Researchers have concluded that a painting said to be from Fernand Léger’s “Contraste de formes” series (1913-1914) is a fake. Scientists from Italy’s Institute of Nuclear Physics used radiocarbon tests to prove that the work was created no earlier than 1959, four years after the artist’s death. The painting’s authenticity was first questioned in the 1970s by the British art historian Douglas Cooper. After Cooper announced his suspicions, the work was never exhibited or catalogued.

Scientists used the “bomb peak” method to date the canvas in question. Between the late 1950s and early 1960s nuclear weapon testing greatly increased the radiocarbon concentrations in the atmosphere, and in exchange, all of the living organisms in existence at the time. By comparing the radiocarbon in a small unpainted sample with the known levels during the “bomb peak,” researchers concluded that the cotton plant used to make the canvas was cut after Léger’s death.

Details of the Institute of Nuclear Physics’ findings will be published in the “European Physical Journal Plus.”