ABSTRACT IMPLEMENTATION OF A ¯-NQR SYSTEM AT THE NSCL FOR GROUND STATE QUADRUPOLE MOMENT MEASUREMENTS By

The nuclear electric quadrupole moment, Q, is a direct measure of the nuclear charge distribution, and provides an important test of nuclear structure models. The ¯ detected nuclear quadrupole resonance (¯-NQR) method is a technique to measure ground state Q of unstable nuclei. A ¯-NQR system has been constructed at the NSCL. Several challenges had to be overcome to build the ¯-NQR system, including the implementation of multi-radio frequencies, high rf magnetic ¯eld strength, short rf application time due to the short half-life of exotic nuclei of interest. The new system has four function generators to produce the required rf signals for I · 2 nuclei. The rf signals are ampli¯ed to a maximum of 250 W. After the ampli¯er, a switched LCR system is used to maximize power delivered to the rf coil. Six variable capacitors, a 50 resistor or impedance matching transformer, and an rf coil represent the complete LCR circuit. An rf leak test performed on the constructed system showed no signi¯cant rf leak-age from the high voltage rf box, which holds the resistor, transformer, and variable capacitors. Rf magnetic ¯eld strengths were measured to be 18.2 G and 17.6 G for frequencies of 700§10 kHz and 1200§10 kHz, respectively, at maximum power. First application of the new ¯-NQR system will be a precision measurement of the Q of 37K. A value 114.7§38.2 mb has been reported in the literature, and a new value with reduced error is important to test the predictions of sd shell model calculations. The Q of 35K will be measured to ¯nd evidence for in°uence of weak proton binding energy in the Q of this very neutron-de¯cient nucleus. To my mother, my family, all my teachers and friends ii