Heavy Ion Energy Accumulation in the Tandem Van de Graaff Accelerator

Abstract

A new energy-accumulation method has been found for accelerating very small but usable beams of artificial fission fragments such as bromine and iodine ions to energies three times higher than those previously available from tandem Van de Graaff accelerators. Energies up to 120 MeV now available cover completely the energy range found for the fission particles from uranium. The ions have been used to study the behavior of silicon solid-state fission-particle detectors of many types. For the first time direct calibration methods are available to aid in experimental studies of the fission process. Further work will be directed toward an experimental study of the stopping power of various elements for heavy ions.

Charge States and Charge-Changing Cross Sections of Fast Heavy Ions Penetrating Through Gaseous and Solid Media

“…On the other side, since its relative intensity increases when heavier ions are accelerated, one may choose to enhance it even more by admitting small amounts of gas throughout the second half of the acceleration system. This procedure is called continuous stripping (Moak et al 1963) and has the advantage of producing small beams of significantly increased energy. An example for an energy spectrum of that kind is shown in Fig.…”

Significance of the Lattice Contribution to Mössbauer Quadrupole Splitting: Re-Evaluation of theFe57mNuclear Quadrupole Moment

“…We may express these latter quantities as ?=(l-22)?v»i+(l-7j?iat (2) 7}q=(l -R) 77val2val+ ( 1 -Too) ^lat^lat (3) where gVai, rjv&i refer to the gradient produced by the charge distribution of the nonspherical 3d "valence" electron of the ferrous ion ( 5 D, 3d Q ) in a crystal field, and gi a t, o/i a t arise from the charge distribution of all other ions in the lattice. The Sternheimer factors, 1,2 (1 -R) and (1-y^), represent the effects of polarization of the ferric-like ( 6 S } 3d 5 ) core by the EFG of the valence and lattice charge distributions. It is generally agreed that the valence term accounts for the major part of the field gradient in ferrous * …”

Charge States and Charge Changing Cross Sections of Fast Heavy Ions Penetrating Through Gaseous and Solid Media.

“…Pulse height spectrum of iodine ions strippedcontinuously in the Oak Ridge 7-MV tandem van de Graaff accelerator. The ions are deflected through a 90 magnet onto a silicon surface barrier detector; fromMoak et al (1963).FIG. 3.4 Charge state spectrum of 110-MeV iodine ions stripped in hydrogen at 0.6 Torr in a gas cell of length 50 cm, recorded with a position-sensitive detector 2 cm in length.…”