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 HiRadMat Technical Review, July 2014 Previous In-Beam Test: HRMT-10, 2012 Beam LDV/camera  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 Open trough Assembly Tungsten powder response to a 440 GeV proton beam pulse at HiRadMat

3 HiRadMat Technical Review, July 2014 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: i.direct momentum transfer between grains (i.e. shock-transmission through the bulk solid) ii.An electrostatic mechanism iii.Trough Wall vibrations exciting the powder

4 HiRadMat Technical Review, July 2014 Apparatus for the HRMT-22 In-Beam Test Top window to view sample disruption Lighting re-configured to allow a view of the full trough length Outer Vessel Inner Vessel High Speed Camera LDV Horizontal linear stage to switch between samples Sample #1 ‘Small’ particles Trough Sample #2 ‘Large’ particles Trough Sample #3 ‘Small’ particles Trough Sample #4 ‘Large’ particles Tube

5 HiRadMat Technical Review, July 2014 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 HiRadMat Technical Review, July 2014 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 Energy deposited in a tungsten powder sample from FLUKA simulation 30 cm long sample 6. Reconfigure the lighting rig More intensive lighting to permit a faster camera frame rate

7 HiRadMat Technical Review, July 2014 HRMT-22 Outer Containment Vessel

8 HiRadMat Technical Review, July 2014 HRMT-22 Inner Containment Vessel

9 HiRadMat Technical Review, July 2014 Part NameDRG No.MaterialMass (g)QuantityTotal Mass (g) Outer Box SidesTD Al Alloy Inner Box CoverTD Al Alloy Outer Box Base PlateTD Al Alloy Glass Window Soda-lime Glass Light Bracket PostTD Copper OFHC Inner Box Base PlateTD Al Alloy Optical Window Retainer Al Alloy Pressure relief valves/Pipes St. Steel10911 Tungsten Powder Tungsten8501 Outer Box Feedthrough FlangeTD St. Steel7741 Powder Trough SaddleTD Titanium Alloy (TiA14V) M6x16 Screws A2 St. Steel M6x25 Screws A2 St. Steel Beam Window FlangeTD Al Alloy Pressure Sensor St. Steel body Ball valves Brass2171 Tungsten Powder Holder - InnerTD Pure Titanium1011 Tungsten Powder Holder - OuterTD Pure Titanium891 Beam WindowTD Titanium Alloy (TiA14V)22488 M4x16 Screws A2 St. Steel LED cluster Extra Screws A2 St. Steel441 Window Packer Gasket Klingersil kg total mass

10 HiRadMat Technical Review, July 2014 Experiment Outline Sample #1 Small grains Open Trough Vacuum 2x10 11 ppp Eruption ? Vacuum Same beam Vacuum 1x10 12 ppp Helium 2x10 11 ppp Y N Eruption ? Y N Helium 2x10 11 ppp Y N ? Option ‘A’ Higher Intensity Option ‘B’ Vary the Beam Posn. Helium 2x10 11 ppp Vary intensity and monitor container wall with LDV Sample #2 Large grains Open Trough Sample #3 Small grains Open Trough Sample #4 Large grains Closed Tube Start End

11 HiRadMat Technical Review, July 2014 Preliminary Pulse List HRMT-22 Beam Pulse List Created: DRAFT 04-July-2014 Beam Pulse List No IntensityBeam spot [mm] Bunch spacing [ns] Pulse length [us] # bunchesp/bunchTotalSigma_xSigma_y E E E E E E E E E E E E E E E E Total5.80E+12 Allow for a total budget of up to 1e13 protons (a few extra shots?)

12 HiRadMat Technical Review, July 2014 Observed Eruptions Observed eruption threshold is well below the melting temperature of tungsten Temperature Jump in Vessel Components Note: We do not intend to approach the melting point in the tungsten grains or any other part of the apparatus.

13 HiRadMat Technical Review, July 2014 Activation Studies: FLUKA Model Geometry Inner Container (Al)container Outer Container (Al) Powder Sample (W) Beam Window (Ti alloy) BEAM  Irradiation Profile used in the simulations : 1 x protons 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 HiRadMat Technical Review, July 2014 Activation Dose Rates (μSv/h) 1 hour 1 day 1 week 1 month 2 months 4 months 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 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

15 HiRadMat Technical Review, July 2014 Activation Dose Rate Summary Cooling time Outer Vessel Dose Rate [uSv/h] – Top of container Inner Vessel Dose Rate [uSv/h] – Top of container Maximum Dose Rate on the Tungsten Sample [uSv/h] 1 hour2.74 x x x day1.55 x x x week x month months months  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 HiRadMat Technical Review, July 2014 Radiation Protection Assessment

17 HiRadMat Technical Review, July 2014 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 HiRadMat Technical Review, July 2014 Other Safety Considerations

19 HiRadMat Technical Review, July 2014 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 HiRadMat Technical Review, July 2014 CFD Model of Pressure rise in sealed sample holder 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 Inner containment vessel rated for 2 bar internal pressure 0.25 bar

21 HiRadMat Technical Review, July 2014 Sample cool down time (time between shots) T3 T1 T2 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

22 HiRadMat Technical Review, July 2014 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