Domain: Engineering — Nuclear Engineering
Target concept: Nuclear Physics Experiment

Video generation prompt: The figure shows two neutron detectors side by side, with the left one being a fast neutron detector and the right one a slow neutron detector. In the experimental setup for distinguishing between slow and fast neutrons (including a neutron source, graphite moderator, fast neutron detector, and slow neutron detector), the detectors are first directly aligned with the neutron source. After a few seconds, a 10 cm thick graphite moderator is inserted between the neutron source and the detectors. The changes in count rates of both detectors before and after the insertion of the graphite moderator are observed.

Evaluation guide:
(i) Target concept: Neutron energy-dependent detection via moderation in nuclear instrumentation.
Minimum mechanism: Graphite must act as a neutron moderator (slowing fast neutrons via elastic scattering), causing measurable count-rate inversion between fast- and slow-neutron-sensitive detectors.
(ii)Storyline: Frame 1–3: Static wide shot showing neutron source directly aligned with two adjacent detectors (left unlabeled but positioned as fast detector, right as slow detector). Frame 4–6: Graphite moderator enters frame from bottom/top and slides continuously into position *between* source and detectors, fully occupying the line of sight. Frame 7–10: Detectors display updated count-rate signals (left reduces activity, right increases activity), with no further motion or repositioning. Fixed frontal viewpoint; no camera movement; all objects fully visible and occlusion-consistent throughout.

Manual:
Experimental Procedure
1. Place neutron source facing two side-by-side detectors (left: fast neutron detector; right: slow neutron detector).
2. Record initial count rates on both detectors.
3. Insert 10 cm graphite moderator between source and detectors.
4. Record new count rates on both detectors.
Observation of Experimental Phenomena
Before moderator insertion: left detector shows high count rate; right detector shows low count rate.
After moderator insertion: left detector shows low count rate; right detector shows high count rate.
Summary of Experimental Principles
Fast neutrons are attenuated by graphite moderation, reducing counts in fast detector; slow (thermal) neutrons increase in flux after moderation, increasing counts in slow detector — demonstrating neutron energy discrimination via moderation.

Prompt Grounding rubric:
level_1: No neutron source, no graphite moderator block, and no two side-by-side detectors that could be told apart as fast versus slow are visible; nothing is ever inserted between source and detectors; no before/after comparison is shown at all.
level_2: A neutron source and two objects placed near each other appear, but neither object is visually distinguishable as the fast detector versus the slow detector; the graphite moderator block is missing or unrecognizable; no insertion of the moderator ever happens.
level_3: Two side-by-side detectors, a neutron source, and a solid graphite-like block are all visible from a fixed viewpoint, with the detectors initially facing the source directly; however the block is never actually inserted into the gap between source and detectors, so no before/after comparison plays out.
level_4: The two detectors keep a consistent left/right position throughout (left = fast, right = slow), whether or not they also carry an additional clear cue such as color, shape, icon, or label; the neutron source and the graphite moderator block are both visible; the block is inserted into the gap between source and detectors in the correct order, with source-and-detectors aligned first and the block inserted afterward.
level_5: Level 4's correctly ordered setup holds, and additionally the left and right detectors never swap which position holds the 'fast' one (the fast detector stays on the left, the slow detector stays on the right), no duplicate or replacement source, detector, or moderator appears partway through the clip, and the moderator block is only introduced after the initial alignment shot is already on screen; it is never present from the very first frame.

Scientific and Causal Correctness rubric:
level_1: Neither detector's indicated count rate changes at all; both detectors respond identically to the moderator; or the graphite moderator appears to have no effect on either detector's signal.
level_2: Only one detector's signal changes, but it changes identically to, or in the opposite direction of, what the physics predicts; the moderator is inserted but no detector's response tracks with that insertion; there's no visible difference between how the left and right detectors behave.
level_3: The left (fast) detector's indicated signal is high before the moderator goes in and drops after; the right (slow) detector's indicated signal is low before and rises after; but the two detectors show this using inconsistent indicator types, such as one blinking an LED while the other displays a number.
level_4: The left detector's high-before/low-after pattern and the right detector's low-before/high-after pattern both show up clearly, and both detectors use the same type of indicator (both blinking lights, both proportional brightness, or both numeric counters), so the comparison is apples-to-apples.
level_5: Level 4's matched-indicator, correctly timed count pattern holds, and additionally neither detector's signal changes at all during the alignment phase before insertion; the left detector's drop and the right detector's rise both happen only once the moderator block has fully settled into place between source and detectors, with no partial or in-between readings shown.

Spatiotemporal Consistency rubric:
level_1: A detector, the source, or the moderator block pops into view or vanishes with no motion behind it; the room's lighting or shadows suddenly jump to a different look; any on-screen detector label flickers on and off; a detector's housing visibly splits apart or breaks.
level_2: The moderator's insertion motion jumps, freezes mid-slide, or briefly reverses; one detector rotates or slides on its own while the other stays put; the background geometry looks warped; the lighting shifts unevenly frame to frame; the camera view shifts or zooms unexpectedly.
level_3: The source, the detectors, and the moderator each stay where they were placed relative to one another; the moderator slides in along a straight, continuous path from off-screen into the gap between source and detectors; the source and detectors keep the same size and orientation, and the moderator never appears to pass through the source or a detector as if they weren't solid.
level_4: Level 3's steady placement and clean insertion path hold, and additionally the moderator's slide-in motion shows no visible hesitation, sudden speed-up, or overshoot past its final position; neither detector visibly shakes or vibrates; the lighting and shadow direction stay the same from the alignment shot through to the final count-rate readout; any blinking indicator lights blink at a steady, consistent rate with no visible glitches.
level_5: Level 4's smooth, steady insertion holds, and additionally the source, moderator, and detectors stay lined up in a straight row throughout the insertion; the left and right detectors stay equally spaced from the center line and parallel to each other; the scene shows no sudden shifts in perceived depth or perspective; and if any motion blur appears on the moving moderator, it looks consistent with its speed rather than appearing on objects that aren't moving.