Forensic applications of 14C at CIRCE

International audience; The decreasing trend of the radiocarbon pulse produced during the atmospheric tests of nuclear weapons(bomb-carbon) coupled with high sensitivity accelerator mass spectrometry (AMS) measurements, drasticallyincreased the precision of radiocarbon age determinations since the second part of the sixties,allowing the application of radiocarbon AMS to a wide range of studies previously not directly involvingconventional radiocarbon dating (i.e. food authenticity, forensic, biochemistry). In the framework ofauthenticity evaluation of artworks, high precision radiocarbon (14C) AMS measurements (DR/R < 0.3%)reduce the conventional uncertainty of the dating to few decades, allowing precise age estimation ofmaterials containing carbon (C). The Centre for Isotopic Research on Cultural and Environmental heritage(CIRCE) during its activity on AMS 14C dating achieved high precision measurements opening the opportunityto these kinds of applications. This paper presents the main results obtained from radiocarbonmeasurements on a set of bone samples analyzed for the determination of the post-mortem interval inthe framework of an unsolved case investigated by the Rome prosecutor office. The chronological characterizationof the wooden support of the ‘‘Acerenza portrait’’ is also presented with the aim to evaluateits age and to further investigate the possibility to attribute this artwork to Leonardo da Vinci.Bomb-14C dating on the lipid and collagen fractions of bones allows the evaluation of the year of thedeath of the individuals by means of ad hoc calibration data sheet with the typical few years precisionand difference between collagen apparent age and the year of death appeared in agreement with theage of one individual estimated by dating of tooth collagen. Conventional radiocarbon dating on bothwood and wood extracted cellulose leads to an estimation of the portrait wood board age (2r) of1459–1524 AD (57% relative probability), 1571–1631 AD interval (42% relative probability).and 1559–1563 AD (1% relative probability). These results attribute with the highest relative probability an agecomprised within the life span of Leonardo (1452–1519) to the support.