Beam line Experiment area SC magnet Pion production target COMET Facility Beam line Experiment area SC magnet Pion production target

Construction of high-p/COMET beam lines Beamline magnets Dx7, Qx8 Steel-septum (Lambertson) magnet, Current-septum magnets x2 Collimators (H, V) 小沢の発表に含まれている 3 of existing beamline magnets (Dx1, Qx2) are replaced to avoid interference with new line Most of beamline magnets (Dx7, Qx6) are reused ones vertically steering magnets (x2) to make a bump orbit for beam extraction to high-p/COMET Installation in SY has started

Construction of high-p/COMET beam lines Beam plugs High-p beamline magnets Dx5, Qx3 FM Beam plugs high-p beam dump COMET beamline magnets Dx5, Qx4 小沢の発表に含まれている COMET beam dump Capture Solenoid Most of beamline magnets (Dx8, Qx5) are reused ones Installation in Hall will start next JFY

Top View of the Branching Point from A-line Steel-Septum (Lambertson) Magnet Current-Septum Magnet existing beam line high-p/COMET beam line 小沢の発表に含まれている 5° in total

Steel-Septum (Lambertson) Magnet yoke vacuum chamber coil 小沢の発表に含まれている bending field field free hole proton beam

Operation Modes at Branching Point 10-4 protons 小沢の発表に含まれている T1 T1 + High-p COMET all protons are delivered to T1 target 10-4 protons are branched into high-p/COMET line all protons are bent into high-p/COMET line vertical beam position at BP is adjustable using 2 steering magnets

COMET Hall : B1F Plane View

COMET Hall : B1F Plane View Machine Room Beam Room 小沢の発表に含まれている Beam Dump Exp. Room

COMET Hall : Section View Control Room Installation Yard Machine Room 小沢の発表に含まれている Exp. Room Beam Room

Radiation Evaluation Radiation level around the COMET building was evaluated using MARS simulation. 2.6 mSv/h 0.7 0.05 2.6 mSv/h (#167) 0.05 mSv/h (#100) 0.7 mSv/h (#135) Each Box in the left figure corresponds to each point in right plot. Radiation contamination of the soil is estimated to be smaller than the limitation of 11 mSv/h.

Radioactivation of Air / Water Radioactivation of air in the beam room / experimental room and cooling water after 90-days operation was evaluated based on MARS. Half Life Air Beam room (Bq/cc) Exp. Room Air Evacuation Limit Water Drain 3H 12.26y 3.1E+00 7.07E-03 5.0E-03 542 60 7Be 53.4d 2.3E+00 7.32E-03 2.0E-03 1408 30 15O 2.04m 6.0E+01 1.00E-01 7.0E-04 180567 5 13N 9.97m 8.1E+01 2.01E-01 2558 11C 20.4m 5.1E+00 2.00E-02 5113 0.1 41Ar 1.85h 3.7E+01 4.81E-01 5.0E-04 NA 施設としてはかなり重要ですがかなり細かいので説明も大変。飛ばしても問題無いと思います。質問が出れば私か深尾くんが説明します。 - Radioactive nuclide density in air exceeds evacuation limit. Both beam room and experimental room are air-sealed during beam operation. - Radioactive nuclide density in cooling water exceeds drain limit. 7Be is collected by filter. Short-life nuclides density is sufficiently reduced in 1 day. 3H must be drained after diluting.

Air ventilation diagram of the COMET Hall 重要ではないですが、ちゃんと設計してますという状況説明のみ。一次ビームラインは放射性物質が漏れた際もファルタ−通して排気できるように設計されています。

Superconducting Magnet Iron Yoke Tungsten Shield Proton Target 8GeV proton m 6.4m Status of SC Mag. Production: Engineering design of SC coils has been initiated Procurement of superconducting cable was started. 5T 吉田君スライド。まだ設計段階で写真はないです。 Pion Capture Solenoid Transport 3T Field distribution in OPERA3D

Layout in experimental hall is almost fixed. Layout in exp. hall Layout in experimental hall is almost fixed. Concept of yoke, shield is developed. Detailed design of coil structure, cooling system, current leads etc. are underway. ~15 MPa ~30 MPa SEQV Model-2 FEM analysis of Mises stress in coils with thick outer shell pure Al thermal link GFRP(BT) spacer GFRP(BT) Al strip guide lead cable guide Welding to shell Support Shell 2-phase He CS0 coil structure 吉田君スライド。まだ設計段階で写真はないです。 Conceptual Design of Tungsten Shield Supports Supports 40ton shield with <5mm distortion

Production Target Phase I (Radiation cooling) Graphite (IG-43) Refractory material and so is tolerant to high temperature operation Experience in T2K Tungsten (optional) Larger muon yield Radiation cooling may be OK but need careful assessment Phase II (Active cooling) Tungsten Bad chemistry between tungsten and water Helium cooling instead of water cooling Chrisのノートから

Energy Deposit by 3. 2kW proton beam on a graphite rod (4cm diam Energy Deposit by 3.2kW proton beam on a graphite rod (4cm diam. & 60cm L) Chrisのノートから

Temperature distribution material emissivity of 0.75 Chrisのノートから

Accident Scenarios (Phase I) Accidental fast extracted beam pulse T2K target temperature rise in a cycle is 100K sx = 4mm in T2k while sx=2mm in COMET 750 kW in T2K while 3.2kW in COMET Well below graphite evaporation temperature Detection system of extraction failure and temperature monitoring are mandatory Loss of vacuum during operation Any sublimation or oxidation ? The COMET target is expected to run at a temperature well below the level May be possible to contain the target within a thin metal capsule Protects the target from oxidation and radiates the heat load An alternative is Coat the graphite with a refractory metal e.g. tantalum or iridium Connecting the pump exhausts to a vessel through a filter system is an issue Failure of any of dipole magnets bending the beam from the high-p line Status will be included in MPS; If any of them is off, stop the accelerator Even if any magnet fails during extraction, magnetic field goes down slowly due to the coil inductance and thus the beam won’t localize a small area on the beam duct/magnet.

COMET Phase I Facility Schedule JFY 2013 2014 2015 2016 COMET building design construction Solenoid magnet SC wire Capture magnet Transport magnet Cryogenic system Magnet system test Radiation shield Beam dump Pion target Design & test 2013 Design of the building & beam line Bid tendering and start construction Design of superconducting solenoid magnets and start of construction Production of SC wires as well Design of the pion production target 2014 Completion of the building Construction of superconducting solenoid magnets Start magnet and radiation shielding (and beam dump) installation Transport solenoid Start preparation of cryogenic system Tests of the target production target 2015 Preparation of cryogenic system Construction of the pion production target 2016 Installation of the capture solenoid Completion of the cryogenic system Tests of the magnet system Installation of the target Ready to accept the 8GeV beam