1 CONSIDERATIONS ON WARM MAGNET MEASURED DOSES 2012 September 3rd Francesco Cerutti for the team key contributions by TE-MSCDavide Tommasini and Pierre Thonet DGS-RPJulia 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# (until June) from the TCP HL dosimeters Proton losses in P3 of the order of [several] % wrt P7tight 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 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 kGy (~5%) for beam kGy vs 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 September 3rd F. Cerutti CWG# (until June) from BCT & LUMI (injected ― dumped ― collided) 1.45 [1.7] 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): for 50fb -1 (one year?) projected MBW dose: 5 MGy including a factor of 2 for 7TeV operation projected MQW dose: 0.7 MGy  for 300fb -1 (until LS3??) projected MBW dose: 30 MGy projected MQW dose: 4-5 MGy

2012 September 3rd F. Cerutti CWG# kGy 60 kGy one would get by normalizing to beam 1 protons lost in P7 IP7 TCP.D C B 6L7.B1 v h s MBW MQW beam 1 s TCAP 5 assuming a horizontal halo for lost protons per beam MEASUREMENTS VS EXPECTATIONS peak dose for intermediate collimator settings taking for 4 TeV with tight settings 2250kGy kGy measured

2012 September 3rd F. Cerutti CWG#147 6 RADIAL AND AZIMUTHAL GRADIENT (MBW) M. Brugger, Jun kGy > 500 kGy kGy kGy J. Trummer beam 1 entering x beam 1 pointing outwards 0.2h beam lifetime 250kGy ~3 MGy assuming a horizontal halo 0.5mm x 0.5mm transverse resolution 1cm x 1cm transverse resolution

2012 September 3rd F. Cerutti CWG#147 fallen off (487.3 kGy) 25.7 kGy kGy 59.6 kGy 7 RADIAL AND AZIMUTHAL GRADIENT (MQW) J. Trummer beam 1 entering x 60kGy 1cm x 1cm transverse resolution ~ MGy 0.5mm x 0.5mm transverse resolution beam 1 pointing outwards x

2012 September 3rd F. Cerutti CWG#147 8 REASONS FOR CAUTION kGy kGy 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

2012 September 3rd F. Cerutti CWG#147 9 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 lost protons (corresponding to 7fb -1 ) give a projection of 30 MGy on the MBW and 5 MGy on the MQW for 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?

2012 September 3rd F. Cerutti CWG#147 h h beam 1 10 IP3