Development of a variable energy RFQ for cluster acceleration
An RFQ (radio-frequency quadrupole) has been designed and built as a postaccelerator for the cluster accelerator facility at the IPN (Institute de Physique Nucleaire) Lyon, France. The four-rod RFQ resonator is designed for variable energy by means of a variable frequency of the resonator between 80 and 110 MHz. The properties of the RFQ for the typical cluster mass ranges of up to 50 u are discussed and the status of the project is reported.<<ETX>>
RFQ ion accelerators with variable energy
Abstract RFQs are low-energy rf accelerator structures which can efficiently transport and accelerate high-current ion beams. Whilst usually RFQs, like all rf accelerators, have a fixed velocity profile and output energy per amu, attempts have been made to vary the ion beam energy by changing the resonator frequency. The 4-rod λ/2-RFQ resonator developed in Frankfurt for heavy-ion acceleration is well suited for such an application. Results of the work on variable-energy VE-RFQs are presented and the status of the variable-energy cluster accelerator project is discussed.
One hundred percent tumor induction in mouse skin after repeated beta irradiation in a limited dose range.
Repeated beta irradiation of the backs of mice three times a week with radiation doses of 250 to 1180 cGy per exposure induced 100% incidence of tumors. The incidence of skin tumors appeared to be determined by the total number of repeated exposures in this dose range. An abrupt delay in tumor emergence was observed when the radiation dose was reduced from 250 to 150 cGy per exposure, indicating the existence of a critical threshold. Mouse skin resembles human skin rather than rat skin in its response to radiation.