EB Meeting, 9th of February 2001M.Bosman / IFAE-Barcelona 3 Comparison of Shower Simulation Packages with Identical Simplified ATLAS Geometry Reviewed by I.Dawson MOTIVATION Compare FLUKA and G3-CALOR predictions for an “ATLAS-like” environment - identical Geometry/Material descriptions - same p-p event sample and see where there is agreement/disagreement + understand origin + find eventual problems Use as input for assigning safety-factors ? - weighted by significance of “Benchmarking” ? - include FermiLab-MARS into study ?
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EB Meeting, 9th of Febru ary 2001 M.Bosman / IFAE-Barcelona 1 Report on Radiation Task Force Progress Members: M. Bosman (chair), I. Dawson, M. Huhtinen, S. Loyd, P. Norton, M. Shupe, I. Štekl, G. Stevenson, W. Witzeling, ATLAS Management (ex off.), Physics Coordinator (ex off.) Contact persons : M.Dentan, D.Fournier, M.Nessi, L.Nisati, G. Mikenberg, S.Stapness, H.Ten Kate Activities: • First meeting on 28th of september 2000 • Second meeting on 30th of january 2001 Event generator Particle transport Geometry and material Impact on detector elements Work plan
Transcript
EB Meeting, 9th of February 2001 M.Bosman / IFAE-Barcelona 1
Report on Radiation Task Force ProgressMembers: M. Bosman (chair), I. Dawson, M. Huhtinen, S. Loyd, P. Norton,
M. Shupe, I. Štekl, G. Stevenson, W. Witzeling, ATLAS Management (ex off.), Physics Coordinator (ex off.)
Contact persons : M.Dentan, D.Fournier, M.Nessi, L.Nisati, G. Mikenberg, S.Stapness, H.Ten Kate
Activities: • First meeting on 28th of september 2000
• Second meeting on 30th of january 2001
Event generator Particle transport Geometry and material Impact on detector elements Work plan
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Outline of the meeting
Review of the three elements in radiation calculations • Shower parameterization
- Comparison of different programs on identical simple geometries: FLUKA, G3-CALOR
- Benchmarking on experimental data/other programs• Geometry/Material composition
- Document/update description with system inputs - Check how critical geometry description is some regions: gap,
toroid ... Upgrade to necessary level - Optimization of shielding
• Event generator - comparison of different generators
and
• Review of requests for radiation information • Status of activation studies
EB Meeting, 9th of February 2001 M.Bosman / IFAE-Barcelona 3
Comparison of Shower Simulation Packageswith Identical Simplified ATLAS Geometry
Reviewed by I.DawsonMOTIVATION• Compare FLUKA and G3-CALOR predictions
for an “ATLAS-like” environment
- identical Geometry/Material descriptions- same p-p event sample
and see where there is agreement/disagreement + understand origin + find eventual problems
• Use as input for assigning safety-factors ?
- weighted by significance of “Benchmarking” ?- include FermiLab-MARS into study ?
EB Meeting, 9th of February 2001 M.Bosman / IFAE-Barcelona 4
Comparison of Shower Simulation Packageswith Identical Simplified ATLAS Geometry
• Results so far for Iron (Fe with 3.5% C) and Copper (pure Cu)
- Neutrons and Photons- Compare fluxes:
- in front of calos: < 1.2 (Fe), > 0.9 (Cu)(numbers = ratio G3CALOR/FLUKA)
- in front of calos: < 1.1 (Fe), < 1.1 (Cu)- behind calos & Mu-Chambers (Fe):
0.4-2 (p), 0.7-4. (, )
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Comparison of Shower Simulation Packageswith Identical Simplified ATLAS Geometry
• Problem of K0’s: more KL than at outer calo surface!KL fly through calorimeter in G3-CALOR: all kaon transport done by G3-FLUKA (same problem as FLUKA)- FLUKA updated for K0 transport by A.Ferrari- G3-CALOR?
- FLUKA fix applicable to G3-FLUKA ??- use GHEISHA for K0 transport ??- understand if KL contribute still crucially after the “correction”,
uncertainty on K0 transport • Future plans include: Adjust density of calorimeter material to
reproduce # of int
- Understand origin of differences for the various species(weight effort as a function of importance for background)
- look at pure Fe, cladding, ...
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Benchmarking of Shower Simulation packages
Experimental Data:• Benchmarking of Atlas hall background measuring neutron/photon fluxes (BGO) behind Fe absorber• RD5: punch-through of ,muons behind Fe absorber• Punchthrough in Lar+Tilecal prototype
Comparison between Particle Transport Packages: FLUKA(Ferrari) / G-CALOR / G-CALOR+GAMLIB
Fe / Fe(96.5%)-C(3.5%) /Cu/Cladding ATLAS
FLUKA(CMS) / MARS(Fermilab)
Steel/Concrete/BPE CMS
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Benchmarking of Shower Simulation packages
• Benchmarking of Atlas hall background (I) measuring neutron/photon fluxes (BGO) 40/120 GeV /K+/p beam Iron absorber (11/14) abs (EndCap) @ 6-10cm and 56-60cm from axis compare to FLUKA(Ferrari)
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Benchmarking of Shower Simulation packages•Test beam w.r.t ATLAS conditions
•End-Cap chambers see about 3-6 times more flux coming from beam line that from IP trough calorimeter•Additionnal 25% from reflection on the cavern wall
•Using TP36 FLUKA Atlas simulation, taking into account above factors The predicted photon fluence rate emerging from calorimeter is
4-8 kHz/cm2 to be compared to the rate estimated by interpolating test beam data of 7.3 kHz/cm2
•Can the factor 1.2 uncertainty be applied as an overall neutron/photon fluence in ATLAS?
•validity for other materials•validity at very large angle w.r.t. shower axis
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Benchmarking of Shower Simulation packages
Experimental Data:
• RD5: punchthrough studies with Iron absorber , K, P of 10-300 GeV from 0.1 to 30 abs Compared to G3-FLUKA and G3-GHEISHA
10 GeV protons; compare lateral particle fluxes and spectra
for neutrons/photons/charged particles
agreement for lateral neutron/photon leakages is very good
difference in proton spectra in BPE
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Benchmarking of Shower Simulation packages
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Possible Strategy?
• Continue cross-checks with simple geometry
-Differences as a function of number of abs
-Extend to other materials (concrete, LAr calorimeters at
cryogenic temperature, Cladding Polyethylene,...)
-Understand origin of (large) differences !!
-Cross-check “differential” material study FLUKA/G3 used to
establish optimum geometry/shielding composition
-Implement K0 sector
-Extend comparison to MARS (I.Dawson has formal agreement of
author N. Mokhov)
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Possible Strategy?
• For the case of the full ATLAS simulation, FLUKA is probably the most benchmarked program : used to provide “best estimate” of radiation. • Not to forget: need the necessary level of accuracy of geometry and material description (see next subject)• Ideally, when we compare predictions for the full ATLAS setup of FLUKA and G3CALOR, they either agree within our estimated safety factors or we understand the origin of the difference and we know which “answer” should be the most reliable.• Safety factors will depend on “place” and “particle type”
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Event GeneratorReviewed by I.Štekl
• Differences DTUJET/ PHOJET/ PYTHIAParticle composition, energy distribution for different pseudorapidity regions
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Geometry / Material composition
Reviewed by M.Shupe
• Comparison between FLUKA, GCALOR, DICE geometriesUpdate / Documentation
• GAP region modelling studies• Toroid region modelling studies• Overview of shielding issues in ATLAS
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Geometry / Material composition
• Comparison between FLUKA, GCALOR, DICE geometriesUpdate / Documentation
Lar EM, End-Cap pendingID: in preparation (TRT F.Luehring, SCT, Pixel via I.Dawson)Muon: chamber dimension/material, coils?Beam pipe: G3 needs updateShielding: see later Comment: a useful and necessary exercise ...
not completed yet
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Gap region modelling studies
• Comparison DICE / Shupe model of crack- Finger model OK - Different “filling factor” between crate & fingers test- lighter “ID cable density” test- gap opening (4 cm, 8 cm) test
• Results of study (see next transparencies)• Conclusion: predicted radiation levels do not critically depend on gap
material description, dimension:-radiation flows also inbetween vertical cryo walls, ITC’s shields the cable path-Finger electronics and plume (self-) shielded by fingers
• Question: beam flange acts as a source of radiation “below” the gap
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Toroid shielding modelling studies• Toroid shield rather “thin” due to the limited radial extension• Add shielding blocks in toroid itself (see figure)• Test sensitivity of radiation to that addition of moderator blocks
critical! Needs more carefull geometry description in simulation• Further study needed:
Optimisation material/thickness/costHydrogenous material consideredMaterial H fraction density merit(for equal volume)Wax 14.8% 0.903 1.epoxy 8.47% 1.15 0.73PE 14.3% 1.1 1.18Some questions: material in “tight” boxes, release of hydrogen, cold
Dopants: Li versus B (sarurates for smaller thickness but need Pb absorb ’s
• Time scale: 3 months
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Forward shielding modelling studies• New technical solution for large forward shield
+ possibility of staging construction• Study of different configurations (see transparencies)
-only cylindrical part -Outer forward muon: radiation at low ℒ = 2 x high ℒ-Between mid and outer fwd: 1.2 -mid fwd: 0.3
-Add TAS outer shield section -Outer forward muon: radiation at low ℒ = 0.2 x high ℒ-Between mid and outer fwd: 0.9 -mid fwd: 0.2
-Cladding useful in front of mid forward muon chamber•Conclusion: full envelope needed at low luminosity
optimize cladding (learning from past experience)
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Status of shielding studies by regionRegion Critical? Work in progress
Calorimeter material + densities
yes Finalize update in simulation
GAP services probably not Continue improving model, verify basics w. Fluka, et new NIEL, Dose, check beam pipe (flange), follow gap opening
PLUGS 1,2,3 needed Minor dim. + material adjustment
JD region yes (“known”) Optimize 10 cm cladding, verify W core ratio w. FLUKA
JT region yes! Update toroid moderater geometry, optimize material
JF region full envelope needed
Optimizing cladding (update chicanes)
JN region maybe Study QUAD shield addons, high stat. For charged particles
Fcal Moderator yes (ID) Further optimisation “flange sector”
EB Meeting, 9th of February 2001 M.Bosman / IFAE-Barcelona 21
Update of requests from systems
request from M. DentanRADIATION LEVELS AND SAFETY FACTORS FOR ATLAS ELECTRONICS RADIATION HARDNESS ASSURANCE Improvements requested: • TILE, LVPS: R=410 & Z=300 => TID, NIEL, SEE? • Pixels: by domains of 1cm x 1cm => TID, NIEL, SEE? • CAVERN: by domains of 1m x 2 3m => TID, NIEL, SEE? • Each (R, Z) domains in ATLAS => are they hot spots? Values if any? • Each (R, Z) domains in ATLAS => improved Safety Factors ? • ATLAS and UX15 => TID, NIEL & SEE maps, up to Z = 16.7 m (footbridge along the wall between UX15 and USA15). Questions: • Which simulator:FLUKA? G CALOR? • Effects on radiation levels of reflexion on cavern walls? • Current ATLAS tables (M. Shupe): G CALOR, 1034 cm 2 .s 1 • Radiation levels for R and Z other than those of the tables ?
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ConclusionGoals :• provide to the various systems the relevant input to evaluate the effect of radiation on their system• provide them with the safety factor valid for their case
• We have defined a “ road” towards our goals:•Updated geometry/material description•Understanding of the critical area, required level of detail•Simple geometry = useful handle to understand shower models Detailed comparison between programs = rather thorough cross- check of the full chain used in with the different programs: many steps, many numbers, many possibilities to make mistakes ...•Improve our estimate of uncertainty level: most critical are shower models – a lot of work needed
