M. Glaser 1 , S. Guatelli 2 , B. Mascialino 2 , M. Moll 1 , M.G. Pia 2 , F. Ravotti 1
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Transcript of M. Glaser 1 , S. Guatelli 2 , B. Mascialino 2 , M. Moll 1 , M.G. Pia 2 , F. Ravotti 1
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Simulation for LHC Radiation BackgroundSimulation for LHC Radiation Background
Optimisation of monitoring detectors Optimisation of monitoring detectors and experimental validationand experimental validation
M. Glaser1, S. Guatelli2, B. Mascialino2, M. Moll1, M.G. Pia2, F. Ravotti1
1CERN, Geneva, Switzerland2INFN Genova, Italy
IEEE Nuclear Science SymposiumSan Diego, CA
30 October – 4 November 2006
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Radiation monitoring at LHCRadiation monitoring at LHC
The effect of radiationeffect of radiation on installed equipment is a major issue major issue for for LHC experiments
Necessary to monitor radiation fieldsmonitor 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 issueCritical issue
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 Sensor CatalogueCatalogue
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 GroupSolid State Radiation Sensor GroupEvaluation of various radiation monitoring detectors
Optimisation Experimental measurements + simulation
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
RadFETs RadFETs PackagingPackaging
Commercial packagingCommercial packaging cannot satisfy all the
experiments requirements(size/materials)
DevelopmentDevelopment & studystudy
in-house at CERN
~10 mm2 36-pin Al2O3 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 Al2O3
X = 3-4 % X0
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 validationPackaging under validation• Type of materials• Thickness• Effects of lids
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Geant4 Radmon Geant4 Radmon SimulationSimulationStudy 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
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Study of packaging effectsStudy 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 validation2. Predictive evaluations in other conditions
No packaging With packaging With a ceramic or FR4 lid
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
GeometryGeometry
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
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
PhysicsPhysicsElectromagnetic 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 validationK. Amako et al., Comparison of Geant4 electromagnetic physics models against the NIST reference dataIEEE Trans. Nucl. Sci., Vol. 52, Issue 4, Aug. 2005, 910-918
Hadronic validationIn progress
See “Systematic validation of Geant4 electromagnetic and hadronic models against proton data” in NSS session N22
See other talks in N38
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Primary particle generationPrimary 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%
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Test beam at PSITest beam at PSI
Experimental data
Front incident p – No packagingFront incident p - 520 m Alumina lidFront incident p - 780 m Alumina lidFront 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 No significant effects observed with different packaging Geant4 simulation in agreement with experimental data: Geant4 simulation in agreement with experimental data:
Kolmogorov testKolmogorov test p-value = 0.416p-value = 0.416 for not observing any material/thickness dependencefor not observing any material/thickness dependence
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Complementary validation studiesComplementary 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
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Packaging +
ceramic front cover
Effects predicted at various proton Effects predicted at various proton energiesenergies
Al2O3 lid thickness (μm)
Ave
rage
ene
rgy
depo
sit (
MeV
)
Front incident p - Packaging + 520 m AluminaFront incident p - Packaging + 2340 m AluminaFront incident p - Packaging + 3000 m AluminaFront 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 lid254 MeV FR4 lid150 MeV Al2O3 lid 50 Mev Al203 lid
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Thresholds for Thresholds for radiation background radiation background detectiondetection
Ene
rgy
depo
sit p
er e
vent
(MeV
)
260 μm thick Al2O3 lid2.34 mm thick Al2O3 lid
Simulation
protons
Proton energy (MeV)
Simulation
Electron energy (keV)
Ene
rgy
depo
sit p
er e
vent
(eV)
electrons260 μm thick Al2O3 lid780 μm thick Al2O3 lid2.34 mm thick Al2O3 lid
+
260 μm thick Al2O3 lid2.34 mm thick Al2O3 lid
Pion+ energy (MeV)
Ene
rgy
depo
sit p
er e
vent
(MeV
)
Simulation
Work in progress Packaging
+ Ceramic
front cover
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
JSI TRIGA neutron reactor JSI TRIGA neutron reactor facilityfacility
Study the RadFET response to neutronsneutrons
– Evaluate the contamination from photons in the JSI test data
Photon energy spectrum
1.000E+08
1.000E+09
1.000E+10
1.000E+11
1.000E+12
1.000E+13
1.000E+14
1.000E+15
1.000E+16
1.000E+17
1.000E+18
1.000E-06 1.000E-05 1.000E-04 1.000E-03 1.000E-02 1.000E-01 1.000E+00 1.000E+01
Energy (MeV)
d(flu
x)/dE
[n /
MeV
cm
2 s
]
Neutron energy spectrum
Energy (MeV)
d(flu
x) /
dE [n
/ M
eV c
m2
s]
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
Preliminary Preliminary resultsresults
260 μm thick Al2O3 lid2.34 mm thick Al2O3 lid
photons
Ave
rage
ene
rgy
depo
sit (
eV)
Al2O3 thickness (m)
Work in progress
Quantitative analysis
RadFET calibration vs. experimental data
Experimental data
Packaging +
Ceramic front cover
Ave
rage
ene
rgy
depo
sit (
eV)
neutrons
Al2O3 thickness (m)
M. Glaser, G. Guatelli, B. Mascialino, M. Moll, M.G. Pia, F. Ravotti
ConclusionConclusionRadiation 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