RILIS Resonant Ionization Laser Ion Source by Pallav

RILIS Resonant Ionization Laser Ion Source by Pallav Kosuri KTH, Royal Institute of Technology, Stockholm, Sweden 1. Introduction 2. Ionization Schemes a) The laser ion source has been developed as a versatile tool for ionization of a wide range of elements. Because of its chemical selectivity it is a convenient way to obtain a beam free of isobaric contamination, and in some cases it may even provide a beam prepared in a particular isomeric state. The high chemical selectivity is due to the narrow bandwidth of the laser beams, as well as the high precision with which they can be tuned to stimulate specific electronic transitions. b) c) 618. 2 nm 297. 3 nm 551. 7 nm 719. 8 nm 579. 6 nm 327. 4 nm 234. 9 nm Be Tb Typical ionization schemes for a (a) 2 -step double resonant ionization, (b) 3 -step triple resonant ionization, (c) 3 -step ionization with two resonant steps and a non-resonant final step 3. Ionization Chamber The reaction products in the proton target are transported to the ionization cavity by diffusive and effusive processes. Once there, they are photoionized by the laser beams and consequently extracted using a high voltage (60 k. V) extraction electrode. The chemical selectivity – that is, by atomic number – of RILIS complements the mass separator to produce a pure singly charged ion beam. A-selection by mass separator Z-selection by RILIS Sb 128 9. 01 h Selected nuclide 4. Laser Setup The setup consists of 3 copper vapor lasers, one oscillator and two amplifiers. The CVL beams contain 2 wavelengths and can be used directly as well as to pump a set of up to 3 dye lasers. The frequency of the tunable dye laser beams can finally be doubled or tripled by using non-linear BBO crystals. Two moveable lambdameters are used to continuously monitor the frequency beam profile. After achieving the desired wavelengths the beams have to be directed onto a 3 mm wide circular target area in the ionization chamber, 20 m away. All laser beams have to be focused and overlap within this area at all times. The focusing and directing of the beams are accomplished by optical telescopes and motor-controlled prisms/mirrors, respectively. Since this high-precision system is very sensitive to variations in temperature and other fluctuations in the environment, a reference beam is reflected back to the lab for constant monitoring and optimization of the beams. 5. Isomeric Selectivity ~13 GHz 68 m. Cu 327. 4 nm 68 Cu 68 g. Cu Energy levels and excitation spectrum for the two 68 Cu isomers 68 Cug (I=1) and 68 Cum (I=6) separated by hyperfine splitting. 6. Future Outlook © B. Marsh 2005 287. 9 nm Sc Find new or improve existing ionization schemes ―New off-line spectroscopy lab Nuclear physics research ―Investigate mean square nuclear charge radius by studying isotope shifts ―Investigate nuclear magnetic moment by studying HFS