1. First AWAKE dump calculations Helmut Vincke

2. Beam on dump Muon axis inside and outside CERN Distances: Beam impact point to end of West hall: ~300 m Beam impact point to CERN fence: ~600 m

3. 30 cm iron target (not used for pure dump calculations Carbon core (radius 20 cm length 2 m) Iron dump (radius: 1.5 m, length: 7 m) Concrete part (radius: 5 m, length 9 m) Fluence detectors behind dump + fluence detectors at distances of 100, 200 and 300 meters

4. Beam parameters used Energy: 450 GeV Intensity: 3E11 per shot, 2 shots per minute RP design criteria to be considered in terms of dose rates 1.Optimization criterion for CERN personnel: 100 uSv/year  equivalent for dose rate: 0.05* uSv/h in case 2000 hours (working hours) are considered for dose rate calculation 2.Maximum dose rate in non-designated areas (permanent work place): 0.5 uSv/h Beyond 100 uSv/year optimization means have to be considered 3.Optimization criterion for members of the public outside CERN: 10 uSv/year  0.001* uSv/h in case 8900 hours (permanent occupancy) are considered for dose rate calculation * If this dose rate can be achieved no limitation in terms of time restriction of beam operation has to be considered.

5. Muon dose inside CERN territory

6. Beam directly on carbon core dump (dose per 3E11 protons) cm

7. Beam directly on carbon core dump cm

8. Beam on iron core dump cm

9. Beam on target followed by iron core dump (representing beam loss situation) cm

10. Beam on target followed by carbon core dump (representing beam loss situation) cm

11. Muon fluence as a function of distance to the dump Fluence detectors behind dump + fluence detectors at distances of 100, 200 and 300 meters

12. Muon fluence (lethargy plot) for the beam on carbon dump case

13. Muon fluence for the beam on carbon dump case (integral fluence as a function of energy)

14. Muon fluence (lethargy plot) for the beam on target case (representing beam loss situation)

15. Muon fluence (lethargy plot) for the beam on target case integral fluence as a function of energy

16. Gedankenexperiment: 1.Iron dump 2.we can bend the beam by 5 degree 3.Beam height at impact in dump: 1m Max. dose rate at a distance to dump of 30 m: ~9 uSv/h Max. dose rate at a distance to dump of 100 m: ~ 0.9 uSv/h Max. dose rate at a distance to dump of 200 m: ~ 0.25 uSv/h Max. dose rate at a distance to dump of 290 m: ~ 0.16 uSv/h Dose rate at entry point of beam (muon) axis to soil (distance to dump: 2.5 m): ~1240 uSv/h To reduce the dose rate to 0.05 uSv/h at the end of the West Hall (290 m downstream the dump) we need to bend the beam by 7 degree Considering a 5 degree bend of the beam, 75000 bunches (per year) with an intensity of 3E11 protons can be used to stay below 100 uSv (per year) at the end of the West Area. (considerations for public not included, see following slides)

17. Muon dose outside CERN

18. Beam on dump Muon axis inside and outside CERN Distances: Beam impact point to end of West hall: ~300 m Beam impact point to CERN fence: ~600 m

19. Beam on iron core dump - muon dose rate outside CERN 5 degree line CERN fence 3E-2 uSv/h cm

20. Considering again a continuous beam and a 5 degree bend of the beam: The dose rate for a frequency of 1/30 Hz is much too high at the CERN fence (3E-2 uSv/h). If we want to respect the 10 uSv per year optimization limit we need limit ourselves to about 1.25E16 protons per year (40000 shots@3E11) This assumption does not take any morphology of the area (height profile of area) into account. Information on that is required. Continuation of Gedankenexperiment:

21. Conclusions on the dump calculations Maximum dose rate in permanent work places of non-designated areas (0.5 uSv/h): Hitting the beam dump directly: the radius of the muon cone having a dose rate of higher than 0.5 uSv/h which can be found 300 m downstream the dump: 30 m in case of a carbon core dump 15 m in case of a pure iron core dump 100 uSv/year optimization limit for CERN areas: considering a 5 degree bend of the beam we need to limit ourselves to about 75000 bunches (per year) with an intensity of 3E11 protons. Applying this limitation we respect the 100 uSv (per year) limit at the end of the West Area (300 m downstream of the dump). 10 uSv per year optimization limit for public areas: considering a 5 degree bend of the beam we need to limit ourselves to about 1.25E16 protons per year (40000 bunches). In case we lose particles upstream the beam dump (illustrated by a beam-on-target case) the muon dose downstream is significantly higher than for the beam on iron dump case. Hence, beam losses upstream the beam dump must be reduced to a absolute minimum. Further studies required. The muons in the center of the beam axis have energies up to hundreds of GeV  almost impossible to shield them.

22. Particle losses due to beam interaction inside the plasma Two possible materials (data received by Patrick Muggli): 1.Lithium with a density*length of: 1.2×10 -5 gr cm -2 2.Rubidium with a density*length of: 1.4×10 -4 gr cm -2 For both materials the losses in the plasma can be expected to be lower than the losses inside the plasma cell windows (thickness assumed to be 100 um).

23. First coarse estimates about the lateral shielding criteria Annual dose per year: 100 uSv (optimization limit for CERN personnel) In case 4 m of concrete wall: we are allowed to lose 1E13 particles per year each 20 m. This criteria can be possibly relaxed up to a factor of 10 higher beam losses due to the low occupancy of the surrounding areas (parking place, sheep area). Conditions for this factor 10 to be discussed. For one full loss of 3E11 protons the dose would be 3 uSv behind 4 m of concrete. Annual dose per year: 10 uSv (optimization limit for public outside CERN) CERN fence is located at a lateral distance of 35 m: In case of a concrete wall of 4 m thickness: total acceptable particle losses: ~2.5E13 protons per year per each 100 m. 1 m of concrete (or material with equivalent shielding power) reduces the dose by a factor of 10.  losses can be higher in case of local shielding. Strategy to be followed for lateral shielding: Beam line is already surrounded by shielding Keep losses low along the line Local shielding in the area of loss points. Amount of shielding has to be adapted to the real losses

24. Final remark These numbers reflect a first order of approximation concerning the shielding situation. Detailed studies in terms of shielding, material, air and water activations have to be conducted to conclude on the radiological situation.