The 14 MeV N-D analysing power

Abstract

The angular distribution of the analysing power of deuterium for elastically scattered 14.1 MeV polarized neutrons has been measured. The polarized neutrons are produced by polarization transfer in the T(d, n)4 He reaction initiated by 150 keV deuterons. The vector polarized deuterons are produced by an "atomic beam" type polarized ion source. The deuteron polarization and hence the neutron polarization is reversed by the switching of three radio frequency transition units. The neutron polarization is inferred from the deuteron tensor polarization. The tensor polarization is found from measurements of the asymmetry of neutrons from the d, T reaction and the neutron polarization inferred, both assuming a simple s wave reaction. The value of the neutron polarization was typically 0.55 and remained within a few percent of this over a period of several weeks. A beam of neutrons is defined by the detection of the associated alpha particles from the d, T reaction with a thin N.E.102A plastic scintillator viewed by a 56 A.V.P. photomultiplier. The scattering nuclei (deuterons) are contained in an organic liquid scintillator (N.E.230). This is encapsulated in a glass cylinder of dimensions 5cm diameter and 10cm long designed for horizontal mounting. The recoil deuteron is detected in this scintillator viewed by a 56 A.V.P. photomultiplier. The left-right scattered neutrons are detected in 5 x 10 x 10cm volume of N.E.102A plastic scintillator. Three or four pairs of these are used at different scattering angles to increase the data taking rate. A triple coincidence is formed between the alpha detector, the recoil deuteron in the scatterer and an event in a side detector. For each event six parameters specifying scatterer recoil energy, scatterer pulse shape, scatterer to side detector time of flight, side detector recoil energy, scattering angle and polarization are recorded on magnetic tape. Since the data is recorded event by event restrictions may be placed on each of these parameters off-line from the experiment. The data is finally analysed in the form of six two-dimensional matrices formed from scatterer energy-time of flight, scatterer energy-pulse shape, and time of flight-side detector energy, one of each for polarization up, down for each side detector.