EuCARD-2 is co-funded by the partners and the European Commission under Capacities 7th Framework Programme, Grant Agreement EuCARD2 ColMat HDED : Past & Future work ColUSM ♯ 50, 16 January 2015

Past & future F. Carra: MoGr and CuCD mandatory to achieve -50% impedance for HL-LHC. With HL-LHC parameters, CuCD major failure, CFC and MoGr minor damage: – Proposed models will be improved to consider material pseudo- plasticity and tension/compression asymmetry, as well as temperature and strain-rate contribution to the mechanical resistance. – Need to review impact parameters for HiLumi. Find worst case in terms of impacting beam sizes (after ongoing tests with old reference case). O. Sacristan: Thermo-mechanical characterization of MoGr and CFC. Different resistance in the 2 planar directions of CFC (previously considered as transversally isotropic material). – Complete the characterization of MoGr final grade. – Complete CuCD characterisation (samples from RHP).

Past & future L. Peroni: dynamic characterisation of collimator materials at high temperature (up to 1000°C), strong tension/compression asymmetry found in Inermet180 – Optimize setup of dynamic measurements of brittle materials (MoGr, CuCD, CFC, etc) at room and high temperature. – CuCD tests with samples without screw threads? E. Quaranta: Impact distribution coordinates in TCT for different failure scenarios available for FLUKA and AUTODYN simulations. – Compare with FLUKA and other codes composite parameters used to model MoGr and CuCD in SixTrack. – Take into account electronic contribution to energy deposition calculated by FLUKA.

Past & future M. Tomut: results of irradiation tests at GSI on LHC collimator material samples – Irradiated carbon fibers showed strong radial contraction. – Beneficial effect of heat treatment on MoGr radiation-induced deformation. – Thermal diffusivity degradation in MoGr very fast at low fluencies with respect to CuCD, but plateau reached at higher fluencies. Much better behaviour than pure graphite. – Finalize tests on carbon fibers irradiated with Au ions. – Complete sample characterisation (treated at 1800˚C) and data analysis. – Provide a list of post-irradiation measurements already completed on irradiated samples + list of ongoing and planned measurements – Provide energy loss profile in the irradiated samples.

Past & future A. Ryazanov: results on MoCuCD. – Clarification on axis labels and data normalisation would be helpful. N. Simos: results of irradiation tests at BNL on LHC collimator material samples. – Wait for the most radioactive samples to cool down before handling for measurement. – Complete analysis of irradiated samples (student from CERN). – What is the impact of different grades of MoGr (samples > 2 years old were irradiated)? – How do we analyse the X-ray data? Action CERN and Graz: finalize proposal for microphone measurements for HRM tests, with clear responsibilities for different experiments.

Discussion on DPA and future work Parameters to account for damage are: – DPA – He/H transmutation (especially for high energetic particles). Can we measure it? – Electronic stopping (presently taken into account only as temperature increase, could produce damage – DPA – in non-metallic materials); Damage correlation between different types of irradiations (projectile and energy) should take into account (do we believe we can do it?!!): – Primary recoil energy spectra; – Displacement dose rate, DPA/s; – Transmutation production rates, He/DPA and H/DPA; – Kinetics of irradiation-induced defect production and accumulation behaviour due to pulsed irradiation; – Production of single point defects and defect clusters.

Discussion on DPA and future work Damage threshold for graphitic material under proton irradiation ~ 0.2 DPA. o Is this threshold valid also for energetic protons, where He/H transmutation is relevant? o To be noted that 30-40% degradation in electrical conductivity could be nevertheless relevant to LHC. o To be noted that according to FLUKA, for ultimate HL-LHC (at 4000 fb -1 ), horizontal primary collimators would reach 0.3 DPA. o MoGr seems less radiation resistant than CuCD. It could still be ok if DPA estimations are confirmed. – Graphite is a metal-like in the graphitic plane and an insulator in the perpendicular one. The electronic contribution to DPA is should be taken into account.

Highlights from GSI meeting Do we all agree on the Figure of Merit proposed by Nikolai? FoM proposed by Eng. team Factor if one does not reach DPA max

What can we do to validate materials MT proposed to bombard -Samples charged with He. Would that allow to measure He transmutation? -New samples with light ions below track formation threshold. Drawback is that damage accumulation would be too slow. Benchmark DPA calculations against experimental data (Latest from GSI? Other data?). Should DPA calculation include electronic stopping for non metallic materials? Is it possible to measure DPA (to be linked to measured properties degradation) on GSI data?