hiradmat beam time request form · 2020-05-04 · high energy and high intensity proton beams on...

HiRadMat - Experiment Proposal EDMS No: 1213282

Version 4.0

HiRadMat Beam Time Request Form Designation

Experiment Name Proposal 2002

Acronym HRMT-HED

Date 24/02/2020

General

Responsible/primary contact Person completing this beam request

Name François Xavier Nuiry

Home institute CERN

E-mail [email protected]

Phone 0041754119640

Participating institutes

CERN List of participating institutes, relevant information for Transnational Access (if necessary).

Number of team members

10 Estimated number of persons participating to the preparation and/or the experiment with travel/stay at CERN.

Interested in Transnational Access

No More information at http://cern.ch/hiradmat

Scientific description

Executive summary The HL-LHC project has recently approved a new LHC beam dump system (HL-LHC baseline v3.0). In that context the design of a new LHC beam dump assembly is required in order to fulfil the HL-LHC beam impacts (see reviews https://indico.cern.ch/event/784431/ and https://indico.cern.ch/event/870677/ ). The HIRADMAT-TDE experiment will consist in impacting high energy and high intensity proton beams on different low-density materials pre-selected as possible candidates to be part of the future LHC External Beam Dump core (TDE). One of the objectives of the new design will be to keep reasonably low values of energy density peak (hence peak temperatures) in the dump core material.

A very short (couple of sentences) description of the scientific purpose and the experimental setup.

HiRadMat - Experiment Proposal

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Probing the robustness of low-density carbon-based materials is also of importance for progressing on the design of dumps and absorbers for future colliders like FCC-hh and FCC-ee. The beams stored in these machines pose severe challenges for beam-intercepting devices due to the high stored energy and the small transverse beam sizes.

Scientific motivation The present LHC Beam dump is made of an 8.5 m long and 720 mm diameter stainless steel tube, filled with:

- 1.73 g/cm3 graphite Sigrafine® blocks; - 1.1-1.2 g/cm3 flexible graphite Sigraflex® sheets.

In 2018, EN-STI inserted some 0.5 mm thick Sigraflex samples in the HRMT43 experiment, executed in collaboration with Fermilab. Sigraflex® samples were installed profiting from some space remaining in the last positions of two samples carriers, made up of 24 thin samples. The different sample carriers (SC) received the following beams:

- SC 1: one pulse of 288 bunches, 3.51*1013 POT, sig_x: 0.27 mm, sig_y: 0.22 mm;

- SC 2: one pulse of 216 bunches, 2.53*1013 POT, sig_x: 0.28 mm, sig_y: 0.21 mm.

The experimental setup was recently opened at Culham Centre for Fusion Energy (UK) to execute Post Irradiation Examination and the Sigraflex® samples have been unexpectedly observed to be quite damaged by the beam impact (photo below):

Profilometry and SEM inspections are planned on these samples in Q1 2020, to understand the type of damage that occurred on the material. At the same time, blocks of higher density isotropic graphite (such as the SGL 7550) were unscathed by the highest intensity beams, confirming the results already obtained in the HRMT28, HRMT35 and HRMT44 experiments.

Extended description of the scientific purpose (couple of paragraphs) including the expected scientific results.

beam Impact


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The peak energy density achieved in the Sigraflex® samples located in SC 1 was 3.5 kJ/cm3. The peak energy density achieved in the Sigraflex® samples located in SC 2 was 2.7 kJ/cm3. These values are already below the peak energy densities expected in the LHC dump for the HL “regular” dumps (3.6 kJ/cm3), and therefore calls for further investigation on the behavior of the Sigraflex materials at this high energy densities. However, in case of one extraction kicker missing, the value will be close to 4.8 kJ/cm3 and even worse for other extraction system failure scenarios. The new LHC dumps (to be ready by 2025) should be able to survive several thousands of regular dumps every LHC run, for a total lifetime lasting at least up to 2040 (see EDMS 2311633). The preliminary Sigraflex® samples results following HRMT43 suggest to: à Further study the use of this material as beam intercepting material, to anticipate any eventual operation limitations during run 3, and to confirm (or not) and precise the Sigraflex® material response (the CERN-NTNU collaboration is indeed exploring the material properties of Sigraflex at high temperatures); à Broaden the possible materials choices, by testing other promising grades, with densities around 1 g/cm3 and even below, to keep local peak temperatures in the future LHC dump as reasonably low as possible (See energy deposition studies presented at the TDE review in January 2020: https://indico.cern.ch/event/861851/ ). In that context, carbon based materials are particularly interesting because of their high thermal shock resistance and the possibility for them to operate at temperatures up to 3200°C. Experimental measurements of carbon interaction with nitrogen (foreseen production of CN at temperature greater than 1500 C) could also be foreseen, in an experimental apparatus separated from the rest. Low-density carbon-based materials will also be of essential importance for protection devices and beam dumps in future high-energy colliders, like the FCC-ee (45.6-182.5 GeV electrons) and FCC-hh (50 TeV protons). The beams in these colliders pose a severe challenge for the absorber material robustness because of the high stored beam energy (8.5 GJ in FCC-hh) and the small transverse beam size (emittances of one picometer in FCC-ee). To safely absorb the FCC-ee and -hh beams, the energy needs to be sufficiently diluted inside the dump


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block. In order to decrease the dilution requirements for these machines, very low-density carbon-based materials are promising absorber candidates due to the reduced thermal peak load inside the dump core. Graphite could also be a suitable material for passive beam diluters which can complement or replace more complex kicker-based systems. Simulation studies indicate that a few cm thick Graphite block could be used for diluting the FCC-ee beams, without the need of an active dilution system. Testing these materials in HiRadMat will improve the knowledge about their robustness, which is essential for progressing on the design of FCC dumps and dilution systems. In particular, it is foreseen to test a first possible diluter prototype for FCC-ee. In particular, given the reduced dimensions of such passive diluter (cylinder of 100 mm diameter by 30 mm length), an integral test of the entire device would be possible in HRMT, allowing to benchmark the numerical models used to simulate the thermos-mechanical behavior of this device. The graphite cylinder would be enclosed in a metallic tube (probably titanium) and the entire assembly would be properly instrumented in order extract all the necessary data to crosscheck the results obtained from finite element simulations.

Measurement methods

HiRadMat beam instrumentation to check both the beam spot size and the beam location are requested. Offline measurement methods: Metrology measurements, High definition pictures, and possibly micro-tomography and ultrasonic controls. Online measurement methods: HD cameras, vacuum pressure monitoring, and if possible, a surface displacement measurement of some targets (Laser Doppler Vibrometers or LVDTs depending on the dynamics expected). Temperature measurement instrumentation will be also needed.

Description of online and offline measurement methods enabling the analysis in view of the scientific purpose. Please include HiRadMat beam instrumentation (dedicated BTV/BPKG) if required.

Additional comments

Experimental Setup

Equipment to be installed

The set-up used for the previous experiments (in 2018) HRMT46, 48 and 49 is proposed to be used for this experiment. The vessel is made out of aluminum to reduce the activation and its design is compliant for operation under vacuum or under static (or recirculating) inert gas.

Text, drawings and photos (can add as attachment to submission)


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As an alternative, EN-STI also has the large vessel used for the HRMT28, adapted for collimators material.

Dimensions The large dimensions (1600 mm × 770 mm × 650 mm) of the setup provides flexibility in the sample holder design choice, allowing the optimization of the handling operations and saving dose after the experiment. The dimensions also give some flexibility in the target design choice.

External envelop values; Length (in beam direction), width, height

Weight (total) Around 1 ton. Stiffeners have been added for HRMT46, 48 and 49, to reduce the deformation of the HiRadMat supporting table.

Material inventory

Target All targets will be made of solid materials. The targets will be dimensioned in order to obtain peak energy densities and temperature comparable to those expected in the TDE dump core during regular dumps and other failure scenarios. In that context, with target densities around 1 g/cm3 (some of the sampes have densities up to ±2.5 g/cm3 or down to 0.1 g/cm3), target lengths of maximum few tens of centimeters will be enough. The following materials are candidates for the HIRADMAT-TDE experiment. The exact final list of materials will be detailed at the Technical board stage.

- Sigraflex® (SGL); - Extremely low density carbon felt Sigratherm® rigid

and soft felt (SGL); - Sigrasic® (SGL); - Sicabond® (SGL); - Very low density and high conductivity graphite

sheets: Perma-foil® (Toyo Tanso); - Flexible graphite Papyex® (Mersen); - Flexible carbon foams (Schunk).

Material directly exposed to the primary beam. Elements and isotopic composition if known. Respective weight and state (liquid, gas, solid)


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The material orientation and stacking plays a large role in the final behavior of the system, and an energy deposition optimization shall help in defining the best design. A combination of different materials (TDE-core optimized composite) can be suggested.

Support Supports will be made of both stainless steel 304L and 316L and aluminum 6000 series.

Material NOT directly exposed to the primary beam (support, confinement …). Elements and isotopic composition if known. Respective weight and state (liquid, gas, solid)

Measurement/observation tools

Online monitoring All online monitoring tool is standard from previous experiments executed by EN-STI and for which operational experience can be demonstrated: - BLM located at the bottom of the experimental STAND B in TNC. - BTV.660524 on STAND A. - High definition cameras (Rad hard and non-rad hard): Ahlberg Z630 HD rad hard camera; Standard HD camera Axis M1125; Thermo Fisher Scientific rad hard camera 8827DX7; Reflex camera (in TT61) with mirrors; -If possible, and depending on the target, (LDV) Laser Doppler Vibrometer from Optomet with optical fibre head (OBJ-DF-64). - Pressure sensor (Pirani Gauge from CERN store SCEM 18.40.30.D). - A set of temperature sensors (PT100 or thermocouples) as well as a pyrometer, if it is compliant with the acquisition speed required and if adapted to the experimental setup.

A list of online monitoring methods to be used. Describe the online monitoring tools to verify the successful conduct of the experiment.

Post-irradiation analysis and decommissioning

Metrology measurements at the CERN metrology lab, in an RP controlled area, as already done for several past experiments. If there is no risk of contamination (according to HRMT28, HRMT44 and HRMT45 experience), the complete samples will be transported by means of a dedicated radioactive transport at the metrology workshop. Metrology measurements before and after jaw dismounting will ideally be carried out. Micro-tomography is proposed, at CERN or at the ESRF synchrotron facility in Grenoble (as already done for HRMT28). Nevertheless, this technique is known to generate multiple reflection artifacts for isostatic graphite and shall be checked for felts and foils. The dismantling of the experiment will take place in the EN/STI RP-compliant bunker in 867/R-P58, as already done for HRMT46/48/49, which used the same setup. The experiment will be stored in a radioactive storage at CERN for re-use later.

Specify what kind of post-irradiation analysis will be conducted (e.g., destructive tests, etc.) and provide details on how and where this analysis will be conducted. Add also a description on how the equipment will be handled and treated after the irradiation and what the final destination of the material will be.


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Additional comments The experiment shall respect the space requirements described on drawing SPSXMUSR0143. The experiment is proposed to be installed on STAND B or C. If installed on STAND B, a clash with the STAND C area is expected, but manageable. Final location will depend on the available optics on target. The experimental team is aware that the beams available in 2021 will be limited to pre-LS2 beams at best. Another similar experiment might be repeated in the future if and when higher intensities will be available at HiRadMat.

e.g. special requirements on the infrastructure (beyond standard cabling, electrical power, water cooling)

Beam parameters

Particle type protons Protons

Pulse intensity (range)

The maximum possible value: around 1.2*1011 protons

The maximum possible value: around 3.46*1013 protons

Indicative range for beam intensities

No. bunches 1 288 Indicate if a fixed value is desired or quote the range to be scanned. Details of beam parameters can be found at http://cern.ch/hiradmat.

Intensity/bunch Max 1.2*1011 Max 1.2*1011 Spot size 0.313 mm × 0.313 mm or

lower 0.313 mm × 0.313 mm or lower

Number of pulses 40 ±30 Estimated number of pulses on target

Integral intensity 4.8*1012 ±1.0*1015 Estimate of total integrated intensity on target during the experiment

Additional comments Beam used for the initial beam location and spot size setting up.

Beam required for the experiment itself. Several shots per target will be requested, with an intensity increase.

N.B.: These are indicative values; a detailed pulse list will be requested from the experiment at a later stage during the approval process. Safety and radiation protection aspects

General Safety The setup planned to be used has already demonstrated its compliance with respect to safety, through experiments HRMT46/48 and 49. The samples can be put under primary vacuum (~5*10-2 mbar) or under inert gas environment. Nitrogen or argon are candidates: the inert atmosphere could be applied only to a subset of target, depending on needs, enclosing the samples in a dedicated box (as for HRMT43). Nitrogen gas is not inert at T>1500°C with carbon materials: Interaction between C and N2 >1500 °C can lead to cyanogen & hydrogen cyanide formation, and mass reduction. A dedicated experimental system might be foreseen. A leak tight containment will be guaranteed.

Indicate any major safety aspects (e.g. vacuum/pressure-volume, chemicals, gases/flammable, cryogenics, magnetic field) apart from radiation/activation items


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Radiological risk As the tank will be reused from a previous experiment, it is necessary to take into account its residual dose rate. The activation of the setup used for HRMT46/48 and 49 on July 2019, was equal to the following values (9 months after the experiment):

- 30 µSv/h at 40 cm; - 250 µSv/h at 10 cm.

However, these values are definitely higher than the empty setup itself, because it presently host the n_TOF Sol4 target, which is the main source of the residual dose rate value. This target will be removed in S1 2020, allowing to get a precise measurement of the bare setup residual dose rate. In addition, the downstream flange is made of stainless steel, which is the biggest contributor of the dose rate of the tank itself. If judged to be problematic, it could be exchanged for a Ti one. For the proposed HRMT-TDE experiment, one could get a first approximation of what will be the activation looking at what was obtained for HRMT44 experiment. In the case of HRMT44, the most impacted target was 2.1 m long and was made of 1.84 g/cc graphite blocks. It received three 288 bunches shots. The experiment has been done in July 2018 and on January 2019, this target was 12 µSv/h at 10 cm. For HRMT-TDE, if we assume 25 cm long targets made of 1 g/cm3 carbon-based materials, the inelastic interactions will be four times lower than the one got for HRMT44. Providing that three to five high intensity shots per target are expected in shots HRMT-TDE, the final residual dose rate values are expected to be similar to what was obtained for HRMT44.

Evaluate the radiological risk for the experiment. During the irradiation: • activation, dose rate,

contamination. • assessment of the risk of

release of radioactivity by melting/vaporization (e.g., under which conditions you expect melting or if it can be excluded etc.)

At the time of handling and post-irradiation analysis: • type of radiation (i.e.

Alpha, beta, gamma, neutron etc.), dose rate, and contamination.

Contamination risk The targets are located inside tight vessels, so even in case of contamination, it should remain in the container and treated after transport to the 867/R-P58 bunker (capable of dealing with contamination risks).

Provide information of the foreseen containment preventing contamination outside the containment during irradiation and handling

Additional comments

N.B.: A detailed safety assessment will be requested following the approval of the HiRadMat Scientific Board. Schedule

Experimental timeline Preparation in BA7: 2 weeks maximum. Beam time: In principle, two shifts maximum. Estimated cool-down time before post irradiation analysis: about 1 month behind the dump in TNC.

Proposed timeline of the experiment. Indicate the preparation time in the tunnel, the beam time and the estimated cool-down time before post-irradiation analysis/removal.

Earliest date Available slot in 2021. Indicate the earliest date you could be ready using SPS beam time


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Latest date November 2021. This experiment is a key part of the material selection process for the future LHC beam dump core, for which the design and production will at least last from 2022 to 2025. In addition, the LHC Dump being part of the Russian in-kind for the HL-Project, CERN shall specify as early as possible to the Russian institutes the material to be used. Depending on the experimental results and the LHC dump design status in 2021, another HiRadMat experiment in 2022 or 2023 could be requested, depending on the availability of higher beam intensities.

If applicable; with justification

Additional comments

General remarks

- This application form shall be sent to [email protected] with complete information (fill empty table cells only) and in the

original doc-format. You will be contacted individually for the further steps of the application process. - Any remarks or questions shall be addressed to [email protected] only. - The HiRadMat facility is part of ARIES co-funded by the European Union’s Horizon 2020 Research and Innovation

Programme under Grant Agreement no. 730871. Any scientific publication related to HiRadMat shall include the statement:

- More details can be found at http://cern.ch/hiradmat.

hiradmat beam time request form · 2020-05-04 · high energy and high intensity proton beams on...

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