Resonant-beam-test technique

The resonant beam test technique forms the basis of the ASTM Standard E756-83 for measuring the viscoelastic properties of damping materials. Fundamentally, the beam test requires that the resonant frequencies of a metal-beam, mounted in cantilever fashion, be determined as a function of temperature and frequency the beam is then coated with a polymer and the resonant frequencies and corresponding modal damping of the composite beam are determined as a function of temperature and frequency. From these two data sets, the vibration damping properties of the polymer can be evaluated. The ASTM Standard provides the necessary equations to obtain the complex modulus data from the collected test data and also provides guidelines for the proper choice of the specimens (1.21. The principal difference between the beam test and the other methods used here is that the beam test calculates the material properties from the test results on the metal beam and the composite beam whereas the... 

Metastable muonium atoms in the 2s state have been produced with a beam foil technique at LAMPF and at the Tri University Meson Physics Facility (TRI-UMF) at Vancouver, Canada. Only moderate numbers of atoms could be obtained. The velocity resonance nature of the electron transfer reaction results in a muonium beam at keV energies. Very difficult and challenging experiments using electromagnetic transitions in excited states, particularly the 2 Si/2 2 Pi/2 classical Lamb shift and 2 Si/2-2 P3/2 splitting could be induced with microwaves. However, the achieved experimental accuracy at the 1.5 % level [18,19,20], does not represent a severe test of theory yet. 

The room temperature in-plane shear, interlaminar shear, and axial Young s moduli of beams cut from plates of two different C/C laminates have been determined by a resonant beam method. The technique and evaluation method are described in detail. The results are discussed and compared to data from static tests. 

Comment on collisional depolarization studies. The resonance fluorescence experiments described above have served to stimulate and test the development of recent sophisticated theories of collision broadening. However, the hope that new information on interatomic forces would be obtained by these experiments has not been realized. This is largely because the observed broadening is the mean effect of collisions averaged over all possible relative orientations and over the thermal velocity distribution of the ensemble. It may be that in the future more detailed information on the interatomic potentials could be obtained by combining tunable dye laser excitation and atomic beam scattering techniques. 

Abstract. Laser spectroscopy of hydrogen-like and helium-like ions is reviewed. Emphasis is on the fast-beam laser resonance technique, measurements in moderate-/ ions which provide tests of relativistic and quantum-electrodynamic atomic theory, and future experimental directions. 

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