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Results for “Collimation”
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Design, construction, and beam tests of a rotatable collimator prototype for high-intensity and high-energy hadron accelerators
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Improved simulation of beam backgrounds and collimation at SuperKEKB
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Beam shaping using an ultrahigh vacuum multileaf collimator and emittance exchange beamline
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Files describing work on alternating blade 3D printed collimator
The dataset contains relevant data and simulation files. See the README.MD for more details.
LIGA Fabricated X-Ray Collimating Grid for Tiled Arrays
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Thick Film UV Lithography Fabrication of Large Area, Fine Pitch Collimating Grids for X-Ray Astronomy
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Mechanical Design of New quad Pinhole Mini-Beam Collimator with Motorized Pitch and Yaw Adjuster Provides Lower Background for X-Ray Crystallography
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Direct Fabrication of Complex Radial Collimators
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Dual-axis optoelectronic level based on laser auto-collimation and liquid surface reflection
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Ultrafast and Highly Collimated Radially Polarized Photons at Room Temperature from a Colloidal Quantum Dot Coupled to a Hybrid Nanoantenna
To harness the potential of radially polarized photons for classical and quantum communication applications, we demonstrate an on-chip, room-temperature device, which generates highly directional radially polarized photons at very high rates. The photons are emitted from a giant CdSe/CdS colloidal quantum dot (gQD) accurately positioned at the tip of a metal nanocone centered inside a hybrid metal-dielectric bullseye antenna. We show that due to the large and selective Purcell enhancement specifically for the out-of-plane optical dipole of the gQD, the emitted photons can have a very high degree of radial polarization (>93%), based on a quantitative metric. Our study emphasizes the importance of accurate gQD positioning for optimal radial polarization purity through extensive experiments and simulations, which contribute to the fundamental understanding of radial polarization in nanostructured devices and pave the way for implementation of such systems in practical applications using structured quantum light.
Magnetic electron collimation in three-dimensional semi-metals
While electrons moving perpendicular to a magnetic field are confined to cyclotron orbits, they can move freely parallel to the field. This simple fact leads to complex current flow in clean, low carrier density semi-metals, such as long-ranged current jets forming along the magnetic field when currents pass through point-like constrictions. Occurring accidentally at imperfect current injection contacts, the phenomenon of "current jetting" plagues the research of longitudinal magneto-resistance, which is particularly important in topological conductors. Here we demonstrate the controlled generation of tightly focused electron beams in a new class of micro-devices machined from crystals of the Dirac semi-metal Cd 3 As 2 . The current beams can be guided by tilting a magnetic field and their range tuned by the field strength. Finite element simulations quantitatively capture the voltage induced at faraway contacts when the beams are steered towards them, supporting the picture of controlled electron jets. These experiments demonstrate direct control over the highly non-local signal propagation unique to 3D semi-metals in the current jetting regime, and may lead to applications akin to electron optics in free space.
Collimated protons accelerated from an overdense gas jet irradiated by a 1 µm wavelength high-intensity short-pulse laser
We have investigated proton acceleration in the forward direction from a near-critical density hydrogen gas jet target irradiated by a high intensity (10 18 W/cm 2 ), short-pulse (5 ps) laser with wavelength of 1.054 μm. We observed the signature of the Collisionless Shock Acceleration mechanism, namely quasi-monoenergetic proton beams with small divergence in addition to the more commonly observed electron-sheath driven proton acceleration. The proton energies we obtained were modest (~MeV), but prospects for improvement are offered through further tailoring the gas jet density profile. Also, we observed that this mechanism is very robust in producing those beams and thus can be considered as a future candidate in laser-driven ion sources driven by the upcoming next generation of multi-PW near-infrared lasers.
New type of large-scale experiments for laboratory astrophysics with collimated jets of laser plasma in a transverse magnetic field
We report the results for the first complex experiment on the formation of an extended (up to ∼0.5 m) plasma jet in a magnetic field (up to 300 G) in vacuum. The jet appears due to the injection of laser plasma bunches with a kinetic energy up to ∼50 J across the magnetic field (in a solid angle Ω ≈ 1 sr) and a high degree of magnetisation of ions on the calculated scale field-induced deceleration of the bunch as a part of a sphere. A plastic target (polyethylene) has been irradiated by a CO{sub 2} laser in the most energy-efficient regime (near the plasma formation threshold), implemented at the expense of a wide radiation spot (diameter 2 – 3 cm) on the target. In a new-type model Super-Jet experiment on a large KI-1 facility at the Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences (ILP SB RAS), the probe data on the internal structure and dynamics of plasma concentration and magnetic field strength in transverse jets, on the influence of instabilities and Hall effect have been obtained for the first time in laboratory modelling of space and astrophysical jets. (paper)
Features of multilayer mirror application for focusing and collimating X-rays from inverse Compton scattering sources
We have analysed the use of X-ray interference multilayer mirrors as the elements of a focusing scheme for a compact source based on inverse Compton scattering. An algorithm is proposed for selecting mirror parameters, which takes into account the properties of the radiation source. The dependence of wavelength on the viewing angle and the energy line broadening for a fixed viewing angle are found to be the main limitations in the use of multilayer mirrors. Efficient radiation collection calls for the application of broadband mirrors. It is shown that the efficiency of multilayer mirrors in a Kirkpatrick – Baez X-ray focusing setup exceeds that of total external reflection mirrors by an order of magnitude, and that stack multilayer mirrors offer a small advantage over the periodic ones. The overall efficiency of source radiation collection in the photon energy range ΔE = 10 – 12 keV amounts to 12 % for the two-mirror Kirkpatrick – Baez setup. For a spectral region with a bandwidth ΔE/E = 3 %, the efficiency ranges up to 69 %. (paper)