2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27288The longitudinal ultrasonic attenuation at low temperatures for a $d$-wave superconducting order parameter is examined. The ratio of the superconducting to normal state attenuation, $α_{s}/α_{n}$, depends strongly on the direction of propagation of ultrasound with maxima corresponding to nodes of the order parameter on the Fermi surface. We propose that measurements of ultrasonic attenuation in a single crystal of the high-$T_{c}$ superconductors can give the information regarding the position of nodes.3 pages, REVTeX, 3 figures are compressed and uuencoded by uufiles; decoding instructions are at the beginning of fileCondensed Mattertext