Energy deposition by radiation: the CERN experience with FLUKA WAMDO Workshop A.Ferrari, M.Magistris, A.Presland, M.Santana, A.Tsoulou,V.Vlachoudis CERN Tue 4/4/2006

2 The “FLUKA team” (AB-ATB-EET) 4 staff + 2 fellows Past and present tasks: n_TOF physics and engineering CNGS physics, engineering, optimization, radiation protection IR4 radiation damage and shielding Machine protection elements (TCDQ, TDI, TCDD) IR7 machine protection and damage to electronics Code development In this talk: Short introduction to FLUKA (mostly examples) An example relevant for cold magnets: IR7

3 Part I: FLUKA Authors: A. Fasso 1, A. Ferrari 2, J. Ranft 3, P.R. Sala 4 1 SLAC Stanford, 2 CERN, 3 Siegen University, 4 INFN Milan Interaction and Transport Monte Carlo code Web site:

4 FLUKA Description FLUKA is a general purpose tool for calculations of particle transport and interactions with matter, covering an extended range of applications spanning from proton and electron accelerator shielding to target design, calorimetry, activation, dosimetry, detector design, Accelerator Driven Systems, cosmic rays, neutrino physics, radiotherapy etc. 60 different particles + Heavy Ions Hadron-hadron and hadron-nucleus interaction TeV Electromagnetic and μ interactions 1 keV – TeV Nucleus-nucleus interaction TeV/n Charged particle transport – ionization energy loss, mcs, higher order processes Neutron multi-group transport and interactions 0-20 MeV interactions Transport in magnetic field Combinatorial (boolean) and Voxel geometry Double capability to run either fully analogue and/or biased calculations Maintained and developed under INFN-CERN agreement and copyright More than 1000 users all over the world

5 FLUKA – Hadronic Models Inelastic Nuclear Interactions Hadron-Nucleon 5 GeV - ≈100 TeVDual Parton Model (DPM)  ≈100 TeV DPMJET-III GeV Resonance production and decay model Hadron-Nucleus < 5 GeVPEANUT : Sophisticated Generalized Intranuclear Cascade (GINC) pre-equilibrium High EnergyGlauber-Gribov multiple interactions Coarser GINC Nucleus-Nucleus < 5 GeV/nmodified version of rQMD-2.4 High EnergyDPMJET-III All models: Evaporation / Fission / Fermi break-up / Fragmentation  -deexcitation of the residual nucleus Elastic Scatteringand Charge exchange Elastic Scattering and Charge exchange Phase shift based hadron-nucleon cross sections. Tabulated nucleon-nucleus cross sections

6 Nonelastic hA interactions at high energies: examples Rapidity distribution of charged particles produced in 250 GeV  + collisions on Aluminium Data from Agababyan et al., ZPC50, 361 (1991). Double diff distribution for  + production from 450 GeV/c p on Be H.W Atherton CERN SPY : PLB 425, 208 (1998)

7 Negative muons at floating altitudes: CAPRICE94 Open symbols: CAPRICE data Full symbols: FLUKA primary spectrum normalization ~AMS-BESS Astrop. Phys., Vol. 17, No. 4 (2002) p. 477

8 Hadron/muon fluxes in the atmosphere Hadron flux at sea level, KASKADE H. Kornmayer et al, JPG 21, 439 (1995). Tel Aviv horizontal muon flux: up to 10 TeV

9 Thin target examples p + 80 Zr  p + X (80 MeV)p + Al   - + X (4 GeV/c)

GeV/n fragmentation Fragment charge cross section for 158 AGeV Pb ions on various targets. Data (symbols) from NPA662, 207 (2000), NPA707, 513 (2002) (blue circles) and from C.Scheidenberger et al. PRC, in press (red squares), histos are FLUKA (with DPMJET-III) predictions: the dashed histo is the electromagnetic dissociation contribution

11 Cern Neutrino to Gran Sasso Engineering and physics: target heating, shielding, activation, beam monitors, neutrino spectra Energy dep. In CNGS target rods, GeV/cm 3 /pot Muons in muon pits: horizontal distribution for beam alignment

12 LHC Cleaning Insertions Two warm LHC insertions are dedicated to beam cleaning Collimation systems: IR3: Momentum cleaning IR7: Betatron cleaning Normal operation: 0.2 hours beam lifetime 4×10 11 p/s for 10 s Power = 448 kW Quench limit: 5 mW/cm 3

13 IR7: Overview Motivation Geometry and Simulation setup Studies: Collimator robustness  Accident scenarios Energy on the superconducting magnets  Active absorbers Dose on warm magnets  Passive absorbers Beam Loss Monitors  Signal in BLM’s as a function of the loss point Summary

14 IR7 Layout contains over 200 objects Warm section 2 Dispersion suppressors Collimators with variable positioning of the jaws  Challenging simulation work E6C6 IP7 A6 C6E6 UJ76 RR77 RR73 LHC optics files Top beam energy Primary collimators:6  Secondary collimators:7  Absorbers:10  IR7 layout

15 Geometry Implementation Dynamic FLUKA input generation with several ad-hoc scripts Detailed description of more than 20 prototypes Magnetic field maps: Analytic + 2D Interpolated Prototypes are replicated rotated and translated. Adjust the collimators planes during runtime! Dynamic generation of the ARC (curved section) Optics test: Tracking up to 5 , both vertical / horizontal, reproduce beta function. Central orbit reproduced to 1 μm after 1.5km

16 Warm magnets FLUKA geometry exported to PovRay, a RayTracer for creating three-dimensional graphs.

17 Cold magnets The superconducting dipoles (MB) are made out of 4 sections to account for the curvature of the real dipoles

18 Secondary collimators

19 IR7 Virtual Tour

20 Collimator robustness: C is the only viable choice TT40 test beam: energy deposition (J/cm 3 ) for GeV protons on the collimator prototype

21 Primary Inelastic collisions map Generated by the SIXTRACK program (AB-ABP) 3 scenarios: Vertical, Horizontal and Skew Pencil beam of 7 TeV low-beta beam on primary collimators Spread in the non-collimator plane: 200  m Recording the position and direction of the inelastic interactions FLUKA source: force an inelastic interaction on the previously recorded positions Beam Loss Map

22 Active Absorber Layout S=

23 Peak Power deposition in MQTLHA6

24 Current layout: horizontal losses A6v C6h E6v F6h A7h 60 cm long TCP jaws Tertiary halo W insert in active absorbers Passive absorbers for MBW’s and MQW’s protection

25 Current layout: vertical losses A6v C6h E6v F6h A7h 60 cm long TCP jaws Tertiary halo W insert in active absorbers Passive absorbers for MBW’s and MQW’s protection

26 Impact of the passive absorber on the most exposed MQW Most of the radiation passes through the beam pipe => The most important parameter is the inner radius. Constraint: 30 MGy over 10 years MGy per year

27 Simulation Accuracy Sources of errors: Physics modeling: Uncertainty in the inelastic p-A extrapolation cross section at 7 TeV lab (corresponding to √s = 115 GeV) Uncertainty in the modeling used  Factor ~1.3 on integral quantities like energy deposition (peak included) while for multi differential quantities the uncertainty can be much worse Layout and geometry assumptions It is difficult to quantify, experience has shown that a factor of 2 can be a safe limit Beam grazing at small angles on the surface of the collimators. Including that the surface roughness is not taken into account  A factor of 2 can be a safe choice. Safety factor from the SIXTRACK program is not included! In the case of the final focus quadrupoles: Uncertainty in the 7+7 TeV center-of-mass interactions (≈10000 TeV in the lab)  A factor of 1.4 can be a safe choice

28 Conclusions FLUKA: developed jointly by INFN and CERN for a variety of applications Show case: detailed description of the IR7 setup, with dynamic generation of all the necessary input files using the latest optics. Powerful tool used for various studies:  Energy deposition on Collimators, Warm Objects, Superconducting magnets  Si Damage calculations, Shielding studies for electronics  Ozone production… Results for IR7:  With 5 absorbers (3 in the straight section, one at the beginning of the arc) we are below the quench limit of 5 mW/cm 3 assuming a safety factor of 2-3.  3 passive absorbers are required in order to protect MBW’s and MQW’s

29 END