HL-LHC alternatives R. Tom´ as, O. Dominguez and S. White Many thanks to G. Arduini, P . Baudrenghien, H. Bartosik, O. Br¨ uning, X. Buffat, R. Calaga, E. Shapochnikova, H. Damerau, S. Fartoukh, R. Garoby, G. Iadarola, R. de Maria, V. Litvinenko, G. Rumolo and B. Salvant Review of LHC & Injector Upgrade Plans Workshop October 2013 Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.1/25
Contents ⋆ Assumptions ⋆ Alternatives and merits ⋆ US1 performance ⋆ US2 performance ⋆ Exotic ⋆ Summary & Outlook Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.2/25
Assumptions ⋆ Efficiency is 50% and it is defined as T fill + T turn − around N fills T run ⋆ Average fill length is either optimum or 6 hours. ⋆ Turn-around of 3 hours. ⋆ US1 and US2 crossing angles are 10 σ and 12 σ , respectively ⋆ US1 and US2 goals are 170 fb − 1 y − 1 and 270 fb − 1 y − 1 , respectively Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.3/25
Alternative 1: 8b+4e R. Garoby, H. Damerau ⋆ Double splitting instead of triple splitting in the PS for more bunch charge and 2/3 bunches. A PSB bunch becomes: ⋆ In the LHC: 1840 bunches with 2.4 × 10 11 ppb ⋆ Details in Heiko’s talk ⋆ First beam tests in injectors in 2014 ⋆ Merits: Significantly lower e-cloud, no cost Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.4/25
Alternative 1: 8b+4e, lower e-cloud 10 Heat load (W/m) 1 25ns (LHC post LS1) 25ns (LHC post LS1 with 4-bunch gaps) Measured HL at LHC (Fill #3429) 0.1 1.3 1.4 1.5 1.6 1.7 1.8 1.9 δ max Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.5/25
R. Garoby, Alternative 2: 200 MHz in LHC E. Shapochnikova, R. Calaga ⋆ 200 MHz (3 MV) allows to inject more intense longer bunches into the LHC and to have bunch length leveling ⋆ Potential first design of the 200 MHz SC cavities that would work from injection to store. http://cern.ch/rcalaga/LHCRF/PrelimDraft.pdf ⋆ Merits: 2.5 × 10 11 ppb, σ z =15 cm, lower e-cloud, bunch length leveling and significantly lower heating for most LHC devices. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.6/25
Alternative 2: SC 200 MHz in LHC R. Calaga The 200 MHz SC quarter-wave cavity is even smaller than the current 400 MHz. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.7/25
200 MHz ( σ z =15 cm) has lower e-cloud 10 Heat load (W/m) 1 25ns (US2 baseline) 25ns (US2 with f RF =200 MHz) Measured HL at LHC (Fill #3429) 0.1 1.3 1.4 1.5 1.6 1.7 1.8 1.9 δ max Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.8/25
US1 performance L year [ fb − 1 ] N fill Pile-up ǫ β ∗ x,y 1 10 11 [ µm ] [cm] Opt. 6h [h] [ mm ] US1 1.9 2.62 20,40 181 181 6.1 140 1.5 flatter 1.9 2.62 20,80 169 168 6.6 128 1.1 8b4e 2.4 2.62 20,80 153 150 7.3 141 1.2 50ns 3.5 3.0 20,80 142 118 12 143 1.1 200MHz 2.56 3.0 20,80 232 224 8.1 138 1.1 240 200MHz 2.56 3.0 20,40 228 8.5 138 1.4 8b4e still better than 50ns. 200 MHz has excellent perfor- mance also with lower e-cloud than nominal. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.9/25
US1 fill comparison I 2.6 3 3 2.4 2.8 2.8 ppb [10 11 ] 2.2 ε x [10 -6 m] ε y [10 -6 m] 2.6 2.6 2 2.4 2.4 1.8 2.2 2.2 1.6 2 2 1.4 1.2 1.8 1.8 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US1 8b4e Time [h] Time [h] Time [h] 200 1.3 0.6 0.8 1.2 0.5 0.7 1.1 σ z [dm] β x [m] β y [m] 1 0.4 0.6 0.9 0.3 0.5 0.8 0.7 0.2 0.4 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.10/25
US1 fill comparison II 5.5 1.5 1.5 1.4 1.4 L [10 34 cm -2 s -1 ] 5 µ peak [mm -1 ] 1.3 1.3 4.5 µ [100] 1.2 1.2 4 1.1 1.1 3.5 1 1 3 0.9 0.9 2.5 0.8 0.8 2 0.7 0.7 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US1 US1 8b4e 8b4e Time [h] Time [h] Time [h] 200 200 2.5 3.5 3.5 L int [100fb -1 y -1 ] 2 3 3 ξ x [0.01] ξ y [0.01] 1.5 2.5 2.5 1 2 2 0.5 0 1.5 1.5 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.11/25
US2: CC with 200 MHz? σ z = 15 cm 40 200 MHz 20 x [ µ m] 0 -20 -40 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Longitudinal location [m] σ z = 7.5 cm 40 400 MHz 20 x [ µ m] 0 -20 -40 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Longitudinal location [m] 2 σ envelopes with β ∗ =15 cm. CC RF curvature reduces overlap above 1 σ for 200 MHz. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.12/25
US2 performance L year [ fb − 1 ] N fill Pile-up ǫ β ∗ x,y 1 10 11 [ µm ] [cm] Opt. 6h [h] [ mm ] US2 2.2 2.5 15,15 261 232 9.3 140 1.2 276 200MHz 2.56 3.0 15,15 234 11 140 1.3 200MHz (no CC) 2.56 3.0 10,50 255 233 10 139 1.6 200 MHz with CC gives the best performance with lower e-cloud and it is robust against non-working CCs. Can we improve the pile-up density? Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.13/25
US2 fill comparison I 2.6 3 3 2.4 2.8 2.8 2.2 ppb [10 11 ] ε x [10 -6 m] ε y [10 -6 m] 2 2.6 2.6 1.8 2.4 2.4 1.6 1.4 2.2 2.2 1.2 2 2 1 0.8 1.8 1.8 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US2 200 Time [h] Time [h] Time [h] noCC 1.3 0.7 0.7 1.2 0.6 0.6 1.1 0.5 0.5 σ z [dm] β x [m] β y [m] 1 0.4 0.4 0.9 0.3 0.3 0.8 0.2 0.2 0.7 0.6 0.1 0.1 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.14/25
US2 fill comparison II 5.2 1.5 1.6 5 1.5 L [10 34 cm -2 s -1 ] 1.4 µ peak [mm -1 ] 4.8 1.4 4.6 1.3 µ [100] 1.3 4.4 1.2 1.2 4.2 1.1 4 1.1 1 3.8 1 0.9 3.6 3.4 0.9 0.8 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US2 US2 200 200 Time [h] Time [h] Time [h] noCC noCC 3 3.5 3.5 L int [100fb -1 y -1 ] 2.5 3 3 ξ x [0.01] ξ y [0.01] 2 1.5 2.5 2.5 1 2 2 0.5 0 1.5 1.5 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.15/25
Pile-up density leveling? ⋆ The 1 st proposal for pile-up density leveling was crab kissing (S. Fartoukh) ⋆ In general, we can level at constant pile-up density rather than at constant luminosity ⋆ This implies lower integrated luminosity ⋆ There are four options: • β ∗ levling with σ z =10 cm • 800MHz + β ∗ leveling • Crab kissing • 800MHz + Crab kissing Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.16/25
800 MHz - bunch profile 0.04 Nominal 800 MHz 0.03 density [cm -1 ] 0.02 0.01 0 -30 -20 -10 0 10 20 30 s [cm] Assuming 8 MV 800 MHz system to provide 10- 12.5 cm rms bunch length. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.17/25
Pile-up leveling in US2 nominal L year [ fb − 1 ] N fill Pile-up ǫ β ∗ x,y 1 10 11 [ µm ] [cm] Opt. 6h [h] [ mm ] US2 2.2 2.5 15,15 261 232 9.3 140 1.2 β ∗ -level 2.2 2.5 15,15 250 232 9.5 142 1.0 800MHz 2.2 2.5 15,15 252 232 9.1 141 0.9 Peak pile-up density can be leveled to 1.0 mm − 1 without any new hardware and with little loss in performance. A new 8 MV 800 MHz system can slightly help to reduce the pile-up density. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.18/25
Pile-up leveling in US2 with 200 MHz The first step in 200 MHz is to have a minimum bunch length of 10 cm with flat β ∗ =7.5, 30 cm, then leveling pile-up density with β ∗ is also possible. L year [ fb − 1 ] N fill Pile-up ǫ β ∗ x,y 1 10 11 [ µm ] [cm] Opt. 6h [h] [ mm ] 200MHz 2.56 3.0 15,15 276 234 11 140 1.3 σ z 10cm 2.56 3.0 7.5,30 272 233 11 140 1.1 β ∗ -level 2.56 3.0 7.5,30 272 233 10 141 1.0 Pile-up density can also be leveled to 1 mm − 1 with the 200 MHz. Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.19/25
US2 β ∗ Leveling comparison I 2.6 3 3 2.4 2.8 2.8 2.2 ppb [10 11 ] ε x [10 -6 m] ε y [10 -6 m] 2 2.6 2.6 1.8 2.4 2.4 1.6 1.4 2.2 2.2 1.2 2 2 1 0.8 1.8 1.8 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US2 200 Time [h] Time [h] Time [h] 1.3 1 0.6 0.9 0.8 0.5 1.2 0.7 σ z [dm] β x [m] β y [m] 0.6 0.4 1.1 0.5 0.4 0.3 0.3 1 0.2 0.2 0.1 0.9 0 0.1 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.20/25
US2 β ∗ Leveling comparison II 5.2 1.5 1.1 5 L [10 34 cm -2 s -1 ] 1.4 µ peak [mm -1 ] 4.8 1 4.6 1.3 µ [100] 4.4 1.2 0.9 4.2 4 1.1 0.8 3.8 1 3.6 3.4 0.9 0.7 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 US2 US2 200 200 Time [h] Time [h] Time [h] 3 3.5 3.5 L int [100fb -1 y -1 ] 2.5 3 3 ξ x [0.01] ξ y [0.01] 2 1.5 2.5 2.5 1 2 2 0.5 0 1.5 1.5 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 Time [h] Time [h] Time [h] Rogelio Tom´ as Garc´ ıa HL-LHC alternatives – p.21/25
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