Domain: Engineering — Nuclear Engineering
Target concept: Alpha Particle Nuclear Physics

Video generation prompt: Alpha particle scattering experimental setup (vacuum chamber, gold foil target, fluorescent screen, radioactive source), with the radium radioactive source placed at one end of the vacuum chamber, the gold foil target fixed at the center of the chamber, and the fluorescent screen attached to the other end of the chamber. After activating the vacuum pump to evacuate the chamber, observe the fluorescent screen.

Evaluation guide:
(i) Target concept: Rutherford-style alpha scattering requires three mechanistic prerequisites: (1) a vacuum environment so alpha particles are not absorbed by air, (2) a thin gold-foil target whose massive, positively charged nuclei produce strong Coulomb repulsion, and (3) a scintillating screen that turns each particle impact into a localized flash of light. Minimum mechanism: alpha particles must travel unimpeded from the radium source through the gold foil to the screen; only impacts on the screen produce a visible flash; the great majority of particles pass through with little or no deflection and land near the center of the screen, in line with the radium-foil axis, while only a small minority are deflected enough by Coulomb repulsion to land measurably off that central alignment, toward the screen's outer region.
(ii)Storyline: Phase 1 (Setup): a static wide shot shows the intact vacuum chamber with the radium source (left), gold foil (center), and screen (right) all simultaneously visible, with no occlusion. Phase 2 (Activation): the vacuum pump engages (a visible cue), and the chamber's interior is confirmed clear (no fog or haze). Phase 3 (Detection): the screen stays dark until the radium source is shown active; then brief, non-overlapping flashes appear on the screen: most cluster near its center, directly in line with the radium-foil axis, while a clearly smaller number appear well off that central region, toward the screen's outer area; each flash is isolated in time and position. Perspective constraint: a fixed frontal viewpoint with no camera movement; the chamber's full depth stays visible; the gold foil must look discernibly thinner than the chamber walls and the radium housing.

Manual:
Experimental Procedure
1. Place the radium source at the left end of the vacuum chamber.
2. Mount the gold foil target at the exact center of the chamber's interior.
3. Attach the fluorescent screen to the right end of the chamber.
4. Activate the vacuum pump to evacuate the chamber.
5. Observe the fluorescent screen for flashes.
Observation of Experimental Phenomena
After evacuation and radium activation, transient bright flashes appear on the fluorescent screen: most cluster near its center, directly in line with the radium-foil axis, while a visibly smaller number appear well off that central region, toward the screen's outer area.
Summary of Experimental Principles
Alpha particles from the radium source pass mostly straight through the thin gold foil and strike the screen near its center; a small fraction are deflected by Coulomb repulsion from the gold nuclei enough to strike the screen visibly off-center, toward its outer region — evidence for a small, concentrated positive nucleus within the atom.

Prompt Grounding rubric:
level_1: None of the four core objects (vacuum chamber, radium source, gold foil target, fluorescent screen) is identifiable anywhere in the scene; the shot shows an unrelated setup or no apparatus at all.
level_2: At least one, but not all four, of the core objects (vacuum chamber, radium source, gold foil target, fluorescent screen) is correctly present and positioned; the rest are missing, mislabeled, or replaced with unrelated objects.
level_3: All four core objects are present: a sealed chamber (cylindrical or rectangular), a small radium source housing near one end, a thin gold-foil disc near the center, and a flat fluorescent screen near the opposite end; but at least one is mispositioned (e.g., the foil sits off-center, the source is not near an end, the screen is not near the far end) or rendered incorrectly (e.g., the foil looks silver-gray instead of gold, the screen looks opaque black instead of pale and glowing).
level_4: All four core objects are present, correctly typed, and correctly positioned: the radium source near one end, the gold foil centered, the fluorescent screen near the opposite end; their arrangement relative to one another stays fixed for the whole video; none of them appears or disappears partway through; none is hidden from view for the entire duration; the chamber looks intact and sealed.
level_5: Everything described at the 4-point level is present; in addition, the vacuum pump's activation is visibly indicated (e.g., an animated pump, a status readout, or a moving pressure gauge); the chamber's interior stays clear the whole time, with no fog, haze, or condensation, so the line of sight from the radium source to the gold foil to the screen is never blocked.

Scientific and Causal Correctness rubric:
level_1: No flashes appear on the fluorescent screen at all; the screen shows uniform darkness or a static, unchanging color; or the screen displays an animation unrelated to particle scattering (e.g., scrolling text or a rain effect) instead of localized flashes.
level_2: Flashes appear on the screen, but with no visible concentration near its center relative to its edges: for example, they are scattered with no discernible pattern, or the overwhelming majority sit at the outer edge with almost none near the center; or flashes appear before the radium source is shown active; or the flashes are shown as a continuous glow rather than brief, discrete events.
level_3: Flashes appear only after the radium source is shown active; most of them cluster near the center of the screen, in line with the radium-foil axis, representing largely undeflected transmission, while a visibly smaller number appear off that central region, toward the screen's edges; but the difference in density between center and edge is not clearly distinguishable, or a flash occurs at the exact moment the pump activates rather than clearly afterward.
level_4: Everything described at the 3-point level holds; in addition, the density of flashes at the screen's center is clearly and visibly greater than at its outer edge (roughly 80% or more of visible flashes land within about the central third of the screen), and the handful of edge flashes sit at a noticeably greater distance from the central axis than the main cluster, consistent with a minority of particles undergoing pronounced Coulomb-repulsion deflection while most pass through nearly undeflected; no continuous glow or afterglow lingers between flashes.
level_5: Everything described at the 4-point level holds; in addition, flashes never appear on the gold foil itself or in the empty chamber volume, only on the screen surface; no flash occurs before the radium source is shown active; the flashes' timing looks irregular rather than rhythmic or periodic; the small number of edge flashes are each clearly separate rather than forming a solid ring or band along the edge.

Spatiotemporal Consistency rubric:
level_1: The gold foil or the radium source housing appears to jump instantly from one position to another between frames; the vacuum chamber's outline bends, folds, or breaks apart; the fluorescent screen's glow abruptly disappears or inverts to a shadow; the screen flashes on and off with no connection to the radium source being active or the pump running; the camera angle snaps or zooms with no visible reason.
level_2: At least one clear break in continuity occurs: the radium source housing vanishes and reappears at a different spot; the gold foil's size or outline changes suddenly between frames; the fluorescent screen's surface ripples or bulges visibly; the general illumination switches character (e.g., from a directional glow to flat ambient light) with no matching event on screen; a jump-cut causes an object's position to shift discontinuously.
level_3: The chamber, radium source housing, gold foil, and fluorescent screen all keep their relative positions and shapes stable throughout; none of the objects teleports or deforms; the lighting stays directionally consistent, as if radiating from the radium end with the screen lit from the front; there is no tearing or double-imaging at object edges; at most, the screen's edge shows a faint, barely perceptible wobble, or a hand or label briefly passes in front of the gold foil before clearing.
level_4: No spatial jumps, shape distortions, or lighting inversions occur anywhere in the sequence; no core object (chamber, radium source, gold foil, screen) is blocked from view for any extended stretch; the chamber, source, foil, and screen stay rigidly fixed in their relative arrangement; any visible motion, such as a pump-status indicator, moves smoothly and plausibly; object edges and shadows stay continuous from frame to frame with no visible break.
level_5: Everything described at the 4-point level holds; in addition, the chamber's walls show no shimmering refraction or stray internal reflections; each flash on the fluorescent screen looks crisp rather than smeared or trailing, even as flashes come and go; there is no perceptible parallax shift between the radium source in the foreground and the screen in the background across the whole sequence, confirming a fixed camera with no drift or translation.