Europhys. Lett., 76 (6), pp. 987-993 (2006)
DOI: 10.1209/epl/i2006-10400-6

Acoustic detection of high-energy electrons in a superconducting niobium resonant bar

M. Bassan^{1, 2}, D. Blair³, B. Buonomo⁴, G. Cavallari^{4, 5}, E. Coccia^{1, 2}, S. D' Antonio^{1, 2}, G. Delle Monache⁴, D. Di Gioacchino⁴, V. Fafone^{1, 4}, C. Ligi⁴, A. Marini⁴, G. Mazzitelli⁴, G. Modestino⁴, G. Pizzella^{1, 4}, L. Quintieri⁴, S. Roccella⁴, A. Rocchi^{1, 2}, F. Ronga⁴, P. Tripodi⁴ and P. Valente<sup>4

1</sup>  Dipartimento di Fisica, Università Tor Vergata - I-00133 Roma, Italy
²  INFN, Sezione Roma2 - I-00133 Roma, Italy
³  Department of Physics, University of Western Australia Nedlands, WA 6907, Australia
⁴  INFN, Laboratori Nazionali di Frascati - I-00044 Frascati, Italy
⁵  CERN - Geneva 23, Switzerland

alessandro.marini@lnf.infn.it

received 29 August 2006; accepted in final form 27 October 2006
published online 23 November 2006

Abstract
We have performed an experiment based on a suspended cylindrical bar, hit by an electron beam, for investigating the results on cosmic rays detected by the gravitational wave antenna Nautilus. The experiment is aimed at measuring the amplitude of the fundamental longitudinal mode of oscillation of a niobium bar, excited by the pressure impulse due to the local interactions of high-energy electrons. We report on the amplitude measurements in a wide temperature range. For niobium in normal state the amplitude agrees within few percents with the predictions of the underlying theory. The amplitude shows a discontinuity at the temperature of transition to superconducting state and, in this state, we measure a reduced amplitude with respect to the normal state. Data in the superconducting state are compared with two models.

PACS
04.80.Nn - Gravitational wave detectors and experiments.
61.82.-d - Radiation effects on specific materials.
74.25.-q - Properties of type I and type II superconductors.

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