CLIC Drive Beam and LHC Based Fel-Nucleus Collider

The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.Comment: Presented at PAC05, 16-20 May 2005, Knoxville, TN, US

Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet

Ruthenium compounds play prominent roles in materials research ranging from oxide electronics to catalysis, and serve as a platform for fundamental concepts such as spin-triplet superconductivity, Kitaev spin-liquids, and solid-state analogues of the Higgs mode in particle physics. However, basic questions about the electronic structure of ruthenates remain unanswered, because several key parameters (including the Hund's-rule, spin-orbit, and exchange interactions) are comparable in magnitude, and their interplay is poorly understood - partly due to difficulties in synthesizing sizable single crystals for spectroscopic experiments. Here we introduce a resonant inelastic x-ray scattering (RIXS) technique capable of probing collective modes in microcrystals of $4d$-electron materials. We present a comprehensive set of data on spin waves and spin-state transitions in the honeycomb antiferromagnet SrRu$_{2}$O$_{6}$, which possesses an unusually high N\'eel temperature. The new RIXS method provides fresh insight into the unconventional magnetism of SrRu$_{2}$O$_{6}$, and enables momentum-resolved spectroscopy of a large class of $4d$ transition-metal compounds.Comment: The original submitted version of the published manuscript. https://www.nature.com/articles/s41563-019-0327-

Single top or bottom production associated with a scalar in \gamma p collision as a probe of topcolor-assisted technicolor

In the framework of the topcolor-assisted technicolor (TC2) models, we study the productions of a single top or bottom quark associated with a scalar in \gamma-p collision, which proceed via the subprocesses c\gamma -> t\pi_t^0, c\gamma -> t h_t^0 and c\gamma -> b\pi^+_t mediated by the anomalous top or bottom coupling tc\pi_t^0, tch_t^0 and bc\pi_t^+. These productions, while extremely suppressed in the Standard Model, are found to be significantly enhanced in the large part of the TC2 parameter space, especially the production via c\gamma -> b\pi^+ can have a cross section of 100 fb, which may be accessible and allow for a test of the TC2 models.Comment: 13 pages, 4 figures, comments and references adde

1 mJ pulse bursts from a Yb-doped fiber amplifier

Cataloged from PDF version of article.We demonstrate burst-mode operation of a polarization-maintaining Yb-doped fiber amplifier capable of generating 60 mu J pulses within bursts of 11 pulses with extremely uniform energy distribution facilitated by a novel feedback mechanism shaping the seed of the burst-mode amplifier. The burst energy can be scaled up to 1 mJ, comprising 25 pulses with 40 mu J average individual energy. The amplifier is synchronously pulse pumped to minimize amplified spontaneous emission between the bursts. Pulse propagation is entirely in fiber and fiber-integrated components until the grating compressor, which allows for highly robust operation. The burst repetition rate is set to 1 kHz and spacing between individual pulses is 10 ns. The 40 mu J pulses are externally compressible to a full width at half-maximum of 600 fs. However, due to the substantial pedestal of the compressed pulses, the effective pulse duration is longer, estimated to be 1.2 ps. (C) 2012 Optical Society of Americ

CLIC-LHC Based FEL-Nucleus Collider: Feasibility and Physics Search Potential

The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The tunability, monochromaticity and high polarization of the FEL beam together with high statistics and huge energy of LHC nucleus beams will give an unique opportunity to determine different characteristics of excited nuclear levels. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.Comment: 19 pages, 3 figure

Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering

We show that high resolution Resonant Inelastic X-ray Scattering (RIXS) provides direct, element-specific and momentum-resolved information on the electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates that the e-p coupling can be extracted from RIXS spectra by determining the differential phonon scattering cross section. An alternative, very direct manner to extract the coupling is to use the one and two-phonon loss ratio, which is governed by the e-p coupling strength and the core-hole life-time. This allows measurement of the e-p coupling on an absolute energy scale.Comment: 4 pages, 3 figure

Development of a rapid-scan fiber-integrated terahertz spectrometer

Scientists in terahertz (THz) wave technologies have benefited from the recent developments in ultrafast laser technologies and RF technologies and applied these new gained techniques into characterizing a wide variety of phenomena. Undoubtedly, the most successful of these applications has been in the development of time-domain terahertz spectroscopic and imaging systems which has been utilized in the characterization of dielectrics and semiconductors. This pulsed technique has allowed users to characterize dynamical behavior inside materials under illumination with picosecond resolution. Typically pump/probe or similar dynamical measurements require the use of amplified pulses derived from free-space solid state lasers in the μJ-mJ range and since interferometric techniques are typically used in pulsed measurements the measurement time of a THz spectrum can last at least tens of minutes. Better systems can be realized based on fiber laser technologies. Here we discuss the advantages of a THz spectrometer driven by an ultrafast Ytterbium doped fiber laser whose repetition rate can be tuned rapidly allowing for rapid dynamical measurements. The efficient gain medium, robust operation and compact design of the system opens up the possibility of exploring rapid detection of various materials as well as studying dynamical behavior using the high brightness source. © 2013 Springer Science+Business Media New York

Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers

Cataloged from PDF version of article.We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule- and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns. (C) 2011 Optical Society of Americ

High-speed, thermal damage-free ablation of brain tissue with femtosecond pulse bursts

We report a novel ultrafast burst mode fiber laser system and results on ablation of rat brain tissue at rates approaching an order of magnitude improvement over previous reports, with no discernible thermal damage. © 2015 IEEE

Repetition rate tuning of an ultrafast ytterbium doped fiber laser for terahertz time-domain spectroscopy

Repetition rate tuning enables the fast acquisition of THz pulse profiles [1]. By using this method we demonstrate a compact and broadband terahertz time domain spectroscopy system (THz TDS) driven by ytterbium doped fiber laser source. The importance of this method is realized in that Yb:doped fiber lasers can be amplified to sub-millijoule pulse strengths more easily than other types of fiber lasers [2]. Hence, it has the potential to be used in excite-THz probe experiments. Furthermore, the repetition rate-tuning adds flexibility in the excite-probe techniques. These attributes as well as THz generation and detection are investigated with the laser that was developed. © 2013 IEEE