E. Paloni, S. Bettoni, R. Pantaleo, M Biagini, et al. IR Design Update M Sullivan For E. Paloni, S. Bettoni, R. Pantaleo, M Biagini, et al. SuperB Workshop Elba, Italy May 31 - Jun 3, 2008

Outline CDR design New design Layout SR backgrounds More to do Summary Overall With detector Near the IP Radiative Bhabhas SR backgrounds HER LER More to do Summary

CDR Design Shared QD0 Offset outgoing beams Significant SR power from outgoing offsets Strong bending also bends the radiative bhabhas

New Design QD0 has two centers – one for each beam (septum QD0) Bore has to be cold – no room for warm bore Means very low SR power on the walls Minimal bending of incoming and outgoing beams QDO centers are parallel to detector axis

New Design (2) Final focus magnets are close to the IP Final soft bend magnets are further outboard Still include an extra HEB QD0 part Offset the QD0H quadrupole by -4 mm on the upstream beam line in order to deflect the x-rays from QF1H magnet away from the IP beam pipe and away from the cold bore of the downstream QD0 This offset is presently not on the downstream HER (HER is slightly asymmetric – could be made symmetric or anti-symmetric)

New IR design with BaBar

New IR design with luminosity gammas

New IR design with BaBar

New IR design with BaBar BSC envelopes are 15 sigma + 1 mm

Beam parameters used Parameter HER LER Energy (GeV) 7 4 Current (A) 1.44 2.50 Beta X (mm) 20 35 Beta Y (mm) 0.2 0.2 Emittance X (nm-rad) 0.8 2 Emittance Y (pm-rad) 1.4 3.5 Sigma X (m) 7 4 Sigma Y (nm) 30 20

Magnet parameters Quad G (k/m) L(m) from IP (m) QD0 -1633 0.25 0.40 QD0H -1207 0.20 0.75 QF1L 374 0.50 0.90 QF1H 399 0.70 1.15 Dipole B (kG) L(m) from IP (m) B1L -0.77 5.4 10.25 B1H -1.35 5.4 10.25

Radiative Bhabhas

SR Bkgds Masks or beam pipe surfaces HER SR Dist. Radius sigma Power Gammas (m) (mm) X Watts >10 keV -1.85 15 23 8288 2.8x109 -0.95 10 34 184 6.2x107 -0.65 5 33 179 6.1x107 -0.40 6 75 0 0 -0.10 10 >100 0.157 5.2x104 +0.10 10 >100 1.6x10-4 59 +0.40 6 75 236 8.6x107 +0.65 6 39 0.3 1.0x105 On the cold bore We gain a factor of 10000 from SA and a factor of 30 from backscatter rate ~330/crossing -- almost ok?

SR bkgds (2) Masks or beam pipe surfaces LER SR Dist. Radius sigma Power Gammas (m) (mm) X Watts >10 keV -1.40 15 33 1539 7.6x107 -0.90 15 48 4 2.0x105 -0.65 10 59 45 2.1x106 -0.40 6 75 0 0 -0.10 10 >100 0 0 +0.10 10 >100 0 0 +0.40 6 75 0 0 +0.65 6 39 0.2 7.3x103 On the cold bore

SR power and bkgds 179 W 45 W 0.2 W 236 W 0.2 W 0.3 W

8288 W 184 W 4 W 1539 W

More to do on SR backgrounds Calculate the rate of photons through the detector beam pipe Deviate orbit by at least +/- 1 sigma to see if power levels and backgrounds are still ok Put in compensating solenoids and the detector field More careful calculation of backscattered photons Tip scattering rate and incidence on detector beam pipe Check forward scattered photon rate from upstream soft bend magnets

More to do on engineering Can QD0 be built? Transition space from warm bore to cold bore Magic flange location (CESR and KEK have done it) Bellows location to relieve stress on detector Be beam pipe Magnet supports Vacuum supports Where can we put pumping? Is QD0H PM or SC? (Probably SC) Looks like all the final focus magnets are in the detector field (hence all are most likely SC) Compensating solenoids Cryostat size Warm bore for the other IR magnets 30-40 beam sigmas best aperture so far for the present design One mask is at 23 sigma X

HOM calculations Can’t really do much until we have an engineering design Need: The location of joints and bellows Beam pipe cross-sections Details about septum junction Mask locations … This issue is one of the most difficult ones to get right everywhere. You essentially have to design and then model the entire machine before you can find out if you have any unexpected weaknesses. Even then you usually discover the weakness only after it has bitten you. The experience of the B-factories (PEP-II and KEKB) has helped to shed light on this issue.

Detector beam pipe No doubt Be Double layer How thick? The closer to the beam the more cooling we need Most likely need Au coating on inside Thickness TBD Cooling fluid (gas does not cool enough)

Summary The new IR design looks much better from a lattice point of view Less bending at the IP Lower emittance growth It also looks better from a radiative bhabha background point of view Minimal bending With a BaBar cartoon drawn in, it looks like all of the final focus magnets need to be superconducting More challenges for the cryostat design A good start but there is much more to do before we have something we know we can build…

Extra slides

SR power Magnet Dipole (kW) Quad (kW) Total (kW) QD0 4.660 QD0H 4.461 0.126 4.587 QF1L 0 0.013 0.013 QF1H 0 0.295 0.295 B1L 3.241 0 3.241 B1H 17.508 0 17.508 Under construction…