Betatron cleaning in IR3: results of FLUKA calculations. Fluka team

Transcription

1 Betatron cleaning in IR3: results of FLUKA calculations Fluka team R2E Meeting, July 17 th 2008

2 Goal of the study Verify the impact of the optional temporary functional move of the betatron cleaning to IR3 Outline: Description of the scenario considered Results: Warm section (dose to warm magnets) Cold section (peak power density in cold magnets) Superconducting link cable (peak power density) Dose to cables High-energy hadron fluence in UJ33 and UP33 due to beam-gas interaction, and estimation of level due to collimation Conclusions

3 Betatron cleaning in IR3: Scenario 2 LHC optics unchanged Four vertical secondary collimators are placed in the location of the phase 2 secondaries and one vertical primary collimator is placed in the location of the phase 1 scraper. Used settings: TCP (hor/ver) at 6s, TCS (hor/ver) at 7s TCLA(hor/ver) at 10s FLUKA simulations use a loss map (provided by R.Assman et. al.) with the following set-up: Beam 7 TeV Horizontal halo Nominal losses Normalization factors: Loss rate of 4.3E11 p/s (0.2 h beam lifetime, nominal intensity) Annual losses: 1E16 p/y Scenario description

4 M M Warm section Normalization: 1E16 p/y MGy/y Stat. Error MBW.C6L % MBW.B6L % MBW.A6L % MQWA.E5L % MQWA.D5L % MQWA.C5L % IR7: MBW.B6L 3.3 MGy/y MQW.E5L 0.9 MGy/y

5 Cold section Normalization: 4.3E11 p/s Element Peak Error [mw/cm3] % MQ.7R - MQ.8R % MQ.9R % MQ.10R % MQ.11R % MQ.12R - MQ.13R % MB.A8R % MB.B8R % MB.A9R % MB.B9R % MB.A10R % MB.B10R % MB.A11R % MB.B11R % MB.A12R % MB.B12R % MB.C12R % MB.A13R % MB.B13R % MB.C13R % TCPs IP UJ33 Peak in MQ.11R MQ.11R Statistical error of the second step of the simulation. To reduce run time a two step approach has been followed: Step 1: mapping of protons entering the DS with a fast simulation (EM cascades disabled, etc.) Step 2: protons obtained from step 1 are tracked with a full simulation in the cold section.

6 Superconducting link cable Liquid helium Copper Copper Steel Position1

7 Superconducting link cable Possibly statistics Normalization: 4.3E11 p/s

8 Dose to cables Normalization: 1E16 p/y

9 Normalization: High energy hadron fluence in UJ33 and UP33 due to beam-gas interaction Nominal current (3.68E+18 p/s) H 2 density: 1E+15 molecules/m full days of operation per year Loss rate: 4.1E11 p m -1 y -1 Very conservative Results: Attenuation factor in UP33: ~10 4 Hadron UP33 entrance due to beam gas: 10 9 cm -2, inside of the UJ ~10 5 cm -2 From the beam1 loss map, the respective fluence is obtained from the mirrored position of the UP entrance (z=~22000 cm) due lo losses on collimators. The value obtained is ~10 10 cm -2. Taking into account the attenuation in UP, we expect a fluence inside of the UJ ~10 6 cm -2 (This value is consistent with the one stated by Igor Kurotchkin, November 2005)

10 Results consistent with IR7 Peak power deposition in superconducting link cable seems quite high (~10-15 mw/cm 3 ): Check the real quench limit for the cable Dose to cables is fully consistent with previous RP calculations (peak of 50 kgy/y). No problems of cable lifetime expected. Beam gas interaction is not a problem for electronics installed in UJ33 High energy hadron fluence in UJ33 seems not to be a problem (~10 6 cm -2 ), but better to check for cryo installations Conclusions Given the probable differences in past and present assumptions the observed mismatch by a factor of 2-3 between MARS (Protvino) and FLUKA results is largely within the expected uncertainties However, for a better understanding it is recommended to study a standard IR3 scenario and get further and more detailed information on past simulations assumptions.