J-PARC High Intensity Neutrino Beam T. Sekiguchi (KEK) on behalf - - PowerPoint PPT Presentation

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J-PARC High Intensity Neutrino Beam T. Sekiguchi (KEK) on behalf - - PowerPoint PPT Presentation

Jan 07, 2023 235 likes •571 views

J-PARC High Intensity Neutrino Beam T. Sekiguchi (KEK) on behalf of T2K Beam Group Contents Introduction to J-PARC Neutrino Beamline Current Status Prospect for Beamline Upgrade 2 J-PARC Hadron Experimental Facility

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SLIDE 1

J-PARC High Intensity Neutrino Beam

  • T. Sekiguchi (KEK)
  • n behalf of T2K Beam Group
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SLIDE 2

Contents

  • Introduction to J-PARC Neutrino Beamline
  • Current Status
  • Prospect for Beamline Upgrade

2

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SLIDE 3

J-PARC

Materials and Life Science Experimental Facility (MLF) Hadron Experimental Facility Rapid Cycle Synchrotron (RCS) (3 GeV synchrotron) (25 Hz, 1MW) Linac (330m) Main Ring (MR) (30 GeV synchrotron) (0.75MW)

  • 500 m

Neutrino Experimental Facility

3

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SLIDE 4

J-PARC

Materials and Life Science Experimental Facility (MLF) Hadron Experimental Facility Rapid Cycle Synchrotron (RCS) (3 GeV synchrotron) (25 Hz, 1MW) Linac (330m) Main Ring (MR) (30 GeV synchrotron) (0.75MW)

  • 500 m

Neutrino Experimental Facility

4

J-PARC is a versatile experimental facilities for various fields of science

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SLIDE 5

J-PARC Neutrino Beamline

5

Beam Dump P r i m a r y B e a m

  • l

i n e

  • Extraction

Point Muon Monitors 110m 280m 295km To Kamioka

Main R i n g

  • Target

Horns

P

  • π

µ

ν

Decay Volume Near Neutrino Detectors

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SLIDE 6

Features of J-PARC Neutrino Beamline

  • High intensity beam
  • 750 kW proton beam (30 GeV, 3.3×1014 protons/pulse)
  • Off-axis neutrino beam (2~2.5°)
  • Narrow band beam ~ 0.6 GeV
  • flux peak at 1st oscillation max.

θ"

Target Horns Decay Pipe

SK

Oscillation Maximum

6

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SLIDE 7

Design Philosophy of Neutrino Beamline

  • Tolerance for high power beam
  • All beamline components designed for 750 kW beam
  • Equipments that cannot be replaceable after irradiation are

designed for 3 or 4 MW beam.

  • Remote maintenance
  • Secondary beamline equipments are highly irradiated with more

than 1 Sv/h.

  • Beamline components inside Target Station can be replaceable

remotely.

7

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SLIDE 8

Secondary Beamline

  • Target Station (includes target and horns)
  • Decay Volume
  • Beam Dump

8

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SLIDE 9

1 5 . m

  • 10.6m

Baffle

Graphite Collimator

Horn-1 Horn-2 Horn-3

Beam window Ti-alloy

DV collimator

L a r g e f l a n g e , s e a l e d w i t h A l p l a t e s , t = 1 2 m m

  • Target Station

9

26mmφ x 910mm

Ti-6Al-4V (0.3mmT) Graphite IG-430U He-gas cooling

Target

OTR

Target Horn1

All equipments inside Helium Vessel can be replaceable

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SLIDE 10
  • Graphite target
  • 26mmφ × 910mm-long rod (IG-430U)
  • Covered by 0.3mm-thick Ti case
  • Helium cooling
  • Cooled with 200m/s helium flow
  • Thermal stress @ ΔT~200K ⟹ ~7 MPa
  • Tensile strength 37 MPa
  • Radiation damage is key issue
  • Remote exchange
  • Exchangeable with manipulators

Target

ΔT~200K ~7MPa (Tensile strength 37MPa)

736oC 30GeV-750kW (~20kW heat load)

10

30 GeV, 3.3x1014 ppp (~40 kJ heat load)

26mmφ x 910mm

Ti-6Al-4V (0.3mmT) Graphite IG-430U He-gas cooling

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SLIDE 11

Magnetic Horn

  • Aluminum alloy conductors

(A6061-T6)

  • Coaxial cylindrical structure
  • inner=t3mm, outer=t10mm
  • Allowable stress=25 MPa (taking into

account corrosion)

  • Safety factor ~2
  • 320 kA pulsed current (rated)
  • 2.1 T (max.) toroidal field
  • 2~3 ms pulse width
  • 2.48 s cycle ⟹ 1.3 s for 750 kW
  • Water cooled
  • Total heat load 25 kJ @ 750 kW
  • 15 kJ (beam) + 10 kJ (Joule)
  • Spraying water to inner conductor

11

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SLIDE 12

Target Station / Decay Volume / Beam Dump

  • Decay Volume (DV)
  • 100 m long
  • 2~2.5° OA angle for SK and HK
  • water-cooled iron ⟹ 4 MW beam acceptable
  • Beam Dump (BD)
  • Graphite core + water-cooled Al plates
  • Acceptable for 3 MW beam
  • Helium Vessel (TS, DV, BD)
  • 1500 m3 gigantic helium vessel
  • Filled with 1 atm. helium gas.

Maximum 77 MPa

Decay Volume Beam Dump Helium Vessel @ TS

12

Thermal stress@4MW

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SLIDE 13

Operation Status

  • Achieved beam power so far
  • 335~350 kW continuous operation
  • 1.8×1014 protons/pulse ⟹ world’s highest intensity
  • Accumulated 1.1x1021 POT
  • 7.0×1020 POT for neutrino mode
  • 4.0×1020 POT for anti-neutrino mode

13

Big earthquake Horn replacement

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SLIDE 14

Limitation for High Power Beam

  • What are real problems in high power operation?
  • Things to be well considered at design stage.
  • Mechanical strength
  • Cooling
  • Fatigue
  • These issues are major consideration, however,
  • In reality, beam power is limited by
  • treatment of radioactive wastes
  • radioactive water.
  • radioactive air.
  • production of hydrogen from water radiolysis

14

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SLIDE 15

Radio-active Water Disposal

  • Radio-active water @ 750 kW
  • 7Be: 300 GBq/year ⟹ 99.9% removed by Ion Exchangers.
  • 3T: 150 GBq/year ⟹ Diluted many times (80 times/year)
  • Limited dilution tank size → 0.5 MW
  • Highly-activated water can be taken by tanker truck.
  • 750 kW will be accepted.
  • For BD/DV downstream cooling water, connection equipment

for tanker truck was prepared and tested.

Remove 99.9 % of 7Be 80times /year

Water disposal system at TS

15

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SLIDE 16
  • H2 produced by water radiolysis
  • Expected production rate ~40L/day@750kW
  • Hydrogen removal by recombination
  • Forced flashing inside horns ⟹ H2 reaches catalyst efficiently
  • H2 density after 2 week operation < 0.7% @335 kW
  • 1 MW beam acceptable (w/ keeping H2 density < 2%)
  • Degasifier will be introduced for higher recombination efficiency.

Hydrogen Production in Horns

Catalyst canister (Catalyst = Alumina pellet with 0.5%Pd ) Buffer tank Pump Suction pump He vessel Height ~8m Service Pit Machine Room H2O He He gas line H2 Beam

Forced circulation

16

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SLIDE 17

Current Acceptable Beam Power

17

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SLIDE 18

10 Year Term Plan of Beam Power Improvement

  • Design beam power = 750 kW
  • Will be achieved in 2018
  • Beam power over 750 kW is recently being considered.
  • Aim for 1.3 MW beam by 2026
  • Proton intensity = 3.2×1014 protons/pulse.
  • Repetition cycle = 1.16 sec. with new MR power supplies.
  • Can our beamline accommodate to 1.3 MW beam?

18

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SLIDE 19

Prospect for Hardware Upgrade

19

  • Cooling capacity
  • Apparatuses themselves can withstand 1.3 MW beam.
  • Improvement of flow rate both for water and helium circulations is

needed.

  • Replacement with larger pumps
  • Replacement with larger-size plumbing
  • ⟹ These will be feasible but need 1 year for modification.
  • Radiation
  • Radioactive air
  • Reinforcement of air-tightness ⟹ 1.3 MW can be manageable.
  • Radioactive water disposal
  • Enlargement of dilution tank
  • Modification of existing tank ⟹ ~1.3MW
  • New facility building for water disposal ⟹ 2MW
  • 2 years for construction (no beam stop needed)
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SLIDE 20

Horn Operation Improvement

  • Operation status
  • 250 kA operation for physics data taking since 2010.
  • Mainly due to refurbishment of old K2K PS (rated 250 kA).
  • Currently, operated with 2.48 s cycle.
  • 1.3 s for 750 kW (not operated with the existing PS)
  • 3 PS configuration for 320 kA and 1 Hz operation
  • New power supply developed (2 PS’s already produced).
  • Also, low impedance striplines newly developed.
  • Timeline
  • Production of the last PS, transformers, part of striplines
  • Aim to start 320 kA operation from summer 2017.

Power&supply&(New)&

6.4&kV&@&250&kA&

Old& Old& Power&supply&(New)&

5.2&kV&@&250&kA&

Summer 2015~

Power&supply&(New)& Power&supply&(New)&

5.6&kV&@&320&kA& 5.8&kV&@&320&kA&

New&

New& New&

New& Power&supply&(New)&

5.4&kV&@&320&kA&

New&

New&

Summer 2017~

20

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SLIDE 21

Improved Acceptable Beam Power

21

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SLIDE 22

Summary

  • J-PARC Neutrino Beamline
  • High intense narrow band beam.
  • Designed for 750 kW beam
  • Operation status
  • 350 kW stable operation so far.
  • Need improvements on some components such as radiation issues,

hydrogen production and so on.

  • Beamline improvement
  • 1.3 MW beam scenario is being discussed.
  • Necessary improvements
  • Higher cooling capacity for every components
  • Treatment of radioactive wastes
  • Horn operation (320 kA and 1 Hz)

22

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SLIDE 23

Supplemental Slides

23

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SLIDE 24

Stripline Cooling

  • Forced helium flow for stripline cooling.
  • Large heat deposit at Horn2 (due to defocused pions)
  • Insufficient helium flow rate for Horn2. → 0.54 MW
  • Double flow rate for Horn2 → 1.25 MW
  • Water-cooled striplines
  • Necessary when beam power goes beyond 1 MW.
  • Under conceptual design.

24

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SLIDE 25

Radio-active Water Disposal

  • For beam power > 750 kW,
  • larger dilution tanks are necessary.
  • Solutions
  • Enlarging the existing dilution tank ⟹ 1.3 MW at max.
  • New facility building for radio-active water disposal ⟹ 2 MW
  • Its operation can be started from 2018 in earliest case.

Beam Dump Primary Beam-line

  • Muon

Monitors 110m 280m

  • Main

Rin

Target Horns

P

  • π

µ

ν

Decay Volume

New facility building

25

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SLIDE 26

Radioactive Air

NNN2013, Kavli IPMU

  • Helium compressor

Helium compressor Cooling water system Cooling water system Machine room Service pit Ground floor Concrete shields Storage area Building Chimney stack Exhaust system Radiation monitor for exhaust air Target Horns Helium vessel

Short-lifetime radio-activity like Ar41(τ~2h) produced in underground area

26

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SLIDE 27

Radioactive Air

NNN2013, Kavli IPMU

  • Helium compressor

Helium compressor Cooling water system Cooling water system Machine room Service pit Ground floor Concrete shields Storage area Building Chimney stack Regulation by law: < 0.5 mBq/cc Exhaust system Radiation monitor for exhaust air Target Horns

Go out through exhaust line Leakage of radioactive air from underground area through gaps

Helium vessel

27

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SLIDE 28

Improvement of Air Tightness

Caulking between concrete shields Lay the air-tight sheet Lay the protection sheet under air-tight sheet Air-tight sheet (made of the same material for balloon) Protection sheet (over air-tight sheet)

28

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SLIDE 29

Radioactive Air (Current)

NNN2013, Kavli IPMU

  • Helium compressor

Helium compressor Cooling water system Cooling water system Machine room Service pit Ground floor Concrete shields Storage area Building Chimney stack Regulation by law: < 0.5 mBq/cc Caulking + Air-tight sheet Exhaust system Radiation monitor for exhaust air Target Horns Go out through exhaust line Leak rate reduced, but leakage happens through the edge of sheet. Helium vessel

29

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SLIDE 30

Radioactive Air (Improvement Plan)

NNN2013, Kavli IPMU

  • Helium compressor

Helium compressor Cooling water system Cooling water system Machine room Service pit Ground floor Concrete shields Storage area Building Chimney stack Regulation by law: < 0.5 mBq/cc Caulking + Air-tight sheet Exhaust system Radiation monitor for exhaust air Target Horns Go out through exhaust line Helium vessel

Add air-tight lamination (made of steel and air-tight material) under concrete shields

30

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SLIDE 31

Flux Improvement by Neutrino Beamline

  • Magnetic horn current
  • 250 kA ⟹ 320 kA (rated)
  • 10 % improvement of neutrino flux at far detector

10% 250kA 320kA Courtesy)of)T.Nakadaira

31

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SLIDE 32
  • Another benefit of 320 kA operation
  • Low contamination of wrong-sign neutrino background
  • 5~10% reduction at peak (Eν~0.6 GeV)

Flux Improvement by Neutrino Beamline

32

Neutrino mode Anti-neutrino mode

νμ νμ νμ

  • νμ

νe νe νe νe