Energy deposition studies at IR7
description
Transcript of Energy deposition studies at IR7
Energy deposition studies at IR7
M. Santana, M. Magistris, A. Ferrari, V. Vlachoudis
Collimation collaborationmeeting 09-05-2005
Introduction
Motivation
Large Hadron Collider : 27 km cryogenic installationLarge Hadron Collider : 27 km cryogenic installation
LHC is a proton-proton colliderLHC is a proton-proton collider 2 proton beams at 7 TeV of 32 proton beams at 7 TeV of 3××101014 14 pp++ each each stored for 10-20 hours in collisionstored for 10-20 hours in collision total stored energy of 0.7 GJ (sufficient total stored energy of 0.7 GJ (sufficient to melt 1 ton of Cu)to melt 1 ton of Cu)
~5000 cold magnets~5000 cold magnets Tiny fractions of the stored beam suffice to quench a Tiny fractions of the stored beam suffice to quench a
superconducting LHC magnet or even to destroy parts superconducting LHC magnet or even to destroy parts of the accelerators.of the accelerators.
The LHC collimation system will protect the accelerator The LHC collimation system will protect the accelerator against unavoidable regular and irregular beam loss. against unavoidable regular and irregular beam loss.
from MC2005 V. Vlachoudis
Two Stage Cleaning
Secondary halo
p
pe
Pri
mar
yco
llim
ator
CoreCore
Diffusionprocesses1 nm/turn
Shower
Beam propagation
Impact parameter
≤ 1 m
Sensitive equipment
Primary Primary halo (p)halo (p)
e
Shower
p
Tertiary halo
Secondary collimator
79.54.54Titanium
96.41.77Graphite
34.48.96Copper
971.848Beryllium
88.82.7Aluminum
Escaping
%
Density g/cm3
Material
Example for 1 m long jaws!
Secondary collimators intercept halo --> Shower energy escapes Secondary collimators intercept halo --> Shower energy escapes to downstream elements! so then... to downstream elements! so then... What happens downstream?What happens downstream?
RADWG-RADMON Workshop Day, CERN 01/12/2004 5
E6C6
IP7A6
A6C6E6
UJ76
RR77
RR73
IR7 layout
LHC lattice and optics files V6.5
1. Primary and Secondary collimators, Scrapers, Absorbers
Normal operation 0.2 hours beam lifetime 4×1011 p/s for 10 s
RADWG-RADMON Workshop Day, CERN 01/12/2004
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IR7 Geometry
UJ76
RR73 RR77
Geometry of the dipoles
Tesl
a
14m long objects with a field of 8.3 Tesla: 5mrad bend ~3cm sagitta.The superconducting dipoles(MB)are made out of 4 straight sections to accommodate the trajectory.
Magnetic field maps
● General routine for handling magnetic field maps (Analytic and/or 2D Interpolated) with the use of an external file with a special format
● Magnetic field type– CONSTConstant field– QUAD 2D Analytic quadrupole field– QUADINT 2D Analytic+Interpolated quadrupole field– INTER2D 2D Interpolated field
● Symmetries:– NONE No symmetry– X, Y, Z Symmetrical on plane X, Y, Z (-x x, …)– XY On both planes XY– XYZ On all planes XYZ
● Table with interpolated data (Bx,By,Bz)● Quadrupole analytic description
– Origin of the magnetic field map origin– Limiting radius up to where to consider an analytic field
● Translation and Rotation of the field map● Field intensity / gradient specified per region or lattice
from MC2005 V. Vlachoudis
Magnetic field example
MQW – Warm Quadrupole
XY SymmetryAnalytic
2D Interpolated
from MC2005 V. Vlachoudis
Primary Inelastic collisions map
● Generated by the COLLTRACK V5.4 program– 3 scenarios: Vertical, Horizontal and Skew– Pencil beam of 7 TeV low-beta beam on primary collimators– 100 turns without diffusion– Impact parameter: 0.0025 – Spread in the non-collimator plane: 200 m– Recording the position and direction of the inelastic interactions
● FLUKA source: Force an inelastic interactions on the previously recorded positions
Beam Loss Map
M. Brugger et al
from MC2005 V. Vlachoudis
Execution timeBiasing● Importance biasing: radially decreasing● Leading particles biasing● High energy cuts on EMF on regions far away● Weight Windows per region
Statistics● 30% on maximum● Linux Cluster● 64 CPU’s @ 3GHz● 1 week run
Improvements:● Bias the diffractive/inelastic
scattering ratiofrom MC2005 V. Vlachoudis
Collimators
Collimators Material ChoiceNot driven so much by the standard collimationbut rather by the faulty operations or malfunctions● Worst Accident scenarios:
– Due to a spontaneous rise of one of the extraction kicker modules during the coast, part of the 7 TeV/c beam is spread across the front of a collimator jaw.
– Faulty kick by the injection kicker where a full batch of protons hit the front of a collimator jaw at 450 GeV/c
● Very fast absorptions of part of the proton energy:
– Instantaneous temperature rise– Thermally induced stresses (overheating/melting)
Limits material choice which can be used and still be compatible with other machine requirements.
● FLUKA-2002-4 A.Fasso, A.Ferrari, J.Ranft, P.R.Sala Proceedings of the Monte Carlo 2000 Conference, Lisbon, Oct. 23-26 2000, Springer-Verlag Berlin, p 955-960 (2001)
from MC2005 V. Vlachoudis
Collimators
Criteria:● Primary and secondary collimators
are the closest elements to the beam● Activating single scattering for thin
layer on jaws● Jaw halfgap / tilt variable during
runtime Primaries:
Gap: 6 Jaws: C-CLength: 20cm... may be changed to 60
Secondaries:Gap: 7 Jaws: C-CLength: 100cm
Absorbers:Gap: 10 Jaws: Cu or WLength: 100cm
from MC2005 V. Vlachoudis
Secondary Collimator
Maximum Energy density in TCSGA6L1 carbon jaws
Simulations
Simulation Strategy● Dynamic FLUKA input generation with several ad-hoc scripts● Detailed description of 20 prototypes located in a virtual parking zone.● Prototypes are replicated with the LATTICE card, rotated and translated.● Magnetic field maps: Analytic + 2D Interpolated● Dynamic generation of the ARC (curved section)● Optics test: Tracking up to 5 , both vertical / horizontal, reproduce beta
function
Input FilesInput Files• FLUKA input template• Twiss files• Collimator summary• Absorbers summary• Prototype Info
mklattic.rBRexx Script
Fluka Input Fluka Input (.inp)(.inp)
• LATTICE definitions• Curved Tunnel creation• Magnetic Fields Intensity• Scoring cards
Fluka Fluka ExecutableExecutable
• LATTICE transformations• Dynamic adjustment of
collimator gaps
Fortran FilesFortran Files• Source routine• Si Damage 1 MeV n eq.• Magnetic Field• History Tracking
Automatic Geometry Creation
1. Initial input file template2. Space Allocation & Geometry Creation3. Lattice generation4. Magnetic Fields mapping
Implementation of vertical and horizontal absorbers
Beam profile
z(m)
Geometry
Like secondary collimator, with Cu jaws and10 sigma halfwidth
Steps to launch a simulation
● 1) Modify active absorbers:
#icoll Name Material Length Rotation Tilt(jaw1) Tilt(jaw2) Halfgap N_Impacts N_InelInt Impact(av) Impact(sig)# [m] [rad] [rad] [rad] [m] (protons) (protons) [m] [m] 1 TCL.A4R7.B1 CU 0.000 0.1571000E+01 0.000000E+01 -0.1669557E-04 0.3517000E-02 267759 120004 0.8801409E-05 0.2861191E-04# 1 TCL.A4R7.B1 CU 0.000 0.0000000E+01 0.0000000E+01 -0.1669557E-04 0.1931000E-02 267759 120004 0.8801409E-05 0.2861191E-04# 1 TCL.A6R7.B1 CU 1.000 0.1571000E+01 0.0000000E+01 -0.1669557E-04 0.1585000E-02 267759 120004 0.8801409E-05 0.2861191E-04# 1 TCL.A6R7.B1 CU 0.000 0.0000000E+01 0.0000000E+01 -0.1669557E-04 0.3859000E-02 267759 120004 0.8801409E-05 0.2861191E-04...
twiss/absorber_summary.dat
"RCOLLIMATOR" "TCL.A4R7.B1" 0 0 20022.5326 0.00 0.00 0.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 "RCOLLIMATOR" "TCL.A6R7.B1" 0 0 20148.3344 0.00 0.00 0.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Absoluteposition
V6.5_absorbers.b1.phase1.data
Use twiss/tensigma.dat
1.000 = active0.000 = inactive # = no line
0.1571 = Vertical0.0000 = Horiz.
- Each absorber must be defined in both files (inactive absorbers count but not hashed lines).- There cannot be two active replica of the same absorber.
Steps to launch a simulation
● 2) Modify geometry, activate relevant USRBIN in ir7.fluka
– USRBIN -39.0 must always be active.● 3) Check for errors in prototypes etc.:
– $ fluka.r -m ir7.fluka ir7.i– $ mcnpx ip i=ir7.i
● 4) Select appropiate beam file:– Check ir7.fluka:
– Check run.sh to include that beam:
BEAM 7000.0 PROTONSOURCE beam1*SOURCE A7*SOURCE B7
ir7.fluka
SOURCES="Twiss/beam1.dat Twiss/beam2.dat Twiss/beam1V.dat Twiss/beam1H.dat Twiss/beam1S.dat Twiss/beam1VP.dat Twiss/beam1VPH.dat Twiss/beam1VPS.dat Twiss/beam1VPV.dat Twiss/beam1VS1.dat Twiss/A7.dat Twiss/B7.dat Twiss/nbeam1.dat"
run.sh
Steps to launch a simulation● 5) IF a new prototype has been designed, include it in prototype.pos:
● 6) Compile geometry --> ir7.inp:– $ make proper– $ make
● 7) Check correctness of ir7.inp:– Check number and type of absorbers ir7.inp.– Make plots of newly introduced elements:
● $ flukaplot.r ir7.inp flukair7● 8) Make a test run:
– Check results and speed.– Check lattice tables:
● $ EnLattice.pl < 'ir7.inp' 'usrbinf_39' '1'● 9) RUN and analyze.
prototype.pos
# Absorber (like Hybrid)TCL 0 0 TCL2 -2000.0 0.0 5060.0 100.0 -#
One or two beams(normalization)
File with formatted results $ usbsuw to summarize $ usbfuf to format
1 or 2 beams
Correction of beam direction.
x
x
z
yOnly primaries are affected
85% inelastic scattering(minor consequences)
15% diffractive scattering(deviated and partially
lost)
40% more dose in MQTLH,
but still below limit
Much higher dose in the curved section,but still well below the limit
0.5 mrad rotation
Mq6totMQ7
MBA8R
MBB8R MQ8
MBA9R
MBB9R MQ9
MBA10R
MBA11R
MBB11R MQ11
MBA12R
MBB12R 0
2
4
6
8
10
12
14
16
18
20
22
24Dose increase for correct beam
Dose
corr
ect
/ u
nco
rrect
beam
Results:warm elements
Preliminary results for the straight section (corrected beam)
Total energy deposited in the MBWB6L:Corrected beam: 28.4 kW
(Uncorrected beam: 37 kW)
Energy deposited in the TCSGA6L1:Total energy: 20 kW
(Uncorrected beam: 22.6 kW )Energy in both jaws: 5.1 kW
(Uncorrected beam: 1.02 kW )
Hot spot with no physical meaning, due to the beam error
Heat in the finger collar of the TCSGA6L1
16.9 W 80.4 W
Energy deposition in flanges
W/cm3
TCSGA6L1
<-front
back->
70 W
22 W
457 W
85 W
Passive absorber
● Most of the radiation deposited in the MBW insulator comes from inside the beam pipe.
● The efficiency of the absorber strongly depends on the inner radius.Ideal absorber. Pipe size. Fe absorber. 2 cm radius (pipe
is 4 cm)
5-10 MGy/y ~ 1 MGy/y
● Need for smaller radius. Cu absorber? Ideas?
Results: cold elements
Implementation of vertical and horizontal absorbers
1 Finally selected.
TCL.A6R7.B1s= 20148.33
TCL.C6R7.B1s= 20179.29
TCL.E6R7.B1s= 20213
6 candidate absorbers in straight section
2 candidate absorbers before curved section
4 Finally selected
TCL.B7R7.B1s= 20236.65
Beam 1
Beam 2
TCL.A7R7.B1s= 20251.65
TCL.A4R7.B1
TCL.F6R7.B1
4+1: A6vC6hE6vF6h-A7h
Number of simulations: 442******* Straight Section *************** * MQTLHA6R ******************* * max heat in coil:........ 0.759 mW/cm3 (+- 19.9 %) * Total heat in the coil:.. 0.35 W (+- 7.00 %) * heat in MQ:.............. 1.22 W (+- 4.10 %)** * MQ6 group ****************** MQTLHA6R 1.22 (+- 4.10 %) W MQTLHB6R 0.40 (+- 5.37 %) W MQTLHC6R 0.26 (+- 6.13 %) W MQTLHD6R 0.19 (+- 7.87 %) W MQTLHE6R 0.14 (+- 9.74 %) W MQTLHF6R 0.13 (+- 9.93 %) W ------------------------------------ TOTAL 2.07 (+- 2.83 %) W******* Curved Section ****************Total energy in coils and magnets of MQ[7-11]R. MQ7 | max: 0.286 (+-99.0%) | 1.796e-01 +- 30% | Total: 0.433 W +- 18.0 % MQ8 | max: 0.699 (+-82.8%) | 1.193e-01 +- 47% | Total: 0.227 W +- 26.4 % MQ9 | max: 0.245 (+-65.5%) | 1.474e-01 +- 55% | Total: 0.264 W +- 33.2 % MQ10 | max: 0.132 (+-99.0%) | 3.124e-02 +-100% | Total: 0.074 W +- 46.5 % MQ11 | max: 0.284 (+-99.0%) | 1.566e-02 +-100% | Total: 0.034 W +- 49.2 %Total energy in coils and magnets of MB[A-B][8-11]R. MBA8R | 1:inner_coil 1.120e-01 +- 30% | 1:outer_coil 5.637e-02 +- 28% | max: 0.143 (+-98.2%) | MBB8R | 2:inner_coil 8.321e-01 +- 17% | 2:outer_coil 4.208e-01 +- 17% | max: 0.400 (+-85.5%) | MBA9R | 3:inner_coil 3.937e-01 +- 24% | 3:outer_coil 2.060e-01 +- 24% | MBB9R | 4:inner_coil 3.069e-01 +- 30% | 4:outer_coil 1.721e-01 +- 29% | MBA10R | 5:inner_coil 3.439e-03 +- 58% | 5:outer_coil 1.343e-03 +- 59% | MBB10R | 6:inner_coil 2.132e-04 +- 69% | 6:outer_coil 4.892e-05 +- 69% | MBA11R | 7:inner_coil 2.003e-01 +- 37% | 7:outer_coil 1.135e-01 +- 36% | MBB11R | 8:inner_coil 1.085e-01 +- 42% | 8:outer_coil 6.023e-02 +- 42% |
Radiation in the MBA8
Heat spikes in MB's
Radiation in the MQ's
1W +- 0.5 W 1W +- 0.5 W 0.01W +- 0.01 W
mW
/cm
3
Comparison between A7h and B7h
Part of the beam halo will interact with the absorbers and generate a hadronic shower => energy deposition in the cold
magnets
The contribution from B7h will be 15% higher than A7h, but still at an acceptable level.
Peak values in MQ7:
A7h => 0.22 mW/cmc (*) B7h => 0.26 mW/cmc (*)
(*) values refer to 1 proton interacting out of 10,000 lost in TCP. Error is below 6%.
MQ7 MBA8R MBB8R MQ8 MBA9R 0.1
1
10
100
1000
10000
Energy deposition in coils (W), total beam lost in the last absorber
A7h
B7h
Po
we
r (W
)
Tertiary halo
Comparison between A7h and B7h
● Simulations were run with corrected beam.● The accuracy of the magnetic field in the MB was improved.
● Low energy photons were fully simulated.
from PAC2005 M. Santana et al.
Comments
Simulation accuracy. Sources of error
- Physics modeling:– Uncertainty in the inelastic p-A extrapolation cross section at 7 TeV lab
– Uncertainty in the modeling usedFactor ~1.3 on integral quantities like energy deposition (peak included)while for multi differential quantities the uncertainty can be much worse.
- Layout and geometry assumptions: It is difficult to quantify, experience has shown that a factor of 2 can be a safe limit.
- Beam grazing at small angles on the surface of the collimators: Including that the surface roughness is not taken into account a factor of 2 can be a safe choice.
- Safety factor from the tracking program COLLTRACK is not included!
from MC2005 V. Vlachoudis
Some facts ...
- Challenge:– 'Filter twice 450 kJ' in such a way that superconducting elements get less than 5 mW/cm3!
– Track showers along 1.5 km of tunnel and build up statistics with rare occurring events.
- Resources: Over 7 years of equivalent CPU-(2.8 GHz) over 15 months in a 3 man-year effort.
- Models and scripts: one of the most complex simulations in FLUKA.
Related works:UJ & RR's
electronicsprotection
K. Tsoulou
RADWG-RADMON Workshop Day, CERN 01/12/2004
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NoAbsorbers
A6vC6Eh6v Absorbers
RR77RR73
Dose
(G
y/y
)
UJ76
Flux (
cm-2/y
)
A6vC6hE6v
beam1
beam2 E6vC6hA6v
No Absorber vs. Absorber (tunnel)
Mean values ± 2m horizontally and ± 1m vertically.
RADWG-RADMON Workshop Day, CERN 01/12/2004
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Three Absorber Case for UJ76
Dose (Gy/y)
Dose (Gy/y)
Doses in racks ≤ 5 Gy
Similar to NoAbsorber case !
Related works:Ozone productionin IR7. Accident case studies,...
A. Pressland
Introduction
● Radiation induced production of O3 around IP7.– dose estimates provided by Fluka – assumed 4.1 1016 lost protons per year. – assumed all Fluka energy loss in air is ionizing.
● Enclosures around regions of high dose (O3 concentration)– enclosures seal the tunnel in areas where the ozone– voided independently of the main tunnel– air corridor to allow passage of tunnel air towards TU76
Tunnel Section
Energy scorings● Annual dose (GeV/cm3) based 4800 beam-hours ● Complient with the standard 104 – 105 Gy/year
Calculation (1)• Fasso et el (1982) LEP Note 379 gives the following differential equation
I = ionizing energy deposited in air per unit time, in eVcm-3s-1
G = number of ozone molecules formed, in eV-1 (7.4 10-2 eV-1) = dissociation constant for ozone, in s-1
(2.3 10-4 s-1)N = concentration of ozone at time t, in cm-3
k = decomposition constant, in eV-1cm3
(1.4 10-16 eV-1cm3)Q = ventilation rate, in cm3s-1
V = irradiated volume, in cm3
• Integration leads to the following concentration kinetics:
dNdt
IG αN kIN QVN
N t IGα kI Q V
1 exp α kI Q V t
formation
dissociation
decomposition
ventilation
Calculation (2)
• More useful steady state formulation in a tunnel– average energy , Iave, is deposited per unit time– air circulates with speed v ms-1
– length z of tunnel is irradiated
This is a special case of the previous equation wherethe concentration N cm-3 increases with distance z traversedand air traverses a length z meters of tunnel in z/v seconds accumulating a concentration N(z) molecules of ozone
N zIaveG
α kIave1 exp α kIave z v
Results
● Steady state results for air exiting regions
● Assumed ventilation rates– 10 m3s-1 for the main tunnel– 0.2 m3s-1 for the enclosures
● Parts per million conversion requires– air density of 1.202 kg m-3
– molecular weight of 28.95 g mol-1 – Avogadro constant NA = 6.022 1023
NO3 (ppm) 4.3 10-38.9 10-34.63 10-4
Encl. 2Encl. 1Tunnel
Results
● Concentration kinetics using averaged dose– assumes ‘magic ventilation’ where air is not considered to travel to the
ventilation point through a radiation environment.– only useful to compare growth rates etc
Tunnel Enclosure 1 Enclosure 2
2.3 10-4 ppm5.1 10-2 ppm 2.5 10-2 ppm
25 mins300 mins
300 mins