STATE: QUANTUM_ACCUMULATION
HITS: 5,000
The double-slit tool calculates fringe spacing as wavelength times screen distance divided by slit separation. Its saved defaults are six hundred fifty nanometers, one point two meters and one hundred micrometers. The resulting spacing is seven point eight millimeters. Doubling slit separation to two hundred micrometers halves it to three point nine millimeters. These bars follow the numerical formula; the displayed pattern itself uses a separate normalized angular coordinate. For two slits the saved intensity is a single-slit diffraction envelope times cosine squared beta. Alpha is pi times slit width times sine theta divided by wavelength. Beta replaces slit width with slit separation. At the center both factors are one. At beta equal to pi over two, cosine squared is zero, so the envelope cannot prevent an interference minimum. This plotted curve evaluates both factors for the saved width twenty micrometers and separation one hundred micrometers. Switching on the which-way detector in this source removes the cosine-squared interference factor and returns only the diffraction envelope. It does not calculate a microscopic measurement apparatus. It models decoherence as an explicit branch. The source samples hits by rejection sampling that chosen intensity and builds a histogram. A finite histogram fluctuates; changing particle count does not change the underlying analytic formula. The reported peak count is a mode label set by the source, not a fitted measurement of all visible maxima.