Simulation for LHC Radiation Background Optimisation of monitoring

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 M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Radiation monitoring at LHC The effect of radiation on installed equipment is a major issue for LHC experiments 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 Critical issue A radiation monitoring system adapted to the needs of radiation tolerance understanding from the first day of LHC operation M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Solid State Radiation Sensor Group Evaluation of various radiation monitoring detectors Optimisation Experimental measurements + simulation www. cern. ch/lhc-expt-radmon/ Sensor Catalogue 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 2 x Rad. FETs (TID) [REM, UK and LAAS, France] 2 x p-i-n diodes (1 -Me. V Feq) [CMRP, AU and OSRAM BPW 34] 1 x Silicon detectors (1 -Me. V Feq) [CERN RD-50 Mask] M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Rad. FETs Packaging The configuration of the packaging of the sensors can modify the chip response, inducing possible errors in the measurements Commercial packaging cannot satisfy all the experiments requirements (size/materials) Development & study in-house at CERN 1. 8 mm § High integration level ~10 mm 2 36 -pin Al 2 O 3 chip carrier up to 10 devices covering from m. Gy to k. Gy dose range § Customizable internal layout § Standard external connectivity Packaging under validation • Type of materials • Thickness • Effects of lids M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti Radiation Transport Characteristics 0. 4 mm Al 2 O 3 § X = 3 -4 % X 0 § e cut-off 550 Ke. V § p cut-off 10 Me. V § photons transmission 20 Ke. V § n attenuation 2 -3 %

Geant 4 Radmon Simulation Radmon Team (CERN PH/DT 2 + TS/LEA) and Geant 4 Advanced Examples Working Group 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 Geant 4 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 M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Study of packaging effects Experimental test – 254 Me. V 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 packaging With packaging M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti With a ceramic or FR 4 lid

Geometry Geant 4 offers advanced functionality to model the detector geometry precisely The full geometry has been designed and implemented in detail in the Geant 4 simulation Packaging REM-TOT-500 LAAS M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

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

Physics Electromagnetic validation K. Amako et al. , Comparison of Geant 4 electromagnetic physics models against the NIST reference data IEEE Trans. Nucl. Sci. , Vol. 52, Issue 4, Aug. 2005, 910 -918 Electromagnetic physics – – – Hadronic interactions – In progress See other talks in N 38 Neutrons, protons and pions § Elastic scattering § Inelastic scattering • Nuclear de-excitation • Precompound model • Binary Cascade model up to E = 10 Ge. V • LEP model between 8 Ge. V and 25 Ge. V • QGS model between 20 Ge. V and 100 Te. V • Neutron fission and capture Hadronic validation See “Systematic validation of Geant 4 electromagnetic and hadronic models against proton data” in NSS session N 22 Low Energy-Livermore processes for electrons and photons Standard model processes for positron Low Energy ICRU 49 parameterisation for proton & ionisation Multiple scattering for all charged particles Secondary particle production threshold = 1 mm – a particles § Elastic scattering § Inelastic scattering with Tripathi, Ion. Shen cross sections • Binary. Ion. Model between 80 Me. V and 10 Ge. V • LEAlpha. Ineslatic model Decay M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

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

Test beam at PSI 254 Me. V protons Front/back illumination Various materials and thicknesses Measurement: dose Front incident p – No packaging Front incident p - 520 mm Alumina lid Front incident p - 780 mm Alumina lid Front incident p - 2340 mm Alumina lid 254 Me. V p Experimental data Average energy deposit (Me. V) No significant effects observed with different packaging Geant 4 simulation in agreement with experimental data: M. Glaser, G. Guatelli, B. Mascialino, M. Moll, Pia, F. for not observing any material/thickness dependence Kolmogorov test p-value =M. G. 0. 416 Ravotti

Complementary validation studies Systematic validation of Geant 4 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 Geant 4 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 Geant 4 electromagnetic and hadronic physics And others in progress M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Effects predicted at various proton energies Predictive power of the simulation to investigate the effects of the packaging at various proton energies Study the effect for 50 Me. V, 150 Me. V protons Study of the effect of the front lid 50 Me. V p Average energy deposit (Me. V) Front incident p - Packaging + 520 mm Alumina Front incident p - Packaging + 2340 mm Alumina Front incident p - Packaging + 3000 mm Alumina Front incident p - Packaging + 4000 mm Alumina 254 Me. V 150 Me. V 50 Mev Packaging + ceramic front cover Al 203 lid FR 4 lid Al 2 O 3 lid Al 203 lid Visible effects at low energy Average energy deposit (Me. V) M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti Al 2 O 3 lid thickness (μm)

Packaging + Ceramic front cover Work in progress Energy deposit per event (Me. V) Thresholds for radiation background detection Simulation protons 260 μm thick Al 2 O 3 lid 2. 34 mm thick Al 2 O 3 lid electrons Simulation 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 M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Electron energy (ke. V) Ravotti Simulation Energy deposit per event (Me. V) Energy deposit per event (e. V) Proton energy (Me. V) p+ 260 μm thick Al 2 O 3 lid 2. 34 mm thick Al 2 O 3 lid Pion+ energy (Me. V)

JSI TRIGA neutron reactor facility Photon energy spectrum Study the Rad. FET response to neutrons – Evaluate the contamination from photons in the JSI test data d(flux) / d. E [n / Me. V cm 2 s] Neutron energy spectrum Energy (Me. V) M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti

Preliminary results Average energy deposit (e. V) Packaging + Ceramic front cover neutro ns 260 μm thick Al 2 O 3 lid 2. 34 mm thick Al 2 O 3 lid Al 2 O 3 thickness (mm) Rad. FET calibration vs. experimental data Work in progress Quantitative analysis M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti Average energy deposit (e. V) Experimental data photons Al 2 O 3 thickness (mm)

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 Geant 4 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 Geant 4 simulation tool M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M. G. Pia, F. Ravotti