Alessandro Bertarelli - CERN · 10e-10 torr 10e-9 torr 10 torr kg/m³ @ Tm Bi 544 271 -4 24 806 83 208.98 10050 5.90E-04 0.012 Ga 303 30 493 538 1677 31 69.72 6095 6.75E-04 0.032

A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007

LHC Collimations Phase II:Preliminary Design meeting

LHC Collimation

Phase II

SpecificationMeeting

8th February, 2008

CERN Geneva

Alessandro Bertarelli1

1TS department – Mechanical and Material Engineering GroupCERN, Geneva


Limits of Phase I Collimators

1. Resistive ImpedanceAccording to RF simulations, Phase I Collimator Impedancewould limit LHC beam intensity to ~40% of its nominal value!

2. Cleaning efficiencyCleaning efficiency (i.e. ratio escaping protons / impacting protons) should be better than 99.9% to limit risks of quench at SuperConducting triplets


Phase II Design GuidelinesTo overcome this limit, new secondary collimators with an improved jaw material /design should complement the existing system (Phase II)

To achieve the new goal, we need a magic material having:1. High electrical conductivity to improve RF stability2. High thermo-mechanical stability and robustness, i.e.:

a. Low Coefficient of Thermal Expansion b. High Yield Strengthc. Low Young’s Modulusd. High Thermal Conductivitye. High Specific Heat

3. High density (high Z) to improve collimation efficiency (i.e. intercepted and stop a higher number of particles), possibly depending on final jaw length …

4. Strong resistance to particle radiation …


Electrical conductivity [1/Electrical conductivity [1/ΩΩm] m] Directly related to resistive impedance

SteadySteady--state geometrical stability parameter [W/m]state geometrical stability parameter [W/m]Indicates power required to induce a given deflection

Transient Thermal Shock parameter [J/kg]Transient Thermal Shock parameter [J/kg]Gives an indication of the highest acceptable deposited energy per unit mass during a beam impact before damage occurs

Mass density [kg/mMass density [kg/m33]]Related to cleaning efficiency

Phase II Collimator Materials

γ

ραk

Relevant figures of merit:

ανσ

Ecpy )1( −

ρ


Phase II Collimator Materials

My strong Assumption:Max Integrated

Energy on a cross-section

independent of material (assuming infinite jaw length)


Phase II Collimator MaterialsHow Geometrical Stability Parameter is obtained:

αραρ

ρ

ααρ

kek

ey

keBT

BTydAyT

Iy

B

BA

÷⇒÷′′

÷Δ

Δ=Δ=′′= ∫

max

)(1


Phase II Collimator MaterialsHow Thermal Shock Parameter is obtained:

[ ] [ ]

ανσ

νασ

ρ

νασ

Ec

ec

eE

ckgJe

cmJUT

TE

p

p

pp

)1()1(

//

1

maxmax

maxmax

max3

maxmax

maxmax

−=⇒

−=

⇒==Δ

−Δ

=


Phase II Collimator MaterialsGeometrical stability parameter (2) vs. Transient Shock Parameter

Silicon Carbide

SiC Accuratus

SiC Kyocera

Molybdenum

Tungsten

Silicon Nitride

Inermet 170

CuCrZr

Beryllium

Aluminum (6201-T81)

Graphite (R4550)

Diamond-based Cu (80% C)

Diamond-based Al (80% C) Carbon/Carbon (AC150 K)

Glidcop AL-15

Diamond-based Ag (Plansee)

Diamond-based Ag (80% C)

AlBeMet

Aluminum Nitride

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.00E+04 1.00E+05 1.00E+06 1.00E+07

Transient Shock Parameter [J/kg]

Geo

met

rical

Sta

bilit

y Pa

ram

eter

[W

m2/

kg]


Phase II Collimator MaterialsGeometrical stability parameter vs. Electrical Conductivity

Inermet 170

Tungsten

CuCrZr

Beryllium

Aluminum (6201-T81)

Graphite (R4550)

Diamond-based Cu (80% C)Diamond-based Al (80% C)

Carbon/Carbon (AC150 K)

Glidcop AL-15

OFE- Copper

Diamond-based Ag (Plansee)

Diamond-based Ag (80% C)

AlBeMet

Molybdenum

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08

Electrical Conductvity [S/m]

Geo

met

rical

Sta

bilit

y Pa

ram

eter

[W

/m]


Phase II Collimator MaterialsMass density [kg/m3]

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Carbon/C

arbon (A

C150K

)

Graphite

(R45

50)

Glidco

p AL-15

OFE-Copper

CuCrZr *

Berylliu

m

Aluminum (620

1-T81

)

Diamond-bas

ed C

u (80%

C)

Diamond-bas

ed A

l (80%

C)

Diamond-bas

ed A

g (Plan

see)

Diamond-bas

ed A

g (80%

) **

AlBeM

et

Aluminum Nitr

ide

Silicon C

arbide

SiC K

yoce

raSiC

Acc

uratus

Tungsten

Molybden

umInerm

et 17

0Silic

on Nitr

ide


Liquid metals compatible with UHV

303 ©

430 ©


912 ©

505 ©


Candidate liquid metals

GaGa, In and , In and SnSn havehaverelatively low melting temperature (<250 relatively low melting temperature (<250 °°C),C),low low PvapPvap at Tm (< 10eat Tm (< 10e--10 10 torrtorr) and ) and give a heating margin of >200 K from melting to temp. of give a heating margin of >200 K from melting to temp. of PvapPvap = 10e= 10e--10 10 torrtorr

To be studiedTo be studiedAlloysAlloysActivation dangerActivation dangerCircuit materials for chemical compatibilityCircuit materials for chemical compatibilityThermal propertiesThermal propertiesPhysical properties for liquid curtain or filmPhysical properties for liquid curtain or filmAvailability Availability

Tm (K) Tm (°C) Z A ρ, Density A 1/3 / ρ 1 / Z10e-10 torr 10e-9 torr 10 torr kg/m³ @ Tm

Bi 544 271 -4 24 806 83 208.98 10050 5.90E-04 0.012Ga 303 30 493 538 1677 31 69.72 6095 6.75E-04 0.032In 430 157 247 286 1310 49 114.82 7020 6.92E-04 0.020Li 454 181 -2 26 716 3 6.94 512 3.73E-03 0.333Sn 505 232 347 395 1635 51 118.69 6990 7.03E-04 0.020

Interaction length param.

radiation length param.

DT m to … (K)


Phase II CollimationPreliminary R&D activity on materials – organization of a working group

…probably this “magic” material does not exist…we should focus our attention on a mixed approach:

NEW MATERIAL

NEW DESIGN

GOAL: identification of new suitable material(s) and/or jaw assembly integrated design


360º Jaw Concept

Possible Advantages1. Increase of collimation efficiency (Particles

are intercepted on 180º to 360º)…2. Robustness (a new collimation slit can be

used after accidental beam losses)…3. Geometric stability is improved by pressing

the jaws one against the other

Possible Disadvantages1. Loss of 1 dof (one can play with geometry of

collimation pipes)…2. Minimum aperture is fixed3. Impedance??...

Documents

Alessandro Bertarelli - CERN · 10e-10 torr 10e-9 torr 10 torr kg/m³ @ Tm Bi 544 271 -4 24 806 83 208.98 10050 5.90E-04 0.012 Ga 303 30 493 538 1677 31 69.72 6095 6.75E-04 0.032