Search results for "sironta"
showing 10 items of 48 documents
Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers
2019
Plasmonic oligomers can provide profound Fano resonance in their scattering responses. The sub-radiant mode of Fano resonance can result in significant near-field enhancement due to its light trapping capability into the so-called hotspots. Appearance of these highly localized hotspots at the excitation and/or Stokes wavelengths of the analytes makes such oligomers promising SERS active substrates. In this work, we numerically and experimentally investigate optical properties of two disk-type gold oligomers, which have different strength and origin of Fano resonance. Raman analysis of rhodamine 6G and adenine with the presence of the fabricated oligomers clearly indicates that an increment …
Fixed angle inverse scattering in the presence of a Riemannian metric
2020
We consider a fixed angle inverse scattering problem in the presence of a known Riemannian metric. First, assuming a no caustics condition, we study the direct problem by utilizing the progressing wave expansion. Under a symmetry assumption on the metric, we obtain uniqueness and stability results in the inverse scattering problem for a potential with data generated by two incident waves from opposite directions. Further, similar results are given using one measurement provided the potential also satisfies a symmetry assumption. This work extends the results of [23,24] from the Euclidean case to certain Riemannian metrics.
Study of elastic and inelastic scattering of $^7$Be + $^{12}$C at 35 MeV
2022
6 pags., 5 figs., 2 tabs.
Kaon–proton strong interaction at low relative momentum via femtoscopy in Pb–Pb collisions at the LHC
2021
In quantum scattering processes between two particles, aspects characterizing the strong and Coulomb forces can be observed in kinematic distributions of the particle pairs. The sensitivity to the interaction potential reaches a maximum at low relative momentum and vanishing distance between the two particles. Ultrarelativistic heavy-ion collisions at the LHC provide an abundant source of many hadron species and can be employed as a measurement method of scattering parameters that is complementary to scattering experiments. This study confirms that momentum correlations of particles produced in Pb–Pb collisions at the LHC provide an accurate measurement of kaon–proton scattering parameters …
First microscopic evaluation of spin-dependent WIMP-nucleus scattering off 183W
2021
We perform the first consistent calculation of elastic-scattering and inelastic-scattering structure functions for spin-dependent WIMP-nucleus scattering for 183W in a microscopic nuclear-theory framework. The nuclear structure calculations are performed in the microscopic interacting boson-fermion model (IBFM-2). Our results show that while 183W is very insensitive to spin-dependent elastic scattering, the structure function for inelastic scattering is quite sizable at small momentum transfers. Moreover, to our knowledge 183W provides the first studied case where inelastic scattering can compete with elastic scattering as the primary detection signal. peerReviewed
High-resolution scattering experiments at the K130 cyclotron in Jyväskylä
2018
Abstract An experimental setup for nuclear reaction studies induced by light and heavy ions is described. It consists of a versatile Large Scattering Chamber equipped with two rotating tables for mounting detectors. A dedicated beam diagnostic system is used to monitor the energy spectrum of the beam on target. The system provides the necessary feedback for tuning of the K-130 cyclotron to reduce the energy spread of the accelerated beam by at least a factor of 3 down to about 0.3% of the nominal energy while maintaining beam currents around 20 pnA. At lower beam currents a 0.1% energy spread can be achieved. This improvement makes a significant impact on the scope of reaction studies possi…
Controllability method for the Helmholtz equation with higher-order discretizations
2007
We consider a controllability technique for the numerical solution of the Helmholtz equation. The original time-harmonic equation is represented as an exact controllability problem for the time-dependent wave equation. This problem is then formulated as a least-squares optimization problem, which is solved by the conjugate gradient method. Such an approach was first suggested and developed in the 1990s by French researchers and we introduce some improvements to its practical realization. We use higher-order spectral elements for spatial discretization, which leads to high accuracy and lumped mass matrices. Higher-order approximation reduces the pollution effect associated with finite elemen…
Factorization of the soft gluon divergence from the dipole picture deep inelastic scattering cross sections at next-to-leading order
2018
We use a factorization scheme analogous to one proposed for single inclusive forward hadron production to factorize the soft gluon divergence present in the deep inelastic scattering cross sections in the dipole picture at next-to-leading order (NLO). We show numerically that in this carefully constructed scheme it is possible to obtain meaningful results for the DIS cross sections at NLO, and so we are able to quantitatively study the recently derived NLO corrections to the DIS cross sections. We find that the NLO corrections can be significant and sensitive to the details of the factorization scheme used for the resummation of the large logarithms into the BK evolution equation. In the ca…
Multigluon Correlations and Evidence of Saturation from Dijet Measurements at an Electron-Ion Collider.
2020
We study inclusive and diffractive dijet production in electron-proton and electron-nucleus collisions within the Color Glass Condensate effective field theory. We compute dijet cross sections differentially in both mean dijet transverse momentum $\mathbf{P}$ and recoil momentum $\mathbf{\Delta}$, as well as the anisotropy in the relative angle between $\mathbf{P}$ and $\mathbf{\Delta}$. We use the nonlinear Gaussian approximation to compute multiparticle correlators for general small $x$ kinematics, employing running coupling Balitsky-Kovchegov evolution to determine the dipole amplitude at small $x$. Our results cover a much larger kinematic range than accessible in previous computations …
Time-Resolved Coherent Anti-Stokes Raman Scattering of Graphene: Dephasing Dynamics of Optical Phonon.
2017
We report dynamics of the G-mode in graphene probed with time-resolved coherent anti-Stokes Raman scattering measurements. By applying BOXCARS excitation geometry with three different excitation wavelengths, various nonlinear processes can be selectively detected due to energy and momentum conservation and temporal sequence of the pulses. The Raman signal due to resonant coherent excitation of the G-mode shows exponential decay with lifetime of ∼325 ± 50 fs. This decay time is shorter than expected based on the line width of the G-mode in the Raman spectrum. We propose that the unexpectedly short dephasing time is a result of dynamic variation of nonadiabatic coupling of the photoexcited el…