PAMS Seminar: "A Measurement of the 2S1/2-8D5/2 Transition in Hydrogen" by Dr. Adam Brandt

PAMS Seminar: "A Measurement of the 2S1/2-8D5/2 Transition in Hydrogen" by Dr. Adam Brandt
Date and time
4:00 PM - 5:00 PM, September 16, 2021
Description

Adam Brandt is an alumnus of PAMS, graduating in 2014 with a BS in Physics. He recently finished his PhD studies at Colorado State University in atomic physics, and now works at NIST in the Ion Storage group.

Abstract:
Over the past decade, there has been renewed interest in precision spectroscopy of atomic hydrogen and hydrogen-like species due to the so-called proton radius puzzle. The proton radius puzzle arose largely due to a measurement of the Lamb shift on muonic hydrogen, a hydrogen atom where the electron is replaced a muon, which resulted in a determination of the proton radius that was in significant statistical disagreement with the proton radius obtained from hydrogen spectroscopy at the time. We present a new measurement of the 2S1/2ā€“8D5/2 transition with a cryogenic hydrogen beam, and the spectroscopy laser directly referenced to a coherent optical frequency comb. The measured resonance frequency is ?=770649561570.8(2.0) kHz, which corresponds to a relative uncertainty 2.5Ɨ10-12. Combining our result with the most recent measurement of the 1Sā€“2S transition, we find a proton radius of rp=0.8581(50) fm and a Rydberg constant of R8=10973731.568330(52) m-1. Our result has a 3.4 s disagreement with the proton radius obtained from the muonic hydrogen Lamb shift measurement and a combined 1.8 s disagreement with the 2014 hydrogenic world average.

This seminar will be held in Kemper 206.

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Admission

Free

Open to public, alumni, current students, faculty, future students, staff
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