SBLNF: update on secondary beam line SBLNF meeting 12 th November 2012

1. SBLNF: update on secondary beam lineSBLNF meeting 12th November 2012 M. Calviani, A. Ferrari, R. Losito, P. Sala, Hei. Vincke

2. Outline • Updates on the m pits • Prompt dose rate due m downstream the dump • Target design possibilities • Updates on the general target station design • RP aspects pit and He-vessel (to be treated in a separate presentation) M. Calviani, SBLNF meeting

3. Updates on the m pit • Pit1 = 3 m C + 2 m Fe • Pit2 = Pit1 + 10 m Fe M. Calviani, SBLNF meeting

4. Updates on the m pit • Building on top of the m pits necessary for: • Access to the two m pits (concrete shielding) • Location of the hadron absorber cooling station • Location of a potential DP water cooling station (if needed!) • Building will need shieldingif the absorber cooling station will be located there • Total dose on the 1st pit ~1 MGy/y • Potentially no human access since first beam • Diamond-detector the only option? M. Calviani, SBLNF meeting

5. m pits – m spectrum • “thermalized” m spectrum in both pits • We don’t know from which p these m come from! • Shape remains the same as a function of depth •  shift the HE part towards lower energies For increasing depths M. Calviani, SBLNF meeting

6. m pits – m parents spectrum • Energy distribution of parents p/K generating mwhich arrive in the pit1 and pit2 > 3 GeV >16 GeV ~4.6±0.5 GeV pit1 pit2 M. Calviani, SBLNF meeting

7. m pits – sensitivity to misalignment • Sensitivity to proton steering on target • Primary beam 2 mm of target: • ~5 cm off-centre @pit1 • ~35 cm off-centre @pit2 PRELIMINARY ~5 cm ~35 cm M. Calviani, SBLNF meeting

8. m pits – sensitivity to misalignment • Effect on horn/reflector 8 mrad misalignment Target/horn tilted by 8mrad (0.5 deg) Reflector tilted by 8mrad (0.5 deg) PRELIMINARY PRELIMINARY ~40 cm ~40 cm, deformed spectrum Pit2 sensitive only to very high energy m! Pit1 very sensitive! M. Calviani, SBLNF meeting

9. mpits – preliminary conclusions • The foreseen location of the pits are well adapted to sample the neutrino energy of interest • Pit1: 2 meters after C core • Pit2: 10 meters Fe after Pit1 • Important to have at least two pits: • Alignment (longer arm lever) • Monitoring of target health (NuMI experience with failing targets) • Potential use of m flux for n flux prediction (normalization) M. Calviani, SBLNF meeting

10. H*(10) downstream absorber • The hadron absorber significantly reduces the prompt dose rate downstream and lateral • Still a significant amount of m are present around – contributing to the prompt radiation levels Lateral view Top view M. Calviani, SBLNF meeting

11. H*(10) downstream absorber (vertical view) • H*(10) averaged 15 meters downstream the absorber • ~5 mSv/h are reached ~8 meters from beam axis Z = [120-135] m PRELIMINARY Beam axis ~5 mSv/h M. Calviani, SBLNF meeting

12. Potential target configuration • 3 configurations presently being investigated: • “stand-alone” graphite target – CNGS-inspired • T2K-like target (inside horn) • Air/He-cooled beryllium target • For the moment being investigated in parallel • Material choices limited to graphite & beryllium • Energy deposited in the target ~2 kW (for ~240 kW beam power) M. Calviani, SBLNF meeting

13. Target inside horn Magnetic field Thickness minimum possible to maximize magnetic field inside horn Proton beam M. Calviani, SBLNF meeting

14. Target outside horn: Magnetic field Proton beam M. Calviani, SBLNF meeting

15. Potential target configuration • For both solution the present conceptual design is to have a passive or actively He-cooled target M. Calviani, SBLNF meeting

16. Optimisation of target size M. Calviani, SBLNF meeting

17. Solution #1 • Target outside horn: • Graphitetarget, He-flow active cooling (closed loop) • Passive cooling (CNGS) should be excluded due to the high air flow required to cool the external tank • High temperature graphite advantageous for material properties (reduction of radiation damage) • Structural support can be a CNGS-similar configuration • Design possible only if outside horn He inlet He outlet helium Proton beam He outlet He inlet Lateral view M. Calviani, SBLNF meeting

18. Solution #2 • Target inside/outside horn: • T2K approach (graphitetarget, high temperature) • Closed-loop • Cantilever design • He-cooledtarget (requirement of O2<100 ppm) helium Proton beam M. Calviani, SBLNF meeting

19. Solution #3 • Target inside horn: • Graphite/beryllium(low temperature – horn internal conductor) • He cooling • Cantilever design • MiniBooNE-inspired design (open loop) • Beryllium rod and cooling fins (extruded from a bigger block) • “Open” circuit design possible Extraction + purification loop? Proton beam helium Lateral view Front view M. Calviani, SBLNF meeting

20. Energy deposition in target • Graphitecase (1.8 g/cm3) • Similar values for beryllium 4 mm radius target sbeam = 1 mm 10 mm radius target sbeam = 2.7 mm Max ~400 J/cm3/pulse Max ~100 J/cm3/pulse M. Calviani, SBLNF meeting

21. Temperature increase per shot • Graphite and Beryllium, in the “big-target” configuration • DTmaxC = ~80 °C/pulse (~250 °C/pulse for “small”) • DTmaxBe = ~50 °C/pulse (~135 °C/pulse for “small”) graphite beryllium M. Calviani, SBLNF meeting

22. Energy deposition for “small” target • Graphite: • DTmax~250 °C, 9 MPacompressive stress (~60 MPa max) • Beryllium: • DTmax~140 °C, 450 MPacompressive stress (~250 MPa max) • Beryllium small target excluded! graphite beryllium A. Perillo-Marcone M. Calviani, SBLNF meeting

23. Hadron absorber • A CNGS-like approach might be followed for the SBLNF • Graphite core (water cooled) surrounded by Fe shielding • 45 kW deposited in the graphite (primary beam ~10 cm Ø) • 35 kW deposited in Fe • Part of the absorber embedded in the He-vessel • Top Fe needed for m prompt dose rate reduction! Primary beam/hadrons Al water cooling Fe Graphite Al water cooling M. Calviani, SBLNF meeting

24. Roadmap • Collaboration with experiments to address the target position (in/out horn) • Detailed thermo mechanical assessment of target and absorber has started • Graphite and beryllium analysis will proceed in parallel • Follow-ups on: • Requirements for DP cooling! • Requirements for cooling of target chase shielding elements! • Requirements for the target collimator (size/max thermal load) • Objective is to narrow down the main needs in the next few weeks M. Calviani, SBLNF meeting

25. Conceptual design for TS buildings M. Calviani, SBLNF meeting

26. Conceptual design for TS buildings M. Calviani, SBLNF meeting

27. Updates on the target station design • He-vessel: • Vessel need to be thick enough to allow evacuation before accessing the target – T2K are (5)10 cm steel plates • Water or air cooling needed (to be studied) • Avoid concrete shielding in the vessel to avoid 3H production • Dehumidificationto be thought from the very beginning (reduce HTO in air) • Fe shielding blocks (top+lateral) in the vessel (desorption of 3H) Concrete Fe Fe Fe Fe Fe Fe Fe He vessel layer Not in scale M. Calviani, SBLNF meeting

28. Target station building and vault 200 cm He vessel (medium blue) Concrete shielding (red) 300 cm Target chase Iron shielding (dark blue) 300 cm Target & horn/reflector Ground (moraine) M. Calviani, SBLNF meeting

29. Conclusions • m pits well optimized for a low energy neutrino beam • He-vessel adopted as baseline for reduction of air activation • Shieldingand cooling needs in the target chase will be analysed taking into account thermo mechanical and RP aspects (water activation) • Few selected target configurationshave been considered for more detailed thermo mechanical analyses M. Calviani, SBLNF meeting