1. Requirements 2. MARS Simulation for Beam Dump 3. Beam Dump Cooling 4. Layout of Beam Dump & Muon Pit 5. Summary & Schedule

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1 2003/12/3 NBI03, KEK, November 7~11 th, 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 Sakuda,, Y.Oyama Oyama,, & Y.Yamada (KEK IPNS) J-PARCconstruction group 1. Requirements 2. MARS Simulation for Beam Dump 3. Beam Dump Cooling 4. Layout of Beam Dump & Muon Pit 5. Summary & Schedule

2 2003/12/3 NBI03, KEK, November 7~11 th, 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 < 12.5 Sv/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. ( 16 N, 14 O), delayed neutron emission( 17 N): cooling system should also be shielded and be in underground. 3 H production: We are planning to dispose it (<15Bq/cc( <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 active so it is hard to access. Need to bear 20 years, also for 4MW operation.

3 Decay Volume, Beam Dump and MUPIT 2003/12/3 NBI03, KEK, November 7~11 th, An updated design will be shown later 110m

4 2003/12/3 NBI03, KEK, November 7~11 th, MARS Simulation for Beam Dump - symmetrical geometry with iron + concrete r=10/5cm, z=20/5cm, corresponding to OAB 22 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/cm 3 =5,000W/m 3 = DV plate coil, boarder between Iron and Concrete. Hadron Fluence = ( ) /cm 2 /proton at cooling path for 750kW (4MW) operation Dose Equivalent =11mSv / hour / (factor), where factor = Threshold factor Threshold factor (2) [Safety(2)] Former comes if we set neutron energy cutoff threshold (10-3 ev 20MeV) in the simulation to save CPU time. For 4MW operation, latter is taken into account already in the design value

5 2003/12/3 NBI03, KEK, November 7~11 th, symmetrical Geometry Beam: x,y=0.424cm / x,y=0.5mrad HORN Magnetic Field ON/OFF MUON Production ON/OFF

6 2003/12/3 NBI03, KEK, November 7~11 th, Results: Incoming Particle Flux(1) HORN ON OFF / 100,000 p.o.t.

7 2003/12/3 NBI03, KEK, November 7~11 th, Results: Incoming Particle Flux(2) / 100,000 p.o.t. Protons w/o interaction at target (~17%, x,y= 15cm)

8 Results: Energy Deposit and Hadron Fluence Concrete BD Fe 16 J/cm 3, +4.6 /spill 0.02J/cm 3 (Fe-Concrete) Fe ~1.5m DV He ~2.5m MUON 2e -6 /cm 2 /P (Cooling Water Path) ~1.7m 2003/12/3 ~2.5m NBI03, KEK, November 7~11 th,

9 Results: Energy Deposit with/without Muon Production BD Fe DV He Concrete Possible MUPIT location: Fe 3.5m equivalent 2003/12/3 NBI03, KEK, November 7~11 th,

10 Results: Dose Equivalent 2003/12/3 NBI03, KEK, November 7~11 th, Concrete BD Fe DV He Fe ~1.5m 100 Sv/h (Fe-Concrete) 11mSv/h (Concrete-Soil) Iron 4m + Concrete 1.5m

11 3. Beam Dump Cooling Compared to K2K, JPARC project employs 150 intense beam. An efficient cooling is necessary. Super-beam facilities (K2K) E p (GeV) 12 Power (kw) 5 BD loss (kw) ~1 Cooling Scheme (none) Air Cooling CNGS NuMI Choice of core material JHF-SK SJHF-HK HK , ,000 Input: MARS simulation energy deposit, scaled by material density. Check temperature distribution both by static calculation and by transient heat simulation by NASTRAN code. 2003/12/3 NBI03, KEK, November 7~11 th, Graphite+ Al Module Al+Fe core modules

12 Temperature distribution at Equilibrium Ex. Core material: Cu( =400W/m K) 750kW Q( r) 4MW 100 T(r )-TR (t=50) 2000 =125 (1.5m) (1.5m)=600W/m 2 K T(r=0) (r=0)-t(1.5m)=125 (r=0)~ =200 T(r=0) 1.5m 1.5m =300 (60cm) (60cm)=4kW/m 2 K T(r=0) (r=0)-t(60cm)= /12/3 NBI03, KEK, November 7~11 th,

13 Comparison of Core Material Candidates In case of Cooling at r=1.5m Iron Graphite Aluminium Copper Density (g/cm 3 ) Max.Dep (J/cm 3 ) 750kW Core Length (m) Conduc tivity (W/mK mk) ~ /12/3 NBI03, KEK, November 7~11 th, Melting Temp. () 1,535 >3, ,085 Max Temp 750kW (4MW) +660 (3,800) +85 (440) +80 (420) +155 (820) W/m 2 K 750kW (4MW) 600 (3k) 140 (700) 200 (1.1k) 700 (3.5k) 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

14 2003/12/3 NBI03, KEK, November 7~11 th, Cooled with Conv. Coef. =600W/m K Transient heat analysis (NASTRAN) Max. Copper 750kW Iron 750kW Copper 4MW Iron 4MW ,490 Consistent to the analytic calc. 750kW is OK with Copper core. Need measure for 4MW.

15 2003/12/3 NBI03, KEK, November 7~11 th, m 1.5m Cooling Water and Its Treatment (rough estimation) What we need: =14.1m 2, =700W/m 2 K Cool core by 1 inch 20 pathes 750kW 1/41/20 = 9.4kW/path Total amount of water in tubes = 13 litter Water flow rate = 30litter/min = 1.16m/s Twater=4.5, =4.9kW/m 2 K Inner surface area in total = 2.2m ~ 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: 2.6m 3 when diluted to 15Bq/cc equivalent. Details was presented in Radiation Safety Issues

16 4. Layout of Beam Dump and Muon Pit 2003/12/3 NBI03, KEK, November 7~11 th, Core Cu 230t Cooling path Mu Pit Iron block 660t (DURATEC?) Cooling pit (Heat Exchange) Dose Equivalent ~100(40) msv/h Residual Dose 0.2(0.05) usv/h Dose (30d/1d) Temp. raise Air: +1 /1.2h Conc:+1 :+1/1.8h (Air conditioned)

17 2003/12/3 NBI03, KEK, November 7~11 th, Hadron Fluence 2e -6 /cm 2 /P (Cooling Water Path) 11mSv/h (Concrete-Soil) DOSE Eq. 100 Sv/h (Fe-Concrete)

18 2003/12/3 NBI03, KEK, November 7~11 th, Summary A possible BD/MUPIT design is shown. Materials to MUPIT: E>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/m 2 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 ~10 8 /spill/cm 2. Possible design is under discussion with physics group.

19 2003/12/3 NBI03, KEK, November 7~11 th, Schedule FY Conceptual design Technical design Civil construction 07/31 Core Iron block Water system Production Import Installation Installation Installation K2K