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Absorption Spectroscopy and Its Implementation
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
Currently, one of the persisting discrepancies related to QED is the determination of the proton charge radius. Comparing spectroscopic data from muonic hydrogen (μ-p) and normal hydrogen (e-p), the analysis reveals a 4σ discrepancy between the μ-p results and the hydrogen mean value from 11 different transitions (see Antognini et al. 2013; Beyer et al. 2013). This discrepancy is commonly addressed as “the proton radius puzzle.” Proton charge radius values, derived from a range of one- and two-photon transition data, are shown in Figure 7.21. Because the muon has a mass about 200 times heavier than the electron, the μ-p uncertainties are substantially smaller than for the e-p (hydrogen) system. However, it is only the average of all hydrogen laser spectroscopy measurements, together with data from hydrogen Lamb shift and electron–proton scattering, which shows the aforementioned discrepancy: individual hydrogen transition data were not precise enough to determine whether the discrepancy is real or not (note the error bars in the figure, overlapping with μ-p). For the transitions marked with ↔ in the figure, efforts are well under way to improve the statistical errors sufficiently to alleviate this. While successful in principle (see Matveev et al. 2013; Galtier et al. 2015), at the time of writing, no conclusive, final results had been published yet.
Basic Constants, Units, and Conversion Factors
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
proton mass energy equivalent proton-electron mass ratio proton-muon mass ratio proton-tau mass ratio proton-neutron mass ratio proton charge to mass quotient proton molar mass NA mp proton Compton wavelength h/mp c C,p/2 proton rms charge radius proton magnetic moment to Bohr magneton ratio to nuclear magneton ratio proton g-factor 2 p/N proton-neutron magnetic moment ratio shielded proton magnetic moment (H2O, sphere, 25 °C) to Bohr magneton ratio to nuclear magneton ratio
HCAL-J: hadron calorimeter for the study of nucleon form factors at Jefferson Lab
Published in Radiation Effects and Defects in Solids, 2018
V. Brio, V. Bellini, C. Petta, L. Re, C. M. Sutera, F. Tortorici, B. Wojtsekhowski, J. C. Cornejo, G. Franklin, B. Quinn
The first systematic experiments, to determine the internal electromagnetic structure of the hadron matter, date back to the 1950s, at the University of Stanford in California, by Hofstadter and collaborators (3). They did numerous experiments of elastic scattering of electrons on different targets (proton and helium), in order to probe their charge distribution; the results of this investigation were the charge radius measurement of such nuclei.