Scattering electron-proton

Keywords Attosecond dynamics, neutron Compton scattering, electron-proton Compton... 

Model dependence of the Zemach correction, as well as its dependence on the proton radius is theoretically unsatisfactory. A much better approach is suggested in [8], where the values of the proton and deuteron first Zemach moments were determined in a model independent way from the analysis of the world data on the elastic electron-proton and electron-deuteron scattering. The respective moments turned out to be [8]... 

Both the theoretical and experimental data for the classic 2S i/2 — 2Pi/2 Lamb shift are collected in Table 12.2. Theoretical results for the energy shifts in this Table contain errors in the parenthesis where the first error is determined by the yet uncalculated contributions to the Lamb shift, discussed above, and the second reflects the experimental uncertainty in the measurement of the proton rms charge radius. We see that the uncertainty of the proton rms radius is the largest source of error in the theoretical prediction of the classical Lamb shift. An immediate conclusion from the data in Table 12.2 is that the value of the proton radius [27] recently derived form the analysis of the world data on the electron-proton scattering seems compatible with the experimental data on the Lamb shift, while the values of the rms proton radius popular earlier [28, 29] are clearly too small to accommodate the experimental data on the Lamb shift. Unfortunately, these experimental results are rather widely scattered and have rather large experimental errors. Their internal consistency leaves much to be desired. 

With the development of nuclear reactors, giving strong beams of thermal neutrons, crystal structures can now be studied by neutron diffraction, with which the location of the hydrogen atoms is greatly improved. Indeed it is the actual proton which is located for neutrons are scattered by the atomic nuclei, not by the electron density. Since it enables us to locate the proton in A-H B, neutron diffraction is proving of special importance in the study of hydrogen bonds. Deuterons are more powerful neutron-scatterers than protons it is usually advantageous to work with deuteriated materials if possible. 

Studies of positron collisions with atoms and molecules are of interest not only for their own sake but also because comparisons with the results obtained using other projectiles, such as electrons, protons and antiprotons, provide information about the effects on the scattering process of different masses and charges. 

In the course of time (since 1995), the data analysis has been subject to various criticisms [Blostein 2001 Blostein 2003 (a) Blostein 2003 (b) Cowley 2003] which, however, have been refuted by several authors [Chatzidimitriou-Dreismann 2002 (b) Abdul-Redah 2003 Mayers 2004], A further criticism was that all these effects were found on one instrument only, i.e., VESUVIO spectrometer of the ISIS neutron spallation source at the Rutherford Apple-ton Laboratory in UK. There was no possibility to confirm this effect on a different apparatus. However, very recently, this effect was confirmed using an independent experimental method, electron-proton Compton scattering at the Australian National University, Canberra [Chatzidimitriou-Dreismann 2003 (a)]. This experiment has attracted a vast attention by the scientific community [Physics News 2003 Physics Today 2003 Scientific American 2003],... 

Figure 6. Anomalous reduction of scattering intensity from H of Formvar (Ch/L/iLL), as a function of momentum transfer q [Chatzidimitriou-Dreismann 2003 (a)]. The results are normalized by dividing the measured cross section ratios of H to C + O by the "conventional" ratio 21.6. VESUVIO results for full squares 0 1 mm formvar foils and open circles 0 2 mm foils. Large open triangles high-energy electron-proton scattering measurement from Formvar films of 50 — 100 A thickness, as described in Ref. [Chatzidimitriou-Dreismann 2003 (a)].

Very recently, we also succeeded to confirm the NCS results by applying an independent method, namely electron-proton Compton scattering (ECS) [Chatzidimitriou-Dreismann 2003 (a)]. This method is completely different from NCS due to the fact that the Coulomb interaction is involved in contrast to the strong interaction involved in NCS. In addition, the apparatus with which the ECS experiments have been performed is completely different in that the incoming electron beam is monochromatic and the spectra are recorded with respect to energy loss. Therefore, every discussion about the intensity distribution of incident energies or Jacobians is irrelevant. 

To demonstrate this effect, we present in the following NCS and electron-proton scattering (ECS) results from various materials, which reveal the following striking phenomenon [Chatzidimitriou-Dreismann 1997 (a) Chatzidimitriou-Dreismann 2003 (a) Physics Today 2003 Scientific American 2003] ... 

Abstract We present preliminary experimental results of inelastic X-ray scattering (IXS) on molecular vibrations of liquid H2O, DoO and the equimolar H>0 - D >0 mixture. The data analysis indicates the presence of an anomalous shortfall of scattering intensity from the O//-stretching vibrational modes. This effect has no explanation within the frame of conventional X-ray scattering theory. The possible connection of these observations with recent results of neutron and electron Compton scattering from protons in condensed matter is mentioned, as well as their interpretation in terms of attosecond entanglement. 

Keywords Compton scattering, netrons, protons, entanglement, relaxation, electrons, con-... 

R. Rosenfelder, Coulomb corrections to elastic electron-proton scattering and the proton charge radius, Phys. Lett. B 479 (2000) 381-386. 

Hall and Williams reported that some of their films were made up of singlecrystal platelets parallel to the surface of the substrate and having areas of approximately 1000 nm and a thickness of 100 nm (film thickness) [95, 96]. This was determined by the use of both a polarizing microscope and by a scanning electron microscope. The structure of thicker films, produced by multiple evaporations of Pb and conversions to Pb(N2)3, such as used for the far-infrared work, was not reported [95,96,120]. However, the thick films were homogeneous as detected by Rutherford back-scattering of protons [128]. There is also evidence that the disorder was variable from film to film because of variations in the resolution at room temperature of the maximum in the optical extinction at 375 nm [95, 96, 122, 129]. As discussed above, this maximum is sensitive to irradiation, doping, and heat treatment. The resolution of this peak and the associated imperfections in the film are also apparently dependent on the details of the preparation techniques. 

The experimental access to all these other modes has to use methods beyond simple photoabsorption measurements. They have been studied extensively in the case of nuclei by various sorts of scattering experiments (with electrons, protons, ions), which could even provide the full transition formfactors Detailed scattering experiments in the... 

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