overview of collimation concepts...be minimised by using larger collimator jaw gap sizes, and using...

Overview of collimation conceptsEuroCirCol-P1-WP2-D2.2

Date: 24/11/2016

Grant Agreement No: 654305

EuroCirColEuropean Circular Energy-Frontier Collider Study

Horizon 2020 Research and Innovation Framework Programme, Research and Innovation Action

DELIVERABLE REPORT

Overview of collimation conceptsDocument identifier: EuroCirCol-P1-WP2-D2.1

Due Date: 01/12/2016

Report release date: 24/11/2016

Work package: WP2 (Arc lattice design)

Lead beneficiary:

Document status: RELEASED

Domain: Accelerators

Keywords: Hadron collider, collimation

Abstract

This document describes the collimation system concept options to be taken into considerationfor further detailed studies. It also summarizes the relative merits, requirements, constraintsand impacts of each of the options to be considered, and give a classification according tomerit and realization risk.

Grant Agreement 654305 PUBLIC 1

CEA

EuroCirCol-P1-WP2-D2.2 Date: 24/11/2016

Copyright notice:

Copyright © EuroCirCol Consortium, 2015 For more information on EuroCirCol, its partners and contributors please see www.cern.ch/eurocircol.

The European Circular Energy-Frontier Collider Study (EuroCirCol) projecthas received funding from the European Union’s Horizon 2020 researchand innovation programme under grant No 654305. EuroCirCol began inJune 2015 and will run for 4 years. The information herein only reflects theviews of its authors and the European Commission is not responsible forany use that may be made of the information.

Name Partner Date

Authored by: CNRS 05/11/2016

Edited by: Julie Hadre, Johannes Gutleber CERN

Reviewed by: Antoine Chancé, Daniel Schulte CEA, CERN

Approved by: EuroCirCol Coordination Committee 25/11/2016


25/11/2016

19/11/2016

James Molson

www.cern.ch/eurocircol


Contents

1 Layout of the collider ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Factors to consider for collimation system design . . . . . . . . . . . . . . . . . . . 23 Description of collimation system concept options . . . . . . . . . . . . . . . . . . . 43.1 LHC like system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.2 Dispersion suppressor collimators . . . . . . . . . . . . . . . . . . . . . . . . . . 53.3 New collimator materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.4 Combined collimation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.5 Advanced collimation concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Summary of the relative merits, requirements, constraints and impacts of each of

the options to be considered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.1 LHC like system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.2 Dispersion suppressor collimators . . . . . . . . . . . . . . . . . . . . . . . . . . 74.3 New collimator materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.4 Combined collimation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.5 Advanced collimation concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Classification and realization risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11A Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Grant Agreement 654305 PUBLIC i


1 Layout of the collider ringThe current layout (see Figure 1) of the collider ring consists of a ring with 2 high-luminosity insertions and 2 low-luminosity insertions. Currently, only the first beam (H1) is considered and is assumed to run in the clockwise direction. The layout for the other, counter-rotating beam (H2) is exactly the same except that left and right are exchanged. Several collider lengths have been investigated: 3.5, 3.75, and 4.0 times the LHC length (respectively 93.31 km, 99.97 km, and 106.6 km). The range of the possible length of the collider ring is set up by the dipole field for the lower limit and by the geological constraints for the upper limit [1]. The studies were jointly performed with FCC-ee to ensure the compatibility between both colliders [2]. The baseline circumference is 3.75 times the one of LHC, i.e. 99.97 km. This length was chosen as a good trade-off between the feasibility of the dipole field, the geological constraints and the total cost. The collider ring is made of 4 short arcs (SAR), 4 long arcs (LAR), 6 long straight sections (LSS) and 2 extended straight sections (ESS). The parameters of the ring are given in Table 2. The high luminosity interaction points (IPs) are located at PA and PG (in the named

Fig. 1: Layout of the collider ring.

sections LSS-PA[PG]-EXP on the layout). The optics of these interaction regions is assumed to be antisymmetric and is presented in [3] for the former value of L*=36m and in [4] for the current value of L*=45m. In order to mitigate the beam-beam effects, the crossing angles in PA and PG are not in the same plane at the collision. The lower luminosity IPs are located at PF and PH (in the named sections LSS-PF[PH]-EXP). At the current state of the study, these insertions are made of FODO cells. The insertion sections and the RF cavities are located at



PB and PL (LSS-PB-INJ and LSS-PL-RFS on the layout) for H1. The order is reverse for H2. As the trensverse beam separation must be enlarged to 420mm for the RF cavities, a chicane is added at the entrance and at the exit of these sections. These sections are made of FODO cells. The cell length is enlarged to 300m to provide the space required for the insertion of an injection septum [5].

The extraction and the betatron collimation are respectively located at PD[J] (ESS-PD-COL.EXT on the layout) for H1[H2] whereas the momentum collimation section is located in theother ESS at PJ[D]. The extraction [6], the√betatron and momentum collimation sections [7] arescaled from the LHC with the factor k = 50/7 for the betatron functions and the distances [8].The factor k is derived from the ratio of the centre-of-mass energy at collision between the LHC and the collider ring. By multiplying all distances by this factor, we keep then the same gradient in the quadrupoles. The derivative of the dispersion is divided by this factor. The dispersion suppressors (DIS) are similar to the ones used in LHC. Special care has been taken to have a dispersion function lower than in the momentum collimation section in the DIS upstream in order not to spoil the collimator hierarchy.

Table 1: Parameters of the collider ring.

Parameter Value Unitc.m. Energy 100 TeV

Circumference 99.171 kmLSS and ESS length 1.4 and 4.2 kmSAR and LAR length 3.6 and 16 km

β∗ 1.1 mL∗ 45 m

Normalized emittance (25 ns/5 ns spacing) 2.2/0.44 µmγtr 99.580 -

Qx/Qy (collision) 111.31/108.32 -Qx/Qy (injection) 111.28/108.31 -

Q′x/Q′y (Compensated) 2/2 -Beam separation 250 mm

Beam separation (RF) 420 mm

The optics of the current (V7) baseline collimation system as scaled from the LHC system are shown in figure 3. For the previous version, this is shown in figure 2. In moving from the version 6 to version 7 optics, the layout has changed. Previously the betatron collimation system was placed following the beam dump system, and the In addition, the length of the extended straight sections has been reduced.

2 Factors to consider for collimation system designThe primary objective of a collimation system is to protect the superconducting acceleratormagnets, and to reduce any radiation load onto sensitive electronic accelerator equipment.This includes items such as experimental detectors, power supplies, beam diagnostics, etc.The collimation system should also confine losses to a localised region in order to reducethe general radiological activation of the tunnel and machine components in order to allowfast access if required. It should be noted that the radiation load can come from multiple



Fig. 2: The optics of the previous V6 baseline collimation system. Left: betatron collimation insertion.Right: energy collimation insertion.

Fig. 3: The optics of the current V7 baseline collimation system. Left: betatron collimation insertion.Right: energy collimation insertion. Note the reduced length of the insertions.

sources - the slow transverse diffusion of particles in the transverse and longitudinal planes,and also the debris from collisions at the experimental interaction points. The primary measureof a collimation system performance is the cleaning inefficiency, i.e. the leakage of lossesfrom the collimation insertions and into the cold regions of the machine. Another worry ofthe FCC system is the increased stored beam energy will result in an increased power loadonto the primary colllimator jaws. These can be constructed of a low density damage resistantmaterial with adequate cooling, but in order to absorb the secondary particles produced within areasonable length, the secondary collimators must be constructed of a higher density material.It is possible that the power load due to secondary particles could be too high for the collimatorsand magnet systems. Since the collimators are not perfect conductors, and are the aperture



Table 2: A summary of the HL-LHC and the FCC-hh collimator jaw gap sizes shown in beam sigmas.The exact physical gap size depends on the beam emittance available.

Family HL-LHC (σ) FCC-hh (σ)

TCP Betatron 6 7.6TCSG Betatron 7 8.8TCLA Betatron 10 12.6

TCP Energy 12 18.1TCSG Energy 15.6 21.7TCLA Energy 17.6 24.1

TCT 15 10.5

restriction of the machine, there will be a resistive wall wakefield effect. This will lead to bothbeam induced heating of the collimator jaws, and a gradual emittance growth. This effect shouldbe minimised by using larger collimator jaw gap sizes, and using better conducing materials forthe jaws. This must of course be compatible with the required levels of cleaning efficiency andjaw robustness. The collimation system should also reduce the backgrounds due to the beamat the experiment. An experiment saturated by secondary particles produced by the beam inthe straight sections either side of the detectors will reduce their effectiveness. The collimationsystem should try and remove these particles if possible. The collimation system must alsoprotect against fast loss scenarios, such as injection kicker or power supply trips for warmmagnets, where the loss rates might reach high values before the beam extraction systemcan dump the beam. Cold magnets failures are less of a worry due to the high inductance ofthe superconducting magnets, leading to a slower current decay time, thus allowing the beamdump system to fire. Also possible is an asynchronous dump, where either the beam abort gapis filled or an extraction kicker fires at an incorrect time, or not at all. Here the full energy beamcan be kicked into the extraction septum or into arc magnets, resulting in their destruction. Awell designed collimation system can assist in the protection of the more expensive magnets insuch a situation, reducing the length of accelerator down time.

3 Description of collimation system concept options3.1 LHC like systemThe current LHC collimation system consists of two collimation insertions [9]. One is dedicated to betatron (transverse) halo removal, and the other is for momentum collimation (longitudinal). Each system is constructed of a series of double sided rectangular collimator jaws located at pre-calculated longitudinal positions and angles. The jaws themselves are made of different solid materials that are placed into the beam halo such that the beam halo is scattered or absorbed.

A robust damage resistant, but low density set of jaws are placed into the beam such that they are the primary aperture restriction of the machine. These are the primary collimators. Additional secondary jaws are placed at a larger aperture value relative to the beam size, and these catch any secondary particles generated by the primary collimators. Finally high density absorbers are placed downstream with an even larger aperture to catch the remaining particles. This is shown in figure 4. The current FCC collimation system design is a direct copy of the LHC system, but scaled up from the energy of the LHC to that of the FCC.



Fig. 4: The operation of the baseline LHC and FCC collimation systems.

3.2 Dispersion suppressor collimatorsA small fraction of protons that interact with the primary collimators gain a large momentum off-set. These protons can pass through the collimation insertion regions (which have low disper-sion) and enter the dispersion suppressor region where the dispersion rises rapidly to match thestraight section into the arc. Where the dispersion rises, the off-momentum protons are rapidlylost within a small region. The loss rate could be high enough to quench any cold magnets inthis area. Due to this, additional collimators are planned to be installed in these positions toshield the arc magnets from this debris.

3.3 New collimator materialsThe first possible upgrade is to use new materials that provide better cleaning or impedance properties to the beam [10, 11]. This is currently also under consideration for the HL-LHC design. These will be a simple drop in replacement for the currently used jaw materials. No other changes would need to be made. The solution for the HL-LHC is to place collimators into the cold dispersion suppressor regions of the machine to catch the off momentum protons generated. A similar solution is being investigated for the FCC dispersion suppressors.

3.4 Combined collimation systemsA possible solution to the losses in the dispersion suppressor region is to have a combined be-tatron and momentum cleaning system in the same insertion. This could be either one system following the other in the same insertion, or an interleaved system with the functionality of both provided in the same location. This could remove off momentum particles that are generated by the collimation system before they reach the arcs, and increase the cleaning efficiency of the collimation system greatly. This has been previously considered for the LHC [12].



3.5 Advanced collimation conceptsIn addition to previously studied systems, more advanced concepts can be explored. The decreased emittance of the FCC, combined with the possible requirement of beta functions that are less than the natural scaling will lead to smaller collimator jaw gap sizes. The required jaw gap sizes could be smaller than what is mechanically feasible. In addition smaller gap sizes will increase the collimator jaw impedance. An option is to use non-linear magnets to preferentially increase the transverse position of the beam halo over the beam core size [13, 14]. This will allow the collimator jaws to be placed at a larger distance away from the beam core. This will reduce the impedance due to collimator jaws.

Hollow electron lenses consist of a hollow cylindrical electron beam through which the main proton beam can pass through [15]. Halo protons can pass through the electron beam with the net result that their transverse diffusion rate is increased. The net effect is that the halo population at larger amplitudes is depopulated [16]. This directly leads to no direct effect on the absorption of protons; it can only enhance an already existing collimation system. The electron lens can increase the impact factor of protons onto the primary collimator jaws due to the increased diffusion rate. The depopulated halo can also reduce loss spikes due to errors in the beam size or position (for example, due to small ripples on magnet power supplies).

A possible future concept is to use bent crystals as collimators [17,18]. Bent crystals have a property where particles can be channelled between crystal planes if appropriately aligned. The possible bend angle is greater than the scattering angles generated by particles interacting with the amorphous standard collimator jaws. A possible issue is the channelled protons will all be directed into a focused spot, possibly requiring a dedicated “dump”.

An alternative method to assist the collimation systems is to prevent the creation of beam halo by providing an enhanced beam cooling system. The FCC-hh will be the first radiation dominated hadron machine due to the large synchrotron radiation output, leading to a gradual reduction in the beam emittance. A strong quadrupole undulator could preferentially make the beam halo radiate, and not the beam core. Subsequent re-acceleration by the RF system would result in a reduction of the beam halo population. An alternative is to make the full beam radiate and perform full optical stochastical cooling. Such a system was proposed for RHIC [19] and the TEVATRON [20], but was never installed before the shut down of the machine.

4 Summary of the relative merits, requirements, constraints and impacts ofeach of the options to be considered

A brief summary of possible collimation options is given in table 3, and following will be discussion of each option under consideration.

4.1 LHC like systemThe LHC scaled system has been shown to work in the current LHC, and should be easy toreplicate for the FCC. The magnets can be constructed, and the reduced jaw gap sizes requiredfor the FCC have been achieved in operation at the LHC. Further simulation work is taking placeto check if the power load will be acceptable. The current baseline uses this design, but it doesnot provide sufficient beam cleaning.



Concept Merit Requirements Constraints ImpactsStandardLHC likescaling

Proven to work,already inte-grated into thebaseline lattice

None None insufficient beamcleaningquenches

DispersionSuppressorcollimators

Reduces lossesinto the coldregions

Dedicated DS de-sign

Peak power load,space

Reduced DSlosses

Newmaterials

Enhanced sys-tem performance

manufacture ofnew jaws

none Reducedimpedance,increased ro-bustness andcleaning

Combinedsystem

Optimal systemperformance, NoDS losses

New optical de-sign

Increased inser-tion length

Lattice changes,possible increasein the straightsection length

Non-linearsystem


none none Magnet errorscould lead to areduced dynamicaperture

Hollowelectronlens


Small dedicatedregion is requiredfor the hardware

none Reduced beamhalo population

Crystalcollimation


Dedicated dumpsfor channelledbeams

none Enhanced beamhalo removal

Beamcooling

Reduced powerload on the colli-mation system

Large undulatorinsertion

No space toplace such asystem

Increased RFpower and thefull use of a longstraight section

Table 3: A summary table of the possible new collimation concepts currently underconsideration for theFCC-hh.

4.2 Dispersion suppressor collimatorsThe addition of dispersion suppressor collimators should assist in the protection of the coldmagnets, both from off-momentum particles escaping from the collimation system, and alsofrom physics debris from the experimental IRs. The dispersion suppressor design should leavespace for these collimators to be installed from the start. It is not yet known if the addition ofthese extra collimators will be sufficient to protect the cold magnets. For IR debris, it is the onlypossible solution for catching off energy particles produced.



4.3 New collimator materialsNew collimator materials have already been studied for the HL-LHC upgrade, and samples have been tested at the HiRadMat beam line from the SPS [21, 22]. It would be prudent to also use these materials for the FCC baseline. By the time the FCC is constructed, these jaws will already be in use at the HL-LHC, and thus industry will also have experience in their manufacture.

4.4 Combined collimation systemsA collimation system with combined betatron and momentum cleaning will try and remove offenergy protons from entering the arc by combining removal of off energy and large transverseamplitude particles, thus there will be no dispersion suppressor losses. The dispersion peakshould follow the primary betatron collimator in order to remove any off energy protons gener-ated by the collimation system. The result will be better cleaning efficiency without any extrameasures required to be taken. An advantage of this, is that all losses will be confined to thecollimation insertion. Two options are possible for this layout, one where the energy collimationdirectly follows the betatron collimation within the same insertion, and the other being where thetwo systems are interleaved, with the betatron collimators would be placed at positions of zeroor low dispersion. It is highly likely to require more longitudinal space than the current straightsections due to the extra phase advance needed. This could be reduced if both the energyand betatron systems are interleaved, and making full use of the arc dispersion. The opticshas yet to be designed, although an earlier design has explored previously for the LHC. Due tothe combined use of the system, it might be possible to have a dual use for some collimators,resulting in fewer collimator jaws being required overall, and also easing operations.

4.5 Advanced collimation conceptsA non-linear collimation system will use the non-linear field of a skew sextupole to enhance thetransverse position of the beam halo over that of the beam core. Due to the blow up of thebeam halo size, the collimator jaws can be placed further away from the beam core and this willresult in reduced impedance, and also easing the mechanical operation of the beam jaws. Thedisadvantage is a possible reduction of the available dynamic aperture in case the non-linearbump is not perfectly closed. As a consequence thus the loss rate could be increased.

Hollow electron lenses will enhance the beam halo diffusion rate, and thus will increasethe impact factor on the collimator jaws, and provide a clean depopulated region of beam halo.The enhanced impact factor will improve the beam cleaning - the particles will effectively seemore collimator jaw and the probability of being re-scattered back into the beam is highly re-duced. The depopulated halo region will assist in the system performance if there are anyripples in the beam position. They have only been tested at the TEVATRON, and their effective-ness might be reduced at the energy of the FCC. Such a system will be installed in the HL-LHC,thus there will be manufacturing and operational experience.

Crystal collimation will not provide any protection for any failure scenarios, and does notactually absorb any beam energy. These must be provided separately. The cleaning perfor-mance of the crystal critically depends on its angular alignment with the beam. If there is amiss-match, then no channelling will occur and the crystal will not act as expected. They canhighly enhance the bend angle of the beam over the scattering angle produced by traditionalcollimators, thus combined with a dedicated absorber they can produce high quality cleaning.



Since the FCC will be the first radiation dominated hadron machine, the natural radiationdamping could be sufficient. Although studies have been performed for previous hadron col-liders, no dedicated optical stochastic cooling mechanisms have been installed on any hadronmachine. The required space for such an optical cooling system could be excessive, and nospace has been allocated for such a scheme, nor has it been given any study.

5 Classification and realization riskCurrently the only fully explored system is the LHC scaled option. This has been tested with the previous V6 baseline lattice. A subsection of the results of these simulations are shown in figures 5 and 6. This shows the results for a horizontal betatron beam halo for the betatron collimation system on the left, and the results for an off energy beam halo in the energy colli-mation system on the right. The cleaning performance is plotted, and it can be seen that where the dispersion rises at the end of each insertion there is a concentration of beam losses into cold superconducting magnets. The current level of losses in these regions is not acceptable, therefore a more optimised solution will need to be found.

Fig. 5: The losses of the V6 baseline collimation system showing the betatron collimation system with ahorizontal beam halo.

The other options studied for the HL-LHC upgrade can be implemented into the FCC sys-tem without any risk, and these options have been well studied. These are dispersion suppres-sor collimators, new materials, and hollow electron lenses. These options can be consideredlower risk. Simulations of dispersion suppressor collimators are currently in progress.

The higher risk options are the more advanced concepts, such as crystal collimation(although this is currently under testing in the LHC). New optical designs (non linear collimation,



Fig. 6: The losses of the V6 baseline collimation system showing the energy collimation system with anoff energy beam halo.

and combined collimation) will require additional design work and cannot currently be reliedupon, although if successfully realised they could provide the optimal cleaning solution. Anynew optical design might be performance limited due to the fixed (and now reduced) lengths ofthe insertions.

6 ConclusionsA final design for the FCC-hh collimation system will likely require a combination of most of theabove proposed systems. A number of critical potential problems have been observed, andwork is currently under way to attempt to resolve these issues. These currently are related tothe incident power load on the collimation system, and how the energy flow out of the primarycollimators can be diluted. Some of this power will end up into the cold magnets, and studiesare performed at present to determine the maximum energy flow into the cold regions as wellas methods to prevent and or limit these effects. Finally, there is the possible problem of anysolution to the above issues being too large to fit within the current civil engineering constraintson the tunnel size and insertion lengths.

The FCC collimation system will be running in a currently untested regime, and there could be possible issues with the computer codes used to perform the collimation system sim-ulations. Due to the more stringent loss requirements of the FCC-hh, simulations with higher statistical resolving power must be performed at high accuracy. It is critical that the simulations are physically accurate, therefore work has also taken place on benchmarking and optimisation of the collimation system simulation codes, Sixtrack [23, 24], and MERLIN [25]. The results of these studies will be published in a separate report.



7 References[1] J. Osborne et al. “FCC Civil Engineering - Tunnel Optimisation” FCC Week 2016, Rome,

Italy (2016)[2] K. Oide et al. “FCC-ee machine layout and optics” FCC Week 2016, Rome, Italy (2016)[3] R. Martin et al. “Interaction Region for a 100 TeV Proton-Proton Collider” IPAC15, Rich-

mond, USA (2015)[4] A. Langner et al. “Developments on IR baseline design” FCC Week 2016, Rome, Italy

(2016)[5] W. Bartmann et al. “Beam Transfer to the FCC-hh Collider from a 3.3 TeV Booster in the

LHC Tunnel” IPAC15, Richmond, VA, USA (2015)[6] T. Kramer et al. “Considerations for the Beam Dump System of a 100 TeV Centre-of-mass

FCC hh Collider” IPAC15, Richmond, VA, USA (2015)[7] J. Molson et al. “Simulation of the FCC-hh Collimation System” IPAC16, Busan, Korea

(2016)[8] M. Fiascaris et al. “First Design of a Proton Collimation System for 50 TeV FCC-hh”

IPAC16, Busan, Korea (2016)[9] R. Aßmann et al. “The Final Collimation System for the LHC” EPAC 2006, Edinburgh,

Scotland (2006)[10] E. Quaranta et al. “Towards Optimum Material Choices for the HL-LHC Collimator Up- grade” IPAC16, Busan, Korea (2016)[11] A. Valloni et al. “MERLIN Cleaning Studies with Advanced Collimator Materials for HL- LHC” IPAC16, Busan, Korea (2016)[12] D. Wollmann et al. “Predicted Performance of Combined Cleaning with DS-Collimators in the LHC” HB2010, Morschach, Switzerland (2010)[13] J. Resta-López et al. “An Alternative Nonlinear Collimation System for the LHC” EPAC

2006, Edinburgh, Scotland (2006)[14] A. Faus-Golfe et al. “Non-linear Collimation in Linear and Circular Colliders” EPAC 2006,Edinburgh, Scotland (2006)[15] G. Stancar et al. “Conceptual design of hollow electron lenses for beam halo control in the

Large Hadron Collider” (2014)[16] H. Rafique et al. “Simulation of Hollow Electron Lenses as LHC Beam Halo Reducers

using Merlin” IPAC15, Richmond, USA (2015)[17] W. Scandale et al. “Crystal-assisted Collimation Experiment from the SPS to the LHC”

IPAC13, Shanghai, China (2013)[18] D. Mirarchi et al. “Layouts for Crystal Collimation Tests at the LHC” IPAC13, Shanghai,

China (2013)[19] M. Babzien et al. “Optical stochastic cooling for RHIC using optical parametric amplification” Phys. Rev. ST Accel. Beams 7, 012801 (2004)[20] V. Lebedev. “Optical Stochastic Cooing in Tevatron” HB2010, Morschach, Switzerland (2010)[21] A. Bertarelli, et al. “First Results of an Experiment on Advanced Collimator Materials at

CERN HiRadMat Facility” IPAC13, Shanghai, China (2013)


https://indico.cern.ch/event/438866/contributions/1084917/


http://jacow.org/IPAC2015/papers/tupty001.pdf


http://jacow.org/IPAC2015/papers/thpf089.pdf

http://jacow.org/IPAC2015/papers/thpf089.pdf



http://dx.doi.org/10.18429/JACoW-IPAC2016-TUPMR054

http://dx.doi.org/10.18429/JACoW-IPAC2016-WEPMW006

http://accelconf.web.cern.ch/AccelConf/e06/PAPERS/TUODFI01.PDF





http://accelconf.web.cern.ch/AccelConf/hb2010/papers/mopd45.pdf

http://accelconf.web.cern.ch/AccelConf/hb2010/papers/mopd45.pdf

http://accelconf.web.cern.ch/AccelConf/e06/PAPERS/MOPCH091.PDF

http://accelconf.web.cern.ch/AccelConf/e06/PAPERS/WEXFI03.PDF

http://cds.cern.ch/record/1700455

http://cds.cern.ch/record/1700455



http://accelconf.web.cern.ch/AccelConf/IPAC2013/papers/thpfi064.pdf

http://accelconf.web.cern.ch/AccelConf/IPAC2013/papers/mopwo035.pdf

https://doi.org/10.1103/PhysRevSTAB.7.012801

https://doi.org/10.1103/PhysRevSTAB.7.012801

http://accelconf.web.cern.ch/AccelConf/hb2010/papers/tho1c05.pdf




[22] M. Cauchi et al. “High Energy Beam Impact Tests on a LHC Tertiary Collimator at CERNHiRadMat Facility” IPAC13, Shanghai, China (2013)

[23] “http://sixtrack.web.cern.ch/SixTrack/”[24] “https://github.com/SixTrack/”[25] “https://github.com/MERLIN-Collaboration/”




http://sixtrack.web.cern.ch/SixTrack/

https://github.com/SixTrack/

https://github.com/MERLIN-Collaboration/


AppendicesA GlossarySI units and formatting according to standard ISO 80000-1 on quantities and units are usedthroughout this document where applicable.

ATS Achromatic Telescopic SqueezingBPM Beam Position Monitorc.m. Centre of MassDA Dynamic ApertureDIS Dispersion suppressorESS Extended Straight SectionFCC Future Circular Collider

FCC-ee Electron-positron Collider within the Future Circular Collider studyFCC-hh Hadron Collider within the Future Circular Collider studyFODO Focusing and defocusing quadrupole lenses in alternating order

H1 Beam running in the clockwise direction in the collider ringH2 Beam running in the anti-clockwise direction in the collider ring

HL-LHC High Luminosity - Large Hadron ColliderIP Interaction Point

LHC Large Hadron ColliderLAR Long arcLSS Long Straight SectionMBA Multi-Bend Achromat

Nb3Sn Niobium-tin, a metallic chemical compound, superconductorNb-Ti Niobium-titanium, a superconducting alloyRF Radio Frequency

RMS Root Mean Squareσ RMS size

SAR Short arcSR Synchrotron Radiation

SSC Superconducting Super ColliderTSS Technical Straight Section


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