2nd Workshop on a Super B-Factory INFN-LNF, Frascati, Italy IR Design M. Sullivan for the 2nd Workshop on a Super B-Factory March 16-18, 2006 INFN-LNF, Frascati, Italy

Outline Starting point Design considerations First attempt at a design ILC style design Beam parameters Design considerations Andrei’s MAD deck Pantaleo’s novel idea Beam pipe and magnet apertures SR fans First attempt at a design Still to do… Summary

ILC type collision Very small spot sizes Large crossing angle Small emittances Large beta functions

Parameters from Pantaleo’s presentation Optimized flat case in multi-turn regime with Np=2^10^10, Nbunches=5000 (3Km ring), Colliding every turn IP parameters: sigx=2.67um sigy=12.6nm Crab focus on in vertical plane betx=2.5mm bety=80um X_crossing_angle=2*25mrad sigz=4mm sige=5MeV (sige/e=1*10-3) (Lum_sige=7MeV) emix=0.4nm (emix_norm=4um) emiy=0.002nm (emiy_norm=20pm) emiz=4.0um Damping_time (Tau)=10msec Stored time between collision=10usec=0.001Tau=1turn Collision_frequency=100KHz*5000 Lmultiturn=0.8*10^36 (Lsingleturn=1.2*10^36) Vertical tune shift like in PEP!!! (similar currents,100 times more luminosity, 100 times smaller betay)

Some IP Parameters Beta x (mm) 2.5 2.5 Beta y (mm) 0.08 0.08 HER LER Beta x (mm) 2.5 2.5 Beta y (mm) 0.08 0.08 Emittance x (nm-rad) 0.4 0.4 Emittance y (nm-rad) 0.002 0.002 Sigma x (m) 2.67 2.67 Sigma y (m) 0.0126 0.0126 Bunch spacing (m) 0.6 Crossing angle (mrad) ±25 Luminosity 0.81036

Design Considerations Used a MAD deck from Andrei to get started Magnet strengths Magnet positions The quad closest to the IP is shared Panta’s idea is to use a shared sextupole as well The beams are off axis in the sextupole More on this… The shared quad and sextupole have to have a large enough apertures to accommodate both beams The SR fans have to be followed

Shared sextupole The shared quadrupole has to be optimized for the incoming beam This means the outgoing beam (which has a different energy) is getting either too little or too much focusing Enter the shared sextupole With a shared sextupole and with the beams separated the sextupole introduces a quadrupole term to each beam that is opposite in sign This allows us to add quad strength to the HER and at the same time subtract quad strength from the LER And vice versa on the other side of the IP Several possibilities exist Incoming beams on axis with the sextupole, outgoing beams off axis Sextupole axis between the two beam trajectories Caveat: The beam focusing is dependent on the beam orbit

First attempt at a design Crossing angle of 50 mrad total (±25 mrad) Beam energies of 4 and 7 GeV Separate beam pipes at 2.25 m – in front of the second quad The beta functions are presently not well matched to any sort of transport lines Put the shared quad and shared sextupole on the same axis – between the two beams (0 deg in the picture) The shared quad (QD0) together with the crossing angle separate the 2 beams

Layout of IR orbits for ILC version Super B Factory

More to do More back and forth with the optics people Trace out the SR fans – make sure they do not fry the IP beam pipe Trace out the SR from the focusing elements – for detector bkgd masking Radiative Bhabhas. Where do they go? Beam-gas bkgds Find minimum radius beam pipe for IP – probably needs water cooling HOM power

Summary Coming from the ILC design is an interesting approach Shared sextupole allows for a better optics match between the different beam energies Large crossing angle helps to separate the beams Very preliminary first look shows promise…