Mössbauer Effect: Doppler Resonance Scan (2D)

This 2D companion drives the same real Debye-model recoil-free physics as the 3D Mössbauer Effect Lab, but built as a spectrometer reading rather than a 3D scene: a side panel lets you choose the binding mode (free nucleus vs. two crystal-lattice presets) and drag the lattice temperature, which together recompute the recoil energy, the Lamb–Mössbauer recoil-free fraction f and the effective resonance linewidth exactly as the physics dictates. A live transmission-vs-velocity curve plots the real Lorentzian absorption dip, a draggable marker (or the Auto-sweep button) shows the transmission percentage at any Doppler velocity, and a simple source→absorber strip below it fires individual decay events colored by whether that particular photon happened to be recoil-free — so the abstract "recoil-free fraction" number becomes something you watch happen, decay by decay, exactly at the rate f predicts.