Magnetic Field Direction Measurement and Compasses Murchhana Roy

Magnetic Field Direction Measurement and Compasses Murchhana Roy , Wolfgang Korsch University of Kentucky 12. 10. 2018

Outline • Introduction • Horizontal Compass • Vertical Compass • 3 He studies at University of Kentucky

Introduction

Outline • Introduction • Horizontal Compass • Vertical Compass • 3 He studies at University of Kentucky

Horizontal Compass Sectional view through center Image source: “Precision measurements of the Neutron Electric Form Factor at High Momentum Transfers”, Ameya Suresh Kolarkar (2008) Measures the angle made by the horizontal magnetic field with respect to electron beam direction in Hall C.

Horizontal Compass (Cont. ) Side View Images source: “Precision measurements of the Neutron Electric Form Factor at High Momentum Transfers”, Ameya Suresh Kolarkar (2008) Minimized the angle between the geometric and magnetic axes of the cylinder by minimizing the minor axis of the ellipse.

Horizontal Compass (Cont. ) • Angle of reference mirror with respect to beamline was measured (θHall) in. • Angle between reference mirror and compass mirror was measured. • Absolute measurement was taken for a particular position of the compass. Image source: “Precision measurements of the Neutron Electric Form Factor at High Momentum Transfers”, Ameya Suresh Kolarkar (2008) • The compass was moved along the target length and measurements were taken.

Horizontal Compass (Cont. ) • Indicates the deviation of the magnetic field along the length of the target. • Angle varied by about 10 mrad over length of the target. • Error in the measurement was less that 2 mrad or 0. 1˚. Image source: “Precision measurements of the Neutron Electric Form Factor at High Momentum Transfers”, Ameya Suresh Kolarkar (2008)

Outline • Introduction • Horizontal Compass • Vertical Compass • 3 He studies at University of Kentucky

Vertical Compass Side view Measures the angle made by the vertical magnetic field with respect to the horizontal plane in Hall C.

Vertical Compass (Cont. )

Outline • Introduction • Horizontal Compass • Vertical Compass • 3 He studies at University of Kentucky

3 He Studies at University of Kentucky

3 He Polarization Loss in Frequency Sweep NMR Frequency Sweep Rate : Different polarization losses for different sweep rates within Adiabatic Fast Passage ( AFP ) conditions. Image source: Studies Of Magnetically Induced Faraday Rotation By Polarized Helium-3 Atoms Joshua Abney (2018)

Presence of K in the Target Chamber Alkali Metal Transition Wavelength (nm) 780. 03 Rb 794. 76 769. 89 766. 48 K 404. 72 404. 41 Image source: Studies Of Magnetically Induced Faraday Rotation By Polarized Helium-3 Atoms Joshua Abney (2018) Resonant Faraday Rotation from the 404. 721 nm resonance of K Indicates Faraday rotation solely due to the classical magnetic field (~1 -2 m. G) produced by 3 He polarized to 17%.

Summary • The compasses are almost ready for the final testing. • Mirror holders for the compasses are being re-fabricated. • Optical encoder for the vertical compass is being procured. • We expect them to be ready for the experiment within a month. Thank you!