DRAGON Minutes 30 September 2003 Present: Dave Ottewell, Dave Hutcheon, Cybele Jewett (recorder), Nicole Chorney, Zhilong Li, Barry Davids, Alison Laird, Chris Ruiz, Mike Lamey, Lothar Buckmann, Joel Rodgers, Art Olin, Aaron Bebington, Dario Gigliotti, John D'Auria, Mike Trinczek, ? -Solid Target Updates: Peter found an elbow for the cable. DO recommends that we purchase a new turbo pump. -Schedule for Beam: Experiment Dates 947 12C(12C,g)22Mg 1 October - 14 October 952 12C(a,g)16O 16 October - 11 November 824 stable 21Ne 19 November - 20 November 824 21Na(p,g)22Mg 21 November - 2 December TUDA 20Na 3 December - 8 December The following modifications to the above schedule will probably take place: 947 12C(12C,g)22Mg 9 November - 16 November Most of the original 947 time will go to 952 TUDA 20Na 30 November - ? JD: In October we should be clear to do what we like. We may get beam on 7 or 8 October. -JR's Optics Report: He presented a table of first order elements for 16O(a,g)20Ne kinematics in which he compared the beam envelope at the mass slits and the final slits. The quadrupoles and the dipoles have a normal shape, so he used the default settings for them in GIOSP. The large elements agree within a few percent, so the recent work agress with Don's work. The only difference between the two versions should be due to the fringing fields. JR presented a report on GIOSP's prediction of the effects on the beam envelope of varying the five quadrupoles. The fall-off will be rapid when we begin to clip the cone. By next week, there should be a detailed run plan regarding the magnet setting changes/acceptance measurements. JR would like to perform an energy scan and series of magnetic field changes.DH recommends that we use a narrow resonance for the measurements. AO asked whether we should use the correct energy or the optimal energy when we run. DH recommends that we begin with the standard scaling program tune, and see what the acceptance is to ``see what life is like at the mass slits'. According to JR, we need to obtain enough statistics (10 or 20%) on the rate when the quadrupoles are correctly set, and off-set to compare GIOSP with experiment. The lower 2+ state would be better for the acceptance measurements. The cone continues to expand, and is clipped in Q1. This determines the tune quality. In order to go down in energy, we will probably need to change the bore at Q1. Moving the resonance upstream makes the acceptance worse, since the envelope increases more before it reaches the various elements of the separator. Moving Q9 and Q10 to Q1 (removing Q1), and replacing Q9 and Q10 with one large quadrupole might improve things. JR The plan for the optics measurements is for us to check GIOSP, run with the GIOSP tune, and then compare the results. JR is convinced that it would be wise to enlarge Q1. It might help make the problems with the poor acceptance at Q9 and Q10 easier to resolve. In his calculations, JR is using GIOSP to minimize the matrix elements, and not the actual beam envelope. We would like to make it possible to run with 666 keV/u 12C. JD recommended a DRAGON training session for the people who are new to the group. NC's presentation: NC presented a plot of gain changes with time. In her graph, she compared the locations of the 6.917 MeV peak from 12C(a,g)16O runs 8217 and 8439. MT's presentation: CVS is now up and running. AO added counters to show how many counts reached points in the DRAGON. MT inserted counters at SX3 and SX1. NB: In GIOSP, SX3 is refered to as Q7. In GEANT, MT changed the energy of the recoil as it exited the target, and noted the effects the changes had on the acceptance. Changing the energy by 0.5% results in a large acceptance change. According to GEANT, running at -0.5% of the standard tune energy optimises transmission. ML's presentation: ML would like to do some MCP timing tests with a gamma-source. He plans to put the gamma source outside the box so that only the gamma rays would enter the MCP. He plans to use 68Ge, which emits 2 511 keV gamma photons, and/or 22Na, which emits 1.275 MeV and 511 keV gamma photons. These measurements will test the intrinsic operational timing of the MCP. ML is going to start with the MCP, and then use the scinitillator. -Chicago Conference: ISOLDE has an ECR that is almost as bad as ours. They are working on it presently. Jeff Blackmon from ORNL is planning to run with flourine beam in the spring. Chris is still working on the EEC proposal. JD is writing a proposal for transfering from TR13 to OLIS. JD is going to request TR13 to demonstrate how much beam can reach DRAGON. Ultimately he wants C142. -AB's presentation: The recoils in AB's simulation stopped in Anode1 of the ionization chamber because the simulation pressure was 760 torr. The mylar window is too thin for GEANT to recognize its presence. There are two possible solutions to this problem: 1)Use SRIM to calculate the energy loss in the mylar window, and tell GEANT to read in the results of SRIM's calculations rather than directly including the window in the GEANT simulation. 2)Double the thickness and cut the density of the window in half when modeling it in SRIM. AO: AO has a design for a 2cm x 2cm detector with pads. The detector's calculated efficiency is 85%, and it would cost $40,000 to build. One advantage of the detector is that it would provide better energy resolution.