1. On behalf of the FLUKA team
Simulating proton/ion-induced particle showers in the Large Hadron Collider
E. Skordis,
C. Bahamonde, F. Cerutti, A. Ferrari, A. Lechner, A. Tsinganis, V. Vlachoudis
On behalf of the FLUKA team
SATIF-13 12/10/2016
E. Skordis

2. LHC overview 500 kW Beam loss
2*362 MJ total energy stored in both LHC beams
(2808 bunches)*(1.15*1011protons/bunch)*(7*1012eV/proton)*(1.602*10-19Joules/eV) = 362 MJ per beam
̴4000 Beam Loss Monitors are installed in the LHC each capable of triggering a beam dump if the dose exceeds a certain threshold
LHC collimation system:
> 100 movable devices
Capable of cleaning up to 500 kW
Betatron cleaning: IR7, momentum cleaning: IR3
Not all power is absorbed by the collimators themselves
500 kW
Beam loss
SATIF-13 12/10/2016
E. Skordis 2

3. LHC Beam losses Regular losses (slow, partially controlled)
Beam intercepting movable devices (collimators, active absorbers, etc…) -> beam cleaning, magnet protection
Particle collisions at experiments (shower debris, mostly )
Simulated values of interest
Dose to BLMs -> simulation validations
Dose to equipment -> long term damage
Peak power density -> short term limitations (magnet quenchs)
Other kind of losses not presented here
Beam interaction with residual gas
Irregular losses (fast, uncontrolled)
Accident scenarios <- failure or misbehaviour of accelerator elements (magnets, RF, collimators etc..)
UFO’s etc.
SATIF-13 12/10/2016
E. Skordis

4. Energy deposition simulation requirements for collimation losses
Creating source term for further FLUKA simulations
SixTrack-FLUKA Coupling provides input. Map of particles arriving at the collimators
SixTrack : Single particle 6D tracking code for long term tracing in high energy rings -> online coupling with FLUKA handling the interactions with collimators
FLUKA simulation set up
Model complex geometries of all key elements of the LHC
Set up the simulation parameters
Source routine
Magnetic fields routines
Physics settings
Scoring
Etc…
FLUKA MODEL
LHC BLM
Picture
Tracking for Collimation Workshop 30/10/2015
E. Skordis

5. Primary Beam 2 Collimators
IR7 FLUKA geometry
Long Straight Section
Primary Beam 2 Collimators
MQWA.C4R7
MQWA.D5R7
MBW.A
MBW.B
MQWA.E4R7
MQWA.E5R7
Last TCLA
Left Dispersion Suppressor + Arch up to cell 14
SATIF-13 12/10/2016
E. Skordis

6. Collimator Support + Tank
IR7 FLUKA - Sixtrack Simulation
IP7
MQW4
MBW5
MQW5 %
TeV
TCP+TCSG
Jaws
TCAP
MBW
MQW
Beam 2 Pipe
Environment
E -> m +
Neutrinos
Leaving 4 10
12.9
8.5
9.5
8.6
41.6
6.2
2.7
6.5
13.4 12
40.1
5.5
1.9
TCAP.A
Enviroment
Air
Concrete Tunnel
Tunnel Cables
Collimator Support + Tank
Beam Pipe supports
Other Elements =
0.5
30.5
0.9 3 1
4.2
Beam 2 Primary Collimators
Beam 2 Direction
SATIF-13 12/10/2016
E. Skordis

7. IR7 MBWA - MBWB 7 TeV Peak Dose profile
Beam 2
MQWA.C4R7
MQWA.E4R7
MQWA.D5R7
MQWA.E5R7
MBW.A
MBW.B
TCAP
Beam 2
SATIF-13 12/10/2016
E. Skordis
Normalization: p (40 fb-1 )

8. IR7 MQW 7 TeV Peak Dose profile
Beam 2
MQWA.C4R7
MQWA.E4R7
MQWA.D5R7
MQWA.E5R7
MBW.A
MBW.B
TCAP
Beam 2
SATIF-13 12/10/2016
E. Skordis
Normalization: p (40 fb-1 )

9. IR7 2013 Collimation Quench Test FLUKA – Sixtrack Simulations
TCP
TCP Beam 1 Q4
IP7 Q5
BLM integration Time : Running Sum 1 (40 μs)
SATIF-13 12/10/2016
E. Skordis

10. IR7 2015 Evaluating collimation losses
TCP Q4
Beam 1 Col
5.5e+14 p*/
~4.3 fb-1
p* =
2015 equivalent
7 TeV proton lost Q5
Beam 2
IP7
6.5 TeV FLUKA-Sixtrack simulations
SATIF-13 12/10/2016
E. Skordis

11. IR7 2015 Evaluating collimation losses
MBW
6.5 TeV FLUKA-Sixtrack simulations
SATIF-13 12/10/2016
E. Skordis

12. IR7 2015 Evaluating collimation lossesQ4 Q5
MBW
TCP
IP7
6.5 TeV FLUKA-Sixtrack simulations
SATIF-13 12/10/2016
E. Skordis

13. pp debris from the experiments
Energetic secondary particles emitted in forward direction can escape experimental region
Give rise to significant power deposition in the final focus regions (inner triplet Q1-Q3)
Challenging upgrade in the HL era: 1.4x1034 cm-2 s-1 -> 5x1034 cm-2 s-1
SATIF-13 12/10/2016
E. Skordis

14. pp debris from the experiments
BLM benchmark 2016
Collisions at 13 TeV (CM)
Peak luminosity of 1.3x1034 cm-2 s-1
SATIF-13 12/10/2016
E. Skordis

15. particle tracklength fraction
(14 TeV CM)
HL-LHC DESIGN: CODE
INTERCOMPARISON
particle tracklength fraction
in the Nb3Sn coils [%]
photons 88
electrons/positrons 7
neutrons 4
pions
0.45
protons
0.15
Instantaneous luminosity: cm-2 s-1
Integrated luminosity: 3000 fb-1
[MARS calculations
by N. Mokhov
and his team, FNAL]
SATIF-13 12/10/2016
E. Skordis

16. shielding extension (Inermet, 7cm) BPM shielding (Inermet, 18cm)
WP10
team
triplet interconnect optimization to address the Q2b weak point
36 MGy after 3ab-1
shielding extension (Inermet, 7cm)
BPM shielding (Inermet, 18cm)
36 MGy
-15%
-15%
significant benefit from crossing plane swap (hor <–> ver), since the regular inversion of the crossing angle – which pays in the LHC – is applicable only for vertical crossing
SATIF-13 12/10/2016
E. Skordis

17. Beam losses during ion runs in the LHC
- Mostly Pb-Pb (2015)
- General ion run losses are very different from protons
- Pb-Pb runs also have intrinsic beam losses around the collision points ATLAS, ALICE, CMS, LHCb (IP1, IP2, IP5, IP8)
Superconducting dipole magnets (MBs)
BFPP losses deposit energy in several LHC superconducting dipoles
Bound- Free Pair Production (BFPP) is the main contribution to fast Pb-Pb beam burn-­off
SATIF-13 12/10/2016
E. Skordis

18. Beam losses during ion runs in the LHC
Peak power density for HL-LHC:
Linst=6 x 1027cm-2s-1
7 Z TeV
BFPP Quench Test BLM comparison
Beam 2
Beam 2
SATIF-13 12/10/2016
E. Skordis

19. Intercepting BFPP losses with collimator
SATIF-13 12/10/2016
E. Skordis

20. Conclusions
FLUKA is the standart tool at CERN for shielding design and collimator upgrades for future LHC operation at higher intensity and luminosity
Complex beam line models of the insertion regions and dispersion suppressors have been implemented, covering hundreds of meters of beam line
The simulations are essential to relate key quantities (peak dose/peak power inside magnet coils) to measurements (dosimeters/BLMs next to magnets)
Excellent BLM signal reproduction demonstrates the reliability of the simulation models for different loss scenarios
Thank you!
SATIF-13 12/10/2016
E. Skordis

21. BACK UP SLIDES
SATIF-13 12/10/2016
E. Skordis

22. LHC collimation system
Capable of redirecting up to 500kW of proton loss rate in order to protect the Super Conducting Magnets from quenching (stop being SC due to energy deposition -> increase in temperature)
The majority of that power is
deposited in the whole IR7 and IR3
Not all power is absorbed by the collimators themselves
R. Bruce,
500 kW
Beam loss
SATIF-13 12/10/2016
E. Skordis

23. IR7 DS Peak power deposition in the SC coils
SATIF-13 12/10/2016
E. Skordis

24. IR7 DS Peak power deposition in the SC coils
Main Dipoles
Main Quadrupoles
13.4 mW/cm3
Beam 2
4 mW/cm3
SATIF-13 12/10/2016
E. Skordis

25. Magnet coils peak power deposition (radial average) Present layout 1 DS collimators
Main Dipoles
Main Quadrupoles
3 mW/cm3
2.6 mW/cm3
Beam 2
SATIF-13 12/10/2016
E. Skordis

26. LHC BLM System What does BLM System stand for?
Beam Loss Monitoring System
What is it?
Consists of various detectors (active dosimeters), mainly;
Ionisation Chambers (IC)
Little IC
Secondary Emission Monitors (SEM)
in development…
Each detector has different response times and detection range
Each detector serves a different role
What is its purpose?
To measure beam losses around the accelerator and protect the machine from various beam loss scenarios
SATIF-13 12/10/2016
E. Skordis