1 Physics Input for the CLIC Re-baselining D. Schulte for the CLIC collaboration

22 Timeline D. Schulte, CLIC Re-baselining, February 2013 From Steinar

33 Staged Baseline Scenario Developed example scenarios in CDR 0.5, ~1.5 and 3 TeV Energy choices we will be updated based on further LHC findings Design based on 3TeV technology Scenario A with two different structures -> more luminosity at 500GeV Scenario B with a single design -> less cost D. Schulte, CLIC Re-baselining, February 2013

4 Current Physics Base for Staging Example D. Schulte, CLIC Re-baselining, February 2013 A SUSY scenario that is not (yet) excluded by LHC J. Wells et al.

55 Higgs Event Rates in Baseline Scenarios D. Schulte, CLIC Re-baselining, February 2013 Total number of events at 500GeV and 500fb -1 is O(7x10 4 ) Baseline solutions No polarisation With electron polarization: ≈16% more ZH ≈80% more WW fusion Higgs cross sections are based on cross sections calculated by Jan Strube with Wizzard2 I included ISR and beamstrahlung

6 Example Operation Scenario D. Schulte, CLIC Re-baselining, February 2013 StageYear 1Year 2Year 3Year 4Year 5 15%25%50%75%100% 2 and 325%50%100% Assume 200 days/year, 50% efficiency, i.e. 8.64x10 6 s/year E cms Int(L) 0.5 TeV500 fb /1.5 TeV1500 fb -1 3 TeV2000 fb -1

77 Cost of the 500GeV Stage Swiss francs of December 2010 Additional cost for scenario A is ~1GCHF B needs only 2 more years -> we would prefer B D. Schulte, CLIC Re-baselining, February 2013

88 Goals for Next Phase Iterate on energy choices for the stages – First stage optimised for 350GeV for Higgs and top? – Second stage at 1-2TeV? – 3TeV as current ultimate energy? Focus on optimisation of first energy stage – But consider upgrades Identify, review and implement cost and power/energy saving options – Identify and carry out required R&D Re-optimise parameters (global design) – Review figure of merit – Develop an improved cost and power/energy consumption model – Iterations needed with saving options Study alternatives – E.g. first stage with klystrons Need to remain flexible, since we are waiting for LHC findings – But have some robustness of specific solutions and can anticipate this to some extent D. Schulte, CLIC Re-baselining, February 2013

99 Optimisation Ingredients D. Schulte, CLIC Re-baselining, February 2013 Define a figure of merit (FoM) to evaluate one given CLIC design/parameter set -e.g. FoM=-cost for a given physics performance Define a few free parameters to fully describe the design/parameter set -The other parameters are unambiguously defined by the free parameters - Currently: gradient G and a few structure parameters (f RF, Δφ, a, Δa, L S, …) Use optimisation algorithm to find maximum FoM(free parameters) - Currently: a simple full search Allow some human intervention

10 Physics Performance Physics performance can be summarised by – Collision energy Which energy stages are required? At which energies do you want to operate each energy stage? – Luminosity Integrated luminosity for each energy – Luminosity spectrum From single bunch energy spread and beamstrahlung We had chosen 0.35% and at 500GeV n γ ≈1 (comp. to ISR) A trade-off with luminosity – Background We assume that this is a correction that does not to be taken into account D. Schulte, CLIC Re-baselining, February 2013

11 Questions to Physics There is a higgs factory hype – Precise measurements of the higgs at LHC – Circular electron-positron colliders with high luminosity, but limited energy reach Sofar there is no evidence of SUSY Do we need to consider already now more than one scenario corresponding to different LHC findings? – For example: Would the requirements for energy and luminosity be very different with no SUSY? Do we need to put more emphasis on the higgs studies at different energies? – For example HHZ, ttbarH What should be the new figure of merit? – Do we stick to the CDR Volume 3 approach? – Our parameter choice and upgrade strategy may be significantly impacted by these considerations In particular the choice of accelerating structure, which should be fixed soon D. Schulte, CLIC Re-baselining, February 2013

12 HF 2012 (Chicago) D. Schulte, CLIC Re-baselining, February 2013 A. Blondel et al. 10ab -1 in 5 years at 240GeV 1.4ab -1 in 5 years at 350GeV Claims appear aggressive

13 Higgs Case? D. Schulte, CLIC Re-baselining, February 2013 Obviously different energies are of potential interest

14 Example Operation Scenario D. Schulte, CLIC Re-baselining, February 2013 If more integrated luminosity were required in the first stage would produce 200fb -1 in A vs. 100fb -1 in B -> choice might be for A, even if more expensive

15 Conclusion We need to fix the new baseline this year – Can later review it but choice has very strong impact on R&D programme The main linac structure design is directly linked to the choice of parameters It is the central and most critical component Important input from physics – Energy stages – Operation scenario for each stage – Luminosity requirements – Confirmation of assumptions about luminosity spectrum and background – If more than one scenario needs to be considered we should know this as soon as possible D. Schulte, CLIC Re-baselining, February 2013

16 Example Tables D. Schulte, CLIC Re-baselining, February 2013 Maximum energy Operation energies Integrated luminosities Stage 1350GeV250GeVxxxfb GeVxxxfb -1 Stage 21.5TeV500GeVxxxfb GeVxxxfb -1 1TeVxxxfb TeVxxxfb -1 Stage 33TeV2000fb -1 Maximum energy Operation energies Integrated luminosities Stage 1500GeV 500fb -1 Stage 21.5TeV 1500fb -1 Stage 33TeV 2000fb -1 Current table: Design of future table:

17 Reserve D. Schulte, CLIC Re-baselining, February 2013

18 Higgs Event Rates, Reduced ε x D. Schulte, CLIC Re-baselining, February L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s2,795 28,551 6,901 30,097 15,548 16,123 Scenario A: CLIC baseline Scenario A+: aim at n γ =const and ε x >660nm ε x >1200nm N/N 0 Note: scenario B remains unchanged A+ is not baseline but should present no problem In both cases 10% overhead in BDS energy

19 Early Extraction/Purpose-built Collider D. Schulte, CLIC Re-baselining, February 2013 Could extract beam at specific energies in the linac Could only built a linac for a specific energy -> Same performance, But different cost A*: scenario A A*+: with ε x =1200nm Higgs rate could be increased if strongly requested This would favour scenario A

20 Higgs Event Rates L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s795 7,839 2,178 9,108 8,910 9, L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s1,292 13,230 3,674 15,060 15,548 16,123 Scenario A Scenario B D. Schulte, CLIC Re-baselining, February 2013

21 Purpose-built Collider/Early Extraction Scenario A*Scenario B* Energy [GeV] N [10 9 ] nbnb F rep [Hz]50 ε x /ε y [nm]2400/25660/25 β x /β y [mm]8/0.1 σ x /σ y [nm]280/3.2237/2.7200/2.3147/3.2124/2.7104/2.3 σ z [μm]7244 L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s2,400 24,720 5,560 23,491 15,548 16,123 1,294 13,266 3,078 13,395 8,910 9,828 D. Schulte, CLIC Re-baselining, February 2013

22 Purpose-built Collider L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s1,294 13,266 3,078 13,395 8,910 9, L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s2,400 24,720 5,560 23,491 15,548 16,123 Scenario A Scenario B D. Schulte, CLIC Re-baselining, February 2013 Machine is built for the specified energy Charge, normalised emittances and beta- functions are the same as for 500GeV

23 Purpose-built Collider/Early Extraction II L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s3,514 36,510 8,256 36,894 23,569 27,824 Scenario A*+ Parameters are the same as before, except ε x =1200nm D. Schulte, CLIC Re-baselining, February 2013 Could also consider double repetition rate or use double pulsing, which could double the luminosity Need strong interaction with the physics group to understand the required optimisation Luminosity spectrum is compromised at 500GeV

24 Higgs Event Rates at High Energy Stages L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s37,840 5,214 95,250 4, ,850 2,714 Machine purpose- built for each energy D. Schulte, CLIC Re-baselining, February L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s31,042 3,383 95,250 4, ,850 2,714 Scenario B

25 High Energy Stages D. Schulte, CLIC Re-baselining, February (A)1500 (B)3000 L [10 34 cm -2 s -1 ] L 0.01 [10 34 cm -2 s -1 ] σ (e + e - ->ννH) [fb] σ (e + e - ->ZH) ) [fb] events per 10 7 s76,160 4,600 95,250 4, ,850 2,714 Higgs rates with CLIC baseline scenarios A and B Value at 1.5TeV is for B Value at 1.4TeV is for A