Quiroz Darwin R, Cooper Robert J, Foley Elizabeth L, Kornack Thomas W, Lee Garrett J, Sauer Karen L
Quantum Science and Engineering Center, George Mason University, Fairfax 22030, VA, USA.
Twinleaf LLC, Plainsboro 08536, NJ, USA.
J Magn Reson. 2022 Oct;343:107288. doi: 10.1016/j.jmr.2022.107288. Epub 2022 Sep 23.
Interleaved Nuclear Quadrupole Resonance (NQR) detection was conducted on ammonium nitrate and potassium chlorate using two Rb magnetometers, where potassium chlorate is measured during the T limited recovery time of ammonium nitrate. The multi-pass magnetometers are rapidly matched to the NQR frequencies, 531 kHz and 423 kHz, with the use of a single tuning field. For ease of implementation, a double resonant tank circuit was used for excitation, but could be replaced by a broad-band transmitter. All work was done in an unshielded environment and compared to conventional coil detection. The two magnetometers were sensitive, base noise as low as 2 fT/Hz, and were shown to reduce ambient noise through signal subtraction. When an excitation pulse was introduced, however, residual ringing increased the noise floor; mitigation techniques are discussed. The two detection techniques resulted in comparable Signal-to-Noise Ratio (SNR). Interleaved detection using the atomic magnetometers took half the time of conventional detection and provided localization of the explosives.
使用两台铷磁力计对硝酸铵和氯酸钾进行了交错式核四极共振（NQR）检测，其中在硝酸铵的T受限恢复时间内对氯酸钾进行测量。通过使用单个调谐场，多通道磁力计能够快速匹配到531kHz和423kHz的NQR频率。为便于实施，采用了双谐振槽路进行激励，但也可用宽带发射器替代。所有工作均在非屏蔽环境中完成，并与传统线圈检测进行了比较。这两台磁力计灵敏度高，基线噪声低至2 fT/Hz，且通过信号相减显示出可降低环境噪声。然而，当引入激励脉冲时，残余振铃会提高本底噪声；文中讨论了缓解技术。这两种检测技术得到了相当的信噪比（SNR）。使用原子磁力计的交错式检测所需时间仅为传统检测的一半，并能实现爆炸物的定位。
