Our back cover picture has been published in the Advanced Optical Materials journal! The image depicts hackmanite crystal’s coloration mechanism upon X-ray exposure where electron and hole cascades create a color center. The original idea and graphics, which was accepted by the journal, was made by Adj. Prof. Mika Lastusaari:

PhD student Sami Vuori then refined it a bit with Gimp by creating the final version. The picture is related to our article Detection of X-Ray Doses with Color-Changing Hackmanites: Mechanism and Application, which was published in this journal: https://doi.org/10.1002/adom.202100762