Search for a light Higgs resonance in radiative decays of the ϒ ( 1 S ) with a charm tag
Not Available
Lees, J. P.↗
Engineering topics
Chen, C.
Publications and source records attributed to Chen, C..
The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films
The prevention of tritium losses via permeation through structure components is an important issue in fusion technology. The production of thin layers on materials with low diffusivity and/or low surface recombination constants (so-called permeation barriers) seems to be the most practical method to reduce or hinder the permeation of tritium through materials. TiN+TiC+TiN multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel by ion-beam assisted deposition technology. The characteristics of films are tested by XPS ASEM and XRD, which shows that the film are compact and uniform with a thickness of about 15 μm, and have a good adherence with the substrate below 773 K. The diffraction peaks in the XRD patterns for TiC and TiN are broadened, implying that the multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel. Meanwhile, the C-H bonded CH{sub 4}-appears in the infrared spectra of multiple films, suggesting that the CH{sub 4}- is in a static state, so hydrogen atom cannot migrate from the site bonded with carbon to a neighboring site. The measured deuterium permeability in 1Cr18Ni9Ti stainless steel coated with multiple films is 2-3 orders of magnitude lower than that of pure 1Cr18Ni9Ti stainless steel substrate from 473 K to 773 K. However, this barrier is partly destroyed above 773 K.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DNA binding by FOXP3 domain-swapped dimer suggests mechanisms of long-range chromosomal interactions
FOXP3 is a lineage-specific transcription factor that is required for regulatory T cell development and function. In this study, we determined the crystal structure of the FOXP3 forkhead domain bound to DNA. The structure reveals that FOXP3 can form a stable domain-swapped dimer to bridge DNA in the absence of cofactors, suggesting that FOXP3 may play a role in long-range gene interactions. To test this hypothesis, we used circular chromosome conformation capture coupled with high throughput sequencing (4C-seq) to analyze FOXP3-dependent genomic contacts around a known FOXP3-bound locus, Ptpn22. Our studies reveal that FOXP3 induces significant changes in the chromatin contacts between the Ptpn22 locus and other Foxp3-regulated genes, reflecting a mechanism by which FOXP3 reorganizes the genome architecture to coordinate the expression of its target genes. Our results suggest that FOXP3 mediates long-range chromatin interactions as part of its mechanisms to regulate specific gene expression in regulatory T cells.
59 BASIC BIOLOGICAL SCIENCES↗
Measurement of Double-Polarization Asymmetries in the Quasielastic He → 3 ( e → , e ' d ) Process
We present a precise measurement of double-polarization asymmetries in the 3 He(e,e'd) reaction. This particular process is a uniquely sensitive probe of hadron dynamics in 3He and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasi-elastic kinematics at Q 2 =0.25(GeV/c) 2 for missing momenta up to 270MeV/c. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on pm and omega, but are systematically offset. Beyond the region of the quasi-elastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two- and/or three-body dynamics is required.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Measurement of “pretzelosity” asymmetry of charged pion production in semi-inclusive deep inelastic scattering on a polarized He 3 target
An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized ³He target was performed at Jefferson Lab in the kinematic region of 0.16 < x < 0.35 and 1.4 < Q² < 2.7 GeV². Our results show that both π ± on 3 He and on neutron pretzelosity asymmetries are consistent with zero within experimental uncertainties.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
The Physics of the B Factories
This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary version of the Physics of the B Factories book. This uses the notation alpha, beta, gamma for the angles of the Unitarity Triangle. The nominal version uses the notation phi_1, phi_2 and phi_3. Please cite this work as Eur. Phys. J. C74 (2014) 3026.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Single spin asymmetries in charged kaon production from semi-inclusive deep inelastic scattering on a transversely polarized He 3 target
We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3He target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1 < x bj <0.4 for K + and K – production. While the Collins and Sivers moments for K + are consistent with zero within the experimental uncertainties, both moments for K – favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While the K + Sivers moments are consistent with the prediction, the K – results differ from the prediction at the 2-sigma level.
43 PARTICLE ACCELERATORS↗
Nanodot formation induced by femtosecond laser irradiation
The femtosecond laser generation of ZnSe nanoscale features on ZnSe surfaces was studied. Irradiation with multiple exposures produces 10–100 nm agglomerations of nanocrystalline ZnSe while retaining the original single crystal structure of the underlying material. The structure of these nanodots was verified using a combination of scanning transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The nanodots continue to grow hours after irradiation through a combination of bulk and surface diffusion. We suggest that in nanodot formation the result of ultrafast laser induced point defect formation is more than an order of magnitude below the ZnSe ultrafast melt threshold fluence. This unique mechanism of point defect injection will be discussed.
36 MATERIALS SCIENCE↗
Resistive switching and conductance quantization in Ag/SiO{sub 2}/indium tin oxide resistive memories
The Ag/SiO{sub 2}/indium tin oxide (ITO) devices exhibit bipolar resistive switching with a large memory window of ∼10{sup 2}, satisfactory endurance of >500 cycles, good retention property of >2000 s, and fast operation speed of <100 ns, thus being a type of promising resistive memory. Under slow voltage sweep measurements, conductance plateaus with a conductance value of integer or half-integer multiples of single atomic point contact have been observed, which agree well with the physical phenomenon of conductance quantization. More importantly, the Ag/SiO{sub 2}/ITO devices exhibit more distinct quantized conductance plateaus under pulse measurements, thereby showing the potential for realizing ultra-high storage density.
36 MATERIALS SCIENCE↗
A 60 Gb/s MDM-WDM Si photonic link with less than 0.7dB power penalty per channel
N/A
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Measurement of the Target-Normal Single-Spin Asymmetry in Deep-Inelastic Scattering from the Reaction He 3 ↑ ( e , e ' ) X
We report here the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction He 3 ↑ ( e , e ' ) X on a polarized He 3 gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.7 < W < 2.9 GeV , 1.0 < Q 2 < 4.0 GeV 2 and 0.16 < x < 0.65 . Neutron asymmetries were extracted using the effective nucleon polarization and measured proton-to- He 3 cross-section ratios. The measured neutron asymmetries shown are negative with an average value of ( - 1.09 ± 0.38 ) × 1 0 - 2 for invariant mass W > 2 GeV , which is nonzero at the 2.89 σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Excitonic effects from geometric order and disorder explain broadband optical absorption in eumelanin
Explore the source record for details and available documents.
solar (photovoltaic), solid state lighting, photos↗
Transparent capacitors based on nanolaminate Al{sub 2}O{sub 3}/TiO{sub 2}/Al{sub 2}O{sub 3} with H{sub 2}O and O{sub 3} as oxidizers
Transparent capacitors with nanolaminate Al{sub 2}O{sub 3}/TiO{sub 2}/Al{sub 2}O{sub 3} (ATA) hybrid dielectrics have been prepared on quartz glass by atomic layer deposition. The maximal capacitance density of 14 fF/μm{sup 2} at 1 kHz was obtained. Moreover, an ultralow leakage current density of 2.1 × 10{sup −9} A/cm{sup 2} at 1 V was realized by using O{sub 3} as the oxidizer. Fowler-Nordheim tunneling is the main mechanism of the leakage current at high fields, while several conduction mechanisms coexist at low fields. The AlZnO/ATA/AlZnO transparent capacitors exhibit an average optical transmittance of more than 80% in the visible range, which serve as good candidates for integration in transparent circuits.
36 MATERIALS SCIENCE↗
Single spin asymmetries of inclusive hadrons produced in electron scattering from a transversely polarized 3 He target
We report the first measurement of target single-spin asymmetries (A N ) in the inclusive hadron production reaction, e + 3 He↑→h+X, using a transversely polarized 3 He target. This experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons (π ± , K ± and proton) were detected in the transverse hadron momentum range 0.54 < p T < 0.74 GeV/c. The range of x F for pions was -0.29 < x F < -0.23 and for kaons -0.25 < x F <-0.18. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for π + and K + . A negative asymmetry is observed for π–. The magnitudes of the asymmetries follow |A π – |<|A π + |<|A K + |. The K – and proton asymmetries are consistent with zero within the experimental uncertainties. The π + and π – asymmetries measured for the 3 He target and extracted for neutrons are opposite in sign with a small increase observed as a function of p T .
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Highly Crystalline Multimetallic Nanoframes with Three-Dimensional Electrocatalytic Surfaces
Control of structure at the atomic level can precisely and effectively tune catalytic properties of materials, enabling enhancement in both activity and durability. We synthesized a highly active and durable class of electrocatalysts by exploiting the structural evolution of platinum-nickel (Pt-Ni) bimetallic nanocrystals. The starting material, crystalline PtNi 3 polyhedra, transforms in solution by interior erosion into Pt 3 Ni nanoframes with surfaces that offer three-dimensional molecular accessibility. The edges of the Pt-rich PtNi 3 polyhedra are maintained in the final Pt 3 Ni nanoframes. Both the interior and exterior catalytic surfaces of this open-framework structure are composed of the nanosegregated Pt-skin structure, which exhibits enhanced oxygen reduction reaction (ORR) activity. The Pt 3 Ni nanoframe catalysts achieved a factor of 36 enhancement in mass activity and a factor of 22 enhancement in specific activity, respectively, for this reaction (relative to state-of-the-art platinum-carbon catalysts) during prolonged exposure to reaction conditions.
36 MATERIALS SCIENCE↗