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--- lecture:fine_structure_constant_at_cm21 [2020/12/09 06:32] – created Ce Zhang
+++ lecture:fine_structure_constant_at_cm21 [2021/06/04 07:23] (current) – Ce Zhang
@@ Line 1: / Line 1: @@
-====== On determination of the fine-structure constant: Electron g-2 and Atom interferometers ======
+===== On determination of the fine-structure constant: Electron g-2 and Atom interferometers =====
 Makiko Nio (RIKEN)
 Dec2020
+{{ :lecture:cm21_fine_structure_constant.pdf |the slides}}
+Three ways to determine alpha
+Initially comes from the fine structure of the hydrogen atom ( Sommerfield, 1916)
+Change in the SI, 2019
+{{ :lecture:201209:201209-1.png|300}}
+Old method: Quantum hall effect resistance R$_k$ --> no longer available
+==== New method: Atom interferometer ====
+Young’s-double slit interferometer of light
+two points:
+  - coherent
+  - slit
+Our case: atom interference by light
+Manipulation of an atom w/ light
+Gain momentum! from excitation
+Optical lattice to accelerate the atom
+interference occurred at the t0 + 2T + T'
+(the N traveled from different way are different)
+Two sources: Cs and Rb
+measure the h/M, then
+{{ :lecture:201209:201209-2.png|300}}
+R$_\infity$ puzzle --> does not matter
+Ar(M), Ar(me) --> g factor!
+Error sources: largest is the laser beam profile
+==== electron g-2 ====
+Penning trap
+{{ :lecture:201209:201209-3.png|300}}
+==== Be careful ====
+{{ :lecture:201209:201209-4.png|300}}
+should not be an issue for muon g-2, but it is for e g-2
+h/M may not be insensitive to new physics
+**SHOULD study such effect on Mu 1S2S**