1. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Simulation for LHC Radiation Background Optimisation of monitoring detectors and experimental validation Simulation for LHC Radiation Background Optimisation of monitoring detectors and experimental validation M. Glaser 1, S. Guatelli 2, B. Mascialino 2, M. Moll 1, M.G. Pia 2, F. Ravotti 1 1 CERN, Geneva, Switzerland 2 INFN Genova, Italy IEEE Nuclear Science Symposium San Diego, CA 30 October – 4 November 2006

2. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Radiation monitoring at LHC effect of radiationmajor issue for The effect of radiation on installed equipment is a major issue for LHC experiments monitor radiation fields Necessary to monitor radiation fields during early LHC commissioning –to prepare for high intensity running –to prepare appropriate shielding or other measures A lot of work is in progress to ensure that radiation effects do not make LHC commissioning even more difficult than expected A radiation monitoring system adapted to the needs of radiation tolerance understanding from the first day of LHC operation Critical issue

3. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti www.cern.ch/lhc-expt-radmon/ Sensors suitable for dosimetry in LHC experimental environment Mixed-LET radiation field ~5 orders of magnitude in intensity Many devices tested, only a few selected Sensor Catalogue 2 x RadFETs (TID)[REM, UK and LAAS, France] 2 x p-i-n diodes (1-MeV eq )[CMRP, AU and OSRAM BPW34] 1 x Silicon detectors (1-MeV eq )[CERN RD-50 Mask] Solid State Radiation Sensor Group Evaluation of various radiation monitoring detectors Optimisation Experimental measurements + simulation

4. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti RadFETs Packaging Commercial packaging Commercial packaging cannot satisfy all the experiments requirements (size/materials) Developmentstudy Development & study in-house at CERN ~10 mm 2 36-pin Al 2 O 3 chip carrier 1.8 mm High integration level up to 10 devices covering from mGy to kGy dose range Customizable internal layout Standard external connectivity Radiation Transport Characteristics 0.4 mm Al 2 O 3 X = 3-4 % X 0 e cut-off 550 KeV p cut-off 10 MeV photons transmission 20 KeV n attenuation 2-3 % The configuration of the packaging of the sensors can modify the chip response, inducing possible errors in the measurements Packaging under validation Type of materials Thickness Effects of lids

5. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Geant4 Radmon Simulation Study the effects of different packaging configurations –Energy cut-off introduced by the packaging as a function of particle type and energy –How materials and thickness affect the cut-off thresholds –Spectrum of particles (primary and secondary) hitting the dosimeter volume Exploit Geant4 functionality –Realistic detector modeling –Selection of physics models Rigorous software process –In support of the quality of the software results for a critical application Validation of the simulation –Experimental data: proton beam at PSI, Switzerland –Experimental data: neutrons (Ljubljana TRIGA reactor), in progress Radmon Team (CERN PH/DT2 + TS/LEA) and Geant4 Advanced Examples Working Group

6. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Study of packaging effects Experimental test –254 MeV proton beam –Various configurations: with/without packaging, different covers –Measurement: dose in the 4 chips Simulation 1.Same set-up as in the experimental test: for validation 2.Predictive evaluations in other conditions No packagingWith packagingWith a ceramic or FR4 lid

7. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Geometry LAAS REM-TOT-500 Packaging The full geometry has been designed and implemented in detail in the Geant4 simulation Geant4 offers advanced functionality to model the detector geometry precisely

8. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Rigorous software process

9. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Physics Electromagnetic physics –Low Energy-Livermore processes for electrons and photons –Standard model processes for positron –Low Energy ICRU 49 parameterisation for proton & ion ionisation –Multiple scattering for all charged particles –Secondary particle production threshold = 1 mm Hadronic interactions –Neutrons, protons and pions Elastic scattering Inelastic scattering Nuclear de-excitation Precompound model Binary Cascade model up to E = 10 GeV LEP model between 8 GeV and 25 GeV QGS model between 20 GeV and 100 TeV Neutron fission and capture – particles Elastic scattering Inelastic scattering with Tripathi, IonShen cross sections BinaryIonModel between 80 MeV and 10 GeV LEAlphaIneslatic model Decay Electromagnetic validation K. Amako et al., Comparison of Geant4 electromagnetic physics models against the NIST reference data IEEE Trans. Nucl. Sci., Vol. 52, Issue 4, Aug. 2005, 910-918 Hadronic validation In progress See Systematic validation of Geant4 electromagnetic and hadronic models against proton data in NSS session N22 See other talks in N38

10. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Primary particle generation Monocromatic particle beam –Protons: 254 MeV (experimental) 150 MeV 50 MeV –Other particles, variable energy Energy spectrum –Reactor neutron spectrum –Photon background spectrum at Ljubljana TRIGA reactor Geometrical acceptance 7%

11. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Test beam at PSI Experimental data Front incident p – No packaging Front incident p - 520 m Alumina lid Front incident p - 780 m Alumina lid Front incident p - 2340 m Alumina lid 254 MeV p Average energy deposit (MeV) 254 MeV protons Front/back illumination Various materials and thicknesses Measurement: dose No significant effects observed with different packaging Geant4 simulation in agreement with experimental data: Kolmogorov test p-value = 0.416 for not observing any material/thickness dependence

12. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Complementary validation studies Systematic validation of Geant4 electromagnetic physics –Amako, S. Guatelli, V. Ivanchenko, M. Maire, B. Mascialino, K. Murakami, L. Pandola, S. Parlati, M. G. Pia, M. Piergentili, T. Sasaki, L. Urban, Validation of Geant4 electromagnetic physics versus the NIST databases, IEEE Trans. Nucl. Sci. 52-4 (2005) 910-918 Validation of the proton Bragg peak –Reference data from CATANA (INFN-LNS Hadrontherapy Group) –Systematic and quantitative validation of Geant4 electromagnetic and hadronic physics And others in progress

13. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Packaging + ceramic front cover Effects predicted at various proton energies Al2O3 lid thickness (μm) Average energy deposit (MeV) Front incident p - Packaging + 520 m Alumina Front incident p - Packaging + 2340 m Alumina Front incident p - Packaging + 3000 m Alumina Front incident p - Packaging + 4000 m Alumina Average energy deposit (MeV) 50 MeV p Predictive power of the simulation to investigate the effects of the packaging at various proton energies Study the effect for 50 MeV, 150 MeV protons Study of the effect of the front lid Visible effects at low energy 254 MeV Al203 lid 254 MeV FR4 lid 150 MeV Al2O3 lid 50 Mev Al203 lid

14. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Thresholds for radiation background detection Energy deposit per event (MeV) 260 μm thick Al 2 O 3 lid 2.34 mm thick Al 2 O 3 lid Simulation protons Proton energy (MeV) Simulation Electron energy (keV) Energy deposit per event (eV) electrons 260 μm thick Al 2 O 3 lid 780 μm thick Al 2 O 3 lid 2.34 mm thick Al 2 O 3 lid + 260 μm thick Al 2 O 3 lid 2.34 mm thick Al 2 O 3 lid Pion+ energy (MeV) Energy deposit per event (MeV) Simulation Work in progress Packaging + Ceramic front cover

15. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti JSI TRIGA neutron reactor facility neutrons Study the RadFET response to neutrons –Evaluate the contamination from photons in the JSI test data Photon energy spectrum Neutron energy spectrum Energy (MeV) d(flux) / dE [n / MeV cm2 s]

16. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Preliminary results 260 μm thick Al 2 O 3 lid 2.34 mm thick Al 2 O 3 lid photons Average energy deposit (eV) Al2O3 thickness ( m) Work in progress Quantitative analysis RadFET calibration vs. experimental data Experimental data Packaging + Ceramic front cover Average energy deposit (eV) neutrons Al2O3 thickness ( m)

17. M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti Conclusion Radiation monitoring is a crucial task for LHC commissioning and operation Optimisation of radiation monitor sensors in progress –packaging is an essential feature to be finalized Geant4 simulation for the optimisation of radiation monitor packaging –full geometry implemented in detail –physics selection based on sound validation arguments –direct experimental validation against test beam data First results: proton data –packaging configurations: materials, thicknesses –predictive power of the simulations: effects visible at low energy Work in progress: neutron data –first results available, further in depth studies to verify experimental effects Evaluation of particle detection thresholds –Predictive power of the Geant4 simulation tool