness of pulsed Electron Sources by orders of magnitude. In addition, this method leads to femtosecond bunch lengths without the use of ultrafast lasers or magnetic compression. The Electron Source we propose is an ultracold plasma with Electron temperatures down to 10 K, which can be fashioned from a cloud of laser-cooled atoms by photoionization just above threshold. Here we present results of simulations in a realistic setting, showing that an ultracold plasma has an enormous potential as a bright Electron Source.
E J D Vredenbregt - One of the best experts on this subject based on the ideXlab platform.
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analytical model of an isolated single atom Electron Source
Ultramicroscopy, 2014Co-Authors: W J Engelen, E J D Vredenbregt, O J LuitenAbstract:An analytical model of a single-atom Electron Source is presented, where Electrons are created by near-threshold photoionization of an isolated atom. The model considers the classical dynamics of the Electron just after the photon absorption, i.e. its motion in the potential of a singly charged ion and a uniform electric field used for acceleration. From closed expressions for the asymptotic transverse Electron velocities and trajectories, the effective Source temperature and the virtual Source size can be calculated. The influence of the acceleration field strength and the ionization laser energy on these properties has been studied. With this model, a single-atom Electron Source with the optimum Electron beam properties can be designed. Furthermore, we show that the model is also applicable to ionization of rubidium atoms, and thus also describes the ultracold Electron Source, which is based on photoionization of laser-cooled alkali atoms.
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effective temperature of an ultracold Electron Source based on near threshold photoionization
Ultramicroscopy, 2014Co-Authors: W J Engelen, O J Luiten, E P Smakman, D J Bakker, E J D VredenbregtAbstract:Abstract We present a detailed description of measurements of the effective temperature of a pulsed Electron Source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by Electron beam waist scans, Source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the Source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14±3 K were found; for femtosecond photoionization, 30±5 K is possible. With a typical Source size of 25 μ m , this results in Electron bunches with a relative transverse coherence length in the 10−4 range and an emittance of a few nm rad.
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ultracold Electron Source
Physical Review Letters, 2005Co-Authors: Bert Claessens, E J D Vredenbregt, S B Van Der Geer, G Taban, O J LuitenAbstract:We propose a technique for producing Electron bunches that has the potential for advancing the state-of-the-art in brightness of pulsed Electron Sources by orders of magnitude. In addition, this method leads to femtosecond bunch lengths without the use of ultrafast lasers or magnetic compression. The Electron Source we propose is an ultracold plasma with Electron temperatures down to 10 K, which can be fashioned from a cloud of laser-cooled atoms by photoionization just above threshold. Here we present results of simulations in a realistic setting, showing that an ultracold plasma has an enormous potential as a bright Electron Source.
Hidetaka Sawada - One of the best experts on this subject based on the ideXlab platform.
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resolution enhancement in transmission Electron microscopy with 60 kv monochromated Electron Source
Applied Physics Letters, 2016Co-Authors: Shigeyuki Morishita, Masaki Mukai, Kazutomo Suenaga, Hidetaka SawadaAbstract:Transmission Electron microscopy (TEM) at low accelerating voltages is useful to obtain images with low irradiation damage. For a low accelerating voltage, linear information transfer, which determines the resolution for observation of single-layered materials, is largely limited by defocus spread, which improves when a narrow energy spread is used in the Electron Source. In this study, we have evaluated the resolution of images obtained at 60 kV by TEM performed with a monochromated Electron Source. The defocus spread has been evaluated by comparing diffractogram tableaux from TEM images obtained under nonmonochromated and monochromated illumination. The information limits for different energy spreads were precisely measured by using diffractograms with a large beam tilt. The result shows that the information limit reaches 0.1 nm with an energy width of 0.10 eV. With this monochromated Source and a higher-order aberration corrector, we have obtained images of single carbon atoms in a graphene sheet by TE...
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the development of a 200 kv monochromated field emission Electron Source
Ultramicroscopy, 2014Co-Authors: Masaki Mukai, Hidetaka Sawada, K Omoto, Atsushi Kimura, Akihiro Ikeda, Jun Zhou, T Kaneyama, Neil P Young, Jamie H Warner, P D NellistAbstract:Abstract We report the development of a monochromator for an intermediate-voltage aberration-corrected Electron microscope suitable for operation in both STEM and TEM imaging modes. The monochromator consists of two Wien filters with a variable energy selecting slit located between them and is located prior to the accelerator. The second filter cancels the energy dispersion produced by the first filter and after energy selection forms a round monochromated, achromatic probe at the specimen plane. The ultimate achievable energy resolution has been measured as 36 meV at 200 kV and 26 meV at 80 kV. High-resolution Annular Dark Field STEM images recorded using a monochromated probe resolve Si–Si spacings of 135.8 pm using energy spreads of 218 meV at 200 kV and 217 meV at 80 kV respectively. In TEM mode an improvement in non-linear spatial resolution to 64 pm due to the reduction in the effects of partial temporal coherence has been demonstrated using broad beam illumination with an energy spread of 134 meV at 200 kV.
W J Engelen - One of the best experts on this subject based on the ideXlab platform.
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analytical model of an isolated single atom Electron Source
Ultramicroscopy, 2014Co-Authors: W J Engelen, E J D Vredenbregt, O J LuitenAbstract:An analytical model of a single-atom Electron Source is presented, where Electrons are created by near-threshold photoionization of an isolated atom. The model considers the classical dynamics of the Electron just after the photon absorption, i.e. its motion in the potential of a singly charged ion and a uniform electric field used for acceleration. From closed expressions for the asymptotic transverse Electron velocities and trajectories, the effective Source temperature and the virtual Source size can be calculated. The influence of the acceleration field strength and the ionization laser energy on these properties has been studied. With this model, a single-atom Electron Source with the optimum Electron beam properties can be designed. Furthermore, we show that the model is also applicable to ionization of rubidium atoms, and thus also describes the ultracold Electron Source, which is based on photoionization of laser-cooled alkali atoms.
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effective temperature of an ultracold Electron Source based on near threshold photoionization
Ultramicroscopy, 2014Co-Authors: W J Engelen, O J Luiten, E P Smakman, D J Bakker, E J D VredenbregtAbstract:Abstract We present a detailed description of measurements of the effective temperature of a pulsed Electron Source, based on near-threshold photoionization of laser-cooled atoms. The temperature is determined by Electron beam waist scans, Source size measurements with ion beams, and analysis with an accurate beam line model. Experimental data is presented for the Source temperature as a function of the wavelength of the photoionization laser, for both nanosecond and femtosecond ionization pulses. For the nanosecond laser, temperatures as low as 14±3 K were found; for femtosecond photoionization, 30±5 K is possible. With a typical Source size of 25 μ m , this results in Electron bunches with a relative transverse coherence length in the 10−4 range and an emittance of a few nm rad.
Tomohiko Hirano - One of the best experts on this subject based on the ideXlab platform.
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a compact Electron Source for the dielectric laser accelerator
Applied Physics Letters, 2020Co-Authors: Tomohiko Hirano, K Urbanek, Andrew Ceballos, Dylan S Black, Yu Miao, Joel R England, R L Byer, Kenneth J LeedleAbstract:In this work, we design and demonstrate a compact Electron Source that combines an integrated silicon nanotip photoemitter with a compact silicon-based electrostatic lens. The lens simultaneously accelerates Electrons to 30 keV and focuses the resulting beam to a 0.4 μm (RMS) beam diameter with 62 pm-rad normalized emittance at a distance of 20 mm from the cathode. The compact nature of this lens provides a compelling Source for dielectric laser accelerator (DLA) beamlines, ultrafast Electron diffraction, or ultrafast Electron microscopy. Driven by a 220 fs, 1960 nm pulsed laser beam, Electron currents up to 28 Electrons/pulse at 100 kHz are demonstrated. The Electron bunch length is 540 ± 50 fs for photocurrents of <1 Electron/pulse, increasing to 700 ± 80 fs for 28 Electrons/pulse, as measured by cross correlation with a 220 fs pulsed laser beam. The maximum 5D peak brightness is measured to be 6.8 × 1013 A/(m2 rad2) at 28 Electrons/pulse. These results represent a significant step toward developing practical benchtop-sized linear accelerators based on DLA technology or compact ultrafast Electron microscopy and diffraction applications.