IR design status IR Design Status M Sullivan

IR design status IR Design Status M. Sullivan For M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni, P. Raimondi, et al. Super. B Workshop XII LAPP, Annecy, France March 16 -19, 2010 1 Super. B Workshop XII March 16 -19, 2010

IR design status Outline • IR Design – CDR 2 (white paper) baseline • Features • Layout • SR backgrounds • Update on study of Vobly’s Panofsky quads • Summary 2 Super. B Workshop XII March 16 -19, 2010

IR design status Machine Parameters Originally Used 3 Super. B Workshop XII March 16 -19, 2010

IR design status Present Parameters 4 Super. B Workshop XII March 16 -19, 2010

IR design status Parameters used in the IR Design 5 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) 6. 70 1. 89 26 0. 253 2. 00 5. 0 7. 21 36 4. 18 2. 45 32 0. 205 2. 46 6. 15 8. 87 36 +/- 33 Super. B Workshop XII March 16 -19, 2010

IR design status General IR Design Features • Crossing angle is +/- 33 mrads • Cryostat has a complete warm bore – Both QD 0 and QF 1 are super-conducting • PM in front of QD 0 • Soft upstream bend magnets – Further reduces SR power in IP area • BSC to 30 sigmas in X and 100 sigmas in Y (7 sigmas fully coupled) 6 Super. B Workshop XII March 16 -19, 2010

IR design status General Reference Frame 7 Super. B Workshop XII March 16 -19, 2010

IR design status The Present Baseline Design 8 Super. B Workshop XII March 16 -19, 2010

IR design status Larger view 9 Super. B Workshop XII March 16 -19, 2010

IR design status Vertical View – same as before 10 Super. B Workshop XII March 16 -19, 2010

IR design status Beam sizes in QD 0 Beams in the PM slices 45 mm dia. 65 mm dia. These are somewhat out of date. They use the old machine parameter set. 11 Super. B Workshop XII March 16 -19, 2010

IR design status QF 1 cross-sections 12 Super. B Workshop XII March 16 -19, 2010

IR design status SR backgrounds • No photons strike the physics window – We trace the beam out to 20 X and 45 Y – The physics window is defined as +/-4 cm for a 1 cm radius beam pipe • Photons from particles at high beam sigmas presently strike within 5 -6 cm downstream of the IP • However, highest rate on the detector beam pipe comes from a little farther away • Unlike PEP-II, the Super. B design is sensitive to the transverse beam tail distribution 13 Super. B Workshop XII March 16 -19, 2010

IR design status Beam Tail Distribution These tail distributions are more conservative than those used for PEP-II. The Super. B beam lifetime is shorter by about a factor of 10 so the tail distributions can be higher. But we will probably collimate at lower beam sigmas than shown here. 14 Super. B Workshop XII March 16 -19, 2010

IR design status SR from the upstream bends B 1 magnet Kc = 4. 0 ke. V 15 B 1 magnet Kc = 0. 7 ke. V Super. B Workshop XII March 16 -19, 2010

IR design status SR power from soft bends B 0 magnet Kc = 1. 2 ke. V 16 B 0 magnet Kc = 0. 2 ke. V Super. B Workshop XII March 16 -19, 2010

IR design status SR photon hits/crossing LER HER 215 1. 3 E 6 1 E 4 1. 1 E 5 5300 748 1600 4. 4 E 4 7. 5 E 5 1. 8 E 7 17 Super. B Workshop XII March 16 -19, 2010

IR design status SR photon hits/crossing on the detector beam pipe from various surfaces LER HER 0. 24 0. 07 13 8 9 13 10 111 968 105 18 Backscattering SA and absorption rate (3% reflected) Super. B Workshop XII March 16 -19, 2010

IR design status Energy Changes • For the QD 0 and QF 1 magnets we need to keep the ratio of the magnetic field strengths constant in order to maintain good field quality • We want the * values to remain constant to maintain luminosity • We need to match to the rest of the ring • No changes to the permanent magnets • Solutions found by iteration • Solutions found for all Upsilon resonances 19 Super. B Workshop XII March 16 -19, 2010

IR design status Resonance Upsilon 4 S Upsilon 3 S Upsilon 2 S Upsilon 1 S Ecm (Ge. V) 10. 5794 10. 3554 10. 0236 9. 4609 6. 694 6. 553 6. 343 5. 988 QD 0 (T/cm) -0. 97584 -0. 95329 -0. 91969 -0. 86285 QF 1 (T/cm) 0. 60408 0. 59132 0. 57232 0. 54019 4. 091 3. 96 3. 737 QD 0 (T/cm) -0. 63941 -0. 62522 -0. 60435 -0. 56882 QF 1 (T/cm) 0. 37412 0. 36616 0. 35445 0. 33450 QD 0 ratio 1. 52617 1. 52472 1. 52179 1. 51693 QF 1 ratio 1. 61466 1. 61491 1. 61469 1. 61490 1. 02785 1. 02787 1. 02791 Boost ( ) 0. 23763 0. 23775 0. 23793 HER E (Ge. V) LER E (Ge. V) 20 4. 18 Super. B Workshop XII March 16 -19, 2010

IR design status Energy Changes • The 2 S and the 3 S LER energies would have very little polarization • It should be straightforward to develop a procedure to perform an energy scan • To go to the Tau-charm region (Ecm ~4 Ge. V) we will need to remove most if not all of the permanent magnets – With the air-core super quads we would need to approximately preserve the energy asymmetry – We might be able to get more creative by using the PMs to change the actual beam energies 21 Super. B Workshop XII March 16 -19, 2010

IR design status Solenoid compensation • We have recently found out from our colleagues at KEK that we should pay much more attention to the fringe field of the detector solenoid • The radial part of the field causes emittance growth • This also means that we want to minimize the fringing fields of the solenoids • We will need to revisit our compensation schemes and look at ways of minimizing the fringing fields as well as the total integral 22 Super. B Workshop XII March 16 -19, 2010

IR design status To do list • SR – A more thorough study of surfaces and photon rates – Check dipole SR – More detailed backscatter and forward scatter calculations from nearby surfaces and from the septum – Photon rate for beam pipe penetration • Revisit solenoid compensation 23 Super. B Workshop XII March 16 -19, 2010

IR design status Super-ferric QD 0 and QF 1 • Pavel Vobly from BINP has come up with a new idea for QD 0 (mentioned at the last workshop) – Use Panofsky style quadrupoles with Vanadium Permendur iron yokes • This new idea has some added constraints but it is still attractive because it is easier to manufacture and the precision of the iron determines the quality of the magnet 24 Super. B Workshop XII March 16 -19, 2010

IR design status Pictures from Vobly’s paper 25 Super. B Workshop XII March 16 -19, 2010

IR design status The quads can be on axis with the beams 26 Super. B Workshop XII March 16 -19, 2010

IR design status Super-ferric QD 0 • Vobly had a 2 T limit but we Constraints need 10% – Maximum field of no more than 1. 8 T at the pole headroom for tips (we assume this is the same as the half width – any above 4 S should probably lower this limit another 10%-20% energy scan because the pole tip is on the diagonal) – Equal magnetic field strengths in each twin quad – Square apertures • Might be able to relax these a little – If we have room between the windings to add Fe then we can have some magnetic field difference – Might be able to make the apertures taller than they are wide – means the windings get more difficult • For now assume constraints are there and then see what we can do 27 Super. B Workshop XII March 16 -19, 2010

IR design status Permanent Magnets • Upon embarking on the task of looking at the Super-Ferric design we realized we could significantly improve the IR design by improving the permanent magnet performance 28 – Give up some vertical aperture in order to go back to circular magnet designs (~1. 4 stronger field) – Open up the crossing angle 10% to get more space for permanent magnet material – Add a couple of permanent magnet slices in front of the septum (shared magnets but close to the IP and hence minimal beam bending) Super. B Workshop XII March 16 -19, 2010

IR design status Permanent Magnets (2) • Moved some of the slices previously used on the HER to the LER in order to get more vertical focusing to the LER – We now have more equal vertical beta maximums • The beam pipe inside the magnets is 1 mm smaller in radius – 6 mm from 7 mm • The magnetic slices are now only 1 cm long and are perpendicular to the beam line instead of the detector axis – Better packing and better magnetic field performance for each beam 29 Super. B Workshop XII March 16 -19, 2010

IR design status Permanent Magnets (3) • With a 6 mm inside radius beam pipe that is 1 mm thick and allowing for 0. 5 mm of space between magnet material and beam pipe we arrive at a 7. 5 mm inside radius for the magnet material • The chosen remnant field of 13. 4 k. G is conservative. Some materials can reach 14 -14. 5 k. G. All materials are Neodymium-Iron. – This gives us some headroom for packing fraction losses between magnetic blocks • There are two shared quad slices on either side of the IP in fairly close (0. 17 -0. 21 m) – These magnets bend the beams slightly out in X increasing the beam separation for the other magnets • LER beam 1. 864 mrad • HER beam 1. 164 mrad 30 Super. B Workshop XII March 16 -19, 2010

IR design status Details of the permanent magnet slices – – – – – – 31 Name QDSA QDSB QDPA QDPB QDPC QDPD QDPE QDPF QDPG QPDH QDPI QDPJ QDPK QDPL QDPM QDPN QDPO QDPP QDPQ QPDR QDPS Beam both LER LER drift HER HER HER Z from IP m 0. 17 0. 19 0. 30 0. 31 0. 32 0. 33 0. 34 0. 35 0. 36 0. 37 0. 38 0. 39 0. 40 0. 41 0. 42 0. 43 0. 44 0. 45 0. 46 0. 47 0. 48 Len. cm 2 2 1 1 1 1 1 R 1 mm 13 14 7. 5 7. 5 R 2 mm 28 30 12. 5 13. 0 13. 5 14. 0 14. 5 15. 0 15. 5 G T/cm 1. 076 0. 994 1. 392 1. 473 1. 547 1. 616 1. 680 1. 740 1. 796 7. 5 7. 5 16. 5 17. 0 17. 5 18. 0 18. 5 19. 0 19. 5 20. 0 20. 5 21. 0 21. 5 1. 899 1. 945 1. 989 2. 030 2. 070 2. 107 2. 142 2. 175 2. 207 2. 238 2. 266 Super. B Workshop XII March 16 -19, 2010

IR design status Vanadium Permendur Design • We use the above redesigned permanent magnet slices • QD 0 face is 55 cm from the IP. If we move in closer the field strength gets too high. In addition, we lose space for the stronger PM slices • We start by setting the LER side of QD 0 and QF 1 – We impose the beta function match requirements for the LER ( * and the match point at 16. 17 m) and we also try to get the maximum field close to 1. 8 T – We keep the L* value constant but are allowed to change the separation and the lengths of QD 0 and QF 1 • These set the QD 0 and QF 1 strengths for the HER • Add another smaller defocusing quad to the HER behind QD 0 to complete the vertical focusing for the HER • Also add another smaller focusing quad behind QF 1 to complete the horizontal focusing of the HER 32 Super. B Workshop XII March 16 -19, 2010

IR design status Vanadium Permendur Design 33 Super. B Workshop XII March 16 -19, 2010

IR design status VP Design details • PM as described above 34 • Magnet QD 0 H QF 1 H • IP face (m) 0. 55 0. 90 1. 25 1. 70 • Length (m) 0. 30 0. 15 0. 40 0. 25 • G (T/cm) 0. 938 0. 707 0. 407 0. 381 • Aperture (mm) 33 49 75 77 • Max. Field (T) 1. 688 1. 732 1. 526 1. 467 • X offset (mm) 1. 0 2. 3/2. 0 1. 8 • X angle (mrad) 15 17 0. 5/1. 0 20 0. 7 Super. B Workshop XII March 16 -19, 2010

IR design status Latest New Idea • We have discovered there are several rare earth metals that have very high magnetization curves – Holmium – Dysprosium – Gadolinium • Holmium has the highest magnetic moment of any element and is reputed to have a magnetization curve up to 4 T (Vanadium Permendur is about 2. 4 T) • One of the reasons these metals are not used is that they only become ferromagnetic at temperatures well below room temperature (except for Gadolinium) – Curie temperatures • Ho is 20 K • Dy is 85 K • Ga is 289 K 35 Super. B Workshop XII March 16 -19, 2010

IR design status Some properties of these metals* • • • Elem. Ho Dy Ga • • • Fe Pb Sn Cu Ni Al Au Zn Ag • *Wikipedia, Metalprices. com and VWR Sargent Welch Den. g/cc 8. 80 8. 55 7. 90 7. 87 11. 35 7. 31 8. 96 8. 90 2. 70 19. 30 7. 13 10. 50 Young’s Mod. 64. 8 61. 4 54. 8 Shear Mod. 26. 3 24. 7 21. 8 Bulk Mod. 40. 2 40. 5 37. 9 Possion Ratio 0. 231 0. 247 0. 259 Vickers Hard. 481 540 570 Brinell Hard. 746 500 --- Cost $/kg 1000 120 <120 211 16 50 120 200 70 120 108 83 82 5. 6 18 48 76 26 27 43 30 170 46 58 140 180 76 180 70 100 0. 29 0. 44 0. 36 0. 34 0. 31 0. 35 0. 44 0. 25 0. 37 608 ----369 638 167 216 --251 590 38. 3 51 874 700 245 --412 25 0. 4 (scrap) 2 18 15 18 21 34, 000 2 530 These elements appear to be somewhere between Tin and Aluminum in hardness and strength with a density of Ni or Cu 36 Super. B Workshop XII March 16 -19, 2010

IR design status Holmium Design • Set maximum field at 3. 2 T which means 2. 9 T max to allow for headroom to scan above the 4 S • Shorten and bring the magnets closer together to lower beta maximums • Make apertures smaller when possible which allows us to increase the field strength 37 Super. B Workshop XII March 16 -19, 2010

IR design status Holmium design details • PMs as described above • Magnet QD 0 H QF 1 H • IP face (m) 0. 55 0. 80 1. 15 1. 45 • Length (m) 0. 20 0. 10 0. 25 0. 15 1. 494 1. 147 0. 727 • G (T/cm) • Aperture (mm) • Max. Field (T) • 38 34 2. 540 41 2. 351 L/H 67 2. 435 68 2. 472 L/H • X Offset (mm) 1. 3/1. 5 1. 7 0. 7/0. 0 0. 1 • X angle (mrad) 17 10 12 1. 1 Super. B Workshop XII March 16 -19, 2010

Holmium Design 39 IR design status Super. B Workshop XII March 16 -19, 2010

IR design status Beta function comparison with V 12 baseline 40 • • LER x max V 12 316 VP 309 Ho 221 • HER x max 388 480 328 • LER y max 1562 1424 1300 • HER y max 1266 1208 1111 Super. B Workshop XII March 16 -19, 2010

IR design status SR backgrounds for the Super-ferric QD 0 • SR backgrounds have not been checked yet • The outward bending of the beams from the shared quads makes the SR shielding harder • We have some natural inward bending from the QD 0 magnets which we need to steer the QF 1 radiation away from the central chamber • We may find that the bending from the shared quads causes too much trouble but we would like to keep the option open as it improves the beta functions • SR studies may force some iterations to the design 41 Super. B Workshop XII March 16 -19, 2010

IR design status Baseline Summary • The present baseline design for the IR is selfcompensating air core dual quad QD 0 and QF 1 design • All the magnets inside the detector are either PM or SC • The beam pipes inside the cryostats are warm • We have a 30 BSC in X and 100 -140 BSC in Y (7 -10 fully coupled) • Synchrotron radiation backgrounds look ok, but need more study • This is the White paper (CDR 2) design 42 • Radiative bhabha backgrounds should be close to minimal – nearly minimal beam bending Super. B Workshop XII March 16 -19, 2010

IR design status Super- ferric Summary • We are taking a close look at a super-ferric solution using Panofsky style quads • Equal field strengths and square apertures make finding a solution more difficult but there also self-shielding possibilities • The simplicity of construction and the ability to decouple some of the magnetic elements make the idea attractive 43 Super. B Workshop XII March 16 -19, 2010

IR design status Super-ferric Summary (2) • We have also found a rare earth metal (Holmium) that has a very high magnetic moment and consequently a high magnetization curve once the metal gets below its Curie temperature of 20 deg. K (Dysprosium is also an interesting possibility Curie T = 85 deg. K) • If we can use this metal we can put much higher magnetic fields in QD 0 and QF 1 thereby improving the beta functions • We have constructed a Vanadium Permandur design and a Holmium design but neither have yet had the SR backgrounds checked • SR background studies may alter the designs. Work in progress……. 44 Super. B Workshop XII March 16 -19, 2010

Conclusions IR design status • The flexibility of the IR design has been improved by re-optimizing the permanent magnets – We have more focusing in closer to the IP now • This improves the baseline design (which hasn’t yet been fully redesigned) as well as the new Panofsky style magnet design – The IR design now has a better chance of making smaller beta* values than the baseline design • We have two working designs for the Panofsky style magnets – Vanadium Permendur – Holmium – These designs still need to be checked for SR backgrounds 45 • The IR design looks robust with the various options under study Super. B Workshop XII March 16 -19, 2010