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Magnetometry

Magnetometry. Hattie Ring Presentation for Phys 250 4/22/2008. Outline. Magnetometers General Setup Alkali Cell Optical Pumping Optical Probing Methods of Magnetometry DAVLL Combined Pumping and Probing RF vs. DC Magnetometers SERF regime Magnetometry in MRI Remote Detection

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Magnetometry

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  1. Magnetometry Hattie Ring Presentation for Phys 250 4/22/2008

  2. Outline • Magnetometers • General Setup • Alkali Cell • Optical Pumping • Optical Probing • Methods of Magnetometry • DAVLL • Combined Pumping and Probing • RF vs. DC Magnetometers • SERF regime • Magnetometry in MRI • Remote Detection • Future work

  3. Magnetometer General Setup Light Source (probe) Light Source (pump)

  4. Alkali Cell Alkali Atom Cell

  5. Optical Pumping Light Source (pump) Johannes Recht, W. K. (2005). Optical Pumping of Rubidium. Madison

  6. Optical Pumping Light Source (pump) Rochester and Budker (2001). Am. J. Phys. 69, 450-4.

  7. Optical Pumping Light Source (pump) Johannes Recht, W. K. (2005). Optical Pumping of Rubidium. Madison

  8. Optical Pumping Magnetic Field Light Source (pump) Johannes Recht, W. K. (2005). Madison

  9. Optical Pumping Magnetic Field Light Source (pump) Causes atomic polarization to precess Rochester and Budker (2001). Am. J. Phys. 69, 450-4.

  10. Optical Pumping Magnetic Field Light Source (pump) Black, E. D. (2004). Optical Pumping.

  11. Optical Pumping Magnetic Field Light Source (pump) Johannes Recht, W. K. (2005). Madison

  12. Probe Light Light Source (probe) Light Source (pump) • Two different detection modes: • Change in light intensity • Change in polarization

  13. DAVLL RCL LCL Laser Grating Valeriy V. Yashchuk, D. B., John R. Davis (1999). Review of Scientific Instruments 71(2): 341 - 346. Light Source

  14. DAVLL RCL LCL Laser Grating Light Source Valeriy V. Yashchuk, D. B., John R. Davis (1999). Review of Scientific Instruments 71(2): 341 - 346.

  15. Single Laser Setup Light Source (pump & probe)

  16. Rf Magnetometers Rf Coil Light Source (probe) M. P. Ledbetter, V. M. A., S. M. Rochester, D. Budker, S. Pustelny, V. V. Yashchuk (2008). Light Source (pump) Johnson noise can be neglected, allowing for better sensitivity.

  17. Spin-Exchange Relaxation Free (SERF) Oven Light Source (probe) Light Source (pump) • Collision Avoidance: • Buffer gas • Cell coating • Two types of collisions in alkali cells: • Spin-exchange collisions • Can be ignored in SERF • Spin-destruction collisions

  18. Magnetometer with MRI Magnetometer Water Out Encoding Field (B0, Bx, By, Bz) Nitrogen Pre-polarization Field (~ 3 kG) H2O

  19. Magnetometer with MRI 2 magnetometer setups DC magnetometers Modulated single laser setup

  20. Remote Detection Flow Out Magnetometer Flow In Detector s(t) t

  21. Remote Detection Encoding Pulse Flow Out Magnetometer Flow In Detector s(t) t

  22. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) t

  23. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) t

  24. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  25. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  26. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  27. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  28. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  29. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  30. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  31. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  32. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  33. Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  34. Signal (nG) Time (s) Remote Detection Flow Flow Out Magnetometer Flow In Detector s(t) tflow t

  35. 0.5 s 0.7 s 0.9 s 1.1 s 1.3 s 1.5 s 1.7 s 1.9 s 2.1 s 2.3 s Signal (nG) Time (s) Remote Detection Results H2O t-sampling

  36. 0.4 s 0.6 s 0.8 s 1.0 s 1.2 s 1.4 s 1.6 s 1.8 s 2.0 s 2.2 s z y Remote Detection Results Resolution: z, 5mm; y, 2.5mm

  37. 0.4 s 0.6 s 0.8 s 1.0 s 1.2 s z 1.4 s 1.6 s 1.8 s 2.0 s 2.2 s y Remote Detection Results Resolution: z, 5mm; y, 2.5mm

  38. 0.4 s 0.5 s 0.6 s 0.7 s 0.8 s z y Remote Detection Results Flow Mixing Region

  39. Future Work • New System Being Built • Miniaturization • Optimized one-sided geometry • Prepolarization for static imaging • NQR • Measurements • Novel prepolarization techniques • Micro-channel flow, Lab-on-a-chip • RF Magnetometry • Eliminate point-by-point acquisition • Design of system for direct imaging • The Brain • Hand-held scanners

  40. References Black, E. D. (2004). Optical Pumping. http://www.hep.wisc.edu/~prepost/407/opticalpumping/opticalpumping.pdf D. Budker, D. F. K., V. V. Yashchuk, and M. Zolotorev (2002). "Nonlinear magneto-optical rotation with frequency-modulated light." Physical Review A 65(055403): 1 - 4. Dmitry Budker, M. R. (2006). "Optical Magnetometry.“ M. P. Ledbetter, V. M. A., S. M. Rochester, D. Budker, S. Pustelny, V. V. Yashchuk (2008). "Detection of radio frequency magnetic fields using nonlinear magneto-optical rotation.“ I. M Savukov, S. J. S., M. V. Romalis, K. L. Sauer (2005). "Tunable Atomic Magnetometer for Detection of Radio-Frequency Magnetic Fields." Physical Review Letters 95(063004): 1 - 4. Johannes Recht, W. K. (2005). Optical Pumping of Rubidium. Madison ShoujunXu, S. M. R., Valeriy V. Yashchuk, Marcus . Donaldson, Dmitry Budker (2006). "Construction and applications of an atomic magnetic gradiometer based on nonlinear magneto-optical rotation." Review of Scientific Instruments 77(8) ShoujunXu, V. V. Y., Marcus H. Donaldson, Simon M. Rochester, Dmitry Budker, and Alex Pines (2006). "Magnetic resonance imaging with an optical atomic magnetometer." PNAS: 1-4. Valeriy V. Yashchuk, D. B., John R. Davis (1999). "Laser frequency stabilization using linear magneto-optics." Review of Scientific Instruments 71(2): 341 - 346.

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