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HEPL / KIPAC Seminar

Wednesday, October 4, 2017

Tao Wang

Dima Budker Research Group, University of California, Berkeley

Application of Ultra-senstitive Magnetometry
to the Cosmic Axion Spin Precession Experiment

Abstract: The Cosmic Axion Spin Precession Experiment (CASPEr) seeks to measure oscillating torques on nuclear spins caused by axion or axion-like-particle (ALP) dark matter via nuclear magnetic resonance (NMR) techniques. A sample spin--polarized along a leading magnetic field--experiences a resonance when the Larmor frequency matches the axion/ALP Compton frequency, generating precessing transverse nuclear magnetization.

Here we demonstrate a Spin-Exchange Relaxation-Free (SERF) magnetometer with sensitivity ≈ 1 fT/ √ Hz and an effective sensing volume of 0.1 cm3 that may be useful for NMR detection in CASPEr. A potential drawback of SERF-magnetometer-based NMR detection is the SERF’s limited dynamic range. Use of a magnetic flux transformer to suppress the leading magnetic field, is considered as a potential method to expand the SERF’s dynamic range in order to probe higher axion/ALP Compton frequencies.

A ferromagnetic needle magnetometer is another potential magnetic sensor that could be applied in future versions of CASPEr experiments, which in principal has a better quantum noise limit and can operate at cryogenic temperatures.

Bio: Tao Wang is apostdoctoral researcher Dima Budker Research Group University of California, Berkeley.

Time: 4:00pm – 5:00pm

Location: Physics/Astrophysics Bldg., Kistler Conference Rooms 102/103 (Map)

(Light refreshments available 3:45pm; Presentation begins at 4:00pm)

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