Minutes of DRAGON meeting February 12, 2002 Those present: J. King, JD'A., DH, MC, DG, AO, SE, LB (recorder), for the 15O production presentation also: A. Shotter, P. Walden, Suzy Lapi, A. Zyuzin, T. Ruth, and Paul Piccioni ------------------------------------------------------------------------- 15O beam production: S. Lapi presented the results of light oxygen beam production at small cyclotrons, both for the BEARS facility in Berkeley, as well as for experiments, she and collaborators (JD'A, TR, AZ) have done at Madison, Wisconsin. In both cases gas/nitrogen targets with beam energies of the order of 10 MeV are used to stop the protons or deuterons. 14O or 15O are extracted as water and later converted to CO or CO_2. This gas can be transported over considerable distances (500 ft). In the experiment at Madison an actual average production of 2.6x10^8 s^-1 for 14O was achieved, which with optimistic assumption may be fought up into the 10^10 s^-1 range. At the TR13 TRIUMF cyclotron tests are planned to produce 11C to be brought manually to the OLIS ion source to test ion bed production. Challenges include handling of the ammonia produced, the 15N costs and possible recycling. TR mentioned that there is a small 16(p)/8(d) MeV cyclotron available at Baltimore. ------------------------------------------------------------------------- Approval of minutes of Feb. 5, 2002: Minor typo corrections. ------------------------------------------------------------------------------ Last weeks running results: A slide was presented for the excitation function of the 1160 keV resonance (20Ne+p) for charge states 7-10. Only charge states 8 and 9 were important in this case. Another slide was presented showing the ratio of gamma-coincidence events over single recoil events for the same excitation functions. The curve may indicate gamma efficiency losses at the edge of the target. It was also found that the leaky beam can be reduced by about a factor 10 by closing slits to about 15 mm at the charge and final position (for the 280 keV resonance of 21Ne). A 20% yield loss was observed for the single events while no loss was for gamma-recoil events. This maybe due to spacial correlations of gamma-recoil events or the energy acceptance of the separator. It was found that exchanging the hydrogen for helium in the gas target did not change the leaky beam rate. The measured wg of the 1160 keV resonance was below the literature value. -------------------------------------------------------------------------------- Plans: The production of a 24Mg beam has been started at OLIS/DTL. For initial intensity reasons it was decide to run on the 820 keV resonance of 24Mg(p,g). A possible run to measure stopping powers with a small aperture gas cell was discussed. Possible date in April before the radioactive run. ----------------------------------------------------------------------------- Publications: The charge exchange paper is close to submission. A gas target paper may follow thereafter. A write up for a letter on the 825 keV resonance in 21Na(p,g)22Mg will be started asap.