The Lamb shift in muonic hydrogen and the proton radius

By means of pulsed laser spectroscopy applied to muonic hydrogen (μ− p) we have measured the 2S F = 1 1/2 − 2PF = 2 3/2 transition frequency to be 49881.88(76) GHz. By comparing this measurement with its theoretical prediction based on bound-state QED we have determined a proton radius value of rp = 0.84184 (67) fm. This new value is an order of magnitude preciser than previous results but disagrees by 5 standard deviations from the CODATA and the electronproton scattering values. An overview of the present effort attempting to solve the observed discrepancy is given. Using the measured isotope shift of the 1S-2S transition in regular hydrogen and deuterium also the rms charge radius of the deuteron rd = 2.12809 (31) fm has been determined. Moreover we present here the motivations for the measurements of the μ 4He + and μ 3He + 2S-2P splittings. The alpha and triton charge radii are extracted from these measurements with relative accuracies of few 10 − 4. Measurements could help to solve the observed discrepancy, lead to the best test of hydrogen-like energy levels and provide crucial tests for few-nucleon ab-initio theories and potentials

The Lamb shift in muonic hydrogen

The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the 2S1/2F=1–2P3/2F=2 energy splitting (Pohl et al., Nature, 466, 213 (2010)) in μp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a root-mean-square proton charge radius of rp = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp. The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R∞ = 10 973 731.568 160 (16) m⁻¹ and the rms charge radius of the deuteron rd = 2.128 09 (31) fm

The size of the proton and the deuteron

We have recently measured the 2S1/2⁼¹ − 2P3/2 ⁼ ² energy splitting in the muonic hydrogen atom μp to be 49881.88 (76) GHz. Using recent QED calculations of the fine-, hyperfine, QED and finite size contributions we obtain a root-mean-square proton charge radius of rp = 0.84184 (67) fm. This value is ten times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp = 0.8768 (69) fm. The source of this discrepancy is unknown. Using the precise measurements of the 1S-2S transition in regular hydrogen and deuterium and our value of rp we obtain improved values of the Rydberg constant, R∞ = 10973731.568160 (16) m⁻¹and the rms charge radius of the deuteron rd = 2.12809 (31) fm

The Lamb shift in muonic hydrogen 1

Abstract: The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the energy splitting (Pohl et al., Nature, 466, 213 (2010)) in mp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a rootmean-square proton charge radius of r p = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of r p . The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S-2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R ? = 10 973 731.568 16

High Power Thin Disk Laser

In this talk, the latest results for thin disk lasers will be presented. Thin disk lasers can be operated in cw-mode as well as in pulsed mode with pulse durations from 100 fs to microseconds. Results from different institutes and companies will be shown demonstrating the power/energy scalability of the thin disk laser design with good beam quality and high efficiency, simultaneously. Several German companies are selling thin disk lasers with up to 16 kW output power (cw) and with up to 1 kW average power (pulsed) with high energy and high repetition rate. Based on the latest results and numerical models the design of a multi 10 kW to multi 100 kW thin disk laser has been developed. This master-oscillator power-amplifier (MOPA) system is now under construction. The principle design ideas of this system will be given

2 µm Ho:YAG Thin Disk Laser

A Thulium fiber laser pumped Ho:YAG thin disk laser with 15W (cw) or several mJ (pulsed) operation will be presented. Additionally, a narrow (<0.5nm), tunable (30nm) cw operation near 2.09 µm, will be shown

Thin-disk laser – Power scaling to the kW regime in fundamental mode operation

A significant reduction of the influence of the thermal lens in thin-disk lasers in high power laser operation mode could be achieved, using dynamically stable resonators. For designing the resonator, investigations of thermally induced phase distortions of thin-disks as well as numerical simulations of the field distribution in the resonator were performed. This characterization was combined with thermo-mechanical computations. On the basis of these studies, about 500 W output power with an averaged M2 = 1.55 could be demonstrated, using one disk. Almost 1 kW output power with good beam quality could be extracted, using two disks. For the purpose of further power scaling in nearly fundamental mode operation, experiments using more than two disks are in preparation

The Outstanding Qualities of Fiber Lasers and Thin Disk Lasers

In this summery the properties of fiber lasers and thin disk lasers are discussed in detail, showing that both designs are optimized solutions for building solid state lasers with outstanding properties. The advantages and also the disadvantages of each design will be explained and it will be shown that depending on the application the one or the other design will be advantageous. There is no either or, the question is what design is the best solution for which application. Some latest results and demonstrations will support this conclusion

Mode Dynamics and Thermal Lens Effects of Thin Disk Lasers

In principle, the thin disk laser concept opens the possibility to demonstrate high power, high efficiency and good beam quality, simultaneously. For this purpose a very homogeneous pump power distribution on the disk is necessary as well as very low phase distortions of the disk itself. Spatial mode structure and thermal lensing effects in an Yb:YAG thin disk laser have been investigated as function of the pump power in linear and folded resonators. Whereas thermal lensing is shown to be very weak due to the thin disk geometry, a strong correlation of the laser mode with respect to the power density distribution of the pump radiation is exhibited. The experimental results are compared with numerical simulations of the field distribution within the resonator as well as in the far field demonstrating the excellent homogeneity of the disk as laser active medium. The results will be used for scaling the fundamental mode power into the multi-kW-regime