Interleaved NQR detection using atomic magnetometers.

Area of Science:

• Atomic Physics
• Spectroscopy
• Analytical Chemistry

Background:

• Nuclear Quadrupole Resonance (NQR) is a sensitive technique for material identification.
• Conventional NQR detection often requires shielded environments and can be time-consuming.
• ⁸⁷Rb magnetometers offer high sensitivity and potential for noise reduction.

Purpose of the Study:

• To investigate interleaved NQR detection using ⁸⁷Rb magnetometers.
• To compare the performance of atomic magnetometers with conventional coil detection.
• To assess the feasibility of NQR detection in unshielded environments for explosives localization.

Main Methods:

• Interleaved detection of ammonium nitrate and potassium chlorate using two ⁸⁷Rb magnetometers.
• Rapid matching of magnetometers to NQR frequencies (531 kHz and 423 kHz) using a single tuning field.
• Utilized a double resonant tank circuit for excitation and signal subtraction for noise reduction.

Main Results:

• Achieved comparable Signal-to-Noise Ratios (SNR) to conventional coil detection.
• Demonstrated reduction of ambient noise through signal subtraction, with base noise as low as 2 fT/Hz.
• Interleaved atomic magnetometer detection took half the time of conventional methods and provided localization of explosives.

Conclusions:

• Interleaved NQR detection with ⁸⁷Rb magnetometers is a viable and efficient alternative to conventional methods.
• The technique shows promise for rapid, unshielded explosives detection and localization.
• Further mitigation of ringing artifacts can potentially improve SNR further.