Longitudinal relaxation time detection using a high-Tc superconductive quantum interference device magnetometer

The parameters to optimize the measurement of longitudinal relaxation time detection using a high- Tc superconductive quantum interference device magnetometer are investigated. These parameters include the prepolarization field, Bp, the prepolarization time, TBp, and the delay time, Td, to turn on pulses after turning off the prepolarization field. Furthermore, the decreasing of magnetization with the increasing Td of the applied pulse was analyzed to determine the longitudinal relaxation time. We estimated the longitudinal relaxation time to be 2.11±0.04 s and 2.29±0.04 s, respectively, for water determined from nuclear magnetic resonance signals as a function of TBp and Td at 24 °C in a measuring field of 95 μT. The data are consistent with the derived longitudinal relaxation time of water measured from the increase of magnetization with the duration of the polarizing field.