Activation around dump shielding, and design of beam line mask Mathieu Baudin, RP Genevieve Steele, EN-STI Helmut Vincke, RP

Irradiation scenarios calculated Cooling times: 1 hour 1 day 1 week 1 months 4 months 2 years Operation: 20 years with 2E18 protons distributed over 365 days followed by 1 day of operation with 5E12 protons/s 1 operation and 6 cool down scenarios were considered:

Top view cut, beam line level Optimization: 185 cm of shielding on sides and top 170 cm upstream and downstream Optimization of marble and iron layers Additional 10 cm iron on the side to address 24 Na issue after intense irradiation Back view cut, hot spot level Optimized shielding design

Mask to shield QD519 1m long stainless steel 30cm diameter mask would absorb ~2.5GeV per 450 GeV primary proton. This corresponds to a factor ~5 reduction of energy that escapes the dump/reaches the downstream quadrupole. Peak energy deposition seen in the mask itself <10J/cm 3 which corresponds to a temp increase of less than 2 K

Mask to shield QD mm 1 m0.5 m 7682 mm between dump and QD m between mask and QD519 Beam pipe inner diameter: – Ø 100 mm between dump and mask – Ø 83 mm in mask and QD519 Shielding : – 300 mm iron – 200 mm marble – 1m long, square section

Operation 1: 20 years with 2E18 protons per year, followed by 1 day of operation with 5E12 protons/s + 1 hour of cooling. µSv/h With mask Without mask

Operation 1: 20 years with 2E18 protons per year, followed by 1 day of operation with 5E12 protons/s + 1 week of cooling. µSv/h With mask Without mask

Conclusions Boundary conditions for a dump taking 2E18 protons per year. Dump is surrounded by a sandwich structure consisting of: 1. Concrete shielding: 0.35 m top and bottom, 0.45 m lateral, ~0.6 m upstream and downstream. 2. Iron shielding: 1.0 m lateral, top, upstream and downstream. 3. Marble shielding (or concrete): 0.4 m lateral, upstream and downstream, 0.5 m on top (0.6 m in top corners). A mask is added on the beam line between the dump and QD519 to shield the latter: 1.83 mm inner diameter, same as in QD519 (the beam line between the dump and the mask would be of 100 mm inner diameter). 2.The shielding is currently of square section, 30 cm iron followed by 20 cm marble. The total length is 1 m. This will allow to work without restrictions after beam operation outside the dump area (acceptable radiation levels).