Detection and imaging of electric fields, using polarized neutrons

1. An apparatus comprising:

a neutron source adapted to produce a neutron beam;

a spin polarizer adapted to receive the neutron beam and to spin polarize the neutron beam such that the neutron beam has a polarization vector P;

a spin analyzer adapted to polarization-analyze the neutron beam after the neutron beam interacts with a target electric field, an analyzing direction of the spin analyzer being orthogonal to P; and

a neutron detector adapted to detect an intensity of the thus polarization-analyzed neutron beam and to output a corresponding detection signal.

2. The apparatus of claim 1 ,

wherein the neutron source includes one of a neutron facility beamline, a cold neutron generator, a thermal generator, an epithermal neutron generator, or a thermal neutron generator from a moderated fast neutron source; and

wherein the neutron beam is one of monochromatic or polychromatic.

3. The apparatus of claim 1 , wherein the spin polarizer includes one of a neutron supermirror or a He-3 cell.

4. The apparatus of claim 1 , wherein the polarization vector P is at least one of parallel, anti-parallel, or orthogonal to a direction of the neutron beam.

5. The apparatus of claim 1 , further comprising a magnetic guide field generator adapted to produce a guide magnetic field and to guide the neutron beam to the target electric field.

6. The apparatus of claim 5 , wherein the magnetic guide field generator includes a solenoid coil.

7. The apparatus of claim 1 ,

wherein the spin polarizer includes one of a neutron supermirror or a He-3 cell; and

wherein the neutron detector includes one of a neutron supermirror or a He-3 cell.

8. The apparatus of claim 1 , further comprising a magnetically-shielded sample chamber adapted to hold a target generating the target electric field.

9. The apparatus of claim 1 , further comprising a mapper, the mapper adapted to receive the detection signal and to convert the detection signal into a corresponding electric field magnitude of the target electric field.

10. The apparatus of claim 1 , further comprising one of a slit, a pair of orthogonal slits, or a pinhole at an exit of the neutron generator, the one of a slit, a pair of orthogonal slits, or a pinhole adapted to define an imaging resolution of the apparatus.

11. The apparatus of claim 10 , wherein the neutron detector includes:

an imaging screen adapted to generate scintillation photons upon absorbing the thus polarization-analyzed neutron beam; and

a camera adapted to capture a two-dimensional image of the imaging screen, the two-dimensional image corresponding to the detection signal.

12. The apparatus of claim 11 , further comprising a mapper, the mapper adapted to receive the two-dimensional image and to at least one of convert the two-dimensional image into corresponding gray-scale values, convert the two-dimensional image into corresponding electric field magnitudes of the target electric field, or convert the two-dimensional image into a corresponding image for display.

13. A method, comprising:

producing a spin-polarized neutron beam having a polarization vector P;

transmitting the spin-polarized neutron beam through a sample region in which there is a target electric field, the spin-polarized neutron beam interacting with the target electric field;

polarization-analyzing the transmitted neutron beam after the spin-polarized neutron beam interacts with the target electric field, a direction of the polarization-analyzing being orthogonal to P; and

detecting an intensity of the polarization-analyzed neutron beam.

14. The method of claim 13 further comprising guiding the spin-polarized neutron beam to the sample region with a guide magnetic field.

15. The method of claim 13 further comprising mapping the thus detected neutron-beam intensity to a corresponding electric field magnitude of the target electric field.

16. The method of claim 13 , wherein the polarization vector P is at least one of parallel, anti-parallel, or orthogonal to a direction of the spin-polarized neutron beam.

17. The method of claim 13 , wherein the sample region is contained within a magnetically shielded enclosure.

18. The method of claim 13 ,

wherein detecting the polarization-analyzed neutron beam intensity is performed by an imaging apparatus that produces a two-dimensional array of neutron-beam intensity values; and

the method further comprising mapping the two-dimensional array of neutron-beam intensity values to at least one of corresponding gray-scale values, corresponding electric field magnitudes of the target electric field, or a corresponding image for display.

19. The method of claim 18 ,

wherein the steps of producing a spin-polarized neutron beam, transmitting the spin-polarized neutron beam, polarization-analyzing the transmitted neutron beam, detecting an intensity of the polarization-analyzed neutron beam, and mapping the two-dimensional array produce a first data set;

wherein the steps of producing a spin-polarized neutron beam, transmitting the spin-polarized neutron beam, polarization-analyzing the transmitted neutron beam, detecting an intensity of the polarization-analyzed neutron beam, and mapping the two-dimensional array are repeated with one of (1) a polarity of the target electric field being inverted or (2) the target electric field being turned off to thereby produce a second data set;

the method further comprising subtracting the second data set from the first data set.

20. The method of claim 18 ,

wherein the steps of producing a spin-polarized neutron beam, transmitting the spin-polarized neutron beam, polarization-analyzing the transmitted neutron beam, detecting an intensity of the polarization-analyzed neutron beam, and mapping the two-dimensional array produce a first data set;

wherein the steps of producing a spin-polarized neutron beam, transmitting the spin-polarized neutron beam, polarization-analyzing the transmitted neutron beam, detecting an intensity of the polarization-analyzed neutron beam, and mapping the two-dimensional array are repeated with one of (1) a second spin-polarized neutron beam having a polarization vector −P or (2) a direction of the polarization-analyzing being reversed to thereby produce a second data set;

the method further comprising subtracting the second data set from the first data set.