SECONDARY PARTICLE SHOWERS AND ENERGY DEPOSITION

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SECONDARY PARTICLE SHOWERSAND ENERGY DEPOSITION

Francesco Cerutti

team (EN-STI)

HL-LHC Kick off Internal Meeting

2011 Apr 15th

HL-LHC Kick off Internal Meeting 2011 Apr 15th F.Cerutti Secondary particle showers and energy deposition

radiation sources i. collision debris(~ luminosity)

ii. beam losses on the tertiary collimators [ ] iii. beam – residual gas interaction

(~ beam intensity) (~ beam intensity and gas density)

2

WP10 SCOPE [I]

(synergic) overlap with other

WP/activity

HL-LHC Kick off Internal Meeting 2011 Apr 15th F.Cerutti Secondary particle showers and energy deposition 3

issues

• quench

• cooling

• material damage (coils, sensitive equipment ...)

• radiation to electronics (SEE) [ ]

• working conditions of instrumentation [ ]

• background to experiments [ ]

• activation [ ]

warm (TAS, TAN) and cold absorber design

in the following

an overview of the scenario as presently pinned

down

through a lot of work by A. Mereghetti

(past EN-STI fellow)

in fruitful collaboration with TE-MSC

(in particular E. Todesco and E. Wildner)

and thanks to many LIUWG colleagues

WP10 SCOPE [II]

(synergic) overlap with other

WP/activity


THE COLLISION DEBRIS [I]

7 TeV p + 7 TeV p

beyond the present TAS (absorbing ~150W at

L=L0=1034cm-2s-1)

about 2.5% of the interaction products

and 35% of 14TeV, i.e. 630W at L=L0

with a 50mm aperture TAS

about 3.5% of the interaction products

and almost 40% of 14TeV, i.e. 3.5kW at

L=5L0

FLUKA (DPMJET)


THE COLLISION DEBRIS [II]

FLUKA model of the present triplet in P1

spectra evolution through the triplet

striking capturing by the quadrupole magnetic field

LHC Project Report 1167 (2008)

204 T/m

Q1 Q2b Q3Q2a

The TAS provides a significant protection for Q1 only

(and reduces the background to the experiments)


IMPACT ON THE TAS-D2 REGIONmW/cm3 for

L=2.5L0

vertical plane

horizontal plane

peak of 840 mW/cm3

(i.e. 6 GGy/3000fb-1)

1.1kW

1kW

TAN at L=5L0

x=2.5mm x y=2.5mm

x z=5cm scoring grid

neutral

charged


(NOT) QUENCHING THE TRIPLET

Total lengt

h (m)

Gradient(T/m)

Aperture(mm)

36.2 156 90

40.7 125 115

43.6 112 130

45.7 104 140

the longer, the better

0

5

10

15

20

25

20 30 40 50 60Distance from IP [m]

Pea

k P

ower

[m

W/c

m3]

130 mm Phase II

90 mm Phase I

0

5

10

15

20

25

20 25 30 35 40 45 50 55 60 65 70

Peak

pow

er [m

W/c

m3 ]

Distance to IP (m)

90 mm

115 mm

130 mm

140 mm

idea and numbers by E. Todesco

(L=2.5L0)

55mm TAS aperture225 urad half crossing angle vertical crossing

same gradient, larger aperture(“Phase II”)

results and plotsby E. Wildner


SHIELDING OPTIONS•ideally a continuous liner (here 3mm tungsten, green curve) is quite effective

• the role of the interconnections! jump at the Q2a front face with liner

limited to the first element, blue curve

• as an alternative, a thick liner in Q1 (here 13mm stainless steel, purple curve) casting a shadow over Q2a

• end plates of limited help

assumed as totally absorbing! blue curve

L=2.5L0130mm coil aperture

Q1

Q1

Q2a

Q2a

Q2b Q3

Q2b Q3


110mm coil aperture

Q1 Q2a

Q2b

Q3

10mm thick additional liner

75mm residual aperture

mW cm-

3

8.05 m from the IP face 0.25 m from the IP face

1.25 m from the IP face 9.55 m from the IP face

FDDF

L=2.5L0

CROSSING SCHEME & TRIPLET CONFIGURATION

total power at L=5L0: 800W @ 1.9 K + 200W in the absorber & beam screen

HL-LHC Kick off Internal Meeting 2011 Apr 15th F.Cerutti Secondary particle showers and energy deposition

CROSSING ANGLE/PLANE

vertical crossing

L=2.5L0

10

x

y

z

0 vs 142.5 vs 220 urad (half)


USE OF INCREASING APERTURES

45 120 140 180(coil) aperture [mm]

(peak values depend on the coil azimuthal position!)

worse case

increasing aperture effect

10mm Cu liner effect

L=2.5L0

sextupole

skew quadrupo

le

horizontal dipole

corrector

vertical dipole corrector


MATERIAL DAMAGE [I]

r=2.5mm x =2o x z=10cm scoring grid

r=2.5mm x =60o x z=10cm scoring grid

MGy per

100 fb-1

coil insulatormW/cm3 for

L=2.5L0

dose radial profile

150 MGy per 3000 fb-1

vacuum gaskets

1.5 MGy per 3000 fb-

1


MATERIAL DAMAGE [II]

tracklength fraction [%]

photons 88

electrons/positrons 7

neutrons 4.5

pions 0.45

protons 0.15

1 MeV

particle fluence over the inner cable

200mm coil aperture

photons

positive pions

neutrons

[cm-2 per 1000 fb-1]

peak of1017 neutrons cm-2/3000

fb-1

DPA calculation


RADIATION TO ELECTRONICSpredicted high energy hadron fluence from 7 TeV p + 7 TeV p collisions in

Point 1

[units of 106 cm-2 per 100 fb-

1]

UL16 (14): 109 – 1010 UJ16 (14): 1010 – 5 1011 RR17 (13): 109 – 1011 per 3000 fb-1

beam – gas contribution(H2 equivalent density of 1015

molecules/m3,nominal beam intensity along 100 days per

year)of the same order as

the one from beam-beam collisions

RR17: ratio between beam - gas and beam - beam contributions

TCL


CONCLUDING REMARKS

on the basis of the iterative evolution of the HL-LHC layout and optics (magnetic strengths,

crossing angle), a major effort will be required for setting up a suitable geometry model,

extending from the experimental vacuum chamber up to the Dispersion Suppressor, in order

to assess energy deposition / fluence values and investigate the effectiveness of possible

design solutions

estimates – especially for point quantities – are affected by systematic uncertainties (due to

the machine description and the critical dependence on few collision products emitted

inside a tiny solid angle). Therefore reasonable margins should never be forgotten, and

relative comparisons between different configurations have to be considered as inherently

carrying a stronger reliability than absolute predictions, provided that a consistent

simulation framework is constantly used

in parallel, following the underway LHC operation, simulation benchmarking is happily

ongoing

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SECONDARY PARTICLE SHOWERS AND ENERGY DEPOSITION