1

PAST ESTIMATIONSON THE ROLE OF PASSIVE

ABSORBERSFrancesco Cerutti

for the team

2012 June 4th

2012 June 4th F. Cerutti CWG#142 2

• warm magnets and passive absorbers

• IR7 betatron cleaning

• IR3 combined cleaning

• considerations for IR3 momentum cleaning

OUTLINE

2012 June 4th F. Cerutti CWG#142 3

IP7TCP.D C B 6L7.B1

v h ss

MBW

MQW

TCAPA

beam 1

2012 June 4th F. Cerutti CWG#142 4

[M. Karppinen quoted

by M. Brugger

@CWG#89]

for the MQW

IN IR7

2012 June 4th F. Cerutti CWG#142 5

IR7 BETATRON CLEANING

F. Cerutti @CWG#108 for intermediate collimator

settings

BEAM PIPE

HEATING

beam 1 horizontal

halo

COIL

DETERIORATION

for 1.15 1016

lost protons per beam

peak dose

TCAPA B

CTCAPA B

C

with 3 passive absorbers per

beam

2012 June 4th F. Cerutti CWG#142 6

IR7 BETATRON CLEANING

actual layout with metallic collimator

element peak [MGy] stat. err. [%] peak [MGy] stat. err. [%]

MQWA.E5L7 0.9 10 0.3 20

MQWA.D5L7 0.5 10 0.1 15

SLAC

prototype

[L. Lari]

with an additional metallic collimator

for 1.15 1016 lost protons per beam at 7 TeV (beam 1 horizontal halo)

F. Cerutti Conceptual Design Review Phase II Collimation April

2009

2012 June 4th F. Cerutti CWG#142

hv

hv

with 1 passive absorber per beam

and additional vertical collimators

7

IR3 COMBINED CLEANING

M. Mauri R2E Meeting July 17th

2008

for 1016 lost protons per beam at 7 TeV (beam 1 horizontal halo)

beam 1

2012 June 4th F. Cerutti CWG#142 8

IR3 COMBINED CLEANING

TCP. 6 MBW.C B A 6TCAP

A

MQWA.E D

5

TCAP

C

TCAP

B

MQWA.C

5

IP3TCSG. 5

vh vh

with two additional passive absorbers per beam:

L. Lari CERN-ATS-2001-117 (IPAC

2011)

peak dose [MGy]no additional

TCAPswith additional

TCAPs

element\beam energy

7 TeV 3.5 TeV 7 TeV 3.5 TeV

MQWA.E5L3 7.6 2.8 5.1 1.2

MQWA.D5L3 3.8 1.6 3.1 1.4

MQWA.C5L3 4.8 1.6 2.9 1.0

for 1016 lost protons per beam (beam 1 vertical halo)

high peak also on MQWA.E4R3, just downstream of a pair of (h-v)

collimators

2012 June 4th F. Cerutti CWG#142 9

how many losses? [see Mike’s talk]

Over 2011, the TCP BLM in P3 gives almost a factor of 2 difference between beam 1 and

beam 2

Looking at the P3/P7 sharing, wrt to the first TCP BLM in P7 (vertical collimator quite

doubtful assumption), one gets a factor of 3.5 for beam 1 and a factor of 1.15 for beam 2

FLUKA geometry of IR3 rapidly available, thanks to the new FLUKA Element DataBase and

LineBuilder

which loss maps? (and corresponding collimator settings)

readings of passive dosimeters installed 4 months ago in the locations suggested on purpose

(attached to the beam pipe and the MBW external coils, being not accessible the concerned

internal MQW coils), are expected to provide during LS1 relevant data and related

benchmarking opportunities

IR3 MOMENTUM CLEANING

[data kindly extracted by P. Mala and M.

Calviani]

2012 June 4th F. Cerutti CWG#142 10

CONCLUSIONS

Guessed peak dose values in the MQWA.E-C5 L3.B1/R3.B2 (and possibly MQWA.E4

R3.B1/L3.B2) are not reassuring

Dedicated shower calculations for the standard IR3 momentum cleaning scenario

were not performed, and can in principle – after clarifying loss maps and

normalization assumptions - be launched (manpower shortage will be overcome by

the autumn)

Dedicated measurements have been put in place (with Pierre Thonet, Davide

Tommasini, Julia Trummer) and dosimeter reading could be carried out at LS1

The activation of the area (see Stefan’s talk) challenges a late TCAP installation