FLUKA studies on the radiation in the Point 5 Q6-Q7 area: Roman Pots, TCL6 and RR M. Brugger, F. Cerutti, L.S. Esposito, EN-STI-EET, CERN on behalf of the FLUKA team!! Acknowledgement for the valuable input: M. Deile
Summary from previous meeting Summary TCL4 aperture at 15 σ makes no significant difference respect to 10 σ with an even larger aperture, TCL4 would start to not intercept neutral debris: it could be considered not a big issue for D2-Q4, however a greater gradient could be expected in Q7 TCL6 is not necessary to protect Q6 or Q7 when RP are operated However, TCL6 installation might be advisable to substantially reduce losses in Dispersion Suppressor, independently from RP operation If TCL6 is eventually installed in Point 5, it should be installed also in Point 1 maximum power ~ 0.5 mw/cm3 power > 1.0 mw/cm 3 are reached L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!23 few slides extracted L.S. Esposito, from LHC that Collimation presentation Working Group have #168, been 20 added January as 2014 backup material!2
Summary from previous meeting Summary TCL4 aperture at 15 σ makes no significant difference respect to 10 σ with an even larger aperture, TCL4 would start to not intercept neutral debris: it could be considered not a big issue for D2-Q4, however a greater gradient could be expected in Q7 TCL6 is not necessary to protect Q6 or Q7 when RP are operated However, TCL6 installation might be advisable to substantially reduce losses in Dispersion Suppressor, independently from RP operation If TCL6 is eventually installed in Point 5, it should be installed also in Point 1 maximum power ~ 0.5 mw/cm3 power > 1.0 mw/cm 3 are reached all these considerations have been verified only with L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!23 respect to collision debris few slides extracted L.S. Esposito, from LHC that Collimation presentation Working Group have #168, been 20 added January as 2014 backup material!2
Summary from previous meeting Summary TCL4 aperture at 15 σ makes no significant difference respect to 10 σ with an even larger aperture, TCL4 would start to not intercept neutral debris: it could be considered not a big issue for D2-Q4, however a greater gradient could be expected in Q7 TCL6 is not necessary to protect Q6 or Q7 when RP are operated However, TCL6 installation might be advisable to substantially reduce losses in Dispersion Suppressor, independently from RP operation If TCL6 is eventually installed in Point 5, it should be installed also in Point 1 maximum power ~ 0.5 mw/cm3 power > 1.0 mw/cm 3 are reached all these considerations have been verified only with L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!23 respect to collision debris HC-LJ-EC-0033 for the infrastructure installation of TCL6s approved in October Nonetheless it is stated that the installation will proceed if "it is proved that they would bring benefits to the post-ls1 operation" few slides extracted L.S. Esposito, from LHC that Collimation presentation Working Group have #168, been 20 added January as 2014 backup material!2
Outline Nominal LHC operation evaluation TCL6 impact on RR possible mitigation with an iron Maze (like P7) Comparison with 2012 data RadMon TOTEM rate BLM!3
Beam-line w/o TCL6: collision debris 4 High energy hadron fluence 10 16 2 Q4 Q5 Q6 Q7 10 14 X [m] 0-2 10 12 10 10 10 8 [cm -2 / 100 fb -1 ] -4 10 7 /cm 2 150 170 190 210 230 250 270 distance from IP [m] Nominal LHC optics; proton-proton collision at 14 TeV c.o.m. energy (85 mb) High energy (>20 MeV) hadron fluence at beam height (±20 cm) 10 6!4
Beam-line with TCL6: collision debris 4 High energy hadron fluence 10 16 2 Q4 Q5 Q6 Q7 10 14 X [m] 0-2 10 12 10 10 10 8 [cm -2 / 100 fb -1 ] -4 10 9 /cm 2 150 170 190 210 230 250 270 10 6 distance from IP [m]!5
Beam-gas interaction @7TeV with TCL6 4 High energy hadron fluence 10 16 X [m] 2 0-2 Q4 Q5 Q6 Q7 10 14 10 12 10 10 10 8 [ cm -2 / 100 fb -1 ] -4 normalisation given by I ρ σp-h2 L T where I = 0.581 A/e ρ = 10 15 molecules/m 3 σp-h2 = 2 σp-p 76.5 mb, L = 108.9 m (from 160 m to 268.9) T = 100 fb -1 / 10 34 cm -2 s -1 = 10 7 s ~10 8 /cm 2 170 190 210 230 250 270 distance from IP [m] 10 6 contribution to RR fluence from beam gas is lower than the one from collision debris by a factor of few!6
Iron Maze mitigation effect 7
IRON MAZE (like Point 7) Iron maze Test region!8
Effect of the maze in the RR 4 High energy hadron fluence 10 16 2 Q4 Q5 Q6 Q7 10 14 X [m] 0-2 10 12 10 10 10 8 [cm -2 / 100 fb -1 ] -4 150 170 190 210 230 250 270 10 6 distance from IP [m] the maze effectiveness is limited!9
Maze effectiveness 4 High energy hadron fluence 50 X [m] 2 0-2 Q4 Q5 Q6 Q7 10 no_maze / MAZE 1-4 150 170 190 210 230 250 270 0.5 distance from IP [m] Iron maze protection rather limited in large part of the RR!10
Neutron fluence in a test region 10 17 neutron fluence in a RR test region 10 16 [cm -2 / 100.00 fb -1 ] 10 15 10 14 10 13 10 12 10 11 10 10 7+7 TeV p-p interactions TCL6 and Iron Maze only TCL6 no TCL6 1 mev 1 ev 1 kev 1 MeV 1 GeV 1 TeV The limited moderation effect of the maze seems not to justify its installation!11
2012 operation: RadMon, TOTEM rate, BLM 12
RADMON position in RR57!13
Normalisation for 4 TeV operation collision debris normalisation factor = LInt σ = 23.26 fb -1 75 mb beam-gas normalisation factor (limited to the contribution during stable beam) = <bunch population> #bunches ν TSB P_int where - <bunch population> is computed from luminosity (assuming ε = 2.4 μm, β* = 60 cm) - TSB = 73 day 10 hrs 52 mins - frequency = 11.2455 khz - P_int( σ, ρ(s) )!14
Beam gas profile atomic density [ m -3 ] 10 14 10 13 10 12 10 11 10 10 10 9 10 8 10 7 10 6 atomic density longitudinal profile H C O cumulative 0 50 100 150 200 250 distance from IP [m] 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 cumulative Computed by G. Bregliozzi for Point 1 Fill 2736-16/06/2012-17:20-1380 Bunches - 4 TeV - 373 ma (input data refers to the first 5 minute when the CCC declares Stable Beam)!15
Caveat: IR5 vacuum quality in sector 5-6 10-7 10-8 IR5 example of fill 2736 10-9 10-10 IR1 Unperturbed vacuum in 6R5 and 6L5: 5x10-10 10-9 mbar in 6R1 and 7R1 (ALFA): 3 5 x10-11 mbar!16
2012 operation with standard settings 10 15 2012 operation neutron fluence 10 14 [cm -2 / 23.26 fb -1 ] 10 13 10 12 10 11 10 10 10 9 10 8 Roman Pots in garage position TCL5 half gap = 3.55 mm 4 TeV proton debris: R5RM08S debris: R5RM09S beamgas: R5RM08S beamgas: R5RM09S 1 mev 1 ev 1 kev 1 MeV 1 GeV 1 TeV With gas density peaks of the order of 10 13-10 14 molecules/m 3, beam-gas contribution seems negligible!17
Contribution from collision debris only Hadron > 20 MeV [cm -2] RM08S RM09S FLUKA 6.1 10 8 3.0 10 7 DATA 4.56 10 8 (256 upsets) 4.32 10 7 (25 upsets) Normalised at total integrated luminosity in 2012 operation The agreement is within 30%!!!!18
TOTEM operation: fill 3288 Insertion 15 November: Overview TCL5 already at 60 sigma = 21 mm Reference time: 15 November 2012, 18:00 h Beam 1 Beam 2 N-H = XRPH.A6R5.B1 F-H = XRPH.B6R5.B1 F-H N-H N-H = XRPH.A6L5.B1 F-H = XRPH.B6L5.B1 F-T F-B N-T N-B Beam separation F-H N-H F-T F-B N-T N-B BLMEI.06R5.B1E10_XRP BLMEI.06L5.B2E10_XRP (RS09) Mario Deile After the beam separation L ~ 2.5 10 33 cm -2 s -1 10 32 cm -2 s -1 In the simulation, the case where only F-H station was operated is considered p. 24!19
Roman Pot rate 15.11.2012 RP Rate versus RP Distance Beam 1 (Sector 5-6) F-H TCL shadow Beam 2!20
Roman Pot rate 15.11.2012 RP Rate versus RP Distance Beam 1 (Sector 5-6) F-H TCL shadow Beam 2!20
Simple FLUKA estimate of the experimental rate Proton rate [Hz] 8 10 10 7 33 cm -2 s -1 L = 2.5 10 σ = 75 mb 20 MeV transport threshold FLUKA: protons TOTEM exp rate 6 10 5 10 4 10 3 10 0 5 10 15 20 25 30 35 40 45 X [mm] The proton rate is in a fairly nice agreement with the experimental points A more accurate estimate would need a detailed simulation of the detector response to all the particle species!21
BLM response: DATA F-H station @garage vs @14σ Q4 Q5 Q6 Q7 Luminosity drop Which is the reason of the increase here?!22
BLM response: before RP220m was operated BLM Dose Rate [Gy/s x10-6 ] 100 10 1 0.1 0.01 fill3288: TCL6 open @60 debris, RP @ garage beam gas, LSS profile, FH220m @14 DATA 0.001 before RP insertion and beam separation 190 210 230 250 270 Distance from IP5 [m] A "correct contribution from beam-gas interaction should be added to collision debris!23
BLM response: RP220m close @14σ BLM Dose Rate [Gy/s x10-6 ] 100 10 1 0.1 0.01 fill3288: TCL6 open @60 debris, FH220m @14 beam gas - RP220m spike DATA 0.001 at pressure maximum 190 210 230 250 270 Distance from IP5 [m] Constant gas profile equivalent to 8 10 16 H2 molecules/m 3 over 5 m and centred around the RP position can well reproduce the BLM pattern!24
15.11.2012 Comparison BLMs & Beam Vacuum Sector 5-6 Sector 4-5 BLMEI.06R5.B1E10_XRP BLMQI.06R5.B1E30_MQML BLMQI.06R5.B1E10_XRP_MQML BLMQI.06R5.B2I30_MQML BLMQI.06R5.B1E20_MQML BLMQI.06R5.B2I20_MQML BLMQI.06R5.B2I10_MQML From this pressure data, one can conclude that there might be an important vacuum gradient around RP station VGPB.235.6R5.B.PR (4 m downstream of Far: Q6 entrance) VGI.77.6R5.B.PR (6 m upstream of Near) A spike of ~ 10 17 H2 molecules/m 3 would then correspond to few 10-6 mbar VGPB.2.6R5.B.PR (14 m upstream of Near: Q5 exit) VGPB.4.6R5.B.PR (14 m upstream of Near: Q5 exit) Mario Deile p. 26!25
peak power density [mw/cm 3 ] Peak power profile in Q6-Q7 from RP-induced pressure spike 1 0.1 0.01 Q6 4.0 TeV proton 8x10 16 H 2 /m 3 pressure spike peak power density [mw/cm 3 ] 1 0.1 0.01 Q7 4.0 TeV proton 8x10 16 H 2 /m 3 pressure spike 0.001 226 228 230 232 Distance from IP [m] 0.001 259 261 263 265 267 269 Distance from IP [m] normalisation is I ρ σp-h2 L where I = 0.270 A/e ρ = 8 10 16 molecules/m 3 σp-h2 = 2 σp-p 2 37.0 mb L = 5.0 m that gives ~ 5 10 6 interactions/s At 7 TeV a naive extrapolation can give 1 mw/cm 3 peak power density!26
Conclusions TCL6s would considerably rise the radiation level in the RR at ~ 10 9 high-energy hadrons (>20 MeV) / cm 2 / 100 fb -1, that is still to tolerable for the equipment in there Installation of an iron maze like P7 is not justifiable in term of its effectiveness Evaluation for the HL-LHC era still need to be assessed with respect to radiation in the RR after Matching Section layout definition Very nice agreement with RadMon measurement, good agreement with TOTEM rate Observed BLM rises for RP insertion at 4 TeV can be explained by a local pressure spikes of about 10 17 equivalent H2/m 3 (~10-6 mbar) Extrapolation at 7 TeV of the effect of a gas spike of that order gives 1 mw/cm 3 peak power density in the Q7 At 7 TeV, the TCL6 role to protect Q6-Q7 in this scenario can be investigated (nonetheless TOTEM upgrade should much improve the vacuum level)!27
Additional slides 28
TCL@15σ peak power density [mw/cm 3 ] 0.3 0.1 0.01 D2 and Q4 7.0 TeV proton @ L = 10 34 cm -2 s -1 Frascati 2012 15 10 TCL4 at 15 σ provides a sufficient protection of Matching Section elements N.B. Frascati 2012: MADX v6.500 with crossing angle at IP and orbit correctors switched off! No TCL5 on the line peak power density [mw/cm 3 ] 0.001 0.3 0.1 0.01 0.001 152 157 162 167 172 Distance from IP [m] Q5 7.0 TeV proton @ L = 10 34 cm -2 s -1 Frascati 2012 15 10 Q6 7.0 TeV proton @ L = 10 34 cm -2 s -1 Frascati 2012 15 10 Q7 7.0 TeV proton @ L = 10 34 cm -2 s -1 Frascati 2012 15 10 0.0001 194 196 198 200 Distance from IP [m] 226 228 230 232 Distance from IP [m] L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013 259 261 263 265 267 269 Distance from IP [m]!5 29
Effect of RPs peak power density [mw/cm 3 ] 0.4 0.3 0.2 0.1 Q6 7.0 TeV proton @ L = 10 34 cm -2 s -1 w/o RPs RP 1 & 2 RP 4 peak power density [mw/cm 3 ] 4 0.4 10 0.6 0.5 0.3 0.2 0.1 Q7 7.0 TeV proton @ L = 10 34 cm -2 s -1 w/o RPs RP 1 & 2 RP 4 0 226 228 230 232 Distance from IP [m] 0 259 261 263 265 267 Distance from IP [m] Although there is a significant increase in the peak power density on Q6 and Q7, figures are below 1 mw/cm 3 L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!14 30
TCL6 protection of MS peak power density [mw/cm 3 ] 0.4 0.3 0.2 0.1 Q6 7.0 TeV proton @ L = 10 34 cm -2 s -1 RP 1 & 2 RP 4 TCL6 @ 10 peak power density [mw/cm 3 ] 0.6 0.5 0.4 0.3 0.2 0.1 Q7 7.0 TeV proton @ L = 10 34 cm -2 s -1 RP 1 & 2 RP 4 TCL6 @ 10 0 226 228 230 232 Distance from IP [m] 0 259 261 263 265 267 Distance from IP [m] TCL6 reduced the peaks by about a factor 2 3 L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!16 31
DS protection by TCL6 peak power density [mw/cm 3 ] 10 1 10 0 10-1 10-2 10-3 10-4 Dispersion Suppressor 7.0 TeV proton @ L = 10 34 cm -2 s -1 RP @ garage RP @ garage and TCL6 @ 10 Q8 Q9 10-5 260 270 280 290 300 310 320 330 340 350 Distance from IP [m] MB rebinned due to the lack of statistics TCL6 adsorbs about 20 W at nominal luminosity L.S. Esposito, LHC Collimation Working Group #163, 2 September 2013!21 32