# FeaturedI Beyond LHC, future particle colliders and lasers

1. Aug 27, 2017

### kodama

With LHC currently at 13TEV design energy, and a planned higher luminosity upgrade,

is the current plan to double the magnet strength for the current existing LHC to arrive at a 28-33TEV collider, or is it building a completely new future 100 TEV collider near Geneva where LHC is housed but in a completely new tunnel or in China?

Are future lepton collider plans, such as one in Japan, linear or circular?

My understanding is that Japan is planning a linear lepton collider, a Higgs factory at $12 billion but that either CERN or China plans a circular lepton collider. Lastly, has there been any research of either a hadron collider or lepton collider using lasers, with performance significantly beyond current LHC? lasers were one researched way at arriving at nuclear fusion, currently colliders use super conducting magnets to accelerate hadrons at great expense and complexity. has there been any engineering proposals using lasers to assist in the collision? 2. Aug 27, 2017 ### stoomart My understanding is the next stages for CERN are the HL-LHC and FCC: https://home.cern/about/accelerators/future-circular-collider The goal of the FCC is to greatly push the energy and intensity frontiers of particle colliders, with the aim of reaching collision energies of 100 TeV, in the search for new physics. ​ 3. Aug 27, 2017 ### kodama is HE-LHC then DOA? 4. Aug 28, 2017 ### mfb ### Staff: Mentor HE-LHC is still around as idea, but it is not followed that actively. It could be implemented after the HL-LHC lifetime (2035+), it would need significant changes for both the accelerator and the experiments. Projects that get attention: • ILC, a 30 km linear collider in Japan, a few hundred GeV electron/proton collisions (Higgs, top, Z, W) • CEPC, a 50 km ring in China, at about 240 GeV collision energy, just enough for H+Z production. The tunnel could be used for a proton-proton collider later (~50 TeV). • FCC, an ~80-100 km ring at CERN, colliding protons at ~100 TeV or electrons at ~300 GeV collision energy. • CLIC is still around as idea, a powerful low-energy drive beam accelerating the high-energy beam at 100 MeV/m (3 times what conventional cavities can do), for 1-3 TeV collision energy with electrons/protons. CERN is interested, but it could be built elsewhere as well. None of these have funding for construction at the moment. There are several projects testing plasma acceleration with lasers or proton drive beams, but the technology is not ready to make more specific plans for a collider based on that. 5. Aug 28, 2017 ### ISamson There are several projects testing plasma acceleration with lasers or proton drive beams, but the technology is not ready to make more specific plans for a collider based on that. How would these future technologies work? It would be very interesting to know more. 6. Aug 28, 2017 ### mfb ### Staff: Mentor Please mark quotes as quotes. Wikipedia has an introduction Shoot a laser or a proton beam into a plasma, followed by an electron beam with the right timing, and you can accelerate the electron beam by tens of GeV/m, a factor 1000 more than conventional acceleration methods. You could replace kilometers of accelerator infrastructure by a few meters of plasma acceleration - if you get the beam parameters right. 7. Aug 28, 2017 ### ZapperZ Staff Emeritus The history of high energy colliders has always being circular-linear-circular-linear-circular-....... The next one that is on the drawing boards is the latest incarnation of the International Linear Collider (ILC). There have been several design workshops being held for this, and I believe the front-runner currently to host this is either Japan or China. https://www.linearcollider.org/ Zz. 8. Aug 28, 2017 ### mfb ### Staff: Mentor Where are all the linear colliders? SPEAR, DORIS, PETRA, CESR, PEP, LEP - all circular. SLC, in parallel to LEP with its timeline, is the only exception. The flavor physics colliders are all circular as well. ISR, SPS, Tevatron, LHC - the hadron colliders don't have any linear collider. HERA was circular as well. 9. Aug 28, 2017 ### kodama sounds promising and cost effective. how much of a technical hurdle are the beam parameters? if such a collider could be built how would it compare with LHC in terms of discovery potential? 10. Aug 28, 2017 ### ZapperZ Staff Emeritus SLAC and KEK/KEK-B were all linear colliders, and each one of them got significant upgrade after major discoveries at circular colliders. It is why the ILC is the next major accelerator project to be built, and it started way before the Higgs were discovered at the ILC. In fact, many of the specs of the next linear collider will essentially turn the next linear collider as a "Higgs factory". Zz. 11. Aug 28, 2017 ### mfb ### Staff: Mentor KEK-B was a circular collider, and Super-KEKB is a circular collider as well. The acceleration happens in a linear injector, but the collisions happen in the ring. The ILC is planned as linear collider because a circular collider for this energy would be completely impractical ($\frac{\gamma^4}{R^2}$ scaling of synchrotron loss power). This is a new phenomenon. 12. Aug 29, 2017 ### kodama "Researchers at Osaka University are claiming to have fired the most powerful laser in the world. The 2-petawatt (two quadrillion watt) pulse lasted just one picosecond (a trillionth of a second)" at the LHC or lepton collider would it be possible to increase collision energy if at the moment the hardons collide, they were also hit with very very intensely powerful laser beam and highly focused to increase collision energy and hence reach? would would happen if each and every collision at LHC at moment of collision was also hit with a 2-petawatt pulse. would this increase collision energy beyond 13 TEV? (or a lepton collider) assuming engineering hurdles could be overcome, how much of an increase beyond 13 TEV could a 2 petawatt pulse on each and every 13TEV collision could be delivered to the detectors? 13. Aug 29, 2017 ### mfb ### Staff: Mentor How exactly do you imagine the energy to change? Even ignoring that there is no such process: 2 PW * 1 ps = 2 kJ laser pulse energy. 6.5 TeV * 1011 = 100 kJ energy per bunch in the LHC. 14. Aug 29, 2017 ### kodama well hopefully some of the energy contained in the photons of the laser is transferred to the hadrons, increasing collision energies beyond the current 13 TEV, which then collide and fragments and particle decays are detected by detectors. So instead of spending$20+ billion and digging a 50-100km new tunnel and waiting 30 years, which may or may not happen, by 2050 at the earliest for a 100TEV collider, retrofit the existing LHC - or even Tevatron - with lasers and possibly get 100 TEV+ collisions sooner and at a lower price.

- similarly for linear lepton colliders.

15. Aug 29, 2017

### Staff: Mentor

A 1 eV photon in the lab frame has 1/7000 eV in the frame of the proton when approaching it from behind. Even if it would have a notable cross section, the energy gain would be utterly negligible. And even if you could magically make all photons increase the proton energy, see above: It would be a 2% effect.

16. Aug 29, 2017

### kodama

that is 1 ev photon.
x-ray photons on the order 100 keV can be produced in laboratory.
the idea is using say on the order of 10^16 photons in a typical laser beam. clever engineering could raise that number.

and instead of protons collide electrons and positrons and at the moment of collision bombard them with 100 keV photons of 10^16.

i understand this is an engineering challenge, but the cost and time of doing this on an existing collider vs cost of building new collider that is larger with more powerful magnets

17. Aug 30, 2017

### Staff: Mentor

But not at 2 PW power.
That is 160 J.

This is not an engineering challenge. This wouldn't have a notable effect even if you could magically make all the energy go into accelerating particles. You cannot. Even 1/gamma is very optimistic, that would be less than 1 J for proton beams and something in the mJ range for electron beams (as they have a much larger gamma factor.

18. Aug 30, 2017

### kodama

ok

what are the prospects of building a plasma acceleration collider with performance significantly beyond LHC, in the near term future?
I understand the proposed future 100GEV collider is built with existing technology, with a larger circumference 50-100km and more powerful magnets 12-20T but at incredible costs.

is there a reason HEP hasn't devoted engineering resources into building a plasma acceleration collider ?

19. Aug 30, 2017

### Staff: Mentor

The technology is not ready yet. Maybe in 20+ years.
Assuming you mean the FCC concept: 100 TeV, not 100 GeV.
Many projects study plasma acceleration. It is not something you can develop in a year.

20. Aug 30, 2017

### kodama

yes TEV not GEV.

To clarify, the FCC concept: is just a bigger LHC with larger circumference and more powerful magnets and $20 billion price tag. But I've not heard of any HEP-inspired push for a future plasma acceleration with performance significantly beyond LHC to be actually built or that the next collider and research and funding should go into plasma acceleration. and 20+ years is same time frame of a FCC, if FCC gets actually built. no popular articles no news articles that the next collider should be based on plasma acceleration. are there physics questions that plasma acceleration can address that a conventional hardron collider cannot and vice versa. 21. Aug 30, 2017 ### mfb ### Staff: Mentor Yes, because the technology is not ready yet. You can't plan a collider if you have no idea how you would have to build it. 20+ years is the time frame for FCC operation, construction could start by 2025. 20+ years is the time frame for planning a plasma acceleration collider, construction would start by 2040 or so if everything works out. Plasma acceleration could lead to higher energies, that leads to things you can study that you cannot study with existing accelerators. The achievable collision rate is unclear. 22. Aug 30, 2017 ### kodama if plasma acceleration collider could be built, how much would it cost, and what kind of performance could be achieved? Both CERN and China have researched FCC. Would the countless$ billions of dollars spent on the proposed FCC be better spent on making the technology for plasma acceleration collider ready?

23. Aug 30, 2017

### Staff: Mentor

See above: You can't know these things as long as the technology is not ready.
The amount of money spent on FCC design studies is tiny.
What about "there are numerous projects studying plasma acceleration" was unclear?

24. Aug 30, 2017

### kodama

Popular news articles say the projected cost of a FCC is somewhere between $10-20 billion dollars, and includes digging a tunnel to fit a 50-100km ring. the Texas SCSC had a ring partially dug when the whole thing was canned. Would the$10-20 billion that would be spent on FCC and completed by 2050 at the earliest be better spent engineering a plasma acceleration now, based on studies. in effect the LHC is the last of the line of hadron colliders, and future colliders are based on plasma acceleration. Weinberg Witten Hawking et al, testify before US Congress pleading Donald Trump to allocate billions on colliders are based on plasma acceleration as future of HEP.

25. Aug 30, 2017

### Staff: Mentor

Projected cost. Not the money spent on it now.
Where does that year come from?
We cannot do that now.
How often do I have to repeat that?

We don't even know if plasma acceleration can work for colliders at all.