Neutrons, wavelength

Electrons are peculiarly light, so that their wave properties are easy to detect. Heavier particles must have correspondingly lower velocities (and kinetic energies according to eqn 2.22) to give momenta corresponding to suitable wavelengths. Neutrons are commonly used for diffraction. They me... 

The D2O ice samples investigated in this context were prepared inside vanadium sample cans inside an Orange Cryostat on the constant wavelength neutron powder diffractometers D2B (wavelength 1.6 A) and (wavelength 2.4 A), based at the high-flux reactor of... 

BF3 is usually isotopically enriched as normal boron consists of only 20% of the strongly absorbing isotope. For thermal neutrons the He gas detector is considered superior, but for long-wavelength neutrons BF3 is preferred, but is rarely used nowadays because of the corrosive and toxic nature of the gas. Since the capture cross-section of gases is small, He detectors are usually operated above atmospheric pressure, 5-10 bar. They are typically 10-15 cm long and 2-5 cm in diameter. 

Experimental techniques make use of these two features to select the required energy of a neutron beam. The neutron flight time is easily determined on sufficiently large lengths a 5 A wavelength neutron has a flight time, t [L(m)/v(ms )] of 1264 s m ... 

---