22 July 2003 DRAGON Minutes Present: Aaron Bebington (scribe), Ahmed Hussein, Alison Laird, Anthony Olivieri, Art Olin, Cassi Galt, Chris Ruiz, Cybele Jewett, Dario Gigliotti, Dave Huctheon, Dave Ottewell, James Kennedy, Joel Rogers, John D'Auria, Lothar Buchmann, Mike Anderson, Mike Lamey, Pete Machule, Sabine Engel, Shawn Bishop, Uwe Greife, Zhihong Li Correction to previous minutes: Under the MCP section, the first line reads "?for DSSSD vs r.f. Was achieved?.", but should read "?for DSSSD vs r.f. was achieved?.". Under the Acceptance section, the first line reads "?recoil transmitted energy when tuned 1%....", but should read "?.recoil transmitted when the energy was tuned 1%....". Under the 16O(a,g)20Ne section, the second point reads "?.beam energy loss, and gas?.", but should read "?.beam energy, and gas?.". Under the 16O(a,g)20Ne section, the third point reads "distributions chang little?.", but should read "distributions change little?.". Hardware status and plans: DH and UG have measured the energy loss of the 4He ions in hydrogen and helium gas. They ran with pinhole collimators and there was no question of beam position. Results were within a few percent of SRIM 2003. The small apertures get a third of the beam through (3enA), which is plenty for the dE/dx measurements. Future plans are to do two more energies at 400 and 600 keV with a helium beam, and effective length for the gas using a neon beam. Tune takes 7-8 hours, limiting us to one measurement per day. Possible send the neon beam through the MCP to test it. Spare capacitance manometer needs to be replaced, and/or fix the one we have. TUDA have beam for the next 2 weeks, but won't use it for the whole 2 weeks, so DRAGON will have it in between time. New Solid Target Drive: Can replace the gas cell with a 9-postion solid target system. Its control is called up from "SOLTAR" on OPTICS(1) page. A stepping motor drives to one of nine present target positions. Positions calibration is provided by a cam engaging a microswitch. Beam current is picked off on a wiper and a cable can be connected to the current integrator (alternative to FCM2). This new target box has only been tested in air, not been driven in a vacuum. The box contains an "ashtray" at the bottom, so that if one of the targets shatters, it will be collected and not sucked into a pump. There was interference trouble last week, whereby it wouldn't pump down, but has been fixed. Do we have carbon foils? ML has aluminum foils. It needs a cable to the silicon detector. Leakage possible from cable? CCD: There was a software fault last night, whereby it couldn't find the camera. It is now fixed. Do the cyro pumps need to be switched on? Varian dry pumps problem for the new leak detector? Summary Of 12C Meeting: On Monday, there was a 2 hour meeting on what to do next. Possible tunes to increase the DRAGON acceptance (which is the main DRAGON problem). Possible remake of the tubes around the gas target to increase acceptance. Once the acceptance is good, we can then go for higher energies, hopefully having publishable data. A long term plan of modifying DRAGON would be moving the gas target downstream Maybe nine months worth of work. This would mean that the BGO calibration might have to change. The gamma rays and elastics all depend on their position. Changing the downstream part of the frame and moving the quads 50cm is very difficult. It can be done, but a major job. Also, this would make an impact on radioactive beams. 21Na(p,g)22Mg (see attachment 1): SE and SB, the main contributors to this data analysis, are leaving in two weeks. SE was asked to present a summary of her results for this meeting. Looking at the energy levels of 22Mg (page 1), we have published our results on the 0.212MeV state. SE's analysis has been concentrating on the 5 levels above 0.212MeV. 821keV (page 2). All analysis was done using NOVA. Here, we ran at 8+, and SE found resonance energy, width, and wg. Coincidence data was only used for cuts if the recoils weren't easily distinguishable. Most of the time, there was a nice separation of recoils and leaky beam. Among the good runs, there may be data to calculate the gamma branching ratios. RF cuts give a clearer spectrum. 740keV (pages 3-4). Only five good runs, at 8+. Had to rely on Wenjie's charge state calculations. Found a good agreement for tests done at 825, 425, 228 keV/u. 538keV (pages 5-6). Ran at 6+ and 7+. Some other runs, the energy was too high. Used Wenjie's calculations, and found a slight systematic disagreement. The systematic error seems too high for 6+. Also, is the FC4 offset (found using the beta monitor) too big? SE will check both things. 454keV (pages 7-8). Only three faulty runs out of thirty. Ran at 6+ only, and Wenjie's calculations were also used again. Not sure if we can get gamma branching ratios from this data. There are tight cuts on the recoil single time-of-flight. Loss of some cuts cause a quarter of coincidence events with these tight cuts. Thus the recoil single are corrected for the losses. How do we estimate the error? 329keV (page 9). See no coincidence events. Only get an upper limit on wg. SB will continue the analysis in PAW++. We need a draft of the report done before next week. AOB: CG won the student seminar symposium, and therefore, a trip to Lake Louise to present her seminar again. DO is having the DRAGON party at his house on Saturday. See www.triumf.ca/dragon/news.html for more details.