14N and35Cl nuclear quadrupole double resonance study of the structural phase transitions in N-octylammoniumchloride

The structural phase transitions between the non-intercalated phases of the layer structure compound N-octylammoniumchloride have been studied via proton-¹⁴N and proton-³⁵Cl nuclear quadrupole double resonance. The results have been related to an order-disorder model of the octylammonium chains. The temperature dependence of the order parameters of the –NH₃ head groups has been determined.     

Detection of a second Br site in K2Pt(CN)4Br0.3 3.2 H2O (KCP) by 18Br and 39K NMR

By nuclear magnetic resonance we have detected between 20 and 300 K two bromine signals with a temperature-independent intensity ratio of 2.5 ± 0.3 proving the existence of a second Br site in KCP. The result is supported by the observation of three potassium signals. Thus, three types of unit cells exist: 40% contain defect water, 43% have Br in site I and 17% Br in site II.     

Particle-yield modification in jetlike azimuthal dihadron correlations in Pb-Pb collisions at √s(NN)=2.76 TeV

The yield of charged particles associated with high-p(t) trigger particles (83 GeV/c on the away side drops to about 60% of that observed in pp collisions, while on the near side a moderate enhancement of 20%-30% is found.     

NSCL/MSU ECR离子源项目进展报告

Since the last ECR Workshop,NSCL/MSU has been involved in a vigorous ECR ion source R&D program,which resulted in the construction of an off-line test ECR ion source(ARTEMIS-B)for new beam development and ion optics studies.Also the design and partial completion of a 3rd generation,fully superconducting ECR ion source,SuSI has been accomplished.This paper is an overview of the construction projects and the different R&D activities performed with the existing ion sources.These activities include development of metallic ion beam production methods using evaporation with resistive and inductive ovens and sputtering of very refractory metals.Ion optics developments include testing different focusing elements(magnetic solenoid lens,electrostatic quadrupole triplet lens,Einzel lens,electrostatic double doublet quadrupole combined with an octupole lens),and different beam forming and diagnostics devices.The detailed results will be presented at the workshop in separate talks and posters.     

Nonlinear-optical loop mirror demultiplexer using a random birefringence fiber: comparisons between simulations and experiments

A numerical simulation of the switching characteristics of a polarization multiplexed nonlinear-optical loop mirror demultiplexer is presented and compared with experiment. The model assumes that the optical fiber that composes the loop has a randomly varying birefringence, that the signal and the control pulses have the same frequency, and that these pulses are nearly solitons. Factors that affect the shape and the width of the switching window curve are discussed. A phase-dependent modulation of the switching window curve, which is due to incomplete averaging of the light polarization state, is observed both experimentally and numerically. Models in which the randomness is neglected are not able to describe this modulation adequately.     

Element-specific magnetization reversal in Fe/Ce multilayers: : a study by X-ray magnetic circular dichroism and the magneto-optic Kerr effect

Fe/Ce multilayers are magnetically soft with coercive fields of a few Oersteds. In this artificial system, the itinerant 5d electrons of Ce are magnetically polarized by hybridization with the spin–split 3d states of Fe. To obtain an insight into the magnetization reversal process, the element selectivity of X-ray magnetic circular dichroism was used to measure the magnetization of the Ce-5d electrons as a function of an applied magnetic field. Comparison with the magnetization curves studied by the magneto-optic Kerr effect, which averages over the whole system, revealed that the coercivity in the hysteresis of the ordered Ce-5d moments is reduced by 50%. We propose that this is an effect of the magnetically disturbed interface or of the complex non-collinear magnetic structure of the Ce layers detected by recent experiments of X-ray resonant magnetic scattering. The results are compared to the X-ray dichroic and Kerr hysteresis loops of the multilayers Fe/La/Ce/La and Fe/CeH_2−δ. These systems are magnetically harder and their coercivities are identical.     

Magneto-optical measurement on the layer type magnet (CH2)2(ND3)2MnCl4

The linear birefringence (LB) of the antiferromagnet (CH₂)₂(ND₃)₂MnCl₄ has been measured as a function of temperature and in magnetic fields up to 100 kOe. The temperature dependence of the LB points to a pronounced two dimensional magnetic behaviour. No anomaly corresponding to the effect of three dimensional ordering could be detected at T_N. In theffield dependent measurements the spin flop at H_SF = 33.6 ± 1 kOe (T = 4K) could clearly be detected.     

X-Ray Structure Analyses of Alkyl-Substituted N-Acryloyl- and N-Crotonoyltoluenesultams

The X-ray crystal-structure analyses of two N-enoyl-toluenesultam derivatives 1 are reported. The structural differences with their bornanesultam analogues 2 as well as stereochemical aspects with respect to their [4 + 2] and [3 + 2] cycloadditions are discussed.