M. BASSAN†,‡, B. BUONOMO∗, G. CAVALLARI¶, E. COCCIA†,‡,
S. D’ANTONIO†, V. FAFONE†,‡, L. G. FOGGETTA∗, C. LIGI∗,∥, A. MARINI∗, G. MAZZITELLI∗, G. MODESTINO∗, G. PIZZELLA‡,∗, L. QUINTIERI∗,∗∗, F. RONGA∗ and P. VALENTE§
†Istituto Nazionale di Fisica Nucleare – Sezione Roma2,
Via della Ricerca Scientifica – 00133 Rome, Italy ‡Dipartimento di Fisica, Universit`a di Tor Vergata,
Via della Ricerca Scientifica – 00133 Rome, Italy
§Istituto Nazionale di Fisica Nucleare – Sezione Roma1, Piazzale Aldo Moro 2 – 00185 Rome, Italy
¶CERN, CH1211, Gen`eve, Switzerland Received 1 February 2013 Revised 22 May 2013 Accepted 27 May 2013 Published 23 July 2013
We describe a result coming from an experiment based on an Al-Mg alloy (∼ 5% Mg) suspended bar hit by an electron beam and operated above and below the temperature of transition from superconducting to normal state of the material. The amplitude of the bar first longitudinal mode of oscillation, excited by the beam interacting with the bulk, and the energy deposited by the beam in the bar are the quantities measured by the experiment. These quantities, inserted in the equations describing the mechanism of the mode excitation and complemented by an independent measurement of the specific heat, allow us to determine the linear expansion coefficient α of the material. We obtain α = [(10.9±0.4)T +(1.3±0.1)T3]×10−10 K−1 for the normal state of conduction in the temperature interval 0.9 < T < 2 K and α = [(−2.45±0.60)+(−10.68±1.24)T +(0.13± 0.01)T 3 ] × 10−9 K−1 for the superconducting state in the interval 0.3 < T < 0.8 K.
Keywords: Thermal expansion; low temperature; aluminum alloy. PACS numbers: 65.60.+a, 07.20.Mc, 74.70.Ad
http://www.worldscientific.com/doi/abs/10.1142/S0217979213501191
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