----------------------------------------------------------- Minutes of the ABP-RLC team meeting of 03.06.2005 present: EB, UD, PE, AG, JJ, WH, AL, JRL, EM, TP, FR, DS, FZ web site: http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/ ------------------------------------------------------------ (1) Minutes of last meeting, pending actions, announcements ----------------------------------------------------------- => ACTION => compare the size of the longitudinal geometric wake with RW longitudinal wake from A. Koschik (FR) STATUS: PENDING, FR will talk to A. Koschik => ACTION => attempt to derive a general nonlinear theory including the inductive bypass (EM) STATUS: EM proposed the unification of Zotter's linear theory with inductive bypass and Piwinski's nonlinear theory without such bypass plus experience in the SPS as a topic for a Ph.D. thesis. FR encouraged him to find a good student. The title of the thesis could be held a little more general. FR announced that he and Walter Scandale are in the process of recruiting a PhD student for the LHC injector upgrade. => ACTION (EM+FZ): compare and understand the different predictions of the Burov-Lebedev theory calculated by FZ and EM. STATUS: Comparison showed that the impedance used by EM and FZ is not identical. Even using the same impedance their results are not the same, which means the relation between impedance and tune shift differs. EM will ask AK for an independent cross check with the multilayer impedance formula. Following up on the IBS discussion from the previous week, FR emphasized the general interest in this subject, which should make it easy to find collaborators for benchmarking. In particular, FR reported a comment on IBS by Hans Braun, who pointed out that IBS is important for SPS with ions at injection. FR recommended to benchmark the MAD-X simulations against IBS measurements in the SPS or other storage rings. After the meeting FZ checked with HBU and GA, who confirmed his suspicion that no measurements exist of IBS growth rates in the SPS. A single measurement attempt was done and failed. According to GA, the only available measurements may be older data from AA and/or LEAR. An email was sent to FR by E. Tsesmelis, asking for an LHC optics with beta*=2 m. WH will follow up the different issues (crossing angle, beam-beam, etc.) with the optics team and the experiment. In principle optics for every value of beta* are required. An LHC MAC will be held next week Thursday and Friday. FZ will discuss e-cloud progress in the closed session. He will send a list of people to be invited to John. A test presentation was scheduled for Tuesday afternoon. FZ mentioned that he received several phone calls from Fritz Caspers regarding the "electron-cloud killer" of P. McIntyre, which according to Fritz cannot work for at least three different reasons. FZ mentioned that the e-cloud killer could be of interest to the CLIC damping ring, if the impedance can be shown to be small. It was agreed that an impedance calculation would be useful for both LHC and CLIC applications. (2) Impedance of Extraction Chamber and Other Impedances (FR) ------------------------------------------------------------- FR reported on ongoing discussions on the impedance of the extraction chamber, where the beam pipe is split into two, by a block of copper coated graphite, "TCDS". In analogy to the recombination chamber, a parabolic tapering of the TCDS was recommended and is in progress. More recently, AG pointed out that the tapering could lead to the generation of trapped modes, which would not exist otherwise. FR suggested that the situation be studied by numerical simulations, and an answer be provided as soon as possible. FR presented the good news that the Au plating of the ALICE chamber was successful. So the Cu coating will be applied. EM was contacted by Luca Bruno to inspect some scratches on the TDI. He reassured him that the scratches would not impair the impedance quality, especially since they will still be coated. (3) Reports from Meetings (JJ) ------------------------------ JJ reported from the workshop of p-nucleus collisions @ LHC (see http://wwwth.cern.ch/pAatLHC/pAworkshop2.html ). RHIC already collided deuteron and gold beams. In the LHC proton-ion collisions may come around 2011. One issue is the transverse emittance growth from unsynchronized collisions. At the workshop, JJ demonstrated that the situation at the LHC will be better than at RHIC. (4) Partial Review of Ongoing Activities (EM, FZ) ------------------------------------------------- EM did come concluding work on the power losses of the MKE kickers in the SPS. With Bruno Zotter he is studying the effect of finite length. The problem how to best truncate the pertinent matrix is not yet solved. EM also started using HFSS with the help of AG. FZ finished the proceedings of HHH-2004 with the gratuitous help of Michel Goossens. They are now with the CREB. He and FR discussed IBS and gas scattering with Alexander Smirnow, who will provide several modules for inclusion in MAD-X. FZ prepared questions for the RLC exams and corrected the exams (9x13=117 exercises). He prepared a 2005/06 work plan for the EUROTeV WP3 ECLOUD task with detailed milestones. He also prepared milestones for the nonlinear collimation design task in the BDLS task of WP2. Our contribution to WP2 SWMD (spoiler wake field) is still to be detailed. The original idea in the EUROTeV contract was to compute multibunch wake fields from the collimator tanks. FZ debugged the ECLOUD code for simulations of the DAFNE wiggler (so that he can include multibunch wake fields in the paper for the Frascati ELAN/EUROTeV Wiggler workshop proceedings) and for LHC quadrupoles. The simulations for the quadrupole showed a weird effect in the 'move' integration routine, which with the help of Daniel was prevented by adding a simple print command. AG recommended cross check with a different compiler. (5) Highlights from PAC2005 (EB, TP) ------------------------------------ EB held discussions with Giuliano Franchetti on the procedure to make sure that the same tune shift is used in both his code and HEADTAIL. A plan for benchmarking was worked out. A joint article is considered. EB also plans to continue SPS data analysis with GA, helped by Simone Gilardoni. A further plan is to update QUICKPIC. She presented some highlight from the PAC, which included the Prizes and Prize winners, a talk by W. Fischer about RHIC limitations, the session on plasma wake field acceleration, the e-cloud and collective processes session, a study of halo generation due to space charge from Sonnad at SLAC, a new method to characterize chaotic orbits by Sideris, an invitation by T, Katsouleas for an extended visit to USC, a question by S. Berg on the magnetic field created by a localized electron cloud, and a meeting with Vadim Dudnikov. TP reported PAC highlights mostly related to beam-beam, including a discussion with and presentations by Q. Jiang, Y. Alexahin, W. Fischer, and, concerning magnet effects, P. Bauer and M. Martens. TP simulated RHIC with the COMBI code to compare with some "strange" results Ji Qiang showed at PAC. Also, Y. Alexahin asked her to simulate the Tevatron. A tune split is needed at RHIC to suppress strong-strong beam-beam effects. WH mentioned that this is possible in the LHC, reducing a little the operating space in tune diagram. The study with Maripaz Zorzano showed on the other hand, that it is not possible to collide beams at two different nominal working points in the tune diagram, as it had been suggested in 1999. A talk by McIntyre on the LHC energy tripler was also a highlight of PAC2005. (6) The RIA Project ------------------- Following up on a request from the previous RLC meeting, EM prepared some slides describing the RIA project. (7) AOB ------- Other activities and more PAC05 highlights will be reviewed next week. Posted on the web: Slides by EB and EM Web site: http://ab-abp-rlc.web.cern.ch/ab-abp-rlc/