The surface energy of the Bloch wall between ferromagnetic domains is of fundamental importance in domain theory; this energy can be computed if the wall thickness is known. It is proposed that the wall thickness be measured by studying the polarization changes of a neutron beam which is passed through a single Bloch wall. The relation connecting wall thickness, neutron velocity, and polarization change is worked out; the required velocities are such that the experiment can probably be done with existing techniques, if grazing angles of incidence are used.

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Charge-coupled devices (CCDs) show potential for detecting charged particles and ionizing radiation. In particular, the clusters in the pixel images produced can be distinctive for [Formula: see text] and [Formula: see text] radiation, with [Formula: see text] particles causing symmetrical clusters or vertical tracks, and [Formula: see text] particles causing long, curved tracks. This distinction may be exploited by means of a handheld, portable device for in-situ detection, and identification of radioactive contamination. [Formula: see text]-particle track interactions in CCDs have been investigated. Simulative results using CASINO (Monte Carlo Simulation of Electron Trajectory in Solids) attempt to predict the size of [Formula: see text]-particle pixel clusters, using 512 keV and 310 keV electrons to represent [Formula: see text]Cs and [Formula: see text]Co, respectively. The number of pixels that higher-energy electrons traversed peaked at two, while lower-energy electrons had a smaller peak of 2.5 pixels, with a higher proportion of large cluster sizes. This finding is consistent with the higher scattering cross-section for lower-energy [Formula: see text] particles. By contrast, experimental data show a peak at one pixel for both sources, owing to the addition of smaller [Formula: see text] clusters. The [Formula: see text]Co source shows a higher proportion of large cluster sizes than the [Formula: see text]Cs, as was also seen in the simulation; however, the difference was small, as these sources are similar in energy. Simulative and experimental data will be used to process the CCD images further, with the objective of distinguishing between [Formula: see text] and [Formula: see text] radiation. Investigations have also been carried out using a [Formula: see text]Po [Formula: see text] particle source. Horizontal streaks were seen in the images produced, with an average length of 14 pixels. Further research will be performed using an accelerator to obtain different [Formula: see text]-particle energies.

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