Happy birthday, ultra-cold neutron!∗
1 Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Wien, Austria
2 Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
a e-mail: email@example.com
∗ This article covers the music part of a lecture given by H.A. at the International Workshop on Particle Physics at Neutron Sources, PPNS, in Grenoble/France in May 2018 with a composition on the occasion of the 50th anniversary of the first production of ultra-cold neutrons.  H. Abele, H. Lemmel, T. Jenke, Nature 572, 178 (2019).
Published online: 12 December 2019
What is driving the accelerated expansion of the universe and do we have an alternative for Einstein's cosmological constant? What is dark matter made of? Do extra dimensions of space and time exist? Is there a preferred frame in the universe? To which extent is left-handedness a preferred symmetry in nature? What's the origin of the baryon asymmetry in the universe? These fundamental and open questions are addressed by precision experiments using ultra-cold neutrons. This year, we celebrate the 50th anniversary of their first production, followed by first pioneering experiments. Actually, ultra-cold neutrons were discovered twice in the same year – once in the eastern and once in the western world [1, 2]. For five decades now research projects with ultra-cold neutrons have contributed to the determination of the force constants of nature's fundamental interactions, and several technological breakthroughs in precision allow to address the open questions by putting them to experimental test. To mark the event and tribute to this fabulous object, we present a birthday song for ultra-cold neutrons with acoustic resonant transitions , which are based solely on properties of ultra-cold neutrons, the inertial and gravitational mass of the neutron m, Planck's constant h, and the local gravity g. We make use of a musical intonation system that bears no relation to basic notation and basic musical theory as applied and used elsewhere  but addresses two fundamental problems of music theory, the problem of reference for the concert pitch and the problem of intonation.
© The Authors, published by EDP Sciences, 2019
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