Evanescent waves in a time-of-arrival measurement model

The analysis of the model quantum clocks proposed by Aharonov et al. [Phys. Rev. A 57, 4130 (1998); e-print quant-ph/9709031] requires considering evanescent components in the transient regime, previously not examined, and consideration of several aspects of the asymptotic regime. We also clarify the meaning of the operational time of arrival distribution that had been investigated. The accuracy limitation due to the back reaction of the clock is not affected.