1 / 18

Dressed Spin Studies with Polarized 3 He

Dressed Spin Studies with Polarized 3 He. Andrea Esler & Jen-Chieh Peng (UIUC). Steve Lamoreaux & Chen-Yu Liu (LANL). Dressed Spin. Strong RF fields change the effective magnetic moments of neutrons and 3He First 3He spin dressing measurements performed in April 2005

joan-schneider
Download Presentation

Dressed Spin Studies with Polarized 3 He

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dressed Spin Studies with Polarized 3He Andrea Esler & Jen-Chieh Peng (UIUC) Steve Lamoreaux & Chen-Yu Liu (LANL)

  2. Dressed Spin Strong RF fields change the effective magnetic moments of neutrons and 3He • First 3He spin dressing measurements performed in April 2005 • Change of 3He Larmor frequency with a dressing field has been observed. In the B0<<B1 limit, the g factor modification has a simple formula

  3. Effective g factor vs. RF field strength: Dressed Neutron Spin already observed Muskat, PRL 58(20), 1987 Numerical simulations reproduced these results Fits the J0(gB1/w) prediction

  4. Critical dressing equalizes precession rates • Reduce the effect of B0 [instability] on the two species • A check of gn=g3: scintillation no longer modulated Crossing points equalize neutron and 3He g factors: Effective dressed g factors: neutron 3He

  5. Polarized 3He Source Spin flip region 3He detector Injection nozzle Quadrupole analyzer 1 K cold head Quadrupole separator 4 m Experiment Solenoid field 8 Gauss 3He detector RGA Spin polarizer Spin analyzer B1rf 90 cm

  6. Adding an RF dressing field slows down spin precession between the flip coils (or speeds it up…) & changes the minimum transmission frequency Ramsey experiment technique (SOF) Images courtesy Sussex Neutron EDM group Free precession Incoming 3He p/2 pulse Second p/2 pulse +1 Z component of nuclear spin Analyzer & Counter -1 accepts P=+1 state When the RF pulses are applied on resonance (at the Larmor frequency) the 3He spin direction is completely reversed (minimal transmission)

  7. 3He experiment setup Ramsey coils and dressing coils are inside the solenoid source solenoid to analyzer and RGA detector polarizer

  8. 3He beam polarization: P > 95% Unpolarized transmission Full beam transmission RGA pressure reading ” p pulse” field setting Spin-flip magnetic field B1 x distance Dec. 2004: P=99.6% was measured with better shielding

  9. From Dec. 2004 meeting: 1 K “Maxwell” dist. Accepted velocities Img. courtesy S. Lamoreaux • Polarization (as fn. of B1) averages over 3He velocities • P(B1) measures Fourier cosine transform of velocity spectrum • Invert the FT to measure N(v): Velocity spectrum deduced from April measurements needs to be calibrated, but we expect agreement

  10. 3He beam background pressure open and closed shutter 6 nTorr the same, log scale 0.01 nTorr

  11. Mapping the dressing field Dressing magnet coil

  12. Dressing coil field map Average field: 1.6 Gauss / Ampere

  13. 3He dressed spin results I Dressing field frequency 43.5 kHz Increasing dressing field Minimal transmission rate observed at the 3He Larmor precession frequency

  14. 3He Larmor Freq. Dressed at 43.5 kHz Max B field 5.8 G Inconsistent with simple formula; B0~B1

  15. 43.5 kHz data vs. simulation Rough agreement with Bloch-equation simulations – I am working to refine the code

  16. 3He dressed spin results II Dressing field frequency 8.1 kHz Increasing dressing field

  17. 3He Larmor Freq. Dressed at 8.1 kHz Max B field 1.6 G

  18. Outlook • Continue analysis • Understand observed Larmor freq. behavior • Upcoming measurements (this week) will emulate EDM experimental conditions • More intense dressing fields over smaller volume (new coils already built) • Smaller B0 (limited by earth’s field ~5 G) • Larger dressing field frequency ~50-100 kHz

More Related