Challenges and Progress on the SuperBeam Horn Design

1. Challenges and Progress on the SuperBeam Horn Design Marcos DRACOS IN2P3/CNRS Strasbourg NuFact 08 Valencia-Spain, June 30 - July 5 2008 M. Dracos, NuFact08

2. Super-Beam Studies in Europe • Super Proton Driver at CERN (SPL) • Target and collector integration • Hadron Collector • Pulser • Conclusion M. Dracos, NuFact08

3. p p n Conventional Neutrino Beams proton beam Decay tunnel physics hadrons target hadron collector (focusing) Detector M. Dracos, NuFact08

4. SPL Super-Beam Project Accumulator ring + bunch compressor H- linac 2.2, 3.5 or 5 GeV, 4 MW p proton driver Magnetic horn capture (collector) p Target hadrons n, m decay tunnel ~300 MeV nm beam to far detector to be studied in EURO WP2 M. Dracos, NuFact08

5. Super Proton Linac at CERN SPL (http://doc.cern.ch/yellowrep/2006/2006-006/full_document.pdf) M. Dracos, NuFact08

6. SPL (CDR2) main characteristics butch compressor to go down to 3.2 s (important parameter for hadron collector pulsing system) (possible energy upgrade to 5 GeV could be the subject of a 3rd CDR) M. Dracos, NuFact08

7. Proton Target very challenging task • 300-1000 J cm-3/pulse • Severe problems from : sudden heating, stress, activation • Safety issues ! • Baseline for Super-Beam is solid target, mercury is optional (baseline for NF) • Extremely difficult problem : need to pursue two approaches : • Liquid metal target (Merit experiment) • Solid target (extensive R/D program at CCLRC and BNL) • Envisage alternative solutions M. Dracos, NuFact08

8. Proposed collection system horn proton beam 3.7 cm 8.5° 300 kA 4 cm target 16.6 cm 40 cm 80 cm taking into account the proton energy and collection efficiency, the target must be inside the horn M. Dracos, NuFact08

9. CC target He OUT He IN fluidised jet of particles some ideas Proton Target Proposed rotating tantalum target ring (realistic?) Horn Helium cooling of target Liquid Mercury (MERIT) Work at BNL and RAL Experience on T2K target (750 kW) very useful cooling is a main issue… M. Dracos, NuFact08

10. Hadron production Particles coming out of the target 2.2 GeV protons pT distribution not the same for all targets  the choice of the target could influence the hadron collection system (horn shape) pT From now on Hg will be considered M. Dracos, NuFact08

11. Hadron production uncertainties 2.2 GeV protons disagreement between models (Monte Carlo production, interaction and transport codes) p+ momentum more development is needed (simulation, measurements) M. Dracos, NuFact08

12. Proton Energy and Pion Spectra • pions per proton on target. • Kinetic energy spectrum • 2.2 GeV: • <Ek>=300MeV • 3.5 GeV: • <Ek>=378MeV interesting region for SPL SB Ekine (GeV) 1GeV 2GeV cos q hadrons boosted forward 1 0 -1 M. Dracos, NuFact08

13. Proposed design for SPL for pions coming out of the target 500 < pp < 700 MeV/c p+ angle p+ momentum horn region for a Hg target, 30 cm length, 15 mm (x1016/sec) relatively better collection when pproton the target must be inside the horn M. Dracos, NuFact08

14. 2.2 GeV proton beam : <pp> = 405 MeV/c <qp> = 60° 3.5 GeV proton beam : <pp> = 492 MeV/c <qp> = 55° Horn geometry I = 300 kAmp I = 300 kAmp r(m) r(m) B~1/r B~1/r B must be 0 B must be 0 4 cm 4 cm target target 30 cm z(m) 30 cm z(m) M. Dracos, NuFact08

15. 600 kA reflector horn proton beam 3.7 cm 8.5° 300 kA 4 cm Hg target 16.6 cm 12.9° 20.3 cm 4 cm 40 cm 80 cm 70 cm Proposed design for SPL very high current inducing severe problems M. Dracos, NuFact08

16. Focusing Power p- transverse momentum p+ transverse momentum (2.2 GeV option) p- are deflected 20% more p+ with reflector M. Dracos, NuFact08

17. Present Collectors In operation (120 GeV) In operation (8 GeV) completed (12 GeV) CERN horn prototype for SPL Super-Beam (3.5 GeV) In operation (400 GeV) MiniBooNE NUMI CNGS K2K M. Dracos, NuFact08

18. Decay Tunnel Flux vs decay tunnel length (2.2 GeV option) short decay tunnel M. Dracos, NuFact08

19. More about previous studies • S. Gilardoni: Horn for Neutrino Factory and comparison with a solenoid • http://doc.cern.ch/archive/electronic/cern/preprints/thesis/thesis-2004-046.pdf • http://newbeams.in2p3.fr/talks/gilardoni.ppt • A. Cazes: Horn for SPL • http://tel.ccsd.cnrs.fr/tel-00008775/en/ • http://slap.web.cern.ch/slap/NuFact/NuFact/nf142.pdf • http://slap.web.cern.ch/slap/NuFact/NuFact/nf-138.pdf M. Dracos, NuFact08

20. Main Technical Challenges • Horn : as thin as possible (3 mm) to minimize energy deposition, • Longevity in a high power beam (currently estimated to be 6 weeks!), • 50 Hz (vs a few Hz up to now), • Large electromagnetic wave, thermo-mechanical stress, vibrations, fatigue, radiation damage, • Currents: 300 kA (horn) and 600 kA (reflector) • design of a high current pulsed power supply (300 kA/100 μs/50 Hz), • cooling system in order to maintain the integrity of the horn despite of the heat amount generated by the energy deposition of the secondary particles provided by the impact of the primary proton beam onto the target, • definition of the radiation tolerance, • integration of the target. M. Dracos, NuFact08

21. CERN horn prototype cooling system Current of 300 kA p Protons To decay channel B = 0 Hg Target B1/R initial design satisfying both, neutrino factory and super-beam M. Dracos, NuFact08

22. 48.2 kW 67kW 14.9kW 78.7kW Energy deposition in the conductors • MARS +8kW from Joule effect 4MW, 2.2GeV proton beam (1MeV = 1.82 kW) M. Dracos, NuFact08

23. Localization of the energy deposition P (kW) target z (cm) z position of the particles coming out of the target z (cm) power deposited in the inner conductor as a function of z M. Dracos, NuFact08

24. Horn prototype • For the horn skin AA 6082-T6 / (AlMgSi1) is an acceptable compromise between the 4 main characteristics: • Mechanical properties • Welding abilities • Electrical properties • Resistance to corrosion • Same for CNGS …but Al not compatible with Mercury! • tests done with: 30 kA and 1 Hz, pulse 100 ms long • new tests to be done with 50 Hz Electrical and water connections M. Dracos, NuFact08

25. Power Supply for horn pulsing (major issue) values considered by CERN M. Dracos, NuFact08

26. 3 Solutions proposed by ABB schematic versions at the capacitors ends option 1 at the capacitors ends option 2 in the charge option 3 s M. Dracos, NuFact08

27. Pulser simulation parameters • magnetic field with electrical excitation (pulses 100 μs, 50 Hz) • induced current distributions • magnetic forces • temperature and expansion distributions • mechanical constraints and deformations (static+ dynamical), vibration modes • non-linear magnetic and thermal effects in the calculation of mechanical constraints • fatigue (and constraints from radiations if any) studies are needed to make the right choice, increase the system lifetime, reduce the cost M. Dracos, NuFact08

28. protons protons protons protons minimize power dissipation and radiation problems (pulser problems remain as before) 2.5 m use the advantage of the small horn size New ideas 2.5 m same decay tunnel Ø 3 m to be studied in EURO • 2 options: • send at the same time 1 MW per target/horn system • send 4 MW/system every 50/4 Hz possibility to use solid target? M. Dracos, NuFact08

29. superconducting wire (1 mm Ø) in superfluid He, DC power supply New (crazy) ideas use a cryogenic horn (toroidal coil) blow gas He to avoid quenching problems • No problem with power supply (pulser no more needed) • Proton compressor no more needed to be studied in EURO M. Dracos, NuFact08

30. Conclusions • Proton driver characteristics and target have to be fixed before horn design. • Preliminary studies about horn focusing performance for SPL already exist. • Collector studies are necessary to increase the system lifetime. • Target/horn integration to be considered since the beginning. • Multi-physics simulations would be very useful. • New studies will start soon in the framework of EURO FP7 project. M. Dracos, NuFact08

31. End M. Dracos, NuFact08