Proton track

FIGURE 3.8 A typical MeV proton track in water. See text for details. Reproduced from Mozumder (1969), by permission of John Wiley Sons, Inc. ... 

Figure 16 Mean lineal energy for 1 MeV proton tracks (left panel) and 5 MeV alpha particle tracks...

V. Cobut, Y. Frongillo, J.P. Patau, T. Goulet, M.J. Eraser, and J.P. Jay Gerin, Monte Carlo simu lation of fast electron and proton tracks in liquid water I. physical and physicochemical aspects, Radial Phys. Chem. 51, 229 (1998). 

The absence of detectable perturbations in the proton track recoil angle distribution in NEP at small angles and the unsensitiveness of anisotropy measurements to source-detector geometrical relative aspect, demonstrate that most neutrons are emitted within a few centimeters of the anode surface. (0, t) streak images of the neutron emission reconstructed by computer show that the neutron source does not drift up as a whole. Neutron yield variations induced by inserting an obstacle at different distances along the -axis confirm the z extension of the neutron source and do not perturb the neutron production up stream, see Fig. 9. 

Analytical determinations of nitrogen are most often done using classical chemical techniques. Mitchell et al. [398] have applied 14-MeV NAA to characterise N distribution in polymers in a nondestructive fashion using image analysis of the proton track densities. 

Redox reactions are more complicated than precipitation or proton transfer reactions because the electrons transferred in redox chemishy do not appear in the balanced chemical equation. Instead, they are hidden among the starting materials and products. However, we can keep track of electrons by writing two half-reactions that describe the oxidation and the reduction separately. A half-reaction is a balanced chemical equation that includes electrons and describes either the oxidation or reduction but not both. Thus, a half-reaction describes half of a redox reaction. Here are the half-reactions for the redox reaction of magnesium and hydronium ions ... 

Tracks of a-particles and MeV protons are long and cylindrical. Samuel and Magee (1953) found, however, that no unequivocal answer could be obtained for the probability of molecular yield formation since, in a truly cylindrical geometry, no radical can escape recombination in the limit t — So they carried their cal-... 

Another procedure for calculating the W value has been developed by La Verne and Mozumder (1992) and applied to electron and proton irradiation of gaseous water. Considering a small section Ax of an electron track, the energy loss of the primary electron is S(E) Ax, where S(E) is the stopping power at electron energy E. The average number of primary ionizations produced over Ax is No. Ax where o. is the total ionization cross section and N is the number density of molecules. Thus, the W value for primary ionization is 0)p = S(E)/No.(E). If the differential ionization cross section for the production... 

Fast neutron exposure determined by counting individual proton recoil tracks. 

Fig. 1. Luminosity evolution of tracks of 0.5 M0 starting at different central temperature, labelled in the figure. At the bottom we sketch the energy liberated per gram due to the deuterium fusion with protons. The tracks of logT > 6.0 start in the middle of D-burning.

Blackett discovered that the process was not one of disintegration, but one of integration only two tracks were seen after the interaction occurred, meaning that the alpha particle was absorbed as the proton was ejected. The resulting nucleus was a heavy isotope of oxygen. 

D-correlation spectra were collected. This information was used with empirical spectral simulations of proton and carbon spectra to elucidate the structures. The necessary information was thus provided to demonstrate that multiple dimer-like structures were formed through bonding of residual synthetic precursor to each of the hydroxyl sites of the drug substance itself. Three distinct dimers were identified. These species were tracked by LC-NMR, and two were shown to interconvert over time. Analogous trimer structures were also evident at lower levels. 

Another source of overlapping tracks are the knock-on protons produced during fast neutron irradiation of a hydrogenous material. 

Two-Dimensional NMR—Basically, the two-dimensional NMR techniques of nuclear Overhauser effect spectroscopy (NOESY) and correlation spectroscopy (COSY) depend on the observation that spins on different protons interact with one another. Protons that are attached to adjacent atoms can be directly spin-coupled and thus can be studied using the COSY method. This technique allows assignment of certain NMR frequencies by tracking from one atom to another. The NOESY approach is based on the observation that two protons closer than about 0.5 nm perturb one another s spins even if they are not closely coupled in the primary structure. This allows spacial geometry to be determined for certain molecules. 

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