First operation of the charge-breeder electron-cyclotron-resonance ion source at the Texas A&M Cyclotron Institute.
The 14.5 GHz electron-cyclotron-resonance ion source (ECRIS) designed and fabricated specifically for charge breeding has been installed at the Texas A&M University Cyclotron Institute for use in the institute's ongoing radioactive-ion-beam upgrade. The initial testing of the source has just begun with magnetic analysis of the ECRIS beam. The source has only been conditioning for a brief time at low microwave power, and it is continuing to improve. After the source has been conditioned and characterized, charge-breeding trials with stable beams from a singly ionizing source will begin.
The ISOL-MAFIOS Source (invited)
ISOL–MAFIOS is a high‐efficiency Min B ECRIS charge state breeder for short‐lived ISOL beams in the PIAFE project. The ISOL species issuing from a bombarded target are locally ionized (1+) in a given ion source (ISOLDE type). They are then accelerated, magnetically selected, and transported in a long beam line, before being adequately introduced into ISOL–MAFIOS operating in continuous mode. In this system, an ECR plasma (created with a support gas) replaces the usual solid catcher. The ISOL–MAFIOS system captures the (1+) ions and transforms them into (q+) ions. If we call, overall efficiency of ISOL–MAFIOS the ratio of the beam intensities: I(q+) after the magnetic selector/I(1+) before entering in the source, we find for example for Rubidium IRb9+/IRb1+≊120 enA/1000 enA and a ratio at least two times larger for IKr9+/IKr1+. Moreover, an even more important result of ISOL–MAFIOS is that the release time+ionization time is of the order of 10−2 s instead of many seconds for a solid‐state catcher. Thus in ...
Development of a ground-based facility for simulating the omnidirectional near-earth electron environment
Abstract A method is detailed for simulating in the laboratory the omnidirectional near-earth electron environment. This technique can synthesize the directional and energy properties of an arbitrary omnidirectional electron flux by combining a sufficient number of weighted energy and direction increments. A large vacuum chamber has been built, capable of holding three-dimensional structures up to 30 cm in each dimension while maintaining pressures in the 10−6 mm Hg range. The support structure in the chamber rotates around two axes, thereby achieving all angular orientations necessary for the omnidirectional simulation. This chamber was coupled with a beam scanning system to a 4 MeV electron Van de Graaff accelerator which was tuned to provide specified fluences of electrons at the desired energies. The system was used to irradiate a series of hollow aluminum cubes having varying wall thicknesses. Using radiochromic film dosimeters, dose profiles were mapped in the interiors for both one-wall and six-wall exposures. Results of the dose mapping are presented for several monoenergetic cases as well as for the energy spectra from a 235U fission event. The one-wall exposures show dose variations within the interior by a factor of 3.2 ± 0.6 independent of energy or wall thickness. In the six-wall exposure, distributions varied only about 15%.