Beam Cooler and Laser spectroscopy (BECOLA) endstation

Design of BECOLA beam line: bunched or continuous ion beams from RFQ trapwill be transported to one of two experimental legs. One is for production of polarization for Beta-NMR experiment and spectroscopy. The other leg is open for other experiments.

The BEam COoler and LAser spectroscopy (BECOLA) endstation is being developed for experiments with low energy radioactive ion beams at NSCL. The BECOLA endstation will include a cooler/buncher and switchyard followed by two collinear laser beamlines and is designed to operate at maximum beam energy of 60 keV. The cooler/buncher, which operates near 77 K, will capture and cool low energy ion beams from the NSCL gas stopper and release ion beams as short ion bunches with low emittance. Simulations by SIMION 8.0 gives transverse and longitudinal emittances of typically 1 pi mm-mrad and 1.5 eV-micro second, respectively. The bunched or continuous beam will be transported to one of two laser beamlines.

One of the laser beamlines will be dedicated to laser polarization (polarizer). The rare-isotope ions may be neutralized by charge exchange reactions with alkali vapor, and will be optically pumped with circularly polarized laser light. The Beta-NMR technique will be applied for the polarized beam. The BECOLA beam line will also be equipped for the photon counting technique (laser spectroscopy). The bunched beam from the cooler/buncher will be exposed to fixed-frequency laser light and the de-exciting photons will be measured as a function of atom/ion velocity to determine the hyperfine structure. The construction of the BECOLA beamline will be completed around mid-2010. The other leg of the switchyard is open for other experiments.

A laser system for BECOLA beamline has been installed. The 700-1000 nm light from a titanium-sapphire ring laser (Matisse TS, Spectra Physics) pumped by a 15 W solid-state CW laser (Millennia Pro, Spectra Physics) is frequency doubled and the 350-500 nm light is generated (WaveTrain, Spectra Physics) for experiments. The titanium-sapphire ring laser is locked on a precision wave length meter (WSU-30, TOPTICA) for long term stability. The laser light will enter the BECOLA beam line through a window on the side of switchyard and collinearly overlap with the ion/atom beams.

The BECOLA project is funded by the NSF.