| 1. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 3. |
- Berrill, Mark, et al.
(författare)
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Improved beam characteristics of solid-target son x-ray laser amplifiers by injection seeding with high harmonic pulses
- 2010
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 35:14, s. 2317-2319
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Tidskriftsartikel (refereegranskat)abstract
- Injection seeding of solid-target soft x-ray laser amplifiers with high harmonic pulses is shown to dramatically improve the far-field laser beam profile and reduce the beam divergence. Measurements and two-dimensional simulations for a 13.9 nm nickel-like Ag amplifier show that the amplified beam divergence depends strongly on the seed and can therefore be controlled by selecting the divergence of the seed. The near-field beam size of both the seeded and unseeded lasers is shown to be determined by the size of the gain region and the divergence of the amplified beams.
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| 4. |
- Brewer, Courtney A., et al.
(författare)
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High spatial resolution full-field microscopy using a desktop-size soft x-ray laser
- 2007
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Ingår i: Proceedings of SPIE. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- Images with nanoscale resolution were obtained in both transmission and reflection modes using a full-field microscope that is illuminated by an extremely compact λ = 46.9 nm (hv = 26.4 eV) soft x-ray laser. The microscope was used to image the surface of partially processed silicon semiconductor chips containing periodic patterns of polysilicon and metal lines. To characterize the microscope, modulation transfer functions were experimentally built for three different objective zone plates, and images with near-wavelength resolution were obtained.
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| 5. |
- Brewer, Courtney A., et al.
(författare)
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Single-shot extreme ultraviolet laser imaging of nanostructures with wavelength resolution
- 2008
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 33:5, s. 518-520
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated near-wavelength resolution microscopy in the extreme ultraviolet. Images of 50 nm diameter nanotubes were obtained with a single ~1 ns duration pulse from a desktop-size 46.9 nm laser. We measured the modulation transfer function of the microscope for three different numerical aperture zone plate objectives, demonstrating that 54 nm half-period structures can be resolved. The combination of near-wavelength spatial resolution and high temporal resolution opens myriad opportunities in imaging, such as the ability to directly investigate dynamics of nanoscale structures.
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| 6. |
- Brizuela, Fernando, et al.
(författare)
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Extreme ultraviolet laser-based table-top aerial image metrology of lithographic masks
- 2010
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 18:14, s. 14467-14473
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Tidskriftsartikel (refereegranskat)abstract
- We have realized the first demonstration of a table-top aerial imaging microscope capable of characterizing pattern and defect printability in extreme ultraviolet lithography masks. The microscope combines the output of a 13.2 nm wavelength, table-top, plasma-based, EUV laser with zone plate optics to mimic the imaging conditions of an EUV lithographic stepper. We have characterized the illumination of the system and performed line-edge roughness measurements on an EUVL mask. The results open a path for the development of a compact aerial imaging microscope for high-volume manufacturing.
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| 7. |
- Brizuela, Fernando, et al.
(författare)
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Imaging at the Nanoscale With Practical Table-Top EUV Laser-Based Full-Field Microscopes
- 2012
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 18:1, s. 434-442
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Tidskriftsartikel (refereegranskat)abstract
- The demonstration of table-top high average power extreme-ultraviolet (EUV) lasers combined with the engineering of specialized optics has enabled the demonstration of full-field microscopes that have achieved tens of nanometer spatial resolution. This paper describes the geometry of the EUV microscopes tailored to specific imaging applications. The microscope illumination characteristics are assessed and an analysis on the microscope's spatial resolution is presented. Examples of the capabilities of these table-top EUV aerial microscopes for imaging nanostructures and surfaces are presented.
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| 8. |
- Brizuela, Fernando, et al.
(författare)
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Table-top Extreme Ultraviolet Laser Aerial Imaging of Lithographic Masks
- 2010
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Ingår i: 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS). - 9781557528902
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Konferensbidrag (refereegranskat)abstract
- We report the first at-wavelength line edge roughness measurements of patterned EUV lithography masks realized using a table-top aerial imaging system based on a table-top lambda=13.2 laser.
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| 9. |
- Martz, Dale, 1982-
(författare)
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DEVELOPMENT OF A HIGH ENERGY TI:SAPPHIRE LASER FOR THE EXCITATION OF EXTREME ULTRAVIOLET LASERS
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation describes the design, construction and characterization of a high energy chirped-pulse amplification Titanium-Sapphire laser system for the excitation of Extreme Ultraviolet (EUV) lasers. Compact EUV lasers have made possible nano-scale imaging, dense plasma diagnostics and photo-chemistry and photo-physics studies. They also have the potential to make possible a variety of new studies of surfaces and materials and enable the development of unique metrology and processing tools for industry. The components developed to realize high energy operation of the Titanium-Sapphire laser include the development of a Nd:Glass zig-zag slab pump laser and novel 800 nm multi-layer dielectric diffraction gratings for picosecond compression. The Titanium-Sapphire laser was used to pump several table-top EUV lasers. Increased average power operation of a 13.9 nm nickel-like silver laser generating 20 ?W was demonstrated. This is the highest average power obtained from a compact EUV laser to date. Injection seeding of the 13.9 nm EUV amplifier produced laser beams with greatly improved beam characteristics which includes a large reduction in beam divergence and a near Gaussian far-field profile. The laser was also used to pump a gain-saturated table-top laser at 10.9 nm in nickel-like tellurium.
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| 10. |
- Rohringer, Nina, et al.
(författare)
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Atomic and Molecular Inner-Shell X-Ray Lasers
- 2012
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Ingår i: Frontiers in Optics 2012/Laser Science XXVIII. - : OSA. - 9781557529565
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Konferensbidrag (refereegranskat)abstract
- We present experimental results on the first realization of an atomic inner-shell x-ray laser and x-ray Raman laser in the KeV photon-energy regime in Neon. Extension of the scheme to diatomic molecules is discussed.
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