CERN Rüdiger Schmidt Review 30 July 2014page 1 Summary: LIU-SPS external beam dump review SPS external dump review

CERN Rüdiger Schmidt Review 30 July 2014page 2 Scope of workshop and introduction SCHMIDT, Rüdiger ● The SPS has compared to other accelerators a rather high beam power and it is among the most powerful proton accelerators worldwide ● Is motivation clear and sufficient? ● Are specifications complete, with enough margin? ● Are worst-case beams defined, and repeated dumping for extended periods? ● Margins: design is focused on first phase (incl. HL-HC parameters) using known future beam parameters, what are future upgrade options if parameters will further evolve?

CERN Rüdiger Schmidt Review 30 July 2014page 3 SPS beam dumping: from today to LIU era Verena Kain ● Need to dump all beams, all energies, all types (E, emittance, I, repetition period) ● Emergency dump and setting up ● Start with relevant beam parameters that are known ● Max intensity and cycle length are important parameters ● What is the average beam power? This number is most useful to compare different beams. ● New projects: SHIP with 7.2 s cycle length, LAGUNA, …. 320 bunches for LHC, … should be taken into account … what impact does it have on the current design? ● Operation scenario (e.g. waiting time between cycles, after an emergency dump) ● Current dump in LSS1, H and V sweep (V is fast), internal beam dump, injection kickers in same area. Two beam dump blocks, low and high energy, some forbidden zone 28.9GeV-102.2GeV. At 14 GeV high E dump is not sufficient. Bumps are used, depends on optics. ● Dose close to the beam dump: up to mSv/hr ● 86% of energy is absorbed… where does the rest go? ● Graphite is open to beam tube…. issues with vacuum pressure spikes (HW interlock)

CERN Rüdiger Schmidt Review 30 July 2014page 4 SPS beam dumping: from today to LIU era Verena Kain ● Robustness: repetitive dumping is an issue ● Limits were 18 shots, 6 s cycle, then wait 5 min (total 408 s, 8.6e14 protons) ● Limits were exceeded several times per year, no “formal” limit was set ● Damage with current beam parameters can be avoided by operational procedures / SW interlocks ● One shot of LIU standard would go above operational limit (this limit went down from 400 C to 200 C) ● What are the limits? One shot, continuous use. ● Disadvantages, but in principle ok for beam parameters ● HW upgrade…. no dead zones where we cannot dump ● Emergency beam dumps in in forbidden zone (only very few dumps, per mille effect) ● Improved logging needed ● How much beam / power could one put on the external beam dump?

CERN Rüdiger Schmidt Review 30 July 2014page 5 Recently observed problems with present TIDVG, Ivo VICENTE LEITAO ● Issues: prone to water leak, degassing, radioactive in LSS1 ● During LS1 some refurbishment was done ● Al debris found during LS1, Al block damaged, pieces of about 1 cm, clear damage, no visible impact on beam operation, graphite block ok ● Damaged beam dump due to excessive beam load – dumping for extended periods ● New TIDVG ready by 31 August ● Some improvements have been done, and some improvements will be done in the future (e.g. temperature sensors) ● Maintenance with high accumulated dose: training, robotics, design for end-of-life ● Define beam load: what parameters are relevant? ● Are there any other beam dumps or TEDs at CERN in a similar condition? List of dumps, and list of parameters….. for all dumps and TEDs. ● What is the monitoring and recording of data ● Upgraded internal beam dump for LHC, for what load? Emergency beam dump? Operational issues? ● What damaged the present beam dump? CNGS very likely above by a factor of two. ● Status of old beam dumps TIDVG1?

CERN Rüdiger Schmidt Review 30 July 2014page 6 Recently observed problems with present TIDVG, Ivo VICENTE LEITAO ● Outgassing issue for new dump…. ● Initially “protected” by vacuum (valves close and stop beam due to high pressure) ● Damage of upstream part? Nothing seen…. ● Are different dumps needed? ● Emergency and operational beam dump: why have not only one external beam dump? ● Fraction of emergency beam dumps / operational beam dumps

CERN Rüdiger Schmidt Review 30 July 2014page 7 Rradiation Protection considerations, H. Vincke ● TIDV main problem, about 10e18 p/year, severe radiation problems (activation) ● High dose rate, up to 25 mSv/h after 30 h (one meter from equipment), many consequences ● Momentum collimator TIDP is next (3 mSv/h) ● Air activation: release close to Bat. 54 – to public close to 10 muSv/y ● Air-born radioactivity, tunnel monitors trigger ● Both could stop SPS (happened in 2004, and might happen again with beam dump that is outgassing) ● New beam dump should avoid such problems: redesign or external beam dump (external beam dump more promising option) ● External beam dump: LSS1 will become much cleaner: majority of protons should go out (order of a factor of 10) ● New beam dump considerations: prompt dose, activation, air ● Prompt dose: shielding – high E muons go far. Annual muon dose, 550 m concrete to be avoided – not to have a beamline pointing upstream ● 10 m concrete should be present to avoid controlled area ● Shielding well defined, molasse could be used

CERN Rüdiger Schmidt Review 30 July 2014page 8 Rradiation Protection considerations, H. Vincke ● Activation around new beam: no access limitation in the vicinity, concrete shielding of 3 m radius ● Some operational scenarios: 2e18/yr and 2e18/yr + MD -> acceptable, after one day uSv/h ● Other scenarios if there is too little space, can be optimised, not yet fine tuning. ● Air activation: prevent immediate air release (consider location) ● Dose to accelerator equipment: no problem to outside shielded region (cable exchange not required, say, every 10 years) ● What beams can be dumped? How much fraction of the power? ● Integrated power is the parameter ● Momentum collimator TIDP is next (3 mSv/h): can the dose be brought down? Not clear, better when operating without transition ● Fixed target beam after extraction should be also extracted (few % of beam end of each cycle) ● Transport of an activated dup: needs to be considered, but can be done…

CERN Rüdiger Schmidt Review 30 July 2014page 9 Energy deposition considerations for the worst SPS beam scenarios, Genevieve STEELE ● One shot for each beam dump was calculated ● Run 2 beam parameters were considered, up to 4e13 protons ● Sweeping is considered, different for different beams (depends on batch length), is an important factor for one shot, emittance is less of an issue – Run 2 dT increase of 70 C ● Run 3: dT increase of 170 C ● Different cores lead to different T ● Ti – advantages, optimisation still possible ● Increase of high density graphite? C-C? Difficult to get….adding some other material? ● For emergency beam dump do not need to stop 80% protons ● TEDs: dependence of beam spot size. Even more critical…..higher energy deposition, but closed. What would happen? Closed system. Risk to be analysed. ● What is the impact of melted Aluminum? ● TED –could we do some monitoring? ● External dump: beta function of = 1000….1800 m assumed ● Would be 7 m long if only graphite (dT = 1000 C)

CERN Rüdiger Schmidt Review 30 July 2014page 10 Energy deposition considerations for the worst SPS beam scenarios, Genevieve STEELE ● For 4 m, up to 800 C in copper, or up to 450 C with longer graphite part ● Longer graphite absorber could do it ● Less constraints for any external beam dump ● Shock waves – 2 nd order problem, also if the material close to melting temperature? ● Plastifying – how does it evolve with time?

CERN Rüdiger Schmidt Review 30 July 2014page 11 Thermo-mechanical analysis, Florian PASDELOUP ● TIDVG 1 from 2000 to 2004 ● TIDVG 2 from 2006 to 2014 ● TIDVG 3 from 2014 to 20xx ● HL-LHC 4.82 MJ ● Cooling system cools copper part, cooling of Al depends on the Thermal Contact Conductance ● Al is limiting factor, bake-out weakens it: Al at 250 C during 350 h decrease yield strength by 68 % ● dT should not be higher than 150 C ● Stress less than 77 MPa, elastic, higher plastic ● Between 250 and 600 C, not clear, above there is melting ● Plastification can lead to reduced cooling ● For 10 pulses, cooling to the outside not important, heat capacity and conductivity of Al block leads to cooling of Tmax ● Plastification happens after a few shots (for new TIDVG)

CERN Rüdiger Schmidt Review 30 July 2014page 12 Thermo-mechanical analysis, Florian PASDELOUP ● After 47 pulses, temperature reaches 450 C (assuming nominal cooling, too optimistic) ● Ideas: higher density graphite, other material (e.g. boron nitride),eliminate Al and use Ti, improve cooling, … ● Cooling of Al absorber blocks possible? Not obvious, problems in the past…. ● Longer SPS cycles? No real gain…. ● How many pulses to get to melting point? 47 pulses…. ● Copper block is cooled, should be not problem….. ● Interesting to understand observed damage mechanisms of Al (not clear how a 1 cm piece of Al could form)

CERN Rüdiger Schmidt Review 30 July 2014page 13 External beam dump option A: branching off from LSS6, Jose ABELLEIRA ● Two options: TT61 and TNC (HiRadMat) tunnels: old neutrino tunnel or using HiRadMat tunnel ● Extraction system can be re-used ● Some modification of magnets: 4 MBS (larger aperture) instead of 2MBB ● Vertical bending is an issue: option to use existing tunnel, ● No access in HiRadMat when extracting in LSS6 ● Long shielding for muons, 600 m long shielding ● Or have a horizontal beam path, excavation needed, tunnel of 140 m required, complicated option ● Other angle, going through surface. What about molasse? Enough shielding? ● TNC: water activation? Since dump is close to tunnel wall: no issue ● Very close to HiRadMat – HiRadMat dump to be moved ● Could there be only one dump? For HiRadMat and the external dump. No. ● Beam size would be large enough ● Issues with interlock – beams with same energy ● Cost is in the order of several MCHF

CERN Rüdiger Schmidt Review 30 July 2014page 14 External beam dump option A: branching off from LSS6, Jose ABELLEIRA ● Not clear what such external beam dump could ● Civil engineering difficult, access difficult ● Dipole magnets could dilute muons ● Energy and emittance: does beam fit into aperture

CERN Rüdiger Schmidt Review 30 July 2014page 15 External beam dump option B: branching off from LSS4, Francesco Maria VELOTTI ● Studies only done for LHC beam types, extend use of such dump going on (e.g. FT 5%) ● LSS4 dedicated line ● Tunnel enlargement needed ● Behind TT40 create a dump line in TI8 ● MKE.4 could be extended to 21 mus ● Two versions studied…. with different dilutions ● Aperture has been studied (emittances for slow extracted beams) ● CE enlargement is best for CE ● Enough space for sweepers ● Order of 5 MCHF without CE (incl. sweepers) ● What beams can be dumped with what type of systems (Energy, emittance)? ● Not clear if FT beams can fit through aperture…. some magnets might be too small ● Better to have only one cross section ● If we can dump all beams above 150 GeV (LHC), 300 GeV (FT) we would gain a lot, below is 1 % ● Early dumps could be at higher energy, is this preferred? Possibly… ● How to do it operationally – operational scenarios….

CERN Rüdiger Schmidt Review 30 July 2014page 16 External beam dump option B: branching off from LSS4, Francesco Maria VELOTTI ● Operational scenarios….to be developed. ● RP prefers TI8, better shielding, muons no problem, air activation better ● HiRadMat – ventilation system might have to be considered

CERN Rüdiger Schmidt Review 30 July 2014page 17 Civil engineering work, Martin MANFREDI ● LIU-SPS external beam dump in LSS4 was assumed ● Path to access with some distance in several tunnels ● Several options are being studied ● Enlargement 68.5 m * 10.5 m wide or 73 m * 10.5 m or 91 m * 10.5 m (concrete and iron shielding) or 83.6 m * 12.5 m (only concrete shielding) ● Distance between TT41 and new tunnel at least 4.80 m ● Molasse could be used for shielding ● Exchange of the dump to be discussed, several options ● Displacement from TI8 line is fixed ● Different options: CE cost between 8.9 and 12.6 MCHF (incl. 10% contingency and consultants), uncertainty about 50% ● 5 years project, CE works could be done during 20 months, some GS resources needed ● Reinstallation about 6 months… what about operation of Awake? ● Shielding on the back side needed – not needed, could reduce CE (what about water?), could be faster

CERN Rüdiger Schmidt Review 30 July 2014page 18 Civil engineering work, Martin MANFREDI ● Can we access the area when no extraction in LSS4 – probably yes, to be studied ● Shaft PCG8, can it be used? Could be better… ● Should start soon (consultant and contractor) – begin of 2015 when activities should be done in LS2 ● Dedicated extraction line: would it be possible? More kickers, expensive, but would be of some advantage…still not to be discarded ● Extraction kicker in the line… if LHC injection is not permitted, send beam into external beam dump ● Extra extraction kickers in SPS? The it would be better to build a new system in LSS5. ● LSS5: SPS performance (e.g. impedance), use of LSS5 for other applications, cost of new system, radiation in LSS5, radioactive zone in LSS5

CERN Rüdiger Schmidt Review 30 July 2014page 19 Summary ● Motivations for an external beam dump: activation, efficiency of operation (HL-LHC) ● An external beam dump should be designed to be used for the next, say, 40 years (a least it should be designed such that an upgrade is possible) ● Beam parameters improved over the last 40 years, a similar improvement is expected for the future ● Could one external dump use for all beams? ● Logging of parameters to be improved