Neutron spin manipulation

For Larmor labeling of neutron spin

In a magnetic field, with quantum mechanics, the neutron spin is the result of the superposition of the coherent spin states. The spatial and temporal dependence of their wave functions will give the evolution of the neutron spin. The polarization analyzer will collapse the wave functions thus the observation of each spin state can be performed. Classically, the neutron spin can also be described by the Larmor precession of the spin. The analyzer will measure the projection of the spin component that is parallel to the magnetic field. So, we offer a variety of  neutron spin manipulation devices.


Magnetic Wollaston prisms (MWP)

Beam splitter

Similar to the optical Wollaston prism, the two spin states have different refraction index. After the MWP, the two spin states will be split into two beams.

Superconducting device

It employs superconducting materials, including films and tape, which can generate a high magnetic field intensity with almost perfectly defined boundaries.


It can be used as neutron encoder, which is the key component for the Larmor labeling of neutron spin. It can also work as an entangler of neutron spin and path.

Neutron RF spin flipper

Photon exchanger

On resonance, it can exchange photons with the neutrons. Therefore, the two neutron spin states will either gain or lose energy such that they can be split in time domain.

Wavelength independent

With the gradient coil, the flipping efficiency can be independent of the neutron wavelength.


They can be used to create a neutron interferometer in time domain, which can be used to measure the dynamics of the materials. 


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The neutron polarizer can only allow the transmission of one neutron spin state and the other state will be absorbed.

S bender

The S bender is very compact with a length of 80 mm along the beam and cross section of 30 mm x 100 mm. For the wavelength of 4.4 Å, the polarization efficiency is more than 98% and the transmission is above 65% of the spin up component [9].

V cavity

The device is ~80cm long and can be oriented in either options.





Guide fields


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  1. Design and performance of a superconducting neutron resonance spin flipper. R. Dadisman and et. al., Rev. Sci. Instrum. 91, 015117, (2020)
  2. Optimization of a superconducting Radio Frequency Neutron Resonant Spin Flipper. F. Li and et. al., Nuclear Instruments and Methods in Physics Research
    B. 955, 163300, (2020)
  3. Design and characterization of zero-field for high efficiency neutron polarization transport, R. Dadisman and et. al, Nuclear Instruments and Methods in Physics Research A, 940, 174, (2018).
  4. Magnetic field optimization and design of a superconducting neutron Wollaston prism, F. Li and et. al, J. Phys.: Conf. Ser. (2016), 711, 012015
  5. Neutron spin manipulation devices using YBCO films, T. Wang and et. al, Journal of Physics: Conference Series, (2014), 528, 012024.
  6. Superconducting magnetic Wollaston prism for neutron spin encoding, F. Li and et. al, Rev. Sci. Instrum., (2014), 85, 053303.
  7. Design of a cryogen free cryo- flipper using a high Tc YBCO film, S. Parnell and et al, Physics Procedia, (2013) 42, 125.
  8. Performance of a polarised neutron cryo- flipper using a high Tc YBCO film, S. Parnell and et al, Nucl. Instrum. Methods Phys. Res., Sect. A, (2013), 722, 20.
  9. High performance, large cross section S-bender for neutron polarization, Th. Krist and et al., Nucl. Instrum. Methods Phys. Res., Sect. A, (2013) 698, 94-97. 
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