Accelerator Physics Group Meeting March 29, 2001 Present: Jie Wei, John Galambos, Weishie Wan, Marc Doleans, Sang ho Kim, Slava Danilov, Sasha Aleksandrov, Dong O Jeon, Eugene Tanke, Paul Chu, Sarah Cousineau, Andre Shishlo, Nikolay Malitsky Slava reviewed his trip to the VLHC meeting. A low field option is the leading cansidate, with a high field option to possibly occupy the same tunnel later, as an add on. the NLC group appears to be giving up on an independent device and is also interested in sharing the tunnel. Show stoppers include instabilities and ground motion (1.e-10 stability in field level!!!). A proposal for PAC attendees was discussed. The attendence this year will be limited, and a prioritized list was discussed. Other meetings such as Snomass and ICALEPS serve as other venues for people not attending PAC. Sang-ho discussed the RF overhead budget. The Lorentz detuning is the major term, but is uncertain, without a good measurement of the Lorentz detunng coefficient. John Galambos discussed a meeting going on with the IFMIF group (an accelerator based neutron source for Fusion Materials testing). The project is pre-conceptual. It was noted that the Japanese had broken ground on the JHF at JAERI. Paul Chu gave a demonstration of some Cdev client applications with live data. One produced a plot vs. time and another produced a correlation of X and Y. Jie Wei mentioned that Weishi is leaving for LBNL next August.Jeff will take over the global coordinate work and Yannis the magnet measurement work. The ground motion work will be finished and documented in a tech note. John Galambos will try and hire a new person in the applications programming group. Salva and Jeff have completed the transverse instability work.They are now planning a 3-D space charge implementation that is needed for accurate coupling to the impedance effects. Andre will be incorporating the transverse impedance model in UAL. Marc Doleans has included a beam generation capability in his code. He is preparing to model the transverse kick from the fundapental coupler. Sarah is working on modeling the emittance measurement experiment data with ORBIT and has completed the collimator benchmark. Nikolay discussed the database work, in collaboration with the ORNL group. A test will be done soon to see if the MEBT lattice description can be loaded in the new database tables, and then used in Nikolay's Optics database. Weishi is adding the global coordinates of all the elements in the HEBT. Sasha completed a note on an alternate laser type for the laser wire diagnostic, but this option is not the main one due to cost reasons. Also, he is using Trace-3D to investigate MEBT tuning methods, which runs much faster that with parmila. Neural network and genetic algoriths optimization techniques will be investigated as alternates. Jie mentions that a PCR would be done to fix the energy at 1 GeV. We need to stay within the present baseline hardware limits (i.e. power supply capability). We will assume success in the e-polishing of the cavities - namely higher gradients.We need to look at different configurations, and their merits such as stability considerations. A pencil beam is being considered with 10-20% of the nominal emittance for linac commisioning. This would operate at a reduced duty factor, with something like a 100 micro-sec pulse. Also a linac power supply budget needs to be constructed including effects such as Lorentz detuning, micro-phonics, missing cavity operation, reference line temperature changes, etc. The ring PCRs had some confusion, but $2.4 M remain unapproved. We should write notes on our work. The loss source term work on the linac was discussed. The gas stripping term dominates at low energy. Slava noted that we may be near the threshld of the longitudinal instability regarding the injection foil assembly, but the very high Q used in the estimate is likely unrealistic. However the transverse stability is still likely a problem. Jeff reported on the beta beat studies in the ring, from non-systematic errors in the large bore quads. about a 0.4% error produces a 10% beta beat.