Thermodynamic Properties of Block Copolymer Electrolytes Containing Imidazolium and Lithium Salts

We report on the thermal properties, phase behavior, and thermodynamics of a series of polystyrene-block-poly(ethylene oxide) copolymers (SEO) mixed with the ionic species Li[N(SO_(2)CF_3)_2] (LiTFSI), imidazolium TFSI (ImTFSI), and an equimolar mixture of LiTFSI and ImTFSI (Mix). Differential scanning calorimetric scans reveal similar thermal behavior of SEO/LiTFSI and SEO/ImTFSI at the same salt concentrations. Phase behavior and thermodynamics were determined using a combination of small-angle X-ray scattering and birefringence. The thermodynamics of our mixtures can be mapped on to the theory of neat block copolymer phase behavior provided the Flory−Huggins interaction parameter, χ, between the blocks is replaced by an effective χ (χ_(eff)) that increases linearly with salt concentration. The phase behavior and the value of m, the slope of the χ_(eff) versus salt concentration data, were similar for SEO/LiTFSI, SEO/ImTFSI, and SEO/Mix blends. The theory developed by Wang [ J. Phys. Chem. B. 2008, 41, 16205] provides a basis for understanding the fundamental underpinnings of the measured value of m. We compare our experimental results with the predictions of this theory with no adjustable parameters

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Analysis of Order Formation in Block Copolymer Thin Films Using Resonant Soft X-Ray Scattering

The lateral order of poly(styrene-block-isoprene) copolymer (PS-b-PI) thin films is characterized by the emerging technique of resonant soft X-ray scattering (RSOXS) at the carbon K edge and compared to ordering in bulk samples of the same materials measured using conventional small-angle X-ray scattering. We show resonance using theory and experiment that the loss of scattering intensity expected with a decrease in sample volume in the case of thin films can be overcome by tuning X-rays to the pi* resonance of PS or PI. Using RSOXS, we study the microphase ordering of cylinder- and phere-forming PS-b-PI thin films and compare these results to position space data obtained by atomic force microscopy. Our ability to examine large sample areas (~;9000 mu m2) by RSOXS enables unambiguous identification of the lateral lattice structure in the thin films. In the case of the sphere-forming copolymer thin film, where the spheres are hexagonally arranged, the average sphere-to-sphere spacing is between the bulk (body-centered cubic) nearest neighbor and bulk unit cell spacings. In the case of the cylinder-forming copolymer thin film, the cylinder-to-cylinder spacing is within experimental error of that obtained in the bulk

Analysis of Order Formation in Block Copolymer Thin Films Using Resonant Soft X-ray Scattering

Abstract The lateral order of poly(styrene-block-isoprene) copolymer (PS-b-PI) thin films is characterized by the emerging technique of resonant soft X-ray scattering (RSOXS) at the carbon K edge and compared to ordering in bulk samples of the same materials measured using hard Xray small-angle scattering. We show using theory and experiment that the loss of scattering intensity expected with a decrease in sample volume can be overcome by tuning X-rays to the π* resonance of PS or PI. Using RSOXS, we study the microphase ordering of cylinder and sphere forming PS-b-PI thin films and compare these results to position space data obtained by atomic force microscopy. Our ability to examine large sample areas (~9000 µm 2 ) by RSOXS enables unambiguous identification of the lateral lattice structure in the thin films. In the case of the sphere forming copolymer thin film, where the spheres are hexagonally arranged, the average sphere-to-sphere spacing is between the bulk (body centered cubic) nearest neighbor and bulk unit cell spacings. In the case of the cylinder forming copolymer thin film, the cylinder-tocylinder spacing is within experimental error of that obtained in the bulk.

Direct observation of the dead-cone effect in quantum chromodynamics

The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron

Direct observation of the dead-cone effect in quantum chromodynamics

At particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD) [1]. The vacuum is not transparent to the partons and induces gluon radiation and quark pair production in a process that can be described as a parton shower [2]. Studying the pattern of the parton shower is one of the key experimental tools in understanding the properties of QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass m and energy E, within a cone of angular size m/E around the emitter [3]. A direct observation of the dead-cone effect in QCD has not been possible until now, due to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible bound hadronic states. Here we show the first direct observation of the QCD dead-cone by using new iterative declustering techniques [4, 5] to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD, which is derived more generally from its origin as a gauge quantum field theory. Furthermore, the measurement of a dead-cone angle constitutes the first direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron.In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD). These partons subsequently emit further partons in a process that can be described as a parton shower which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass $m_{\rm{Q}}$ and energy $E$, within a cone of angular size $m_{\rm{Q}}$/$E$ around the emitter. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics

Measurement of the lifetime and Λ separation energy of 3ΛH

The most precise measurements to date of the 3ΛH lifetime τ and Λ separation energy BΛ are obtained using the data sample of Pb-Pb collisions at √= 5.02 TeV collected by ALICE at the LHC. The 3ΛH is reconsNN structed via its charged two-body mesonic decay channel (3ΛH→ 3He + π− and the charge-conjugate process). The measured values τ=[253±11 (stat.)±6 (syst.)] ps and BΛ=[102±63 (stat.)±67 (syst.)] keV are compatible with predictions from effective field theories and confirm that the 3ΛH structure is consistent with a weakly-bound system