Acoustic measurement of the low-energy excitations in Nd2-xCexCuO4

The complex dynamic Young's modulus of ceramic Nd2-xCexCuO4 with x = 0, 0.05 and 0.20 has been measured from 1.5 to 100 K at frequencies of 1-10 kHz. In the undoped sample the modulus starts decreasing below ~20 K, instead of approaching a constant value as in a normal solid. The modulus minimum has been interpreted in terms of paraelastic contribution from the relaxation of the Nd^3+ 4f electrons between the levels of the ground state doublet, which is split by the interaction with the antiferromagnetically ordered Cu sublattice. The value of the splitting is found to be 0.34 meV, in excellent agreement with inelastic neutron scattering, infrared and specific heat experiments. With doping, the anomaly shifts to lower temperature and decreases in amplitude, consistently with a reduction of the local field from the Cu sublattice.Comment: 5 pages, 2 figures, submitted to Eur. Phys. J.

Holomorphic Poisson Cohomology

A holomorphic Poisson structure induces a deformation of the complex structure as Hitchin's generalized geometry. Its associated cohomology naturally appears as the limit of a spectral sequence of a double complex. The first sheet of this spectral sequence is the Dolbeault cohomology with coefficients in the exterior algebra of the holomorphic tangent bundle. We identify various necessary conditions on compact complex manifolds on which this spectral sequence degenerates on the level of the second sheet. The manifolds to our concern include all compact complex surfaces, K\"ahler manifolds, and nilmanifolds with abelian complex structures or complex parallelizable manifolds

Design of a liquid helium transfer line support system.

The project regards the design of the liquid helium transfer line for the Production Solenoid; this solenoid is a part of the magnets structure that is going to be used into the Mu2e project at Fermi National Accelerator Laboratory. The first phase of the project involves the cross section layout and the support design with the purpose of limiting the heat load on the coldest pipe inside the line and at the same time reducing the support costs. The second part considers the thermal contraction effects and describes the solutions adopted to reduce its effects on the structures. Finally, it has been carried out a consumptive analysis that demonstrates the operated reduction in costs and the limited total heat load on some target parts in the line

Polynomial Structures in Generalized Geometry

On the generalized tangent bundle of a smooth manifold, we study skew-symmetric endomorphism satisfying an arbitrary polynomial equation with real constant coefficients. We study the compatibility of these structures with the de Rham operator and the Courant-Dorfman bracket. In particular we isolate several conditions that when restricted to the motivating example of generalized almost complex structure are equivalent to the notion of integrability.Comment: 41 page