summary: liu-sps external beam dump review

CERN

Rüdiger Schmidt Review 30 July 2014 page 1

Summary: LIU-SPS external beam dump review

SPS external dump review

CERN


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


SPS beam dumping: from today to LIU eraVerena 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 15-25 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


SPS beam dumping: from today to LIU eraVerena 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


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


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


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


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 1-10 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


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


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 – 2nd order problem, also if the material close to melting temperature?● Plastifying – how does it evolve with time?

CERN


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


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


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


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


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


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


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


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


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

summary: liu-sps external beam dump review

Documents

beam operation

internal beam dump

beam dump blocks

sps beam dumping

relevant beam parameters

current beam parameters

high beam power

dumpemergency beam dumps