1. Radiation Protection Considerations for the CDR Helmut Vincke DGS-RP

2. Contents Latest shielding studies for the West Area Option RP relevant comparison between AWAKE@WestArea and AWAKE@CNGS

3. Latest shielding design studies for the AWAKE@WestArea option

4. West Area 4 TT61 TT4 TT5 Beam from TCC6 - SPS AWAKE 183

5. 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

6. New dump studies considering 300 GeV beam, impact at -1.2 m Beam is bent by 2 degree towards soil and beam impacts dump 1.2 m below surface RP criteria to be met Annual dose limit at the CERN fence: 10 uSv/year. Annual dose limit outside the West hall (non-designated area): 100 uSv/year Annual radiation limit inside the West hall (non-designated area): 40 uSv/y  < 10 uSv/year dose given to members of the personnel during 2000 hours.

7. 5 m 9 m 7 m 2 m long opening for beam entry concrete iron 1.5 m Details of dump structure

8. Muon dose calculations for the new beam energy/dump situation

9. Contour line: 10 uSv/year for ultimate intensity CERN fence Annual muon dose to be expected for ultimate beam operation (2.35E17 protons), larger scale Dose rate at CERN fence above 10 uSv/y Dimension of scales in cm 600m

10. Contour line of 100 uSv/year Contour line of 40 uSv/year ~ 10 uSv/year for 2000 hours Annual muon dose to be expected for ultimate beam operation (2.35E17 protons) inside the WEST HALL Dimension of scales in cm FLOOR100m 200m  Additional shielding required to reduce annual muon dose

11. How to reduce the muon radiation level at the surface Additional shielding Implementation in the cylinder symmetric FLUKA geometry

12. Contour line: 10 uSv/year for ultimate intensity CERN fence Dimension of scales in cm Annual muon dose to be expected for ultimate beam operation (2.35E17 protons), large scale 600m

13. Contour line of 40 uSv/year ~ 10 uSv/year for 2000 hours No backwards shielding implemented yet. Should be easy to eliminate the backwards directed muons Dimension of scales in cm Annual muon dose to be expected for ultimate beam operation (2.35E17 protons) inside the WEST HALL 100m 0m

14. Backscattering and neutron (+ other) radiation

15. Implementation of backward shielding (upstream dump) Additional shielding Dump Backward shielding (4 m wall thickness) Height of entrance: 2m

16. 110 m DUMP Backward shielding Implementation of backward shielding shown as implemented in the floor of West Hall 3.8m

17. Effect of backwards shielding on muon radiation (low statistics but sufficient to show the effectiveness of the backward shielding for muons Contour line of 40 uSv/year ~ 10 uSv/year for 2000 hours Shielding cut open to allow visibility to inside Muons which are directed backward do not have sufficient energy to cross concrete shielding. 100m 0m

18. Contour line of 40 uSv/year Dose from all particles seen in the West Hall Dimension of scales in cm Shielding would be ok if West Area is classified as Simple Control Radiation Areas If we want to obtain work places close to the dump under non designated conditions local shielding (~2.4 m concrete or 70 cm iron + 80 cm concrete) lateral to hot spot is required 100m 0m

19. Final shielding configuration 3 concrete slaps of a thickness of 80 cm Length of 11m, 9m and 7m

20. Dose from all particles seen in the West Hall (final shielding design) 100m 0m Contour line of 40 uSv/year 40 uSv/year line remains inside shielding  dose to personnel < 10 uSv/year

21. Shielding cut open to allow visibility to inside ATTENTION: different scale compared to all other plots Dose from all particles seen in the West Hall (view inside the shielding) Contour line of 40 uSv/year

22. Shielding construction summary Dump: concrete 9m long, radius: 5m, with 7m long iron core (radius 1.5m), beam entry in iron core, dump tilted by 2 degree, beam entry in dump at -1.2m below surface Shielding upstream of dump: 4 m thickness around beam line, should also cover for “lateral” dose caused by accidental losses along beam line. Shielding downstream the dump: same lateral dimension as dump, tilted by 2 degree, length~ 110 m, up to the point where shielding disappears in floor Lateral extra shielding around beam impact point at dump: 3*80 cm slaps, 11, 9 and 7 m long Shielding does not have to be constructed in cylindrical shape. Cylinder symmetry was used in the simulation to obtain fast results. If impact on dump is lowered to -2m the lateral extension of the shielding located downstream the dump can be reduced by 80 cm.

23. hadron absorber AWAKE at CNGS option

24. AWAKE at CNGS (detailed view on facility) Picture: Courtesy of Ans Partons

25. Comparison in terms of RP criteria AWAKE@WestArea versus AWAKE@CNGS Prompt radiation Airborne radioactivity Material activation including residual dose rate aspects Activation of cooling water Ground water and soil activation Residual dose rate and contamination of the area originating from a previous beam operation Subjects reviewed:

26. Prompt radiation West AreaCNGS For a safe beam dump operation a very costly shielding and beam dump system has to be installed Due to muon production beam losses along the beam line have to be kept at an annual level of 1E12 and 1E13 protons CNGS facility which can be found at a depth of approximately 100 meter underground. The muon cone created by the AWAKE beam operation will not cross any accessible area. In case the control room for AWAKE will be placed in ECA4 area (prefered from the RP point of view) the prompt radiations emerging from the AWAKE beam operation will not pose any radiological problems. For the situation implying a control room close to the AWAKE facility (in the access gallery to CNGS) the radiation situation occurring from losses in the proton beam line has to be studied.

27. Airborne radioactivity from the RP point of view Due to the high beam intensities a dedicated ventilation system for the AWAKE facility is required to guarantee the safe operation of the facility. The system has to guarantee that airborne radioactivity is sufficiently diluted before personnel is allowed to enter the experimental area. The ventilation unit has to guarantee that no radioactive air is leaking from the experimental area towards the adjacent non-designated areas. Since the major part of the beam will impact in the hadron stopper the air activation level around the experiment can be expected to be smaller than in the West Hall scenario. The actual level of air activation has to be studied in detail In order to reduce the air activation to a minimum the losses along the beam line and the path length of the proton beam through air should be reduced to a minimum. West AreaCNGS

28. Material activation including residual dose rate aspects Since the annual beam losses along the beam line have be kept below 1E13 protons the radioactivity produced in the beam line components can be expected as uncritical. Exception: beam dump receiving the full beam intensity. Since high density materials are required to build the beam dump core a significant radioactivity production has to be expected in this area.  elevated dose rate close to the dump region. The losses along the beam line can be considered as low. Therefore, the actual material activation produced by the AWAKE operation will be small. The main part of the beam will impact in the hadron stopper. Since the hadron stopper has received in the past already beam intensities which are a factor of 1000 higher than the annual beam intensity of AWAKE no notable change of the activation in this area has to be expected. It can be expected that the AWAKE@CNGS operation will not create a material activation problem. West AreaCNGS

29. Cooling water activation Due to the low beam loss level along the beam line the activation of the cooling water of the beam line equipment can be considered as non-critical. Activation inside the water of a cooled beam dump might be produced. However, first guesses based on experience lead to the assumption that the level of radioactivity produced in the water circuit will be low. Detailed studies required Since the losses along the beam line are expected to be small no significant water activation is expected. Beam end in the hadron stopper and therefore no activation of a water circuit of a dump system West AreaCNGS

30. Ground water and soil activation Taking into account the low limit of beam losses along the beam line and the strong shielding power of the beam dump the activation of the soil surrounding the area can be expected to be low. The same assumption is valid for ground water activation. Due to the low losses along the beam line the ground water (if applicable at that depth) and the soil activation can be neglected. When comparing the AWAKE intensities with those used for the CNGS operation it becomes clear that no notable change in the soil activation will be caused by the AWAKE beam operation. West AreaCNGS

31. Activation and contamination caused by previous beam operations Material activation caused by past beam operations can be expected to be a minor maybe even a non-issue. o The West Area has never received beam high beam power. o Operation was stopped in 2004 resulting in a cool down period of more than 8 years (March 2013). See next page West AreaCNGS

32. Activation and contamination caused by previous beam operations (CNGS) The CNGS target area, which is located downstream the AWAKE facility location, is considered as High Radiation Area.  In order to reduce dose to personnel being present in the AWAKE facility, the AWAKE facility has to be separated from the CNGS facility by an 80 cm thick concrete wall. Access to the CNGS area has to be restricted by adequate means preventing unauthorized access in the CNGS target area. Due to past CNGS operation radioactive dust contamination of the CNGS and the AWAKE area has to be expected.  decontamination campaign of the AWAKE area The future ventilation system operating in the CNGS and the AWAKE area has to guarantee that no radioactive dust is transported from the CNGS side to the AWAKE side.

33. Summary The overall dimensions of the AWAKE shielding @ West Area option were calculated Due to the surface installation location a huge effort in terms of shielding has to be undertaken to comply with the given radiation rules In terms of RP aspects the AWAKE@CNGS and the AWAKE@WestArea options were compared to each other For most of the RP aspects considered the CNGS option seems to be less problematic than the West Area option. In case of the AWAKE@CNGS option precautions have to be considered due to the past high intensity beam operation of this area. All assessments have to be seen as first estimates serving as input for a Conceptional design report. The final quantifications in terms of the RP related aspects will be evaluated at a later stage.

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