CLIC Post-Collision Line and Dump Edda Gschwendtner, CERN for the CLIC Post-Collision Line and Dumps WG

Outline Introduction Background Calculations to the IP Magnet Lifetime 2 2 Outline Introduction Background Calculations to the IP Magnet Lifetime Main Beam Dump Luminosity Monitoring Summary Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

post-collision line Post-Collision Line Beam dump detector beam1 beam2 20mrad detector beam1 beam2 Beam dump post-collision line Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Some Numbers 50 Hz repetition rate 156ns bunch train length 4 4 Some Numbers 50 Hz repetition rate 156ns bunch train length 3.7E9 e/bunch 312 bunches/pulse 14MW beam power e+e- collision creates disrupted beam Huge energy spread, large x,y div in outgoing beam  total power of ~10MW High power divergent beamstrahlung photons 2.2 photons/incoming e+e-  2.5 E12 photons/bunch train  total power of ~4MW Coherent e+e- pairs 5E8 e+e- pairs/bunchX 170kW opposite charge Incoherent e+e- pairs 4.4E5 e+e- pairs/bunchX  78 W Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Purpose of the Post-Collision Line 1 - transport spent beam safely to dump Transport of all charged particles (disrupted beam, e+ e- pairs) as well as beamstrahlung photons to dump Transport non-colliding particles to dump Controlled beam losses in magnetic elements and collimators, with a minimal flux of backscattered particles at the interaction point 2 – implement beam based diagnostics Monitor quality of collisions and luminosity for tuning purposes Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Design Considerations Long drift section required to allow expansion of the beam before hitting the dump. Based upon the characteristics of the disrupted/undisrupted beam and requirements from the exit window and dump Focusing of post-collision beam using quadrupoles not possible  long low energy tail overfocusing would lead to large energy losses Separate the charged particles from bremsstrahlung photons luminosity monitoring  Vertical chicane Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Baseline Design side view 7 7 Baseline Design A. Ferrari, R. Appleby, M.D. Salt, V. Ziemann, PRST-AB 12, 021001 (2009) intermediate dump side view 27.5m 67m 1.5m C-shape magnets window-frame magnets carbon based absorbers ILC style water dump 4m 315m 6m 5 window-frame dipoles and 4 C-shaped dipoles Absorbers and an intermediate dump To reduce beam losses in the magnets Possible background sources: Backscattered photons and neutrons from dump and along post-collision line Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Background Calculations Lawrence Deacon Some changes/improvements done to the BDSIM model of the post-collision line Thickness of elliptical beam pipes between the first 4 magnets An accurate model of the beam pipe after the intermediate dump. complicated shape. Main beam dump filled up with water was 10m thick. These were unrealistic would have shielded the detector from back scattered particles. These have been replaced with beam pipe of the correct thickness. Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Photon Background at IP Lawrence Deacon Per bunch crossing, within a 12x12m2 square plane 3.5m from the IP Input particles Flux [cm-2] <E> [keV] Disrupted beam 7.5± 1.1 360 Beamstrahlung photons <0.5 Coherent pairs – wrong sign 8.4± 0.9 230 Coherent pairs – right sign 6.1± 0.6 300 All 22+3.1-2.6 Per bunch crossing, within a 2x2m2 square plane 3.5m from the IP: All: 72 +46 -18 Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Neutron Background Lawrence Deacon Per bunch crossing, within a 12x12m2 square plane 3.5m from the IP Input particles Flux [cm-2] <E> [keV] Disrupted beam 1.6± 0.5 950 Beamstrahlung photons <0.5 Coherent pairs – wrong sign 1.6± 0.4 350 Coherent pairs – right sign 0.7± 0.2 390 All 3.9+1.6-1.1 Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Origin of Backscattered Photons Lawrence Deacon intermediate dump 27.5m 67m C-shape magnets window-frame magnets 315m Position of last scatter of backscattered photons Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Background Calculations to IP Preliminary results show that background particles at ‘outer edge’ of the LCD is low. The detector yoke and calorimeter will further shield the vertex and tracker against hits from background photons. Even if additional absorbers are needed, space is available in the forward region between the detector (6m) and the first post-collision line magnet (27m) . QD0 Kicker BPM Spent beam Beamcal Lumical N.Siegrist, H.Gerwig Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Energy Deposition in Beam-line Components Lawrence Deacon Magnets 2-4 Masks Int. dump 5-8 1a and 1b Mask 1 Most magnets exceed 100W/m, many exceed kW/m As much energy lost in magnets as masks Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Impact on Magnet Lifetime Lawrence Deacon, Michele Modena Magnet lifetime limited by radiation damage to the coil insulation material. Assume that conventional magnet coils (e.g. Cu insulated with epoxy impregnated fibre glass) can withstand 1E7 Gy. Worst case: Magnet 5  ~6kW. Mass is 6.9E4 kg, so it's dose rate is 8.7E-2 Gy/s. Assuming a homogenous magnet and uniform particle distribution, the magnet lifetime would be only ~4 years.  changes to Post-Collision Line Simulation: Change material of absorbers for magnets 1-4 from graphite to iron Lengthening the intermediate dump with 2 more metres of iron  Assessment on specific CLIC radiation issues necessary Robust coil fabrication technology for doses up to 1010 – 1011 Gy. Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Results for Magnet Lifetime Lawrence Deacon intermediate dump side view 27.5m C-shape magnets window-frame magnets carbon based absorbers ILC style water dump 1a 1b 2 3 4 5 6 7 8 Magnet coil Lifetime [year] - v1 Lifetime [year] - v2 1a + 1b 2500 200 2 5.7 36 3 1.2 7.6 4 8.4 5 11 26 6 13 20 7 19 33 8 170 230 Preliminary results Simulations ongoing Components downstream final dump were omitted Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Main Beam Dump side view disrupted beam Right sign coherent beam beamstrahlung photons disrupted beam + right sign coherent pairs 1.5 TeV 300 GeV 90cm side view 210m to IP: 105m ILC type water dump Right sign coherent beam Beamstrahlung photons Disrupted beam Collided 1.5TeV Beam at water dump 315m from IP Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011 16

Luminosity Monitoring Armen Apyan m+m- pair production Main dump as converter muons  install detector behind dump  perform simulations of expected muon signals at different beam collision parameters  See Armen’s talk Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

30.0 cm diameter window (Ti) Main Beam Dump Alessio Mereghetti Uncollided Beam Parameters CLIC ILC TESLA e- beam energy [GeV] 1500 500 250 e- per bunch [109] 3.72 20 bunches per bunch train 312 2820 bunch energy [MJ] 0.28 4.51 2.26 frequency [Hz] 50 4 5 beam power [MW] 13.9 18.0 11.3 sx [mm] 1.79 2.42 0.35 sy 3.15 0.27 0.5 Area1s = psxsy [mm2] 17.76 2.05 0.55 ILC 18 MW water dump Cylindrical vessel Volume: 18m3, Length: 10m Diameter of 1.8m Water pressure at 10bar (boils at 180C) Ti-window, 1mm thick, 30cm diameter  baseline for CLIC 2011 main dump Length 10.0 m Diameter 1.5 m 30.0 cm diameter window (Ti) 1.0 mm thick 15.0 mm thick Ti vessel Dump axis ILC type water dump Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Energy Deposition in Main Beam Dump Alessio Mereghetti ILC: 240 J cm-3 /bunch train (6 cm of beam sweep); TESLA: ~20 kJ cm-3 / bunch train; 230 J cm-3 per bunch train Dr=2.5 mm; Df=6.0 deg; Dz=20.0 mm; Dx=0.45 mm; Dy=0.78 mm; Dz=20.0 mm; Dr=2.5 mm; Df=6.0 deg; Dz=20.0 mm; ~40 kW cm-1 ILC: 54 kW cm-1; TESLA: 32 kW cm-1; Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Activation of Materials Alessio Mereghetti Rate of production of radio-nuclides for un-collided beam (stable nuclides are not shown – collided beam: ~3% lower values): Main species in H2O: t½ R [s-1] 3H 12.3 y 3.12 1014 7Be 53.6 d 1.14 1014 11C 20 m 3.39 1014 13N 10 m 5.51 1013 15O 2 m 1.19 1015 In the TESLA report, the production rates for 3H and 7Be are expected to be roughly a half of the present values. Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Water - Thermodynamic Transient Cesare Maglioni Instantaneous p rise (kPa due to 1 bunch train) – whole dump, fast-transient analysis Beam energy : 1.5 TeV 3.72E9 e-/bunch dynamic pressure wave, estimated at 5-7 bar at walls (static bath, pin ~ 2-2.5 bar)  Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Window Thermo-Mechanics Cesare Maglioni With such a simplified preliminary design, the window cannot withstand the hydrostatic pressure (10bar) + dynamic wave : only energy deposition analysis 1 bunch-train Temperature rise Steady-State Temperature rise (multi bunch-trains) Temperature rise per 1 pulse: DT=1.44°C Stable temperature after 3-4 sec with DT=24°C Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Considerations & Next Steps Cesare Maglioni Min Water flow = 30 l/s, nominal is 60 l/s, @ v =1.5m/s, Tin = 22°C TH2O,boil = 180°C @ 10bar  drive the choice of the hydraulics of the primary water loop, to be designed for high turbulence, mainly radial water flow and heat evacuation (orthogonal heat flux = 14MW/ps2) If no water circulation is active (failure), water boils after few pulses Energy density peak is at E=230 J/cm3/bunch train. The instantaneous T rise is 55°C. The interlock system must be as fast as 3 bunch trains. The dynamic pressure wave inside the bath, estimated at 5-7bar at walls (in the case of a static bath) has to be taken into account for dimensioning the water tank, beam window, etc..  Hydrodynamic effects due to water flow have to be further analysed. Of help : stiffeners on tank and window, sweeping system, shock absorber / diluter (gas bubbles?  this requires a detailed analysis and dedicated CFD simulations). A steel / copper plate internal to the water bath, near to the end of it, and cooled by water directly, helps absorbing the tail of the beam. Dump window  needs special care, detailed study and the design of a maintenance system Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Summary Many new results achieved since last year Next steps 24 Summary Many new results achieved since last year Background calculations to the IP Magnet life-time estimates Thermo-dynamical results on the beam dump and dump window Muon monitoring for luminosity measurement Next steps Continue work on these issues to come up with a more detailled design Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

SPARE SLIDES Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Post-Collision Line Magnets 26 Post-Collision Line Magnets Designed considerations: average current density in copper conductor < 5 A/mm2. magnetic flux density in magnet core is < 1.5 T. temperature rise of cooling water < 20° K. Dipole names Magnetic length Full magnet aperture horiz. / vert. [m] Full magnet dimensions Power consumption Mag1a1b 2m 0.22 / 0.57 1.0 / 1.48 65 kW Mag2 4m 0.30 / 0.84 1.12 / 1.85 162.2 kW Mag3 0.37 / 1.16 1.15 / 2.26 211 kW Mag4 0.44 / 1.53 1.34 / 2.84 271 kW MagC-type 0.45 / 0.75 1.92 / 1.85 254 kW  All magnets strength of 0.8 T  In total 18 magnets of 5 different types Total consumption is 3.3MW M. Modena, A. Vorozhtsov, TE-MSC Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Magnets C-type Mag1a (window frame type) incoming beam 54.1cm 49 cm 27 Magnets C-type Mag1a (window frame type) incoming beam 54.1cm 40.8 cm 49 cm 34.3cm 20.1cm 5.1cm 11.1cm Mag4 Mag3 Mag2 spent beam Inter- mediate dump Mag1a Mag1b C- type 27.5m 30.5m 38m 46m 54m 67m 75m Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Main Dump 1966: SLAC beam dump 2000: TESLA 28 28 Main Dump 1966: SLAC beam dump 2.2 MW average beam power capacity Power absorption medium is water 2000: TESLA 12 MW beam power capacity Water dump 1.Radiation damage to the window material for long-term exposure to beam current. 2. Water quality. Particular attention should be given to chlorides in water, since they are a major factor in initiating stress corrosion cracking in stainless steel. 3. The radiolytically evolved hydrogen and oxygen can readily be recombined by a catalytic H2-O2 recombiner of modest size, using existing technology. Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

More Detailed View of Main Beam Dump An internal (closed) water loop => heat dilution Vortexes, turbulence, 30 An external water cooling system => heat removal Safety confinement Dump window Dump shielding Water bath Vessel Internal primary water loop External secondary Water cooling system beam 10bar HE Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Collided CLIC Beam at Main Dump Alessio Mereghetti Collided CLIC Beam at Main Dump Distribution of secondary particles generated by the GUINEA-PIG code and transported up to the dump entrance via the DIMAD code (M. Salt). Collided electrons Coherent electrons Photons Window Dump IP-dump distance: 315 m; Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Energy Deposition in CLIC Beam Dump Window 31 31 Energy Deposition in CLIC Beam Dump Window Titanium window: 1mm thick, 30cm diameter, cooling on internal surface by dump water at 180°C  Total deposited Power: ~6.3W max ≈ 4.3 J/cm3 uncollided beam collided beam max ≈ 0.13 J/cm3 uncollided beam collided beam A. Mereghetti, EN-STI Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Assumptions Cesare Maglioni Thermodynamic estimates – some easy numbers to get the feeling : Input punctual values from FLUKA analysis Symmetric un-disrupted beam adsorption (worst case) (Static) water bath Thermodynamic Transient – preliminary simulations Energy Density map from FLUKA analysis Static water bath : meaningful of what may happen in case of major issues with the cooling / circulating system Thermo Mechanics of the (simplified) dump window Simplified geometry (circular ᴓ30cm, flat, Ti-6Al-4V), perfect convection Only Energy Deposition analysis. Energy Density map from FLUKA Symmetric un-disrupted beam adsorption (worst case ?) Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Thermodynamic Estimates Average Power deposited P = 14MW  mass flow : = 60 l/s to keep reasonable DT (50°C) = 25 l/s not to reach boiling point (180°C) Energy Density Peak E* = 230 J/cm3/bunch train  Peak Instantaneous T rise ~ 55 °C interlock system as fast as 3 bunch trains (DT < 180°C) rapid intervention of safety system and valves  Peak Instantaneous p wave~ 560 bar Proportional to initial pressure pi = 10 bar : With exponential (radial) decay  6 – 7 bar at walls Risk of cavitation Edda Gschwendtner, CERN LCWS11, Granada, 26-30 Sept 2011

Considerations & Next Steps Component Issues Possible Solution 1 Window design Stresses due to : Dynamic pressure wave hydrostatic pressure beam heating Choice of material Sweeping system Stiffeners Multiple window design Additional water-jet cooling Low pressure water and free surface 2 Tank integrity Shock Absorbers / gas bubbles 3 Water circuit ... 5 Maintenance Periodical window replacement Management of radionuclides and radiolysis products Remote handling System Automated window exchange system Local, separated storage of water 6 Safety Containment of activated water in case of accident Water tight dump enclosure Safety enclosure + basin Pre-window on beam pipe Interlock and safety system for nuclear pressurized vessel C. Maglioni CLIC Water Dump Thermo-Mechanical Analysis - September 7, 2018 34