Introduction to Irradiation Facilities 1. Challenges at LHC and Why we need Irradiation Facilities...
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Transcript of Introduction to Irradiation Facilities 1. Challenges at LHC and Why we need Irradiation Facilities...
PH-DT Science-Techno Tea1
Introduction to Irradiation Facilities
1. Challenges at LHC and Why we need Irradiation Facilities (Mar CAPEANS)
2. PH Department Proton and Neutron Facilities (IRRAD, B.157) (M.GLASER)
3. PH Department Gamma Irradiation Facility (GIF, B.190) (R. FORTIN)
September 24, 2008
PH-DT Science-Techno Tea2
LHC Detectors’ Technological Challenges
September 24, 2008
Interactions 109 interactions Selection of ~100 events/s
Multiplicity Every 25 ns about 1000 tracks
cross and leave a print on the LHC detectors
Unprecedented Radiation levels
PH-DT Science-Techno Tea3
Radiation levels
September 24, 2008
Estimates: Simulation of number and momentum
spectra of particles arriving to detectors at LHC reference luminosities (and machine-induced backgrounds).
Get radiation dose maps, particle fluxes and energy spectra (photons, neutrons, charged particles).
With magnets on: They affect the low momentum particles
which may loop and hit some of the detectors many times.
With detector materials (location and quantity) as close as possible to reality.
Note that radiation simulation may be wrong by some factors and long-term effects may not be fully predictable.
Simulated radiation dose (Gy/s) map in CMSP.Bhat, A.Singh, N.Mokhov
Expected particle spectra in ATLAS Si-detector
A.Vasilescu, G.Lindstrom
PH-DT Science-Techno Tea4
Radiation field in LHC detectors(photons, charged particles, neutrons)
September 24, 2008
Dose(Gy/year)
Charged Hadrons (cm2/year)
Neutrons(cm2/year)
Pixel system 105 1014 1013
Calorimeters 10 1012 1013
Muon system 10-2 108 1010
Table of Doses in orders of magnitudeDifferent energy range for different
particlesNumbers vary depending on radial
and Z positions wrt to IP
PH-DT Science-Techno Tea5
Radiation Hard Components
September 24, 2008
We need to test the resistance to radiation of every detector and of every detector component: Detector/sensor performance Materials On-detector electronics Powering and data links Fluids (gas, cooling)
Radiation damage mechanisms and their effect differ for sensors, electronics, materials, optical fibres, etc. Inside a detector volume, we need to perform irradiation tests with different particles and energies.
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Radiation effects (Silicon sensors)
September 24, 2008
PH-DT Science-Techno Tea
Add Safety factors (x2, x5…) Radiation Hardness Tests
Expose detectors and components to very large particle rates to attain large doses in a very accelerated manner
Typical test lasts between days and weeks (time needed to achieve target dose)
Detector is powered and monitored; performance is tested before/after irradiation
Detector technology dependences:• For silicon, bulk radiation damage results from non-ionizing
energy loss (NIEL) displacements, so total neutral and charged particle fluence is normalized to flux of particles of fixed type and energy needed to produce the same amount of displacement damage, conventionally 1 MeV neutrons (1 MeV n/cm2/year)
• Scaling with the NIEL is considered reliable for most materials and particles
IMP. > This is not the whole story!
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Radiation effects (Gas detectors)
September 24, 2008
PH-DT Science-Techno Tea
Add Safety factors (x2, x5…) Radiation Hardness Tests
Expose detectors and components to very large particle rates to attain large doses in a accelerated manner
Good tests are done as slow as possible (months) and irradiating areas as large as possible
Detector performance is monitored during irradiation
Detector technology dependences:For gas detectors, we consider amount of charge deposited on electrodes due to avalanches (C/cm per unit time) as the relevant magnitude
IMP. > This is not the whole story!
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Gas detectors in the LHC
September 24, 2008PH-DT Science-Techno Tea
0 0.2 0.4 0.6 0.8 1 1.2
ATLAS TRT
LHCb GEM
ATLAS MDT
"LHCb OT Straws"
LHCb MWPC
CMS CSC
ALICE TPC
C/cm
Accumulated charge per LHC year in C/cm• 1 LHC year = 107 sec• Different safety factors• Calculated for detectors operating at nominal conditions
PH-DT Science-Techno Tea9
TRT Aging Test
September 24, 2008
OK
TRT in LHC Lab TestParticle rate Charged: 5x105
cm2/sNeutron: 3x106 cm2/sPhoton: 107 cm2/s
200 MHz X-rays(1 cm spot)
Gas Gain 2 x 104 2 x 104
Ionization Current Density (mA/cm)
0.1 1
Acceleration factor x10Collected charge per LHC year (C/cm)
12003, T.Akesson et al
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Irradiation Facilities
September 24, 2008PH-DT Science-Techno Tea
A Facility should provide: Broad range of (energies and) intensities of the
beam Monitoring of flux and dose Fast and uncomplicated experimental setup Transparent operating procedure User friendly data acquisition system
Facility with reproducible conditions, available to a large number of users and with user support/services
Specialized infrastructure for a small number of expert users
VS
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Irradiation Facilities at CERN
September 24, 2008PH-DT Science-Techno Tea
Facility
Particle Majority of Users Status Shortfalls
IRRAD Protons and mixed field
Silicon (tracking) detectorsElectronics
In useUpgrade being studied
Parasitic to DIRACLimited rate and spaceExposure of personnel
GIF Photons (+particle beam)
LHC Muon detectors In useUpgrade proposed (2010)
No particle beamLimited rateOld, shutdown in 2009
CERF Mixed field(p+,p,K+)
Dosimetry, FLUKA benchmarking, beam monitors
Used 1-2 weeks/year Limited dose rates
TCC2 Mixed field LHC accelerator components and electronics
Off (used 1998-2004)
ParasiticResidual dose (safety, access)
TT40 Short & intense pulses
LHC collimator studies Used in 2004 and 2006
Space, safetyInterference LHC & CNGS
Maurice
Richard
Next, urgent steps: adapt facilities to current R&D needs• Check discrepancies between LHC predictions and reality• Particle rates at SLHC ~ 10 x LHC (new technologies, longer tests,
more users, etc.)
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Key Messages
September 24, 2008
PH-DT Science-Techno Tea
Testing the effect of radiation on detector systems is fundamental for their correct design and operation, and specially for evaluating their lifetime in the experiments. This is a field of activities on its own!
Radiation dose maps are simulated. We need to add to same safety factors.
Damage in sensors (Si surface/bulk, gas detectors, etc), on- and off-detector electronics, etc. is due to different processes and depend on energy type and energy. Therefore, we need a spectra of particles and energies available.
Irradiation facilities should be user-friendly. Specially they must have a well characterized particle spectra to permit comparative studies.