IR design status IR Design Status and Update

IR design status IR Design Status and Update M. Sullivan For M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni, P. Raimondi, M. Biagini, P. Vobly, I. Okunev, A. Novokhatski, S. Weathersby, et al. Super. B General Meeting XV Caltech, Pasadena, Calif. December 13 -17, 2010 1 Super. B Workshop XV December 13 -17, 2010

IR design status Outline • IR design – Quick recap of the IR design – SR Backgrounds • Anatomy of programs – SYNC_BKG (QSRAD) – MASKING (EGS 4) • Generating high statistics – SR calculations • Power • Rates • Summary and Conclusions 2 Super. B Workshop XV December 13 -17, 2010

IR design status Present Parameters (V 12 lattice) 3 Super. B Workshop XV December 13 -17, 2010

IR design status Parameters used in the IR designs 4 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 +/- 30 Super. B Workshop XV December 13 -17, 2010

IR design status General IR Design Features • Crossing angle is +/- 30 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 in X and 100 in Y (7 fully coupled) • SR scanned to 20 in X and 45 in Y 5 Super. B Workshop XV December 13 -17, 2010

IR design status Details of the permanent magnet slices – – – – – – 6 Name QDPA QDPB QDPC QDPD QDPE QDPF QDPG QPDH QDPI QDPJ QDPK QDPL QDPM QDPN QDPO QDPP QDPQ QPDR QDPS Beam LER LER drift HER HER HER Z from IP m 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 1 1 1 1 1 R 1 mm 7. 5 7. 5 R 2 mm 12. 5 13. 0 13. 5 14. 0 14. 5 15. 0 15. 5 G T/cm 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 XV December 13 -17, 2010

IR design status Vanadium Permendur Design • We allow for 3 mm of space for the coils (new information from Ivan – actually 2. 6 mm) • The central steel section can be very thin because the magnetic field in the steel is nearly cancelled from the twin windings • The QD 0 magnet is aligned as much as possible to the beam axis, however we must slant it with respect to the beam axis in order to accommodate the increasing horizontal size of the beam-stay-clear 7 Super. B Workshop XV December 13 -17, 2010

IR design status Vanadium Permendur “Russian” Design 8 Super. B Workshop XV December 13 -17, 2010

IR design status VP design details • PM as described earlier • 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 0 2 1 0. 408 0. 381 78 • Angle wrt beam (mrad) 13. 33 • G (T/cm) 9 0. 956 0. 706 • Steel aperture (mm) 40 50 74 • Max. Field (T) 1. 49 1. 91 1. 77 1. 51 Super. B Workshop XV December 13 -17, 2010

IR design status Air-Core “Italian” Design • We replace the shared QD 0 and QF 1 parts of the VP design with the air-core design • Also place QD 0 and QF 1 parallel to the detector axis • Then we have the same field strengths and the LER and HER pieces are the same strength as the VP design 10 Super. B Workshop XV December 13 -17, 2010

IR design status Air core “Italian” QD 0, QF 1 11 Super. B Workshop XV December 13 -17, 2010

IR design status AC design details • PM as described above • 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 • Axis offsets (mm) 0. 5 --- 4 --- • Angle wrt beam (mrad) 30 0 27 1 0. 956 0. 706 0. 408 0. 381 • Aperture (mm) 35 50 73 78 • Max. Field (T) 1. 67 1. 77 1. 49 • G (T/cm) 12 Super. B Workshop XV December 13 -17, 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 7 -10 cm downstream of the IP • However, the highest rate on the detector beam pipe comes from points that are a little farther away 13 • This is true for both the vanadium permendur and the air-core design Super. B Workshop XV December 13 -17, 2010

IR design status SYNC_BKG • Originally QSRAD (by Al Clark of LBL) – Histograms the critical energies of the SR fans – Very fast – A setup with as many as 60 masks, 30 magnets and a 20 by 45 beam scan in 0. 1 steps takes seconds to run on a 7 yr old laptop – This allows for rapid masking design changes or for various beam profile runs • Enhancements – Second gaussian beam tail distribution – Offsets and tilts to magnets (Stan Hertzbach of UMass) – Parametrization of the energy spectrum • Series of falling exponentials over the energy range • This function is easily transferred over to the EGS 4 program for efficient photon generation 14 Super. B Workshop XV December 13 -17, 2010

IR design status VP SR photon hits/bunch (>4 ke. V) HER 8. 1 E 6 LER 2. 5 E 6 7. 1 E 4 6. 5 E 5 0 3. 0 E 4 5. 4 E 7 3. 8 E 6 1. 1 E 8 0 SB_SF 10 A_7_A. LIS SB_SF 10 A_4_A. LIS 15 Super. B Workshop XV December 13 -17, 2010

Output from SYNC_BKG for the HER IR design status Source of photons that hit 7 cm from the IP IP 16 Super. B Workshop XV December 13 -17, 2010

Where in the beam profile IR design status Vertical beam sigmas 17 Horizontal beam sigmas Super. B Workshop XV December 13 -17, 2010

Surface 10 cm from the IP IR design status Source of photons that hit 10 cm from the IP 18 Super. B Workshop XV December 13 -17, 2010

IR design status Where in the beam profile 19 Super. B Workshop XV December 13 -17, 2010

IR design status Source for the septum photons 20 Super. B Workshop XV December 13 -17, 2010

IR design status Where in the beam profile 21 Super. B Workshop XV December 13 -17, 2010

IR design status Masking • EGS 4 interface program to track photons that strike a beam pipe surface using input from SYNC_BKG • Fast – 108 photons takes about 2. 5 min. on a 7 yr. old laptop – present code limit is 2 x 109 photons for a single run • Some features – – – – Several photon energy spectra options Twenty different materials with at least 10 layers possible Reflection / transmission / absorption Any angle of incidence to surface Surface can have an edge Surface can have a radial tip Reflected photons can be tracked for possible hit on the inside of a cylinder surface (detector beam pipe) – Reflected (or transmitted) photons can be saved as input to another MASKING run (photon files can be added) 22 Super. B Workshop XV December 13 -17, 2010

Hits/bunch incident on and through (n) the detector beam pipe from the HER IR design status Using a conservative beam tail LER HER 47 51 (12) (4. 2) SB_SF 10 A_7_A series 23 113 (6. 3) 201 (2. 6) Beam pipe has 3 m Au Super. B Workshop XV December 13 -17, 2010

IR design status SR power (VP design) 56 24 115 295 390 205 32 52 42 17 8 Super. B Workshop XV December 13 -17, 2010

IR design status SR power (AC design) 57 25 115 311 402 215 35 57 43 17 8 Super. B Workshop XV December 13 -17, 2010

IR design status SR power that strikes beam pipe inside the cryostats • We can now model the SR power that strikes the beam pipe inside the cryostats and find how much power penetrates the pipe • The most difficult part to control is the section of beam pipe inside the QD 0 • We may find that we will need to coat the inside of the beam pipe with Au or other high Z material in order to increase the x-ray absorption 26 Super. B Workshop XV December 13 -17, 2010

IR design status First few runs looking at QD 0 • Tried three cases – – 1 mm Cu • Power (W) – 10 um Au and 1 mm Cu • Power (W) – 1 mm Au • Power (W) 27 Attenuation 3. 0 x 10 -2 6. 45 1. 4 x 10 -2 3. 01 2. 2 x 10 -5 0. 005 Super. B Workshop XV December 13 -17, 2010

IR design status Summary (1) • We have dusted off the MASKING program and gotten it to run on a PC • We have run one of the IR designs (vanadium permendur) for the HER to get the number of photons/crossing that strike and penetrate the detector beam pipe from photons reflected from nearby surfaces • The HER generates almost all of the SR background for the SVT and the two designs (vanadium permendur and air core) are very similar • The background rates are very similar to the rates seen in the Ba. Bar design (few photons per crossing) 28 Super. B Workshop XV December 13 -17, 2010

IR design status Summary (2) • With the MASKING program working again we can study various parameters that control the background rates • We have found that the SR rates are dominated by the hits on the beam pipe just downstream of the physics window (no surprise) • The thickness of the Au layer on the inside of the pipe ranging from 3 -10 m changes the background rate by about a factor of 2 -3 (again, no surprise) 29 • The high incident photon rate on the septum is compensated by the small solid angle to the detector beampipe to such an extent that this source is smaller than the nearby sources (small angle of incidence on the detector beampipe also helps) Super. B Workshop XV December 13 -17, 2010

IR design status Summary (3) • We have taken a first look at the power going into the cryostat in QD 0 – 1 mm of Cu may be too thin (6 W) – 10 um of Au helps (factor of two) – 1 mm of gold looks very good (Ta should also work as well) 30 Super. B Workshop XV December 13 -17, 2010

IR design status Conclusion • We now have a suite of programs that allows one to do rapid proto-typing on the design • This will allow us to optimize the design for maximum SR background control 31 Super. B Workshop XV December 13 -17, 2010