D O C U M E N T 2 9 0 M A Y 1 9 2 6 3 0 7 a) with grating 0.1 mm b) with grating 0.02 mm 2) If this diaphragm stands 5 mm away from the canal end, then the intensity dis- tribution becomes as follows: (This diaphragm displacement corresponds to the // shift of the tube, which you had proposed.) a) grating 0.1 mm b) grating 0.02 mm With setup III (I without lenses L1 L2), but 1) with the above diaphragm directly at the end of the canal. Result: With gratings 0.1 & 0.02 mm, the same images as above under 1), ap- proximately with the same clarity, total intensity somewhat weaker. 2) This diaphragm taken away. Interference minima do not noticeably occur, & specifically, for either grating. Therefore, the diaphragm put in front contributes substantially to a clear deter- mination of the effect, despite reduced intensity. The interference minima do not occur, mainly for the following reasons: 1) Ray scattering: The exiting canal ray diverges with growing distance from the end of the canal. The scattered atoms are not going to reach the next free spot on the grating with the same phase. Thus the minima disappear for a diaphragm position at 5mm & become blurred with a finer grating. Furthermore, they disappear for this reason in setup III, 2).