Particle physics
Physics beyond the Standard Model
Use a simulated nuclear-recoil spectrum to see how a hypothetical WIMP mass and the detector threshold shape the expected event rate — the logic of direct searches for physics beyond the Standard Model.
Equipment
- Simulated recoil-energy spectrum display (normalized, schematic)
- Slider “Khối lượng WIMP giả định” (assumed WIMP mass)
- Slider “Ngưỡng detector” (detector threshold)
- Mode switch “Chế độ” (direct/indirect) and “Tạm dừng” button
Procedure
Read the recoil spectrum
In direct-detection mode, look at the recoil spectrum: WIMP–nucleus scattering deposits only a few keV, so the expected signal falls steeply with energy. All curves are arbitrarily normalized — the figure shows shapes, not real detector data or evidence.
Vary the WIMP mass
Sweep the WIMP-mass slider. Light WIMPs transfer less energy to a nucleus, so their recoil spectrum is softer and hugs the threshold; heavy WIMPs push recoils to higher energies. Relate the trend to the recoil-energy scale .
Move the detector threshold
Raise the threshold slider and watch the detectable portion of the spectrum shrink — a high threshold hides soft recoils entirely. Then switch the “Chế độ” control to indirect and compare the two search philosophies.
Connect to theory
Explain why a null result still constrains physics: each excluded mass and cross-section region shrinks the parameter space of the effective theory . State one reason real experiments also need background subtraction and annual-modulation checks.