Measurement of mechanical vibrations excited in aluminum resonators by 0.6GeV electrons

We present measurements of mechanical vibrations induced by 0.6 GeV electro ns impinging on cylindrical and spherical aluminum resonators. To monitor t he amplitude of the resonator's vibrational modes we used piezoelectric cer amic sensors calibrated by standard accelerometers. Calculations using the thermo-acoustic conversion model agree well with the experimental data, as demonstrated by specific variations of the excitation strengths with the ab sorbed energy, and with the traversing particles' track positions. For the first longitudinal mode of the cylindrical resonator we measured a conversi on factor of 7.4 +/- 1.4 nm/J, confirming the model value of 10 nm/J. Also, for the spherical resonator, we found the model values for the L = 2 and L = 1 mode amplitudes to be consistent with our measurement. We thus have co nfirmed the applicability of the model, and we note that calculations based on the model have shown that next generation resonant mass gravitational w ave detectors can only be expected to reach their intended ultrahigh sensit ivity if they are shielded by an appreciable amount of rock, where a veto d etector can reduce the background of remaining impinging cosmic rays effect ively. (C) 2000 American Institute of Physics. [S0034-6748(00)00803-0].