The JPARC Neutrino Target Y.Hayato (ICRR, Univ. of Tokyo) for T.Nakadaira & J-PARC n beam-line construction group (I borrowed most of all the transparencies.
Download ReportTranscript The JPARC Neutrino Target Y.Hayato (ICRR, Univ. of Tokyo) for T.Nakadaira & J-PARC n beam-line construction group (I borrowed most of all the transparencies.
The JPARC Neutrino Target Y.Hayato (ICRR, Univ. of Tokyo) for T.Nakadaira & J-PARC n beam-line construction group (I borrowed most of all the transparencies from Nakadaira-san) J-PARC neutrino beam line Primary Proton beam line Proton Energy 50GeV (40/30GeV @ T=0) # of Protons / pulse 3.31014 Beam Power 750kW 4MW @ Phase II Bunch structure 8 (15) bunches/spill Spill width ~5ms Extraction point Target Target station Decay volume beam dump muon monitor Cycle: 3~4 sec Bunch spacing: ~600(300) ns Bunch length: 58ns (Full width) Near neutrino detector Target Station • Accommodate – Baffle: Graphite, 32mmf hole x 1.7m long to protect 1st horn – Target – 3 Horns • Area filled with Helium gas – reduce Tritium, NOx production • Highly radio-activated – ~1Sv/h, – Need remote-controlled maintenance system • Need cooling (Helium vessel, radiation shield,..) 3rd horn 2nd horn 472 beam 1400 900 Target Baffle Trg& 1st horn 809 1400 Baffle 2000 1st Horn 2nd Horn 100 cm 2500 3rd Horn Target dimension • Co-axial 2 layer cooling pipe: Graphite / Ti-6Al-4V, Helium cooling 47.0 Outer pipe 46.4 Ti-6Al-4V Inner pipe 39.6 35.6 26.0 [mm] IG-43 target IG-43 Cooing path Sectional area = 4.610-4 [m2] f=47mm spacer f=26mm One design of the target & surrounding cooling pipe (Not the final design). 陽子ビーム He inlet He outlet Ti-6Al-4V Beam window Ti-6Al-4V 陽子ビーム Target Need further design study Graphite IG-43 } To downstream } To downstream Design of inlet and outlet of He Gas is not fixed. Target cooling : Water or Helium? Disadvantage Advantage Water Cooling Very Efficient High Heat transfer ratio Already tested. Simple circulation system large Irradiation effect Ttarget 300C to avoid the water boiling: Ttarget @ surface < 100C Target container is needed. DPwater= ~2MPa due to the temperature rise by a beam hit. Huge radioactive waste water Helium Gas cooling We can control Ttarget to minimize the irradiation effect. (Ttarget = 400 ~ 800 C) Reduce radioactive waste water No target container is needed Very High flow rate ~ 2000 l/min [0.5MPa] ~ 12000 l/min [0.1MPa] Circulation system is complicated. Special treatment for the high temperature gas (200C) is necessary. Target : Conceptual design • Core: Isotropic-Graphite : IG-43 (Toyo Tanso Co. Ltd) – Energy deposit… Total: ~40kJ/spill (30GeV) DT 200K. seq = 7.5 [MPa] Tensile strength = 37.2 [MPa] MARS Distribution of the energy deposit in the target (w/ 1 spill) J/gK degree proton beam f=47mm cm f=26mm R target DR (target ~ horn) 13 [mm] 3[mm] Energy deposit (30GeV, sx= sy =4.24mm) Target Inner Pipe Outer Pipe Insulator Targeting Efficiency For Gaussian beam 39.3 [kJ/spill] 3.5 [kJ/spill] 1.1 [kJ/spill] 1.5 [kJ/spill] 99.09% (0.91%loss) Helium flow (T gas < 200C, suction=0.03MPa) Cross section Flow rate Avg. speed @ target DP @straight part+1 hex st 459.3 [mm2] 491 [Nm3/h] 246 [m/s] 0.0833 [MPa] Irradiation Effect of Graphite • Expected radiation damage of the target – The approximation formula used by NuMI target group : 0.25dpa/year – MARS simulation : 0.15~0.20 dpa/year • Dimension change : shrinkage by ~5mm in length in 5 years at maximum. ~75mm in radius • Degradation of thermal conductivity … decreased by 97% @ 200 C 70~80% @ 400 C • Magnitude of the damage strongly depends on the irradiation temperature. – It is better to keep the temperature of target around 400 ~ 800 C 400 600 800 1000 Irradiation JAERI report (1991) Temperature(C) -0.5% 2dpa 1dpa 800oC 400oC Dimension change Toyo-Tanso Co Ltd. IG-11 Thermal conductivity (After/Before) 1 2 3 (dpa) FEM simulation of He cooling • Assumptions: 0.19MPa He Initial temperature: 25 C He flow rate: 6000 [l/min] 194 [m/sec] Heat convection rate: 820 [W/m2/K] (50GeV,f=15mm) Target Temperature Max: ~ 500 C Avg. : ~380 C Min: ~ 300 C Helium Temperature Max: ~160 C Avg. : ~40 C (DT = 135 C) FEM simulation of He cooling 25C ~34C ~102C 38C 160C 395C 500C ~380C ~300C (50GeV,f=15mm) • Assumptions: 0.19MPa (Possible pressure drop at the downstream of target is taken into account.) • He Initial temperature: 25 C He flow rate: 6000 [l/min] 194 [m/sec] Heat convection rate: 820 [W/m2/K] fin.