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HiRadMat Proposal HRMT-22: Tungsten Powder Target Experiment

HiRadMat Proposal HRMT-22: Tungsten Powder Target Experiment (A follow-up to the HRMT-10 ‘W-Thimble’ Experiment in 2012) Chris Densham, Otto Caretta, Tristan Davenne, Mike Fitton , Peter Loveridge, Joe O’Dell (RAL) Ilias Efthymiopoulos, Nikolaos Charitonidis (CERN).

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HiRadMat Proposal HRMT-22: Tungsten Powder Target Experiment

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  1. HiRadMat Proposal HRMT-22: Tungsten Powder Target Experiment (A follow-up to the HRMT-10 ‘W-Thimble’ Experiment in 2012) Chris Densham, Otto Caretta, Tristan Davenne, Mike Fitton, Peter Loveridge, Joe O’Dell(RAL) Ilias Efthymiopoulos, Nikolaos Charitonidis (CERN)

  2. Previous In-Beam Test: HRMT-10, 2012 • Single tungsten powder sample in an open trough configuration • Helium environment • Remote diagnostics via LDV and high-speed camera • Successfully identified a beam intensity eruption threshold Beam Open trough Assembly LDV/camera Tungsten powder response to a 440 GeVproton beam pulse at HiRadMat

  3. HRMT-10: What We Learned • Identified an Energy threshold, beyond which significant eruption of the powder occurs • Lift height correlates with deposited energy • Eruption velocities are low when compared to liquid metal splashes HRMT-10: Open Questions • Can Aerodynamic processes alone be shown to account for the observed response? Or is there something else going on? • Can we rule out other mechanisms such as: • direct momentum transfer between grains (i.e. shock-transmission through the bulk solid) • An electrostatic mechanism • Trough Wall vibrations exciting the powder

  4. Apparatus for the HRMT-22 In-Beam Test Top window to view sample disruption Outer Vessel Lighting re-configured to allow a view of the full trough length Inner Vessel High Speed Camera LDV Horizontal linear stage to switch between samples Sample #1 ‘Small’ particles Trough Sample #4 ‘Large’ particles Tube Sample #3 ‘Small’ particles Trough Sample #2 ‘Large’ particles Trough

  5. Key Improvements for a the HRMT-22 Experiment 1. Test in both vacuum and helium environments If we see an eruption in vacuum then it cannot be due to an aerodynamic mechanism. • 2. Vessel updates Elongated beam windows to facilitate hitting multiple samples. Extra optical window in the lid permits a view of the disrupted sample from above. • 3. New Trough Concept multiple samples, stiff (high natural frequency), thermally linked to vessel.

  6. Key Improvements for a the HRMT-22 Experiment 4. Use mono-dispersed spherical tungsten powder To facilitate better correlation of results with analytical / theoretical pressure drop and drag models. 5. View along the full length of the trough To allow better correlation of lift vs energy deposition as the shower builds up along the sample 30 cm long sample 6. Reconfigure the lighting rig More intensive lighting to permit a faster camera frame rate Energy deposited in a tungsten powder samplefrom FLUKA simulation

  7. HRMT-22 Outer Containment Vessel

  8. HRMT-22 Inner Containment Vessel

  9. 43kg total mass 42675

  10. Experiment Outline Start Vacuum 2x1011ppp Vacuum 1x1012ppp Helium 2x1011ppp Sample #1 Small grains Open Trough Eruption ? Eruption ? Eruption ? N N N ? Sample #2 Large grains Open Trough Y Y Y Vacuum Same beam Helium 2x1011ppp Sample #3 Small grains Open Trough Helium 2x1011ppp Option ‘A’ Higher Intensity Option ‘B’ Vary the Beam Posn. Vary intensity and monitor container wall with LDV Sample #4 Large grains Closed Tube End

  11. Preliminary Pulse List Allow for a total budget of up to 1e13 protons (a few extra shots?)

  12. Temperature Jump in Vessel Components • Observed eruption threshold is well below the melting temperature of tungsten Observed Eruptions • Note: We do not intend to approach the melting point in the tungsten grains or any other part of the apparatus.

  13. Activation Studies: FLUKA Model Geometry Inner Container (Al)container Powder Sample (W) Outer Container (Al) BEAM Beam Window (Ti alloy) • Irradiation Profile used in the simulations : 1 x 1013protons in 1 second – 440GeV/c, sigma = 2mm • Cooling times : 1 hour, 1 day, 1 week, 1 month, 2 months, 4 months • Precision simulations: EMF-ON, residual nuclei decays, etc…

  14. Activation Dose Rates (μSv/h) Maximum dose rate on the sample: 3.7 Sv/h Maximum dose rate on the sample: 103 mSv/h Maximum dose rate on the sample : 9 mSv/h 1 week 1 day 1 hour Maximum dose rate on the sample : 925 μSv/h Maximum dose rate on the sample : 476 μSv/h Maximum dose rate on the sample : 241 μSv/h 1 month 2 months 4 months

  15. Activation Dose Rate Summary • A cool-down time of several months is foreseen prior to manually handling the container. • We do not plan to remove the powder sample from its container post irradiation.

  16. Radiation Protection Assessment

  17. Radiation Protection Assessment • Precautions for the Experiment:(ALARA principle) • Offline setup • Remote instrumentation/ diagnostics • Double containment of the powder • Cool-down prior to dismounting the vessel from the experiment table • Do not plan to remove the sample from its container for post irradiation measurements

  18. Other Safety Considerations

  19. Other Safety Considerations • Precautions for the Experiment:(ALARA principle) • Hydraulic pressure test • Helium Leak test • Non-flammable materials • Inert gas / vacuum environment • Low-voltage connections between control room and experiment table • Off-line trial survey/alignment

  20. CFD Model of Pressure rise in sealed sample holder 0.25 bar Inner containment vessel rated for 2 bar internal pressure As a result of convection between gas and hot powder the gas temperature and pressure in the sample holder can increase Peak pressure and temperature depend on cooled surface area of container

  21. Sample cool down time (time between shots) • Wall temperature (t3) maintained by water-cooled base • Sample temperature (t1) depends on pulse intensity • Exponential temperature decay – depends on natural convection between powder and helium and between helium and cooled containment box • In 7 minutes the temperature has returned to within 1% of its value before the pulse T2 T1 T3

  22. Summary • In 2012 the HRMT-10 experiment we observed beam-induced eruptions in a tungsten powder target. A new experimental cell has been designed for the follow-up HRMT-22 experiment. • The rig incorporates the successful safety and containment features implemented with the first experiment: • Double containment • Remote diagnostics • Offline setup • The improvements in the design include: • The possibility to house multiple independent samples • The possibility to test in vacuum and helium environments • Wider camera field of view • More intense lighting (higher camera frame rate?) • Mono-dispersed spherical powder

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