1 considerations on warm magnet measured doses 2012 september 3rd francesco cerutti for the team key...

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CONSIDERATIONSON WARM MAGNET MEASURED

DOSES

2012 September 3rd

Francesco Cerutti

for the team

key contributions by

TE-MSC Davide Tommasini and Pierre Thonet

DGS-RP Julia Trummer, Christophe Tromel, Frederic

Jaquenod

Markus Brugger Luigi Esposito

2012 September 3rd F. Cerutti CWG#147 2

• losses sharing (additional passive absorber in P3?)

• losses scaling (warm magnet lifetime)

• measurements vs expectations

• reasons for caution

OUTLINE

2012 September 3rd F. Cerutti CWG#147

2012 (until June) from the TCP HL dosimeters

Proton losses in P3 of the order of [several] % wrt P7 tight collimator

settings

beam 1 / beam 2 ratios consistent with 2011

measured MQW doses reflect the P3 vs P7 sharing 6.5 kGy vs 60 kGy (~10%) for beam 1

and the lack of TCAPC in P3: 2.5 kGy vs 45 kGy (~5%) for beam 2

3

2011 from the TCP BLMs

Proton losses in P3 and in P7 of the same order (within a factor of 3)

beam 1 / beam 2 ~ 2 in P3 and ~ 0.5 in P7

LOSSES SHARING

>

?

P3 P7

measured MBW doses reflect the P3 vs P7 sharing: 9-16 kGy vs 100-400 kGy (~5%) for beam 1

2-5 kGy vs 330-490 kGy (~1%) for beam 2

additional passive absorber in P3 not justified with this P3 vs P7 sharing, BUT

the latter (dramatically) depends on the collimator settings (see 2011)


2012 (until June) from BCT & LUMI (injected ― dumped ― collided)

1.45 [1.7] 1015 beam 1 [2] protons lost (in the collimators) for ~7fb-1 per experiment

LOSSES SCALING

not the factor of 2?tentative extrapolations (assuming linearity between losses and luminosity, despite the energy upgrade):

1.1 1016 for 50fb-1 (one year?) projected MBW dose: 5 MGy including a factor of 2 for 7TeV operation

projected MQW dose: 0.7 MGy

6.5 1016 for 300fb-1 (until LS3??) projected MBW dose: 30 MGy

projected MQW dose: 4-5 MGy


100-400 kGy

60 kGy

one would getby normalizing to1.4 1015 beam 1 protons lost in P7

IP7TCP.D C B 6L7.B1

v h s

MBW

MQW

beam 1

s

TCAP

5

assuming a horizontal halo

for 1.15 1016 lost protons per beam

MEASUREMENTS VS EXPECTATIONS

peak dosefor intermediatecollimator settings

taking for 4 TeVwith tight settings

2 250kGy

0.5 60 kGymeasured


RADIAL AND AZIMUTHAL GRADIENT (MBW)

M. Brugger, Jun 2008

397.5 kGy

> 500 kGy

106.3 kGy

119.8 kGy

J. Trummer

beam 1 entering

x

beam 1 pointing outwards

0.2h beam lifetime

250kGy

250kGy

~3 MGy

assuming a horizontal halo

0.5mm x 0.5mm transverse

resolution

1cm x 1cm transverse

resolution


fallen off(487.3 kGy)

25.7 kGy

100.4 kGy

59.6 kGy

7

RADIAL AND AZIMUTHAL GRADIENT (MQW)

J. Trummer

beam 1 entering

x 60kGy

1cm x 1cmtransverse resolution

~ MGy0.5mm x 0.5mm transverse

resolution

beam 1 pointing outwards

x


REASONS FOR CAUTION

252.7 kGy

289.7 kGy171.8 kGy

26.5 kGy

J. Trummer

factor 1.7 ?

factor 10 ??

(much more) controlled loss term: p-p collision debris (vertical crossing)

P1

Conversely, BLMs indicates the expected left-right symmetry


CONCLUSIONS Measured doses on the MQWs in Point 3 do not exceed 10% of the ones in Point 7

for the 2012 Feb-Jun collimator settings implying a (strongly) asymmetric sharing of losses

(in P3 few-several percent of P7). Different operation conditions can move the MQW weak point

in P3, with

peak doses – for the same number of integrated losses – possibly higher than those measured in

P7

Doses on the D1 MBWs in P1 (and P5) are of the same order as in the collimation region

400 kGy on the MBW and 50 kGy on the MQW for 1.5 1015 lost protons (corresponding to 7fb-

1)

give a projection of 30 MGy on the MBW and 5 MGy on the MQW for 6.5 1016 lost protons (300fb-

1), at

the levels of the expected failure thresholds. These estimates have to be intended in terms of

orders of

magnitude due to the uncertainties in measurements and losses extrapolation (barely within a

factor of 2) A quite reasonable consistency with predictions from simulations was found (though this,

contrary to others

already available, is far from being a clean benchmarking case)

A hard limit of 0.5 MGy on the HLDosimeters’ reading would imply their timely

replacement. Calibration

up to 5 MGy viable?


h

h

beam 1

10

IP3

1 considerations on warm magnet measured doses 2012 september 3rd francesco cerutti for the team key...

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