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Group Theory for High-Energy Physics
No full textRepresentations of the Lorentz groupGroup factors for beta functions and anomaly coefficients Grand unification groupsHomotopy groups and semiclassical objects in QF
Modulations in magnetostructural coupling in C and Sn deficient
No full textThe structural and magnetic interactions in stoichiometric (Mn3SnC), carbon deficient (Mn3Sn) and tin deficient (Mn3C) antiperovskite compounds are studied using X-ray absorption fine structure spectroscopy and neutron diffraction. The study confirms the presence of local structural distortions only around Mn atoms in the antiperovskite compounds irrespective of their stoichiometry. The distortions in the Mn6C octahedra are such that only Mn atoms are displaced from their crystallographic positions resulting in long and short Mn–Mn bonds. These long and short Mn–Mn bonds are responsible for the presence of ferromagnetic and antiferromagnetic moments on Mn atoms. The C deficiency at the center of the octahedra increases the strain on the Mn6C octahedra and results in a wide variation of Mn–Mn bond distances as a function of temperature and large hysteresis in magnetic properties. On the other hand, Sn deficiency tends to relax strain by giving more space for the octahedra to distort leading to temperature independent Mn–Mn bond distances
Frequency-Detuning Dependent Transient Coaxial RF Coupler Kick in an L -Band Long-Pulse High-Gradient RF Photogun
No full textA transverse kick resulting from the coaxial rf coupler in the L-band rf gun at the photoinjector test facility at DESY in Zeuthen (PITZ) has been systematically studied in simulations and further characterized in experiments. The used rf macro-pulse for the gun is typically 600 μs long and applied to produce a train of up to 2700 electron bunches. The kick is transient and found to be dependent on the detuning of the resonance frequency of the gun cavity. The frequency detuning within the rf pulse results in a variation in the kick strength along the pulse. This leads to a downstream orbit and size change of individual bunches within the train. Using 3D rf field distributions, calculated at resonant and detuned frequencies of the cavity, particle tracking simulations are performed to evaluate the integral kick location and strength, simulate its transient behaviors with respect to gun launch phase and detuned frequency of the gun cavity, and thereby emulate its impacts onto the electron bunch. In the experiments, the temperature of the cooling water for the gun is tuned, allowing detailed characterization of the frequency detuning within the rf pulse and thus measurements of the kick which are of practical interest for machine operation. The resulting orbit and size change along a 240 μs bunch train have been measured downstream at the injector exit for an rf gun peak power of about 5.7 MW. A measured focusing difference between head and tail of the bunch train is evaluated in terms of the gun solenoid current which provides more relevant information for overall tuning of the FELs. This is exemplarily given for both the under- and over-focusing case. The obtained results will be presented and discussed
Finite family groups for fermionic and leptoquark mixing patterns
No full textWe employ a bottom-up and model-independent technique to search for non-Abelian discrete flavour symmetries capable of predicting viable CKM and PMNS matrices alongside of special patterns of leptoquark couplings. In particular, we analyze patterns de- rived when an ultra-violet flavour theory is assumed to break to global Abelian symmetries in Standard Model fermion masses and new Yukawa-like terms sourced by the leptoquark representation. The phenomenology of different classes of these ‘simplified models’ can be explored without reference to explicit model-building assumptions, e.g. the nature of flavour symmetry breaking or any additional field content associated to it, and are also capable of explaining hints of lepton non-universality in . Assuming experimentally interesting CKM and PMNS matrix elements, our algorithm finds an abundance of predictive non-Abelian flavour groups and therefore provides promising directions for future model building in the flavoured leptoquark space, regardless of whether the anomalous measurements withstand further experimental scrutiny
-Containing Clinoptilolite as a Composite Photocatalyst for Dyes Removal from Wastewater under Solar Light
No full textDue to their adsorbent, ion exchange and catalytic properties zeolites are suitable for avariety of applications. We report on the photocatalytic activity of a readily available and inexpensivenatural zeolite clinoptilolite (Z) containing SnO2 (Sn-Z). The Sn-Z samples with 3–15 wt. % of Sn wereprepared by using a precipitation–deposition method. Powder X-ray diraction analysis showed thatthe zeolite structure was unaected by the introduction of the Sn-phase. Diuse reflectance UV/VISspectra of the Sn-Z samples confirmed the presence of SnO2 and X-Ray absorption spectroscopyanalyses suggested that the SnO2 particles mainly resided on the surface of the clinoptilolite, whileATR-FTIR analysis gave some clues that part of the SnO2 phase was incorporated in the pores ofthe zeolite. The presence of SnO2 in Sn-Z increased both adsorption capacity and photocatalyticperformance which could be partially explained by higher surface area and partially with an increasednegative potential of the surface. Adsorption and total degradation of methylene blue (MB) for theSn-Z with the highest amount of Sn (15 wt.%) was about 30% and 45%, respectively, suggesting asynergetic eect between SnO2 and the clinoptilolite lattice. Reusability tests showed that thesecatalysts present a promising material for water purification
IRIXS: a resonant inelastic X-ray scattering instrument dedicated to X-rays in the intermediate energy range
No full textA new resonant inelastic X-ray scattering (RIXS) instrument has beenconstructed at beamline P01 of the PETRA III synchrotron. This instrumenthas been named IRIXS (intermediate X-ray energy RIXS) and is dedicated toX-rays in the tender-energy regime (2.5–3.5 keV). The range covers the L2,3absorption edges of many of the 4d elements (Mo, Tc, Ru, Rh, Pd and Ag),offering a unique opportunity to study their low-energy magnetic and chargeexcitations. The IRIXS instrument is currently operating at the Ru L3-edge(2840 eV) but can be extended to the other 4d elements using the existingconcept. The incoming photons are monochromated with a four-bounce Si(111)monochromator, while the energy analysis of the outgoing photons is performedby a diced spherical crystal analyzer featuring (102) lattice planes of quartz(SiO2). A total resolution of 100 meV (full width at half-maximum) has beenachieved at the Ru L3-edge, a number that is in excellent agreement with raytracing simulations
Carbon heterogeneities in austenite during Quenching & Partitioning (Q&P) process revealed by in situ High Energy X-Ray Diffraction (HEXRD) experiments
No full textBased on the evolution of the positions and intensities of the diffraction peaks, high energy X-ray diffraction (HEXRD) is recognized as the ultimate method to follow quantitatively in situ phase transformations in steels. However, the possible asymmetricity of diffraction peaks is seldom considered, and is known to bear information. A procedure for quantifying their skewness is proposed. In the case of a third generation high strength steel obtained by quench and partitioning (Q&P), the skewness is shown to be due to carbon heterogeneities at austenite/martensite interfaces developed at nanoscale, in agreement with prior post mortem atom probe tomography (APT) investigations
Technical Introduction to the WHIZARD generator
No full textThis is a technical overview on the installation, usage and techical as well as physics capabilities of the WHIZARD event generator