1. AT-VAC SPC 07-07-2008Nicolaas KOS Beam Screens for Inner Triplet Magnets LHC Upgrade Phase 1 Nicolaas KOS  LHC Upgrade phase 1  Inner triplet BS Requirements  Proposals  Examples of cross-sections  Aperture  Manufacturing issues  Next steps

2. AT-VAC SPC 07-07-2008Nicolaas KOS LHC Upgrade Phase 1  V. Baglin and N. Kos represent AT-VAC in the LHC Insertions Upgrade Working Group (LIUWG)  As part of the LHC upgrade activities, the LHC Insertions Upgrade Working Group is mandated to develop conceptual and technical designs of the new layout of the inner triplets and other directly associated equipment in the ATLAS and CMS high-luminosity insertions. The goal of this stage of the upgrade is to be able to focus the beams at the two IPs to a spot size corresponding to b* of 0.25 m, and to reliably operate the LHC with a luminosity of about 2×10 34 cm -2 s -1.

3. AT-VAC SPC 07-07-2008Nicolaas KOS LHC Upgrade Phase 1  The new insertions will be based on the available magnet technology, in particular on the use of Nb- Ti superconducting cables produced for the LHC, and will respect the present interfaces with the two experiments, the available cryogenic cooling capacity and other infrastructure in IR1 and IR5.  The Working Group reports to the Project Leader for the LHC Upgrade Activities and informs the management of the AB and AT Departments. The studies will be summarized in the Conceptual and Technical Design Reports, to be issued in 2008 and 2009.   http://liuwg.web.cern.ch/liuwg/

4. AT-VAC SPC 07-07-2008Nicolaas KOS LHC Upgrade phase 1  Only IR1 and IR5 (ATLAS and CMS)  No modification of Q6 and beyond  Displacement of Q5 and Q4-D2 towards arc  Rotation of beam screens in Q5, Q4 and D2  Replacement of D1, Q3, Q2 and Q1 Larger aperture (cold bore ID 119 mm for 130 mm bore magnets TBC) New design beam screens, interconnections and CWT’s  Redesign of TAS and VAX zone between TAS and Q1

5. AT-VAC SPC 07-07-2008Nicolaas KOS Beam Screen for upgraded triplets – Requirements-  Control gas density in beam tube  Provide sufficient H and V aperture (without BS rotation)  Operation at 5-20 K or 40-60 K  Evacuate heat load  Non-magnetic (μ < 1.005)  Withstand forces during quench  Only for Q1 : Absorber to intercept debris from IP

6. AT-VAC SPC 07-07-2008Nicolaas KOS BEAM SCREEN OPERATING TEMPERATURE RANGES 5 – 20 K40 – 60 K Data compiled by V. BAGLIN AT-VAC

7. AT-VAC SPC 07-07-2008Nicolaas KOS Beam Screen for upgraded triplets – Requirements -  Control gas density in beam tube  Provide sufficient H and V aperture (without BS rotation)  Operation at 5-20 K or 40-60 K  Evacuate heat load  Non-magnetic (μ < 1.005)  Withstand forces during quench  Only for Q1 : Absorber to intercept debris from IP

8. AT-VAC SPC 07-07-2008Nicolaas KOS Power deposition from collision debris TAS Q1 Q2 Q3

9. AT-VAC SPC 07-07-2008Nicolaas KOS Beam Screen - Proposals  2 mm P506 stainless steel for mechanical stability during quench and low magnetic perm. (μ ≤ 1.003)  Cu layer on inner surface to homogenise the BS temperature and give low impedance  ≥ 5 % pumping slot surface  4 laser welded cooling tubes to evacuate heat load (ΔT ≈ 3K between BS and He at 4 x 1 W/m)  Identical BS cross sections in Q1, Q2, Q3 (+D1)  Absorber positioned inside Q1 beam screen

10. AT-VAC SPC 07-07-2008Nicolaas KOS Race Track Design Based on existing beam screen design. Well suited for continuous forming; difficult to press as half shells.

11. AT-VAC SPC 07-07-2008Nicolaas KOS Octagonal Design 42º 48º Well suited to press as half shells. Compromise on aperture.

12. AT-VAC SPC 07-07-2008Nicolaas KOS Optimised octagonal design 42º 48º Well adapted to press as half shells. Increased aperture compared to octogonal design.

13. AT-VAC SPC 07-07-2008Nicolaas KOS Absorber in Q1 BS –1- - BS pumping slots partially masked - Pumping slots to be machined through thick absorber - Absorber weight (8 mm ss) 18 kg/m - Total BS weight (l = 10 m) 240 kg

14. AT-VAC SPC 07-07-2008Nicolaas KOS Absorber in Q1 BS –2- - BS pumping slots remain accesible - Cu plated P506 (11 kg/m) or Cu-alloy (13 kg/m) - Machined sections, unit lenghts to be defined - Screwed / brazed onto inner BS surface - RF contacts between sections ? - Half-aperture loss 9.8 mm compared to Q2 / Q3 - Q1 total beam screen weight 170 kg 9.8 6.1 40.1

15. AT-VAC SPC 07-07-2008Nicolaas KOS Optimised octagonal design - main dimensions in 119 ID CBore 116 ± 0.5 106 ± 0.5 114 ± 0.5 2.2 ± 0.1 16 rows, 50% transparency  5.1 %

16. AT-VAC SPC 07-07-2008Nicolaas KOS Radial BS size (corner) at RT for given cold bore diameter OV = ID/2 -  ID/2 - g - (d+  d) -  b * OV = ID/2 -  ID/2 - g - (d+  d) -  b * Where:OV = nominal vertical beam screen outer half-dimension [mm] ID = nominal cold bore inner diameter [mm]  ID = tolerance on cold bore inner diameter [mm] g = minimum radial gap [mm] d = nominal BS support thickness [mm]  d = tolerance on BS support thickness [mm]  b = tolerance on beam screen outer half-dimension [mm] *) Vacuum Technical Note 01-13, EDMS 350449

17. AT-VAC SPC 07-07-2008Nicolaas KOS Half-Aperture (corner) at 5K for given cold bore diameter AV = 0.99727(ID/2 - 3  ID/2 - 2g - d - 3  d - 4  b - w -  w - bss ) * Where:AV = vertical beam screen half-aperture [mm] 0.99727 = thermal contraction factor for P506 from 293K to 5K ID = nominal cold bore inner diameter [mm]  ID = tolerance on cold bore inner diameter [mm] g = minimum gap [mm] d = nominal sliding ring thickness [mm]  d = tolerance on the sliding ring thickness [mm]  b = tolerance on beam screen outer half-dimension [mm] w = nominal beam screen wall thickness [mm]  w = tolerance on beam screen wall thickness [mm] bss = beam screen straightness error [m/m] = longitudinal distance between rings [mm] *) Vacuum Technical Note 01-13, EDMS 350449

18. AT-VAC SPC 07-07-2008Nicolaas KOS Half-Aperture (corner) at 5K for given cold bore diameter AV = 0.99727(ID/2 - 3  ID/2 - 2g - d - 3  d - 4  b - w -  w - bss ) = 53.0 AV = beam screen half-aperture between corners [mm] 0.99727 = thermal contraction factor for P506 from 293K to 5K ID = nominal cold bore inner diameter [mm]119  ID = tolerance on cold bore inner diameter [mm]1.44 g = minimum gap [mm]0.1 d = nominal sliding ring thickness [mm]0.4  d = tolerance on the sliding ring thickness [mm]0.03  b = tolerance on beam screen outer half-dimension [mm]0.25 w = nominal beam screen wall thickness [mm]2.075  w = tolerance on beam screen wall thickness [mm]0.06 bss = beam screen straightness error [m/m]0.001 = longitudinal distance between rings [mm] 400

19. AT-VAC SPC 07-07-2008Nicolaas KOS Potential gain in half-aperture at zero tolerances AV = 0.99727(ID/2 - 3  ID/2 - 2g - d - 3  d - 4  b - w -  w - bss ) Half-aperture gain  ID = tolerance on cold bore inner diameter [mm] = 0+ 2.2  d = tolerance on the sliding ring thickness [mm] = 0+ <0.1  b = tolerance on beam screen outer half-dimension [mm]= 0+ 1.0  w = tolerance on beam screen wall thickness [mm] = 0+ <0.1 bss = beam screen straightness error [m/m] = 0+ 0.4

20. AT-VAC SPC 07-07-2008Nicolaas KOS Potential gain in half-aperture for pre-measured cold bore ID AV = 0.99727(ID/2 - 3  ID/2 - 2g - d - 3  d - 4  b - w -  w - bss ) dif = measured minimum ID – specified minimum ID ID’ = ID + dif/2 (assuming specified maximum ID unchanged) ΔID’ = ΔID – dif/2 half-aperture increase = dif/4 + 3dif/4 = dif Example : Specified minimum ID = 119 – 1.44 = 117.56 mm Measured minimum ID = 118 mm Half-aperture increase = dif = 118 – 117.56 = 0.44 mm !!!! Requires availablility of all cold bores before finalising the BS design !!!!

21. AT-VAC SPC 07-07-2008Nicolaas KOS Heat load ΔT ~ 3K between beam screen inner surface and He for 1 W/m per cooling tube Support heat load estimated 10 x the value for arc beam screens Q1 Q3 CW-transition : 5 W radiative 3 W conductive + 8 W total BS cool.tubes W/m BS supports 0.05 W/m BS cool.tubes W/m BS supports 0.05 W/m BS cool.tubes W/m BS supports 0.05 W/m Electr.cloud 1 W/m Debris W/m + ------------------------------ Total W/m CW-transition : 5 W radiative 3 W conductive + 8 W total Q2B BS cool.tubes W/m BS supports 0.05 W/m 10 m Q2A 10 m Electr.cloud 1 W/m Debris W/m + ------------------------------ Total W/m Electr.cloud 1 W/m Debris W/m + ------------------------------ Total W/m Electr.cloud 1 W/m Debris W/m + ------------------------------ Total W/m

22. AT-VAC SPC 07-07-2008Nicolaas KOS Manufacturing Issues  Lead time for P506 steel strip >12 months  Co-laminator (Heraeus, D) not interested !/?  Former/welder (Butting, D) not interested !  Octagonal design is more adapted to be built from pressed half shells than race track design  Cu-layer can be applied by means of electroplating (higher RRR, thinner layer)  Absorber attachment+thermalisation

23. AT-VAC SPC 07-07-2008Nicolaas KOS Next steps  Finalisation of input parameters : CB diameter, magnet lengths and interconnect lengths  Continue discussions with CERN workshops (finishing, forming and welded, Cu-plating)  Optimize BS cross section and wall thickness