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Online Models for PEP-II Status and Plans

Online Models for PEP-II Status and Plans. online modeling process and procedure “Twiss” parameters in highly coupled systems recent updates to the LER model continuing work. Database. MAD. DIMAD. AT. Twiss, RMATs. Twiss, RMATs. Model Files. Model Files. LEGO. Input Files. BMAD.

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Online Models for PEP-II Status and Plans

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  1. Online Models for PEP-II Status and Plans • online modeling process and procedure • “Twiss” parameters in highly coupled systems • recent updates to the LER model • continuing work Mark Woodley (NLC)

  2. Database MAD DIMAD AT Twiss, RMATs Twiss, RMATs Model Files Model Files LEGO Input Files BMAD MAD, DIMAD input Magnets, Orbit Magnets, Orbit LERmodel HERmodel Reference Files Configuration Files Configuration Files PEP Online Modeling: Process MCC (VMS) pepoptics (linux) 11 8 7 10 1 SCP Matlab 5 2 6 9 SCP, SSH 4 3 Mark Woodley (NLC)

  3. PEP Online Modeling: Procedure • read reference input files; set magnets to configuration file values • [MAD] use XCORs and YCORs to steer to measured absolute orbit • [MAD] compute coupled Twiss parameters • [DIMAD] compute transfer map about the closed orbit • generate model files for MCC Mark Woodley (NLC)

  4. Twiss parameters in highly coupled systems • MAD finds coupled Twiss from eigenmodes of transverse motion (“Mode 1” and “Mode 2”); association of these modes with the horizontal and vertical planes can become ambiguous when the coupling is large, leading to “mode flipping” and negative (or infinite) beta functions • so far this effect has only been observed in the LER model • Andy Wolski has suggested an alternative representation, based on normal form analysis1, that is directly related to the horizontal and vertical projections of beam distributions and betatron oscillations; defined in this way, the beta functions remain “well behaved” (positive and finite) under all circumstances • “Wolski” coupled Twiss parameters are computed from DIMAD’s fully coupled transfer matrices and returned to MCC 1See http://www-library.lbl.gov/docs/LBNL/547/74/PDF/LBNL-54774.pdf Mark Woodley (NLC)

  5. Mark Woodley (NLC)

  6. Recent Updates to the LER Model • interaction region element positions (Precision Alignment Group meets machine physicists with tape measures) • QD1/QF2 interaction with BaBar solenoid • we now use DIMAD v2.9, which has a more MAD-like input syntax → allows us to use minimally modified reference decks as input to both programs (applies to the HER model, as well … ) create HER-200307.mad from her-jul03.50-1.25.mad - suppress TITLE, ASSIGNs, OPTIONs, and BEAM definition - define THCOR and TVCOR - split BLF and BLFM in half; add THCOR at center of each; remove BLFMCOR and BLFCOR - add THCOR and TVCOR to QD1L and QD1R (between "A" and "B" slices) - add DBMARK56 (center of region 10 straight), DBMARK23 (at SYNCSRC[2]), and DBMARK51 (at IP) - change QF5(L/R) from zero-angle SBENDs with nonzero K1s to QUADRUPOLEs - add TVCOR to BM2L, BM1L, BM1R, and BM2R create HERcorbpm.mad from corbpm.her-nov02.mad - add THCOR and TVCOR replacement lists create LER-200403.mad from ler-200307.mad and ler-200309.mad - suppress TITLE, ASSIGNs, OPTIONs, and BEAM definition - change: "BB+" to BBplus; "BB-" to BBminus; "BW1+" to BW1plus; "BW1-" to BW1minus; "BW2+" to BW2plus; "BW2-" to BW2minus; "LL*" to "LLstar" - set BCC1LC[E2]=0, BCC1LB[E1]=0, BBA[E2]=0, BBB[E1]=0 - split BBM1L, BCC4L, BCC4, and BBM1 in half; move THCOR to center of each; add soft fringe definitions - add THCOR at center of HK1 and HK1L - define TVCOR - add THCOR and TVCOR to QD1L and QD1R (between "A" and "B" slices) - add TVCOR to BM1, BM2, BM1L, and BM2L (center) - add DBMARK66 (center of region 8 straight), MSTEER (center of BM1R), and DBMARK51 (at IP) create LERcorbpm.mad and rLERcorbpm.mad from corbpm.ler.mad - add THCOR and TVCOR replacement lists Mark Woodley (NLC)

  7. Generate “online” model (config/orbit) using original element positions; compute beta functions • Paste magnet/corrector strengths into a deck with updated element positions; compute beta functions • Plot the ratio βnew / βold LER IR Element Positions device delta S distance from (mm) IP (m) -------------- ------- ------------- QUAD SK4 -97.0 -50.492 QUAD QDCY2 -8.0 -30.966 YCOR PR02 3072 70.0 -23.240 XCOR PR02 3064 -60.0 -21.133 BPM PR02 3041 38.8 -9.438 QUAD SK2 -55.0 -9.203 XCOR HK1B -32.4 -8.041 YCOR PR02 3024 -2.4 -5.643 BPM PR02 3024 -2.4 -5.513 QUAD SK1 -2.4 -3.491 QUAD SK1L -0.4 3.519 BPM PR02 2203 -0.4 5.513 YCOR PR02 2202 -0.4 5.840 XCOR HK1AL 29.6 8.039 YCOR PR02 2186 6.9 8.986 QUAD SK2L 33.9 9.219 BPM PR02 2185 -37.8 9.438 YCOR PR02 2152 39.9 23.459 SEXT SCX2L -5.1 27.005 QUAD SK3L 15.9 27.510 YCOR PR02 2092 -118.1 44.687 QUAD QDCY2 -8.1 45.129 QUAD SK4L 83.9 50.482 BPM PR02 2062 -7.1 50.697 QUAD QFBM1L -7.1 51.045 QUAD QDBM2L -7.1 51.875 BPM PR02 2056 -7.1 52.238 YCOR PR02 2056 -7.1 52.496 Mark Woodley (NLC)

  8. QD1/QF2 interaction with BaBar solenoid (new) Detector solenoid (old) Mark Woodley (NLC)

  9. “RIGHT” side “LEFT” side strength of QD1 permanent magnet blocks suppressed by ~1% in the solenoidal field C B A A B C Extent of BaBar Solenoid Field Mark Woodley (NLC)

  10. Continuing work • Andy Wolski and Marco Venturini at LBL have implemented an integrator for a combined solenoid/dipole/quadrupole element (presently available only for Andrei Terebilo’s AT simulation code … ) • steering to absolute orbits when generating the model requires accurate knowledge of BPM-to-magnet-center offsets → BBA; many offsets for HER have been measured and are being routinely removed from measured orbits; LER BBA is ongoing (see Marc Ross’ talk … ) • MIA and ORM analyses are finding errors in our models of HER and LER (see talks of Yiton Yan and Christoph Steier … ); need to fold these results back into the models to make the models more predictive of actual beam behavior • David Sagan’s BMAD program has been ported to SLAC and is now running in both our linux and Windows environments; we are setting BMAD up to do real-time analysis and correction of dispersion and coupling in both rings (see Martin Donald’s talk for related details … ) • automated generation of LEGO input files from the online models is being tested; AT is already able to use the online models Mark Woodley (NLC)

  11. Combined Solenoid/Dipole/Quadrupole Element • in the presence of the BaBar solenoid field, the element sequence at the IP in the LER model: • (QF2R,D2R,QD1R,D1R,B1R,D0R,D0L,B1L,D1L,QD1L,D2L,QF2L) • requires 1131 MAD PARAMETERs, 178 SOLENOIDs, 98 MULTIPOLEs, 46 HKICKs, 178 VKICKs, and 80 BEAMLINEs • use of the SOLDIPQUAD element reduces this to a total of 18 definitions (!) • need to integrate this new element into MAD and DIMAD Mark Woodley (NLC)

  12. BMAD MAD BMAD (Windows, HER lattice) Mark Woodley (NLC)

  13. Uli Wienands, Mike Sullivan, Martin Donald, Jim Turner, Gerry Yocky, Artem Kulikov Yuri Nosochkov, Yunhai Cai, Yiton Yan Tor Raubenheimer, Peter Tenenbaum, Marc Ross CESR James Safranek, Andrei Terebilo, Jeff Corbett Andy Wolski, Christoph Steier, Marco Venturini David Sagan, Mark Palmer Acknowledgements & thanks! Mark Woodley (NLC)

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