Vincent Pelletier, McGill University / Argonne National LaboratoryTitle: A Radio-Frequency Gas Cooler for Injection of Radioactive Isotopes into the CPT Mass SpectrometerAuthors: V. Pelletier, F. Buchinger, J. E. Crawford, S. Gulick, J. K. P. Lee and P. Martinez (McGill University); X. Feng, G. Hackman, D. Hoffman, G. Savard, D. Seweryniak, U. Uusitalo (Argonne National Laboratory); J. Fingler, H. Fukutani, K. S. Sharma (University of Manitoba); J.C. Hardy (University of Texas A&M); G. Gervais (Northwestern University)Abstract: The Canadian Penning Trap (CPT) mass spectrometer is designed to measure masses of ions with an accuracy exceeding 10-8. A novel Radio Frequency (RF) gas was constructed to thermalize high-energy ions and inject them into the CPT under high vacuum. High-energy ions go through a thin Mylar window and are stopped in a gas chamber (150 torr). The gas is continuously evacuated through a small aperture bringing the ions to the entrance of an RF structure composed of four parallel rods. Between the rods, a radio-frequency oscillating quadrupole electric field confines the ions radially while the gas is pumped away. The rods are segmented to have a smooth static electric field gradient to pull the ions along the structure. The focused ions travel through three chambers separated by small appertures and differential pumping brings the pressure down to 10-5 torr in the last section. At the end of this last section, a linear trap is built in the RF structure to accumulate the transported ions and then release them in small bunches to be measured in the CPT. Once fully operational, this RF gas cooler will allow the CPT to perform high-accuracy mass measurement on most radioactive nuclei that can be produced by heavy-ion reactions at ATLAS, Argonne National Laboratory. |