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Requirements MARS Simulation for Beam Dump Beam Dump Cooling Layout of Beam Dump & Muon Pit

4 th International Workshop on Neutrino Beams and Instrumentation (NBI’03) Beam Dump Design for J-PARC Neutrino Project. In collaboration with A.K.Ichikawa, T.Ishida * , J.Kameda T.Kobayashi, M.Sakuda, Y.Oyama, & Y.Yamada (KEK IPNS) J-PARCν construction group. Requirements

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Requirements MARS Simulation for Beam Dump Beam Dump Cooling Layout of Beam Dump & Muon Pit

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  1. 4th International Workshop on Neutrino Beams and Instrumentation (NBI’03)Beam Dump Design forJ-PARC Neutrino Project In collaboration with A.K.Ichikawa, T.Ishida*, J.Kameda T.Kobayashi, M.Sakuda, Y.Oyama, & Y.Yamada (KEK IPNS) J-PARCν construction group • Requirements • MARS Simulation for Beam Dump • Beam Dump Cooling • Layout of Beam Dump & Muon Pit • Summary & Schedule NBI03, KEK, November 7~11th, 2003

  2. 1. Requirements for BD/MUPIT • Radiation shielding at operation • <11mSv/h at the edge of shield (Outer Concrete – Soil) • Residual dose rate in the muon pit • < 12.5μSv/h for the normal controlled area. • Beam dump cooling • ~¼ of total heat is deposited in the Beam Dump. • Radiation in cooling water • H.E.γ(16N,14O), delayed neutron emission(17N): cooling system should also be shielded and be in underground. • 3H production: We are planning to dispose it (<15Bq/cc) by dilution. Hadron fluence at cooling place should be enough low = Cooling path should be as far as possible from beam center. • Redundancy • Core part is highly radio-active so it is hard to access. • Need to bear 20 years, also for 4MW operation. NBI03, KEK, November 7~11th, 2003

  3. Decay Volume, Beam Dump and MUPIT An updated design will be shown later 110m NBI03, KEK, November 7~11th, 2003

  4. 2. MARS Simulation for Beam Dump • Φ- symmetrical geometry with iron + concrete • Δr=10/5cm, Δz=20/5cm, corresponding to OAB 2° • Calculate incoming particle flux, energy deposit, hadron fluence, and dose equivalent of each volume and obtain critical boarder lines for BD design: • Energy Deposit= 0.02Joule/cm3=5,000W/m3 = DV plate coil, boarder between Iron and Concrete. • Hadron Fluence = 1×10-5 (2×10-6) /cm2/proton at cooling path for 750kW (4MW) operation • Dose Equivalent =11mSv / hour / (factor), where factor = “Threshold factor” (2)×[Safety(2)] • Former comes if we set neutron energy cutoff threshold (10-3eV→20MeV) in the simulation to save CPU time. • For 4MW operation, latter is taken into account already in the design value NBI03, KEK, November 7~11th, 2003

  5. Φ- symmetrical Geometry • Beam: Δx,y=0.424cm / ΔΘx,y=0.5mrad • HORN Magnetic Field ON/OFF • MUON ProductionON/OFF NBI03, KEK, November 7~11th, 2003

  6. Results:Incoming Particle Flux(1) HORN ON OFF / 100,000 p.o.t. NBI03, KEK, November 7~11th, 2003

  7. Results:Incoming Particle Flux(2) / 100,000 p.o.t. Protons w/o interaction at target (~17%, σx,y= 15cm) NBI03, KEK, November 7~11th, 2003

  8. Results:Energy Deposit and Hadron Fluence Concrete BD Fe 0.02J/cm3 (Fe-Concrete) 16 J/cm3, +4.6℃/spill Fe ~1.5m DV He MUON ~2.5m 2e-6 /cm2/P (Cooling Water Path) ~1.7m ~2.5m NBI03, KEK, November 7~11th, 2003

  9. Results:Energy Deposit with/without Muon Production BD Fe DV He Concrete Possible MUPIT location: Fe 3.5m equivalent NBI03, KEK, November 7~11th, 2003

  10. Results:Dose Equivalent Concrete BD Fe 100 Sv/h (Fe-Concrete) Fe ~1.5m 11mSv/h (Concrete-Soil) DV He Iron 4m + Concrete 1.5m NBI03, KEK, November 7~11th, 2003

  11. 3. Beam Dump Cooling • Compared to K2K, JPARCν project employs ×150 intense beam. An efficient cooling is necessary. • Choice of core material • Input: MARS simulation energy deposit, scaled by material density. • Check temperature distribution both by static calculation and by transient heat simulation by NASTRAN code. NBI03, KEK, November 7~11th, 2003

  12. Temperature distribution at Equilibrium Q( r) T(r )-TR 600 100 300 α(Δt=50℃) 500 2000 1.5m 1.5m Ex. Core material: Cu(λ=400W/m・K) 4MW 750kW T(r=0)-T(1.5m)=125℃ α(1.5m)=600W/m2K T(r=0)-T(60cm)=300℃ α(60cm)=4kW/m2K T(r=0)~125+50+30=200℃ NBI03, KEK, November 7~11th, 2003

  13. Comparison of Core Material Candidates In case of Cooling at r=1.5m • Higher density = higher local energy deposit  = smaller core size = smaller amount of water • Cu has the highest heat conductivity. = further cooling water path = lower hadron fluence at cooling surface NBI03, KEK, November 7~11th, 2003

  14. Transient heat analysis (NASTRAN) Cooled with Conv. Coef. =600W/m２・K • Consistent to the • analytic calc. • 750kW is OK with • Copper core. • Need measure • for 4MW. NBI03, KEK, November 7~11th, 2003

  15. Cooling Water and Its Treatment(rough estimation) 1.5m 1.5m • What we need: • 2×1.5×π×1.5=14.1m2, × α=700W/m2K • Cool core by 1inchφ×20 pathes • 750kW×1/4×1/20 = 9.4kW/path • Total amount of water in tubes = 13 litter • Water flow rate = 30litter/min = 1.16m/s ⇒ ΔTwater=4.5℃, α=4.9kW/m2K • Inner surface area in total = 2.2m2 　　⇒　2.2×4.9 ~ 14.1×0.7 • Water system: • A circulation path with heat exchanger + a dilution path. • The dilution path= a deposit tank + a dilution tank to dispose water with < 15Bq/cc. • BD: 2.6m3 when diluted to 15Bq/cc equivalent. • Details was presented in “Radiation Safety Issues” NBI03, KEK, November 7~11th, 2003

  16. 4. Layout of Beam Dump and Muon Pit Core Cu 230t Cooling path Mu Pit Iron block 660t (DURATEC?) Temp. raise Air: +1℃/1.2h Conc:+1℃/1.8h (Air conditioned) Dose Equivalent ~100(40) mSv/h Residual Dose (30d/1d) 0.2(0.05) uSv/h Cooling pit (Heat Exchange) NBI03, KEK, November 7~11th, 2003

  17. Hadron Fluence 2e-6 /cm2/P (Cooling Water Path) DOSEEq. 11mSv/h (Concrete-Soil) 100 Sv/h (Fe-Concrete) NBI03, KEK, November 7~11th, 2003

  18. 5. Summary • A possible BD/MUPIT design is shown. • Materials to MUPIT: Eμ>4.5GeV Copper core(1.5m)+Iron block(1.5m)+Concrete(0.5m) Hadron Fluence / residual dose at MUPIT is low enough. • Hadron fluence at cooling path around core is equal to or less than that of DV plate coil, to dispose it with < ×200 dilution. • Convection coef.=700W/m2・K for 750kW operation is enough realistic. • Detailed BD core design is under progress. • Need measure for 4MW operation. This can be achieved with a cooling path at around r=60cm. • Requirements for muon profile monitor settled after BD (J.Kameda) • Good sensitivity for magnet and proton beam position with 2~5 GeV/c threshold and no big difference in this region. • Above ~ 7 GeV/c, the sensitivity become worse. • With 5GeV/c threshold, muon fluence is ~108/spill/cm2. • Possible design is under discussion with physics group. NBI03, KEK, November 7~11th, 2003

  19. Schedule 2004 2005 2006 2007 2008 FY2003 Conceptual design Technical design 07/31 Civil construction Production Installation Core Import Installation Iron block Installation Water system K2K NBI03, KEK, November 7~11th, 2003

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