Status of the GRANIT Facility

Figure 13

Set-up for free fall measurement: in an argon-filled box, the UCN beam is collimated with a 12 cm long absorber-mirror system forming a slit of height 500 μm. A detector with a 15 μm thick titanium window is placed at the distance of 26 cm from the slit, and record the neutron count as a function of the fixed free fall height.