MC Lattice Design Status Y. Alexahin, E. Gianfelice-Wendt, A. Netepenko (FNAL APC) Joint MCTF-NFMCC meeting Fermilab, October 16, 2009 Various MC lattice designs studied 1996 by Carol J., A. Garren 1996 by K.Oide Dipole first (2007) (2007) ~ sat (2007)isfy t (2007)he requirement (2007)s Elianas synt (2007)het (2007)ic (2009) Asymmet (2007)ric dispersion Flat (2007) t (2007)op ________________ 1996 designs (especially by K.Oide) had ext (2007)remely high sensit (2007)ivit (2007)y t (2007)o field errors MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 2 Dipole First IR Design Option - a Quick Fix Dipole before the first quad creates larger dispersion in IR -> weaker sextupoles

It may also help to protect the detector from backgrounds: decay electrons and BetheHeitler muons x y Dx Wx DDx/50 Detector backgrounds Marginal Dynamic Aperture Sensitivity to beam-beam Wy MC Lattice Update - Y. Alexahin 4 th LEMC workshop, Fermilab, June 09, 3 Elianas New Synthetic Design 1 IP wit (2007)h = 1cm quad first (2007) at (2007) 6.5m dipoles fill all available space no oct (2007)upoles chromat (2007)ic correct (2007)ion sext (2007)upoles Good DA but with bad tunes Momentum compaction Sensitivity to beam-beam?

MC Lattice Update - Y. Alexahin 4 th LEMC workshop, Fermilab, June 09, 4 Flat top design (failed attempt) -S1 S1 The idea: y bad effect (2007)s of S1 should be cancelled by -S1 since t (2007)he bet (2007)at (2007)ron phases do not (2007) change much: x = d / x ~ 10-2 x In realit (2007)y dQ y Dx dE y ~ b22 x y2 sin x b22 y2 d t (2007)urned out (2007) t (2007)o be very large (~ 108m-1) Why wit (2007)h Elianas design it (2007) was small despit (2007)e large phase advance error x~0.1?

The answer: small x =24m ! Wy Wx MC Lattice Update - Y. Alexahin Moving t (2007)he sext (2007)upole by a few met (2007)ers t (2007)o t (2007)he focal point (2007) where x=/2 but (2007) x ~0.5m improved t (2007)he DA even more! MCTF-NFMCC meeting, Fermilab, October 16, 5 New paradigm Chromat (2007)icit (2007)y of t (2007)he larger -funct (2007)ion should be correct (2007)ed first (2007) (before is allowed t (2007)o change) and in one kick t (2007)o reduce sensit (2007)ivit (2007)y t (2007)o errors! To avoid spherical aberrat (2007)ions it (2007) must (2007) be y t (2007)hen small x will kill all det (2007)uning coefficient (2007)s and RDTs (t (2007)his will not (2007) happen if y x) Chromat (2007)icit (2007)y of x should be correct (2007)ed wit (2007)h a pair of sext (2007)upoles separat (2007)ed by -I sect (2007)ion t (2007)o cont (2007)rol DDx (smallness of y is welcome but (2007) not (2007) sufficient (2007)) Placing sext (2007)upoles in t (2007)he focal point (2007)s of t (2007)he ot (2007)her -funct (2007)ion separat (2007)ed from IP by = int (2007)eger reduces sensit (2007)ivit (2007)y t (2007)o t (2007)he beam-beam int (2007)eract (2007)ion. These considerations uniquely determine the IR layout. Eliana came very close t (2007)o it (2007) (feminine int (2007)uit (2007)ion!), just (2007) minor correct (2007)ions were needed.

Requirements adopted for the new version: full apert (2007)ure A = 10sigma_max + 2cm maximum t (2007)ip field in quads = 10T (G=200T/m for A=10cm) bending field 8T in large-apert (2007)ure open-midplane magnet (2007)s, 10T in t (2007)he arcs IR quad lengt (2007)h < 2m (split (2007) in part (2007)s if necessary!) no shielding from inside MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 6 7 Streamlined Elianas design correctors multipoles for higher order chrom. correction Dx (m) RF quads sextupoles y bends Chrom. Correction Block x

Wy Wx MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 8 Arc cell Requirements: cancel posit (2007)ive cont (2007)ribut (2007)ion t (2007)o c and dc /dp from IR and CCB (c ~10-3/ IP) maximum dipole packing fact (2007)or (t (2007)o minimize circumference) does not (2007) need t (2007)o be an achromat (2007) great (2007) simplificat (2007)ion! Various t (2007)ypes of arccells considered: FODO (wit (2007)h reversed bends), KEKB and Carols FMCs. A new type of FMC developed: SVC QF1 C C d c 1 DDx 1 1 Dx c ds, ( Dx) 2 ds C0 d p C 0

2 Dx SDDX SDDX DDx/5 SHC SHC x y Dx (and c) is easily cont (2007)rolled by QF1 DDx (and dc /dp ) is cont (2007)rolled by SDDX Sext (2007)upoles are not (2007) st (2007)rong can be organized in usual int (2007)erleaved families As it (2007) came out (2007) from t (2007)he first (2007) at (2007)t (2007)empt (2007), 10 cells are needed per arc phase advances / cell =7/5, 3/2. Ive chosen x,y =7/5 Wit (2007)h 2 IPs C=2.6km, default (2007) t (2007)unes 20 For t (2007)he next (2007) it (2007)erat (2007)ion well t (2007)ry larger cells (46 cells per arc) wit (2007)h x,y =3/2 t (2007)o reduce t (2007)he number and st (2007)rengt (2007)h of quads and sext (2007)s MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 9

Momentum acceptance Minimum nonlinear det (2007)uning at (2007) Qx21.5, Qy 20.5 Qx Such t (2007)unes are best (2007) for orbit (2007) st (2007)abilit (2007)y as well Oct (2007)upole and decapole correct (2007)ors were used t (2007)o reduce Qy and Qy No at (2007)t (2007)empt (2007) t (2007)o correct (2007) DDx globally (only per arccell) p Qy Cert (2007)ainly we can achieve 1%, but (2007) need only 0.3% c x* y* p MC Lattice Update - Y. Alexahin p MCTF-NFMCC meeting, Fermilab, October 16, 10 Dynamic Aperture (MAD8)

CSIy [m] CSIy [m] beam-beam =0.1/IP 1024 passes (512 turns) no beam-beam, 2048 passes (1024 turns) CSIx [m] CSIx [m] DA= CSI / N= 4.5 for N=25 m Nonlinear correct (2007)ion has not (2007) been done yet (2007) (will increase DA) No synchrot (2007)ron oscillat (2007)ions No fringe-fields No magnet (2007) imperfect (2007)ions and misalignment (2007)s (will decrease DA) MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 11 Basic parameters Elianas new Dipole first (2007) New-new

Beam energy, GeV 750 750 750 Number of IPs 1 2 2 Circumference, km 3.6 3.1 2.6 *, cm 1 1 1

_max, km 64 32 48 Moment (2007)um compact (2007)ion 7.7e-5 5.5e-5 9.3e-5 Moment (2007)um accept (2007)ance, % 0.96* 0.63 0.8 Tunes 26.45/24.45 42.1/41.1 21.54/20.54 DA, for =25m

~7 ~3 ~4.5 ------------------------------------------------------------------------------*) st (2007)at (2007)ic accept (2007)ance wit (2007)h no RF MC Lattice Update - Y. Alexahin 4 th LEMC workshop, Fermilab, June 09, KEKB arccell (A. Netepenko) Sasha just finished his version of the ring: cell magnet (2007) lengt (2007)h=5 m, field=12 T, gaps bet (2007)ween t (2007)hem ~ 0.6 m Just (2007) 3 cells/arc C=2.34km ! c=6.4e-6 Difficult (2007)y encount (2007)ered: independent (2007) cont (2007)rol of Dx and c. Probably can be solved (t (2007)here is enough quads) Addit (2007)ional sext (2007)upoles can be inst (2007)alled t (2007)o cont (2007)rol DDx |Dx|=9m is a bit scary Dx|Dx|=9m is a bit scary =9m is a bit (2007) scary ax~3cm MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 12

13 Next steps Ay Qx Qy Ax 2048 t (2007)urns DA for reference emit (2007)t (2007)ance N=10 m (=4.4 for N=25 m) comput (2007)ed wit (2007)h MADX PTC_TRACK Probably t (2007)he t (2007)unes can be lowered t (2007)o provide room for beam-beam t (2007)uneshift (2007) MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, Summary & Outlook Search for t (2007)he opt (2007)imum IR opt (2007)ics finished (Eliana is t (2007)he winner!) Tracking st (2007)udies show t (2007)hat (2007) all requirement (2007)s of t (2007)he high-emit (2007)t (2007)ance opt (2007)ion can be sat (2007)isfied Luminosit (2007)y increased by > 10% due t (2007)o smaller circumference Next steps: Updat (2007)e IR design in accordance wit (2007)h A.Zlobin and N.Mokhov recommendat (2007)ions concerning realist (2007)ic magnet (2007) design and shielding St (2007)udy effect (2007)s of fringe fields, add nonlinear correct (2007)ors if necessary Design orbit (2007) correct (2007)ion and t (2007)uning circuit (2007)s

St (2007)udy effect (2007) of misalignment (2007)s and magnet (2007) imperfect (2007)ions Down-select (2007) arc cell configurat (2007)ion MC Lattice Update - Y. Alexahin MCTF-NFMCC meeting, Fermilab, October 16, 14 IP: DR1: QLB1: marker; drift, L=6.; quadrupole, L=1.5, k1=0.1; ! k1=0.3*G[T/m]/p[GeV/c]=0.1 for G=250T/m in D=7cm aperture (Nb3Sn) DRSH: drift, L=0.3; ! shielding QLB2: quadrupole, L=1.7, k1=0.077; ! k1=0.3*G[T/m]/p[GeV/c]=0.08 for G=200T/m in D=10cm aperture (Nb3Sn) OCT1: octupole, k3l=kO1; DR2: drift, L=0.5; ! shielding & multipole correctors QLB3: quadrupole, L=1.7, k1=-0.052; ! D=15cm aperture (Nb3Sn) DRSH:

drift, L=0.3; ! shielding QLB4: quadrupole, L=1.7, k1=-0.052; ! D=15cm aperture (Nb3Sn) OCT2: octupole, k3l=kO2; DR3: drift, L=1.5; ! vertical correctors QLB5: quadrupole, L=1., k1=-0.038; ! D=15cm aperture DRT2: drift, L=0.25; ! technological gap BE1: rbend, L=6, angle=0.0192; !angle= 0.3*L*B[T]/p[GeV/c], B=8T V=15cm aperture (open midplane Nb3Sn) SLB1: sextupole, L=0.5, k2=-0.346; QF4: quadrupole, L=2, k1=0.034;