Protonation energetics

A number of now extinct radioactive isotopes have existed in the early solar system. This is shown by the variations that they induce in the abundances in their daughter nuclides. Their main use is in establishing a chronology between their parental presolar stellar sources, and the formation of the solar system and the planets. An active debate is presently going on whether some of these short-lived nuclides could have been made within the early solar system by an intense flux of energetic protons from the young sun. 

Nikjoo, H. Boyden-Pratt, N. Uehara, S. Goodhead, D.T. Energy deposition by mono-energetic protons in cylindrical targets. MRC Monograph, 2001. 

We have developed Y-ray and conversion-electron spectroscopy techiques that take advantage of the energetic proton as an indicator of the (t,p)... 

Okihara S, Sentoku S, Sueda K, Shimizu S, Sato F, Miyanaga N, Mima K, Izawa Y, Iida T, Sakabe S (2002) Energetic proton generation in a thin plastic foil irradiated by intense femtosecond lasers. J Nucl Sci Technol 39 1-5... 

A solid sample is bombarded with a beam of energetic protons, causing the emission of x-rays, characteristic of the elements present. May employ a microbeam (hence MICROPIXE)... 

CFi-less membranes are very leaky to protons, but this leakiness is eliminated by the recombination of the membranes with the isolated CFi, or with any of several inhibitors of the CFq portion of the ATP synthase that is still membrane-bound in the CF]-less membrane. It was thus concluded that CFo is a proton channel whose function is to deliver energetic protons to CF , where ATP synthesis takes place. 

The only important source of ionization in the stratosphere, under most conditions, is galactic cosmic rays [32]. These are mostly energetic protons having average kinetic energies of about 100-1000 MeV corresponding to an atmospheric penetration depth of about 10-15 km. Thus, the galactic cosmic ray ionization rate, Q, reaches a maximum of about 10-100 cm" s around this altitude. 

Ikuta, S., Electron correlation effect on the geometries and energetics Proton-bound ammonia dimer, (H/1—H—NHJ+, J. Chem. Phys. 87, 1900-1901 (1987). 

Rao M. N., Garrison D. H., Pahna R. L., and Bogard D. D. (1997) Energetic proton irradiation history of the howardite parent body regolith and impheations for ancient solar activity. Meteorit. Planet. Sci. 32, 531—543. 

Pions abundant. Energetic proton-proton collisions produce proton-antiproton pairs Cp rising... 

In order to protonate a molecule the acidic OH band has to be heterolytically broken. Not withstanding its acidic character, the energy cost to deprotonate a zeolite side is of the order of 1250 kj/gat. This is one of the main reasons why energetically protonation reactions in zeolites are quite different from reactions in superacids. 

As we have already mentioned, sudden perturbations on the Sun (increases in X-ray production, precipitation of energetic protons or electrons) can greatly modify the ionization rate and the morphology of the ionosphere. Table 7.4 presents order of magnitude estimates of the energy penetrating the middle atmosphere, during both quiet and disturbed periods. 

High energy neutrons are absorbed in water mainly by collisions with H-atoms, forming energetic protons which ionize similar to alpha particles (Table 6.2 and Fig. 6.7). In the collision process the H-atoms are knocked from their positions in the molecule also other atoms may be knocked out. The neutron ends its life by being absorbed in an (n,y) process or leaves the system. 

PIXE is a method using X-ray emission for elemental analysis. A high energetic proton beam excites emission of characteristic X-rays from the sample atoms due to inner-shell ionisation. PIXE is not a true nuclear technique, since the ionisation of the atoms by the ion beam and the subsequent emission of characteristic X-rays are purely atomic electromagnetic (rather than nuclear) processes. Methods and data for using K and L lines of X-rays, produced by ion beams (mostly proton beams) are well established and thick or thin samples can be analysed with an absolute precision of 10 % or better. 

NRA Solids, thin films Mono-energetic Protons, deuterons 0.1-5 M-m 10 jim- Element identification (all) 47... 

The starting point for muon experiments is the production of pions (it) in a nuclear reaction initiated by energetic protons (e.g., Be + p — l Be + ir ). Threshold energies for pion production are > 150 MeV but the cross sections peak in the "intermedi-... 

Promethium-147 can also be obtained from the decay of Nd (which in turn can be produced by bombarding a uranium carbide target with energetic protons from a particle accelerator). Mixed with ZnS (a well-known light emitting material), Pm(III) chloride was used in the glow-in-the-dark paint used in analogue watches the particles emitted by the decay of the Pm excite the ZnS, which displays its luminescence. 

Simplified schematic picture of an intranuclear cascade event for an energetic proton incident on a heavy nucleus. The number of scatterings increases as the impact parameter decreases... 

There are different variants of the basic idea. A survey is given in IAEA (1997). In the following, the concept proposed by Bowmann et al. (1992) will be outlined, which would open up the way to using Th as a fertile material that could be transformed into the fissile uranium isotope The approach is illustrated in O Fig. 57.15. A beam of highly energetic protons (1.6 GeV) from an accelerator is directed onto a target of Pb. 

A more energetic proton beam experiment is being investigated at NRL (see Table 3). Cusp injection is used and 120% reversal of a 1.5 kG guide field has been achieved with a propagating beam. 

Fig. 9. Simulation of 8 electron emission by low energetic protons (left) and carbon ions (right) when penetrating tissue tissue is assumed to be water equivalent. The dashed line at x= 0 represents the trajectory of the primary ions, the full lines represent the paths of individual secondary electrons. The size of a DNA heUx is shown for comparison in the left panel. (Courtesy M. Kramer for details see [60])...

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