1. ENERGY DEPOSITION IN HYBRID NbTi/Nb 3 Sn TRIPLET CONFIGURATIONS OF THE LHC PHASE I UPGRADE FermilabAccelerator Physics Center Nikolai Mokhov, Fermilab CERN March 31 – April 2, 2008

2. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 2 OUTLINE Introduction Three Upgrade Configurations Studied MARS15 IR and Quad Models Power Density Maps Peaks w.r.t. Design Limits Heat Loads Summary

3. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 3 INTRODUCTION JIRS project of the LARP aims at investigation of potential of replacing one (on each side of IP) of the NbTi quadrupoles with a Nb 3 Sn one in the LHC Phase I upgrade of high- luminosity IRs. Based on realistic energy deposition calculations, we are trying to derive operational margins for the quads in various configurations. Preliminary results are presented here. Simulations are done with MARS15 (2008), and DPMJET-3 as an event generator for 7x7 TeV pp-collisions at 2.5x10 34 cm -2 s -1, using low-betamax and symmetric optics from John Johnstone. IP5 (R) is considered, with a full crossing angle of 450  rad, segmented absorbers SS or W (possibly) cooled at LN 2 - temperature, as proposed in our paper PRSTAB, 9, 10001 (2006) and Proc. WAMDO06 Workshop, CARE-Conf-06-049- HHH, p. 80 (2006).

4. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 4 1. LOW-BETAMAX OPTICS: LBM-1 in MARS15 Q1: 90-mm NbTi, 167.2 T/m, L=7.06 m Q2: 130-mm NbTi, 121.4 T/m, L=7.787m x 2 Q3: 110-mm Nb 3 Sn, 176.2 T/m, L=3m x 2 TAS aperture: (a)42 mm (b)55 mm 3-mm segment absorbers: W in Q1, SS in Q2, no in Q3

5. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 5 2. LOW-BETAMAX OPTICS: LBM-2 in MARS15 Q1: 90-mm Nb 3 Sn, 206.1 T/m, L=5.65 m Q2: 130-mm NbTi, 121.1 T/m, L=7.787m x 2 Q3: 130-mm NbTi, 121.1 T/m, L=8.711 m TAS aperture: 55 mm 3-mm segment absorbers: SS in Q1, Q2 & Q3

6. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 6 3. SYMMETRIC OPTICS: SYM-1 in MARS15 Q1: 90-mm Nb 3 Sn, 203.8 T/m, L=2.75m x 2 Q2: 130-mm NbTi, 121.9 T/m, L=7.8m x 2 Q3: 130-mm NbTi, 121.9 T/m, L=9.2 m TAS aperture: 55 mm 3-mm segment absorbers: SS in Q1, Q2 & Q3

7. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 7 90, 110 and 130-mm Quad Design OPERA-calculated 2-D magnetic maps: 200, 180 and 125 T/m,  x =  y = 2 mm By Vadim Kashikhin 90-mm 110-mm 130-mm

8. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 8 MARS15 IMPLEMENTATION 90-mm Nb 3 Sn130-mm NbTi Same scale

9. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 9 Beam screens, segment absorbers, cold bore, kapton, LHE, coils, collar, yoke and cryostat in MARS15 Same scale 90-mm Nb 3 Sn130-mm NbTi Cryostat: thermal shield and vessel (R=457 mm)

10. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 10 CONSISTENCY CHECKS Example: LBM-2

11. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 11 Particle Tracks for 1 pp-event at 7x7 TeV Example: SYM-1

12. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 12 POWER DENSITY MAP: LBM-1

13. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 13 Power Density Profiles at Longitudinal Peaks: LBM-1 Quad ends Q1 non-IP Q2b non-IP Q3a IP Q3b IP

14. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 14 POWER DENSITY MAP: LBM-2

15. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 15 POWER DENSITY MAP: SYM-1

16. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 16 Power Density Profiles at Longitudinal Peaks: SYM-1 Q1b non-IP endQ2b non-IP end

17. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 17 QUENCH LIMITS & DESIGN GOAL Quench Limit mW/gmW/cm 3 mW/gmW/cm 3 NbTi1.611.20.533.71 Nb 3 Sn5341.6611.3 Design Goal

18. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 18 Low-betamax-1: Peak Power Density in Cable-1 vs z LBM-1: 42-mm TASLBM-1: 55-mm TAS

19. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 19 LBM-2 & SYM-1: Peak Power Density in Cable-1 vs z LBM-2 SYM-155-mm aperture TAS

20. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 20 Peak Power Density wrt Design Limits

21. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 21 HEAT LOADS At L=2.5x10 34 cm -2 s -1, pp-interactions result in power of 2.24 kW per beam carried out from IP1 and IP5. About 1/3 of this power is deposited in the TAS and triplet. Power dissipation in the TAS scales with the luminosity and decreases with aperture increase thus giving rise to the power deposited in cold components. TAS: 455W at 34mm, 360W at 42mm, and 283W at 55mm. Heat loads in low-betamax (LBM-2) optics (Watts): 109 (Q1), 20 (MCBX), 74 (Q2a), 84 (Q2b), 25 (MQSX), 7 (TASB), 80 (Q3), 11 (MCBXA), 27 (DFBX), 17 (vessel).

22. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 22 HEAT LOAD BALANCE (Watts) LBM-1LBM-2SYM-1 LHe (bore, SC, collar, yoke) 264306292 “LN 2 ” (beam screen and segm. absorber) 173101104 Room T (vessel)20 23 Total457427419 Grand total (TAS included) 740710702 55-mm TAS Q1 to MCBXA ~ 40 m ~6.6 W/m LHe+”LN 2 ” ~11 W/m ~7.7 W/m LHe+”LN 2 ” ~10 W/m ~7.3 W/m LHe+”LN 2 ” ~9.9 W/m

23. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 23 SUMMARY (1) 1.There are always four pronounced peaks in longitudinal distributions of maximum power density in the first SC cable (averaged over the cable area at the azimuthal maxima): close to Q1 non-IP end, Q2a IP end, Q2b non-IP end and Q3 IP end (see also LHC PR 633, 2003). 2.For the configurations considered all the peaks are safely below the design limits (for 55-mm TAS). 3.Increasing TAS aperture from 42 to 55mm, increases first peak by 10% and heat load to the cold components by 75 W. 4.3-mm tungsten absorbers in Q1 provides reduction of peaks by a factor of about 3 and 2 in Q1 and Q2, respectively, compared to the stainless steel ones.

24. JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov 24 SUMMARY (2) 5.Peak in Q3 is practically insensitive to the configuration. 6.Compared to the nominal case, dynamic heat loads to theSC quads are certainly higher at 2.5x10 34 cm -2 s -1 and enlarged TAS aperture, but – because of larger quad apertures and use of absorbers - seem to be manageable, especially with high-Z absorbers cooled at LN 2. 7.Using Nb 3 Sn for Q1 or Q3 instead of NbTi substantially increases operational margins, frees space for instrumentation between quads, and provides verification of this new technology for Phase II. 8.Thanks to J. Johnstone for optics, V. Kashikhin for quad geometry and magnetic field maps, I. Rakhno & S. Striganov for enhancement of analysis tools, and A. Zlobin for coordination.