Fission fragments secondary

Desorption ionization (DI). General term to encompass the various procedures (e.g., secondary ion mass spectrometry, fast-atom bombardment, californium fission fragment desorption, thermal desorption) in which ions are generated directly from a solid or liquid sample by energy input. Experimental conditions must be clearly stated. 

FIGURE 3.10 A typical fission fragment track in water, showing dense overlap of secondary electrons in the penumbra region (shaded). Core is shown dotted. Reproduced from Mozumder (1969), by permission of John Wiley Sons, Inc. ... 

Primary fission products, secondary Sl deexcited fission fragments in their V ground state. These nuclei are far removed from beta stability and are radioactive. 

Figure 6(d). Typical fission fragment track in water. Secondary electrons densely overlap to form the sheath Their LET is about two orders of magnitude smaller than that of the core... 

Washington at the DTM. Richard Roberts and R. C. Meyer were preparing a letter to the Physical Review reporting the discovery of delayed neutrons from fissioa These were not the instantaneous secondary neutrons the Columbia researchers were seeking, but they did confirm that the fission fragments had neutrons to spare and would give them up spontaneously. 

The field-desorption spectra of several aldoses and ketoses ionized by attachment of potassium ions led to the identification of the characteristic fragments formed by loss of small molecules, and related secondary ion analysis was carried out on various purine and pyrimidine nucleosides. Also in the nucleoside field a set of mathematical procedures has been applied to the spectra derived from 125 compounds and has led to pattern recognition and interpretation. Underivatized nucleosides have been studied by a method based on pulsed laser and fission fragment-induced desorption, and also by a chemical ionization technique dependent on a direct exposure probe. ... 

Li, is a common reaction employed in neutron detectors, and these detectors are especially sensitive to slow neutrons because of large thermal neutron cross section of B -°. Another neutron detecting scheme using secondary charged particles to ionize the gas is the fission counter. Here, fission fragments do the ionizing and this detector type is also primarily sensitive to slow neutrons. Most detectors used in reactors and health physics instruments detect slow neutrons by one of the above (or similar) reactions. 

Wien, K. Becker, O. Ion Formation from Organic Solids Secondary ion emission from metals under fission fragment bombardment. Benninghoven, A. Springer Series in Chemical Physics 1983,25,47-51. 

H2 and sodium, in the nickel foil supporting the sample. These impurities react with elemental ions formed from fission fragments of californium 252 to generate secondary ions which behave as Cl agents. A time-of -flight instrument is used to analyse the ions produced. 

Fig. 14.9 The PDMS mass spectrometer at Argonne National Laboratory. The fission fragment source is located in front of the sample film. An accelerating potential of 10 kV is maintained between the sample plate and grid located 3 mm from the sample plate. Region 1 houses the primary ion source, acceleration region, and start detector. Region 2 houses a time-of-flight guide wire, drift tube, and stop secondary-ion) detector. Both regions are maintained at a pressure of less than 1 x 10 mmHg.

In Sections II and III it was shown that secondary and tertiary alkyl cations can be formed by decarbonylation of the corresponding oxo-carbonium ions. This has been found impossible in the case of primary alkyl cations (Hogeveen and Roobeek, 1970) the oxocarbonium ions 13 and 14 were unchanged after one hour at 100°C k < 1-3 x 10 sec ), whereas ion 15 is fragmented by a j3-fission under these circumstances ... 

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