3,072 research outputs found
The Decay with Highly Improved Staggered Quarks and NRQCD
We report on progress of a lattice QCD calculation of the and
semileptonic form factors. We use a relativistic staggered
action (HISQ) for light and charm quarks, and an improved non-relativistic
(NRQCD) action for bottom, on the second generation MILC ensembles.Comment: Presented at Lattice 2017, the 35th International Symposium on
Lattice Field Theory at Granada, Spain (18-24 June 2017
PDMS residues-free micro/macrostructures on flexible substrates
Transfer printing has been reported recently as a viable route for electronics on flexible substrates. The method involves transferring micro-/macrostructures such as wires or ultra-thin chips from Si (silicon) wafers to the flexible substrates by using elastomeric transfer substrates such as poly(dimethylsiloxane) (PDMS). A major challenge in this process is posed by the residues of PDMS, which are left over on Si surface after the nanostructures have been transferred. As insulator, PDMS residues make it difficult to realize metal connections and hence pose challenge in the way of using nanostructures as the building blocks for active electronics. This paper presents a method for PDMS residues-free transfer of Si micro-/macrostructures to flexible substrates such as polyimide (PI). The PDMS residues are removed from Si surface by immersing the transferred structures in a solution of quaternary ammonium fluoride such as TBAF (Tetrabutylammonium Fluoride) and non-hydroxylic aprotic solvent such as PMA (propylene glycol methyl ether acetate). The residues are removed at a rate (∼1.5 μm/min) which is about five times faster than the traditional dry etch methods. Unlike traditional alternatives, the presented method removes PDMS without attacking the flexible PI substrates
High-contrast imaging of 180{\deg} ferroelectric domains by optical microscopy using ferroelectric liquid crystals
Ferroelectric liquid crystals (FLCs) couple the direction of their
spontaneous electric polarization to the direction of tilt of their optic axis.
Consequently, reversal of the electric polarization by an electric field gives
rise to an immediate and lasting optical response when an appropriately aligned
FLC is observed between crossed polarizers, with one field direction yielding a
dark image, and the opposite direction yielding a bright image. Here this
peculiar electro-optic response is used to image, with high optical contrast,
180{\deg} ferroelectric domains in a crystalline substrate of magnesium-doped
lithium niobate. The lithium niobate substrate contains a few domains with
upwards electric polarization surrounded by regions with downward electric
polarization. In contrast to a reference non-chiral liquid crystal that is
unable to show ferroelectric behavior due to its high symmetry, the FLC, which
is used as a thin film confined between the lithium niobate substrate and an
inert aligning substrate, reveals ferroelectric domains as well as their
boundaries, with strong black and white contrast. The results show that FLCs
can be used for non-destructive read-out of domains in underlying
ferroelectrics, with potential applications in e.g. photonic devices and
non-volatile ferroelectric memories.Comment: 12 pages, 3 figure
Rapid and mask-less laser-processing technique for the fabrication of microstructures in polydimethylsiloxane
We report a rapid laser-based method for structuring polydimethylsiloxane (PDMS) on the micron-scale. This mask-less method uses a digital multi-mirror device as a spatial light modulator to produce a given spatial intensity pattern to create arbitrarily shaped structures via either ablation or multi-photon photo-polymerisation in a master substrate, which is subsequently used to cast the complementary patterns in PDMS. This patterned PDMS mould was then used for micro-contact printing of ink and biological molecules
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A Search for Dark Higgs Bosons
Recent astrophysical and terrestrial experiments have motivated the proposal
of a dark sector with GeV-scale gauge boson force carriers and new Higgs
bosons. We present a search for a dark Higgs boson using 516 fb-1 of data
collected with the BABAR detector. We do not observe a significant signal and
we set 90% confidence level upper limits on the product of the Standard
Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots
for b/w printin
ICHEP2012 Physics Highlights
I describe some of the highlights of ICHEP2012 with an eye to the current
status of particle physics.Comment: 12 pages, 5 figures, ICHEP2012, Melbourn
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