698 research outputs found
Temperature dependent infrared absorption, crystal-field and intensity analysis of Ce3+ Doped LiYF4
Infrared absorption has been used to determine the crystal-field levels of the
2F7=2 excited multiplet of trivalent cerium doped into scheelite structure LiYF4
single crystals. A crystal-field analysis well accounts for a total of six experimentally
observed energy levels and the ground state g-values as previously
determined by electron paramagnetic resonance, whilst intensity simulations
confirm the experimentally assigned level symmetries. Temperature dependent
spectral line broadening measurements highlight the importance of coupling to
low frequency phonon modes of the YF8 tetrahedron
The K600 Focal Plane Polarimeter
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Development of an In-Beam Polarimeter for Intermediate Energy Protons Using p+d Elastic Scattering
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
An Absolute Calibration of the p+d High-Energy Polarimeters
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Fiber bundle model with stick-slip dynamics
We propose a generic model to describe the mechanical response and failure of
systems which undergo a series of stick-slip events when subjected to an
external load. We model the system as a bundle of fibers, where single fibers
can gradually increase their relaxed length with a stick-slip mechanism
activated by the increasing load. We determine the constitutive equation of the
system and show by analytical calculations that on the macro-scale a plastic
response emerges followed by a hardening or softening regime. Releasing the
load, an irreversible permanent deformation occurs which depends on the
properties of sliding events. For quenched and annealed disorder of the failure
thresholds the same qualitative behavior is found, however, in the annealed
case the plastic regime is more pronounced.Comment: 4 pages, 4 figure
An Energy Feedback System for the MIT/Bates Linear Accelerator
We report the development and implementation of an energy feedback system for
the MIT/Bates Linear Accelerator Center. General requirements of the system are
described, as are the specific requirements, features, and components of the
system unique to its implementation at the Bates Laboratory. We demonstrate
that with the system in operation, energy fluctuations correlated with the 60
Hz line voltage and with drifts of thermal origin are reduced by an order of
magnitude
Test of a Density-Dependent Effective Interaction Using In-Plane 28-Si(p,p')28-Si Polarization Transfer Measurements
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Investigation of the Effective NN Interaction Through 28-Si(p,p')28-Si Polarization Transfer
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Evidence for Fragmentation of "Stretched" 6- Strength in 28-Si(p,p')28-Si
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Field on Poincare group and quantum description of orientable objects
We propose an approach to the quantum-mechanical description of relativistic
orientable objects. It generalizes Wigner's ideas concerning the treatment of
nonrelativistic orientable objects (in particular, a nonrelativistic rotator)
with the help of two reference frames (space-fixed and body-fixed). A technical
realization of this generalization (for instance, in 3+1 dimensions) amounts to
introducing wave functions that depend on elements of the Poincare group . A
complete set of transformations that test the symmetries of an orientable
object and of the embedding space belongs to the group . All
such transformations can be studied by considering a generalized regular
representation of in the space of scalar functions on the group, ,
that depend on the Minkowski space points as well as on the
orientation variables given by the elements of a matrix .
In particular, the field is a generating function of usual spin-tensor
multicomponent fields. In the theory under consideration, there are four
different types of spinors, and an orientable object is characterized by ten
quantum numbers. We study the corresponding relativistic wave equations and
their symmetry properties.Comment: 46 page
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