Cross-track error

The reverse rates at an adjacent track, when the head was shifted in the cross track direction, have been also simulated. The error occurrence in this case was different from that in down track writing where the field gradient determines the discriminability of bit writing. The full shift margin in the cross track direction was less than 1/3 of that in the down track direction. The small shift margin in the cross track direction is mainly attributed to the broad field distribution in the cross track direction. Therefore, it is essential to use a write head with a high field gradient in the down track direction and a narrow field distribntion in the cross track direction. One of the solutions would be to use shield type heads. 

The maximum tracking error for a saturated cross-eye is about 0.503angular position where the difference pattern has peaks and zero slope. 

The Monte Carlo code KENO was used to calculate the required neutron multiplication factors (keff). mie keif values typically had a standard error of 0.008 and involved the tracking of between 10,000 and 15,000 neutrons. Hansen-Roach 16-group cross-section sets were used with the exception of magnesium, silicon, manganese, and cojqjer, which were obtained by iSDRN calculations, and calcium and zinc which were obtained by GAM-2 calculations. 

The two beams, which form the difference pattern (one beam - -, and one beam —), cross each other at less than 3 dB below their peaks for maximum error slope-sum pattern product and to give increased angle tracking accuracy. This can be seen in Fig. 17.61 in Skolnik (1962) and in Fig. 17.62 in Rhodes (1980), where a comparison is shown between squint angle and the two difference beam magnitude crossover. 

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