1. 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

2. 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

3. 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 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 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)

4. 2012 September 3rd F. Cerutti CWG#147 4 2012 (until June) from BCT & LUMI (injected ― dumped ― collided) 1.45 [1.7] 10 15 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 10 16 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 10 16 for 300fb -1 (until LS3??) projected MBW dose: 30 MGy projected MQW dose: 4-5 MGy

5. 2012 September 3rd F. Cerutti CWG#147 100-400 kGy 60 kGy one would get by normalizing to 1.4 10 15 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 1.15 10 16 lost protons per beam MEASUREMENTS VS EXPECTATIONS peak dose for intermediate collimator settings taking for 4 TeV with tight settings 2250kGy 0.560 kGy measured

6. 2012 September 3rd F. Cerutti CWG#147 6 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 ~3 MGy assuming a horizontal halo 0.5mm x 0.5mm transverse resolution 1cm x 1cm transverse resolution

7. 2012 September 3rd F. Cerutti CWG#147 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 1cm transverse resolution ~ MGy 0.5mm x 0.5mm transverse resolution beam 1 pointing outwards x

8. 2012 September 3rd F. Cerutti CWG#147 8 REASONS FOR CAUTION 252.7 kGy 289.7 kGy 171.8 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

9. 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 1.5 10 15 lost protons (corresponding to 7fb -1 ) give a projection of 30 MGy on the MBW and 5 MGy on the MQW for 6.5 10 16 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?

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