IR Design and SR M Sullivan For M

IR Design and SR M. Sullivan For M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni, P. Raimondi, et al. Super. B Workshop LAL, Orsay, France Feb 15 -18, 2009 Super. B Workshop Feb 15 -18, 2009

IR Design and SR Outline • CDR design • July 2008 design – Improvements over CDR – Layout – Shortcomings • Present Design – – Improvements over July 2008 Layout Parameters SR backgrounds • More to do • Summary Super. B Workshop Feb 15 -18, 2009

IR Design and SR CDR Design • Shared QD 0 – Offset outgoing beams – Significant SR power from outgoing offsets – Strong bending also bends the radiative bhabhas – Crossing angle of +/-17 mrad Super. B Workshop Feb 15 -18, 2009

IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR July 2008 Design • QD 0 has two centers – one for each beam (septum QD 0) – Bore is cold – no room for a warm bore • Means only very low SR power on the cold bore walls allowed – Minimal bending of incoming and outgoing beams • Minimal SR generation – no beam emittance growth • Minimal radiative bhabha backgrounds – QDO centers are parallel to detector axis – Crossing angle of +/-25 mrad Super. B Workshop Feb 15 -18, 2009

IR Design and SR July 2008 Design (2) • Final focus magnets are close to the IP • Final soft bend magnets are further outboard (~8 m) • Included an extra HEB QD 0 part – Offset the QD 0 H quadrupole by -4 mm on the upstream beam line in order to deflect the x-rays from QF 1 H magnet away from the IP beam pipe and away from the cold bore of the downstream QD 0 Super. B Workshop Feb 15 -18, 2009

IR Design and SR July 2008 IR design with Ba. Bar Super. B Workshop Feb 15 -18, 2009

IR Design and SR July 2008 IR design with Ba. Bar BSC envelopes are 15 sigma + 1 mm Super. B Workshop Feb 15 -18, 2009

IR Design and SR Comparison to PEP-II Same scale as previous slide Super. B Workshop Feb 15 -18, 2009

IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR Radiative Bhabhas Super. B Workshop Feb 15 -18, 2009

IR Design and SR Shortcomings • Still have a cold bore – Takes a lot of Z space – No SR allowed to hit the wall – No high current machine has used a cold bore • Still using 15 BSC • All the final focus magnets are in the detector field which means: – QD 0 and QF 1 must be super-conducting Super. B Workshop Feb 15 -18, 2009

IR Design and SR Present Design • After some iterating we have…. • Increased the crossing angle to +/- 30 mrads • Cryostat now has a warm bore – Both QD 0 and QF 1 are super-conducting • PM in front of QD 0 for the LER only – LER has the lowest beta Y* • Soft upstream bend magnets – Further reduces SR power in IP area • Increased BSC to 30 sigmas in X and 140 sigmas in Y Do NOT want • Using the highest luminosity design to design out upgrades parameters – Lowest beta* values and highest emittances Super. B Workshop Feb 15 -18, 2009

IR Design and SR Present Design Super. B Workshop Feb 15 -18, 2009

IR Design and SR Inside the detector Super. B Workshop Feb 15 -18, 2009

IR Design and SR Some more details • Longer QD 0 – QD 0 strength was getting too high – Maintaining the gradient below 1. 2 T/cm • Increased the space for the QF 1 cold mass ( 1. 75 times) Bettoni will • Added a shared quad as part of QD 0 Simona talk on this • Starting parameter for a warm bore design is that 5 mm is enough radial space between the cold mass and room temperature (needs engineering confirmation) • BSC in X is 30 uncoupled (all of the emittance in the X plane) and in Y we use 20% of the total emittance which is about 140 s Super. B Workshop Feb 15 -18, 2009

IR Design and SR Permanent Magnets Kirk Bertsche designed the PM slices • The permanent magnets start the vertical plane focusing for the LER • With the larger crossing angle the beams are far enough apart at 0. 35 m from the IP to have enough space to install a PM that can work on the LER • The PM quadrupole slices have an elliptical aperture to give us more vertical space • Dimensionally the slices are small • The chosen remnant field is high but not the highest Super. B Workshop Feb 15 -18, 2009

Vertical View IR Design and SR Super. B Workshop Feb 15 -18, 2009

IR Design and SR Beam parameters used Parameter HER LER Energy (Ge. V) Current (A) Beta X (mm) Beta Y (mm) Emittance X (nm-rad) Emittance Y (pm-rad) Sigma X ( m) Sigma Y (nm) Crossing angle (mrad) 7 2. 00 20 0. 27 1. 6 4. 0 5. 7 33 4 2. 00 35 0. 16 2. 8 7. 0 9. 9 33 +/- 30 Super. B Workshop Feb 15 -18, 2009

IR Design and SR Magnet parameters • Quad G (k. G/m) • • -522 -1192 399 726 0. 40 0. 30 0. 58 1. 60 B (k. G) -0. 77 -1. 35 L(m) 2. 0 from IP (m) 6. 346 QD 0 L QD 0 H QF 1 L QF 1 H • Dipole • B 0 L • B 0 H L(m) from IP (m) Super. B Workshop Feb 15 -18, 2009

IR Design and SR SR backgrounds • No photons strike the physics window – Trace beam out to 20 X and 45 Y – +/-4 cm for a 1 cm radius beam pipe • Unlike in PEP-II, we are sensitive to the transverse beam tail distributions • Photons presently strike 10 cm upstream and downstream of the IP Super. B Workshop Feb 15 -18, 2009

IR Design and SR SR fans from upstream bends Super. B Workshop Feb 15 -18, 2009

IR Design and SR SR from the upstream bends Super. B Workshop Feb 15 -18, 2009

IR Design and SR SR power (Watts) 854 425 732 2226 73 141 446 919 Super. B Workshop Feb 15 -18, 2009

IR Design and SR Photons/beam bunch 6 e 8 6 e 6 194 4 e 5 7 e 7 1 e 8 Super. B Workshop Feb 15 -18, 2009

IR Design and SR SR to do list • More thorough study of surfaces and photon rates • Backscatter calculations from nearby surfaces and from septum • Photon rate for beam pipe penetration • Orbit deviation study • Beam tail distribution study Super. B Workshop Feb 15 -18, 2009

IR Design and SR Summary • Good progress • SR rates are high near the physics window • More iterations needed to see if the rates can’t be reduced • Need to calculate rates to the physics window from scattering • What is the beam tail distribution? – Need look at various possible distributions Super. B Workshop Feb 15 -18, 2009

IR Design and SR Conclusion • The IR design is firming up • More work to be done…. • Nevertheless the design looks promising • Getting ready for initial engineering studies Super. B Workshop Feb 15 -18, 2009