From rogers@triumf.ca Wed May 8 07:56:20 2002 Date: Tue, 07 May 2002 13:26:17 -0700 From: Joel Rogers To: Dave Hutcheon , rogers@triumf.ca Subject: Minutes of DRAGON meeting May 7, 2002 Minutes of DRAGON Group meeting, 7 May, 2002 Present: L.Buchmann, J.Fallis, D.Hunter, A.Laird, M.Lamey, A.Olin, D.Ottewell, J.Rogers 1. Minutes of previous meeting: adopted. 2. Jobs' progress: DO reported the TP1/TP3 pumping tube has been replaced with a larger one. 3. JR showed the new beam schedule. Dragon has 21Na beam for the next two weeks, starting May 8 (tomorow) at 1700. Two hours intermission will occur for the EMIS tour Saturday at 11 AM. Also, Wesbrook will be closed Sunday morning for a fun run event, but this shouldn't effect beam running. 4. A discussion of what energy to start out with tomorrow ensued. Art showed the state of analysis of the 865 keV/u 21Na data. The new points (see attached) disagree with the old points and the discrepancy cannot be resolved by any simple shift of energy scale. Shawn Bishop sent a memo to the meeting requesting independent re-analysis of the 865 keV data. Joel agreed to do this, hopefully by the end of this week. In the meantime, the initial 21Na running will be to search for the 330 'Rolf resonance'. In preparation, DO will check out the target pumping with 10 Torr gas pressure, to see if the pumps can handle the extra load caused by the new pumping tube. If the pumps will take it, the search for the 330 resonance will be made with the higher pressure. This will allow 20 keV/u steps to span the energy range around 330 keV. It was suggested by Joel, and generally agreed that the energy changes should be scheduled in advance, and preferably at the beginning of the day shift. This is especially important now due to the absence of many key people at the EMIS conference. A sign-up sheet in the counting room should be filled out through the weekend with available personnel (i.e. those "Present" above plus SB). 5. JR showed some figures from his ongoing analysis of the 212 keV/u data. Both time-of-flight, Z-position, and H-energy peaks march along with increasing beam energy, as to be expected from energy loss in the target gas (c.f. attached figures). Gamma energy spectra are contaminated by randoms below about 3.5 MeV, which was therefore adopted as the lower energy threshold for analysis. A much lower energy threshold can be used for acquisition. In particular, it was suggested to lower the CFD threshold for the upcoming runs, leaving the final cut for the analysis. JR also displayed a spectrum of "H-Run-Time" for the elastics(attached). He claims that the complicated fitting of the elastic energy or time-spectra is not needed and the integrated beam can be obtained from the elastic scaler with a multiplicative factor based on the Faraday cup reading at the start of the run. For 6 runs analyzed at 220 keV/u, this method agreed well with the more complicated analysis. JR will write a report detailing this comparison of the two methods.