IOP PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 20 (2008) 104250 (5pp) doi:10.1088/0953-8984/20/10/104250 Non-destructive compositional analysis of historic organ reed pipes A Manescu 1 , F Fiori 1 , A Giuliani 1 , N Kardjilov 2 , Z Kasztovszky 3 , F Rustichelli 1 and B Straumal 4 1 Dipartimento di Scienze Applicate ai Sistemi Complessi (Sezione di Scienze Fisiche), Universit` a Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy 2 Hahn–Meitner-Institute, Glienicker Strasse 100, D-14109, Berlin, Germany 3 Budapest Neutron Centre, Institute of Isotopes, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly Thege 29-33, Hungary 4 Max-Planck-Institut f¨ ur Metallforschung, Heisenbergstraße 3, D-70569 Stuttgart, Germany Received 16 July 2007, in final form 1 October 2007 Published 19 February 2008 Online at stacks.iop.org/JPhysCM/20/104250 Abstract In order to be able to reproduce historic organ reed pipes, a bulk non-destructive chemical composition analysis was performed on the tongues and shallots, focusing mainly on the ratio between copper and zinc and on the presence of lead. Prompt gamma activation analysis results allowed us to observe for the first time that the ratio between the two main components of the brass alloy changed from Cu:Zn = 3:1 for the old tongues and shallots to Cu:Zn = 2:1 around the middle of the 18th century, which is typical also for the modern alloys offered to the organ builders nowadays. We also discovered that the Pb content in the old historic brass alloy diminished until the middle of 18th century when the brass alloy became mainly Pb free. The non-uniform lead distribution inside one of the shallots obtained from a prompt gamma activation analysis (PGAA) experiment was studied by neutron tomography. It gave us a three-dimensonal (3D) distribution of the lead inclusions inside the shallots. The lead particles are concentrated towards the base of the shallot. 1. Introduction and theoretical aspects The organ (figure 1), one of the most sophisticated musical instruments, is an important symbol of European culture. No other musical instrument can compare with the pipe organ in power, timbre, dynamic range, complexity of tone and sheer majesty of sound. The organ evolved through craftsmen slowly accumulating and applying empirical knowledge until the end of 17th century, when the organ attained its modern form. At the beginning of the 19th century during industrialization, the technology of organ production changed drastically [1]. Combined with a transition in music from baroque to the romantic style, this led to an essential change in the sound of organs and organ builders in the 19th and 20th centuries, oriented towards the sound of ‘new’ music. The recently appearing interest in baroque and medieval music led to demand in the market to produce new organs with an old sound. Because old technology based on intuition and the family tradition of organ masters was lost, new technology has to be developed, based on the most modern analytical possibilities and achievements of materials science, as it is known that the alloy composition and properties of the pipes strongly influences the organ’s sound [2, 3]. An organ contains flue and reed pipes constructed of lead– tin alloys (figure 2). There are no moving parts within a flue pipe. Reed pipes (figure 3) contain an additional vibrating part, the Cu-based alloy tongue that vibrates on the shallot and crucially influences the sound—see the scheme of a reed pipe in figure 4. In most cases, both tongues and shallots are made of brass (a copper–zinc alloy). The ratio between Cu and Zn in the brass alloy and the presence of Pb were of prime interest in our study, due to their essential influence on the sound that is obtained. In order to have a good understanding and to be able to have a European-level overview of the situation, we analysed a large number of brass tongues and shallots from different areas of Europe. Different kinds of experimental analyses were carried out, such as microstructural characterization of the tongues and shallots by optical and scanning electron microscopy [4] or residual stress measurements by synchrotron radiation diffraction [5]. 0953-8984/08/104250+05$30.00 © 2008 IOP Publishing Ltd Printed in the UK 1