August 2, 2005, 10:45 am Minutes for DRAGON Meeting Present: Dave Hutcheon (DH), Mike Trinczek (MT), Chris Ruiz (CR), Christof Vockenhuber (CV), Lisa Fogarty (LF), Thomas Kirchner (TK), Benji Wales (BW), Bing Guo (BG), Goetz Ruprecht (GR), Lothar Buchman (LB), Florent Haas (FH), Sandrine Courtin (SC), Marie-Delphine Salsac (MS), Heather Crawford (HC) - recorder. 1. Business arising from previous minutes 2. DRAGON Hardware: Status of Systems: DH: Peter Machule (PM) has fixed the Q3 leak; it was fixed in the same manner as Q5. PM also looked into figuring out a way to stop the beam when the DSSSD detector leakage current increases (avoid destroying detector); best way appears to be through the DC supply to the strips -- there are series resistors which give a 100mV signal when 1uA of leakage current is drawn. Haven't yet discussed how to use electric dipole to stop the beam; would like to put into EPICS some method for ED2 to throw beam off detector in response to an increase leakage current. 3. 16O + 12C --> 28Si + gg FH: Experiment was done in 1980's looking at high energy gammas; 6-7 resonances were seen. Gamma-sphere, Argonne have also looked at reaction, and DRAGON has looked at it with gamma-heavy ion coincidence. Want to look at 6 energies in 20.21-23.28 MeV range (set BGO maximum to 30 MeV); lowest energies are most important (cleanest) -- goal is to look at branching ratios for gamma transitions. Will start with 20.21 MeV (good, TIGRESS was running at this energy on 12C). Must do measurements of 13C target contamination; neutron evaporation reaction with 13C has very different kinematics and interferes. Use a 13C target to determine what can get through DRAGON from this reaction, and establish contamination of 12C targets. Targets are made at Argonne, and should arrive tommorrow. Estimate a mean charge state of 7.7+, measure charge states 7+, 8+ to determine best charge state. Still must determine more detailed run plan, and calibrate BGO detectors, establish triggering and zero-suppression thresholds for BGO array. Would prefer to use a DSSSD, even if not all strips are working -- CV is done with the IC, so it will be switched for an old DSSSD later today or tommorrow. Shifts: There will be one of FH, SC or MS on shift at all times; last time help was available during the day, which worked well. This will continue, and DH would like to have a DRAGONeer around for any energy changes etc. A daytime DRAGON support schedule will be established. Stripper foils (entire alphabet (26)) will be put in place tommorrow. Will start by finding old targets, and practicing venting slowly etc. 4. E989 Analysis CR: Talked to Anuj (AP) on phone -- AP has been working on analysis of pre-DSSSD runs, and has brought the probability analysis as far as DH had gone, and perhaps a bit further. Since pre- and post-DSSSD runs require different calibrations, CR will work on post-DSSSD change runs, but hopefully eventually the use of different calibrations for different runs can be incorporated into the analysis. CR will be updated on normalization, which is still moving along; DH, HC still have groups of runs with apparent poor transmission through the gas target, though this has not be confirmed. Nothing in ELog fully explains the reasons for these troubles. CR: Has begun work on GEANT to determine problem with the energy loss -- may have found the bug, which could be trivial to solve. DH: Has been working on a program to find angular distribution information on gamma cascade. Preliminary testing with simple cases (zero spin states) give expected results. Still working to make sure it works. Goal is to be able to say that it was looked at, and set limits for the expected ranges. The fall beam schedule has this experiment in October (beginning October 6), a month earlier than expected. CR: Argonne did see the state, but haven't got a calibrated state energy; will within next month. Phil Woods agreed to let us know before next experiment, which will give confidence for placing the resonance within the target. There were concerns about using explosive silane gas for charge state distribution measurements; Mike MacDonald has a method which should be okay (safety documents will be written). 5. Kudos DH: EEC recommendations: 40Ca did well, shifts were recommended 22Na also did very well; already 3 shifts are scheduled HC won the student talk competition, and will get to go to the conference in Banff in February. 6. Other business DH is still working on getting an iris to scrape off beam for 26Al experiment; should find out something in next few days. CR: The lead shield must be installed before next experiment. Meeting ends 11:30 am.