Results of the first on-line experiment of the laser ion source

The importance of using a laser ion source in the on-line isotope separator, the principle of laser ion source, laser technique and the structure of hot capillary laser ion source and target chamber are introduced. A high repetition frequncy copper vapor laser and three dye lasers were used. The capillary is made of Nb with inside diameter of 1.7mm and effective length of 3 cm. It was heated by 50-100A direct current and temperature of 1800-2700K can be achieved. The nuclear clear reaction channel used in the first on-line experiment is 50MeV/u O-18 + Ta-nat --> Yb-167 (T-1/2 = 17.5min). A joint operation of accelerator, on-line isotope separator and laser system has been realized. A total separation efficiency of 0.2 % is obtained by comparison of the measured yield of Yb-167 with the calculated yield of Yb-167 by using production cross-section, beam intensity, collection time and the thickness of target. A element selectivity of 3.2 is deduced from the ratio of the corresponding peak areas of Yb-167 and Lu-167 in the gamma spectra of laser on and laser off. A new high spin isomer with long half-life of Yb-167 was found. The methods that may be used to improve the efficiency of laser ion source are discussed.