In comparison to photons and charged particles neutrons cannot directly ionize  atoms.

When neutron interacts with nucleus, it can be produced high energy charged particles or photons. Low energy neutrons can be detected by (n,  ), (n, p), (n,  ) or (n, fission). Since the produced charged particles or photons have enough energy to ionize atoms, they make many of electron-ion pairs depending on their primary energy. When electric field is applied to electron-ion pairs, electrons move to anode and ions move to cathode. As a result small voltage difference is driven, one can detect neutrons.

There are two kinds of methods to measure angular distribution of scattered neutrons. Firstly it is constant scanning method. The soller collimator is installed before tube detector. It rotates around specimen. Secondly one can use position-sensitive detector. Use of position-sensitive detector can be reduced measurement time because it can measure wide angular range of neutron distribution. Additionally it is very useful for small sized samples and fast phase transition research fields.
Many types of position-sensitive detectors were developed by Neutron Physics Department(NPD) including one-dimensional and two-dimensional position-sensitive neutron and X-ray detectors and even low efficiency beam monitoring counters.