Nobel Prize in Physics in 1924 2026-10-18
Awarded to Karl Manne Georg Siegbahn for X-ray spectroscopy. He received the prize in 1925. The Siegbahn precision X-ray wavelength spectroscopy article describes its calibration problems.[ref]
The Nobel Prize in Physics 1924 by Nobel Prize Outreach. Official award record: Manne Siegbahn, X-ray spectroscopy and deferred receipt in 1925