The influence of various parameters on the flux density distribution in the remnant state of bulk Y-123, NEG-123 and Gd-123 superconductors is reported. We discuss the dependence of the trapped field on the active area of the Hall sensor, on the distance between the sensor and the sample surface, on the temperature of the liquid nitrogen bath and on the time between the activation and the start of the measurement. Detailed studies of the activation process (dc and pulsed) have been made. If the sample is not immersed into the liquid, but cooled by exchange gas, direct measurements of the temperature at the sample surface provided evidence for temperature variations during the activation process, which can be related to the various propagation states of the flux front. The results are interpreted in terms of the dissipated energy.
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