# Super and Great Colliders

I’ve recently finished reading two new books on huge collider projects, which make an interesting contrast.

The first is From the Great Wall to the Great Collider, by Steve Nadis and Shing-Tung Yau. It’s a very well-informed and topical book, a bit of a political document, designed to make the case for a Chinese “Great Collider”. This is a proposed machine of up to 100km in circumference, that would operate first as an electron-positron collider, designed to be a “Higgs factory”, allowing precision study of the Higgs. In a second stage the same tunnel would be used for a proton-proton machine with collision energies up to 100 TeV. This would be designed to explore the energy range above a TeV, in much the same way as the LHC, but with seven times the energy, thus a much higher energy reach. This energy would also allow study of Higgs self-interactions.

The Nadis-Yau book is an unusual document in many ways. Yau is a great geometer, but a main concern of the book is something completely different, the question of how one might construct such a huge physics and engineering project. There is a great deal of information in the book about the history and current state of experimental HEP, but from an unusual angle, that of the many Chinese contributions to the subject. I’ve read many histories of HEP, but learned a lot of new things from this one, with its very different emphasis.

This is a short, rather than encyclopedic, book, with about 130 pages of text. It functions well in explaining the case for a large new collider to anyone interested, but has a distinct focus on arguments for the proposal to do this in China. The Chinese government and people in coming years will be deciding whether to go ahead with this, and this book is the perfect place for them to read a serious account of what this proposal is and why it deserves to be taken seriously.

The current state of affairs is that an initial conceptual design has been completed recently, which was reported here. This gave rise to some mistaken reports like this one that the Chinese government had given its approval to the project. There’s still quite a ways to go before that happens, with a final conceptual design not due until next year, and even if there is a go-ahead, construction only starting in 2020-25.

For a detailed look at the physics to be done by such a collider, see this new review article. I was interested to see (page 32) that the previous description by one of the authors of the current situation as leading to only two possibilities (“natural” SUSY or some such, or the multiverse and the end of hope for explaining things) has been expanded to now include a more interesting third possibility: “correlation between the physics of the deep UV and IR”.

Just after finishing the Nadis-Yau book, I got a copy of a new history of the SSC project, Tunnel Visions, by Riordan, Hoddeson and Kolb. This book has been in the works for a long time, with the authors starting to gather material back in the 80s, before the project was cancelled in 1993. I’ve been hearing about the book for quite a while, glad to see that it has finally appeared.

The cancellation of the SSC had a disastrous effect on the US experimental HEP program, moving the center of research conclusively to CERN and its LHC project. A central concern of any book of this kind has to be the “what went wrong?” question. The conclusions drawn are similar to ones I remember often hearing back then in the wake of the disaster: the SSC was a juicy target for a Congress intent on budget-cutting, easily portrayed as out of control (its budget kept increasing from $3 billion early on, to maybe$12 billion at the end), with little support from non-Texas representatives. In some sense the surprising part of the story is that the project got as far as it did before being terminated by an overwhelming Congressional vote.

One part of the story I had never understood was that as the SSC budget expanded it was coming into direct conflict with the plan to keep funding the other HEP labs (Fermilab, SLAC, Cornell, Brookhaven), and that was part of the story of the politics of this within the scientific community. I also hadn’t appreciated the way the challenges of a project of this scale required bringing in companies and other parts of the US military-industrial complex, making it take on some of the aspects of a large defense spending project. A major topic of the book is that of the problematic interaction between this and the standard ways that physicists were used to doing business.

Unlike Nadis-Yau, Tunnel Visions is more of an academic book, with notes and references to a huge number of extensive interviews making up a large part of the text. It’s not at all an inspirational story, nor is there all that much physics discussed. At the same time, it’s the definitive work on a crucial part of the history of high energy physics in the US. One group of people who should definitely be reading it are those planning the Chinese project. Some of the difficulties they will face if they go ahead will be similar: the SSC was an 87km ring, of similar scale to the new proposal. That this almost got off the ground 20 years ago here in the US is a good argument that it is something that could be pulled off in China over the next 20 years if they want to do it.

Based on the fact that the SSC might have worked with more international support, the authors end with the conclusion

Despite the added difficulty of organizing and managing them, pure-science projects at the multibillion-dollar scale should henceforth be attempted only as international enterprises involving interested nations from the outset as essentially equal partners. Nations that attempt to go it alone on such immense projects are probably doomed to failure like the Superconducting Super Collider.

The Chinese proposal is still in its infancy, but there’s reason to expect it might be a “go it alone” project. Given the way the US budget operates, at this point no country is likely to look to the US as a reliable source of sizable funding. CERN has its own proposal for a 100 TeV collider, but it seems hard to believe that both projects will go ahead, although also hard to see the Europeans agree to give up energy frontier physics to China. Many of the lessons of the SSC funding debacle are rather specific to the US and the way budgets are done here. I have no idea what the considerations in China are for projects like this, I guess we’ll start to find out in coming years.

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### 13 Responses to Super and Great Colliders

1. srp says:

The SSC was a classic “Plan B” approach, as described by Freeman Dyson, that overwhelmed the ecology of the field (e.g. destroying funding for the rest of the accelerator community). It is also one of the few instances I know of where the sunk cost fallacy was not allowed to operate in the public sector (“we’ve already spent X on it, we can’t give up now [even though the budget keeps exploding and the completion horizon keeps receding]).

2. Lamont says:

As an incredibly naive first-order guess, doesn’t it seem fairly likely that China could pull it off as a “go it alone” project? All they’d have to do is sell themselves the idea that it would be a point of national pride to do what America was not capable of doing…

3. Thomas says:

I’m glad to see that the Riordan et al. book is out. I’m very interested in the story of the SSC. I feel that the usual story that the SSC was killed by shortsighted politicians is greatly oversimplified. It was clearly a mistake to try a giant leap forward at an entirely new laboratory while there was a healthy program going at Fermilab (and SLAC).

It also not clear to me whether the SSC really would have worked as advertised (this is obviously impossible to know, and I am certainly not an expert). The LHC was a natural evolution of earlier machines, and had significant teething problems. Also, in accounts of the Higgs discovery it is always emphasized how important modern detector technology and computing was in making this possible. I’m not sure that the Higgs could have been discovered almost 20 years ago.

4. TS says:

In terms of scale, ITER is probably the project to compare to. It had its share of organisational trouble, many of which could be traced to a structure where ITER itself has (had?) no funds, but for all I can tell, it seems to be moving forward steadily, in spite of cost overruns, delays and all the usual troubles.

Yet, the comparison falls short in a very important way: ITER is applied science insofar as its aim is — to phrase it boldly — to replace a multi-billion dollar industry, namely that of electricity production. So the motivations for it and the case to be made for it are entirely different. There is also the question whether ITER really is the only game in town, like the chinese accelerator (or the FCC) would be. Wendelstein 7X is supposed to see plasma in 2015.

5. Matt says:

Anyone who followed the news or has seen the pictures of impenetrable smog in Beijing from the last few days probably realizes that China’s least problem is the construction of a new multi-billion dollar particle collider. With an economy in severe trouble and an environment at the brink of collapse I strongly doubt if Chinese politics will ponder about paying for a new toy for particle physicists. Sometimes I feel like the HEP community is like the band aboard the Titanic, keep fiddling away while the ship is sinking. But hey, who knows?

6. jd says:

The most recent Science magazine (end of November) indicates that the timeline for ITER will slip 6 years with a resulting 2B increase in cost. Best not to compare any future accelerator project to fusion.

7. iHEP says:

Matt: A lot of Chinese strategy is based on looking good in front of the world and “catching up” with the US. China also has some fine scientists. Throw in a quasi-dictatorial milieu and I am not surprised at all that they would pick particle accelerators over environmental pollution mitigation.

8. Dave Miller in Sacramento says:

Peter,

I have a fondness for e+/e- colliders, having been involved in some of the early work on the PEP machine at SLAC (I wrote part of the software to model the drift chambers, before I went into theory): this seems to me the cleanest way to study details of the Higgs, and wringing out all the details of the Higgs seems to me the logical next step experimentally.

Do you agree? And, can you tell us the cost estimate for the first-stage (e+/e- collisions) of the “Big Collider”?

On the Riordan book: do they go into details about the physicists who managed the SSC project? I knew the two top guys, but was never clear whether they were part of the problem or just in the wrong place at the wrong time.

You wrote:
>One part of the story I had never understood was that as the SSC budget expanded it was coming into direct conflict with the plan to keep funding the other HEP labs (Fermilab, SLAC, Cornell, Brookhaven), and that was part of the story of the politics of this within the scientific community.

A friend of mine with ties in DC told me at the time that one of the top guys from SLAC was powwowing with Senate staffers around the time the SSC was cancelled: my friend, a former HEP experimentalist who had gone into defense work, was curious about a possible connection but had no inside details as to what was discussed. Does the book go into this? Were people from the four other labs out to get the SSC or was it just that their support was lukewarm or that they merely expressed concern for their own budgets?

Too bad that HEP has become a bit of a political circus, but it is interesting for those of us with a background in the field.

All the best,

Dave

9. Peter Woit says:

Dave,

I do think there’s a good case that an e+/e- machine of sufficient energy to be a “Higgs factory” would be useful to study many aspects of the Higgs. It’s not clear to me though whether you could go to high enough energies this way to study the Higgs self-interaction, which may be the most promising place for something new.

As far as I know, at this point no one is talking about cost estimates for these large colliders, whether in China, at CERN or elsewhere. For one thing, it depends a lot on how you count, but the numbers I would guess will be very large, $10 billion and up. There’s a lot in the book about the people running the project, including some indication of a feeling that it was a mistake that Maury Tigner, the head of the original design team for the SSC, was shunted aside in favor of Roy Schwitters, who became the director. There’s some argument that the fact that Schwitters was not an accelerator physicist, and also not experienced dealing with a project of this scale, were both sources of problems. I think the problem with the other labs was that they needed to fund their own futures. Doing this at the same time that the SSC spending was ramping up made the budget situation for non-HEP physics much tighter and didn’t help with support in the wider physics community. Once discussions started about the cancellation, I’m sure the other labs were closely involved in figuring out how to protect themselves, as well as finding something to do with the large number of people who had moved to the SSC project, and all of a sudden were out of a job. 10. dsatkas says: Correct me if i’m wrong but the reason the LHC uses baryons (protons, lead etc.) instead of leptons (electrons-positrons etc.) is that it’s circular and there is much more radiation emitted with lighter particles (i think it’s m^-4). So if that is correct how will the chinese use electrons-positrons in 100 km facility efficiently? 11. Peter Woit says: dsatkas, The point is that LEP (in the LHC ring), was just a bit too low in energy (209 GeV) to be able to study the Higgs. Now that we know what the mass is, it turns out you don’t have to go that much higher in energy to do so. Even with a much bigger ring, the plan is to go just to 240-250 GeV, but that’s enough. 12. srp says: In more-hopeful news, there’s this: http://www.symmetrymagazine.org/article/shrinking-the-accelerator Probably worth spending maybe$100 million over the next few years to tell if there is or is not a better way going forward.

13. Curious Mayhem says:

The biggest failure of the SSC was not getting international involvement earlier on. The Japanese were riding high at that point, toward the end of the “bubble economy,” and certainly could have spared some money for it. (In 1991, they basically wrote a check to pay for a large part of the 1990 Persian Gulf war to eject Saddam from Iraq.) When the SSC was first proposed in the mid-80s, the project was sold at the political level with a 110%-Americanism — with allusions to Apollo and the Manhattan Project — that was overdone and imposed a cost a few years later, when it became clear that foreign money would be needed. Absurd claims were also made by some political figures; for example, the SSC would cure male pattern baldness (seriously!), which I’m sure made it more attractive to certain politicians.

The SSC was protected until 1993 by the alliance between Bush Sr., who was from Texas, and the Louisiana congressional delegation, which was rewarded with a piece of the LIGO experiment, I believe. But that same period was dominated by deficit politics and the 1990-91 recession. It led Bush Sr. to go back on his promise to not raise taxes and to Perot’s 1992 presidential campaign, in which the interrelated federal and trade deficits were big issues. After Clinton became president in 1993, the SSC rapidly lost its political protection and became a target for budget cutting; it was canceled in the fall of 1993, if memory serves me. There were a couple earlier attempts to kill it, but the Bush Sr.-Texas-LA alliance saved it each time.

The cost overruns were also significant and dramatically stimulated strong reaction from other scientists in other fields against the SSC. No one may remember him now, but the late Rustum Roy of Penn State led the charge against the SSC for the condensed matter folks and was ecstatic when it was canceled; he believed that high-energy physics was too large of the US science budget and produced an oversupply of PhDs.

There’s a 2013 Scientific American article about the SSC that’s worth reading. I can’t vouch for the accuracy of the quotes; e.g., I don’t remember anyone proposing “Gippertron” as a name. But “Desertron” was certainly a contender.

I visited the SSC remains in 1998, and it was a sad sight (or site). Many of us no longer in high-energy physics know that the SSC cancellation was a big reason.

—–

The case against e+/e- is straightforward. For rings, the radiation goes inversely with the mass to the 4th power (see comment above), and that certainly makes hadron colliders more attractive, in the circular case, for energies higher than ~ 10 GeV. That’s one reason why SLAC’s collider for the Z0 (about 90 GeV) was a linear collider, with partial circular arcs at the end, and not circular. The LEP energy was limited to ~ 200 GeV for the same reason. This wasn’t an issue for LEP I, at the Z0, but became a noticeable limitation for LEP II, just above the W+W- pair threshold.

The other problem with e+/e=, not mentioned above that I can see, has to do with incoming fluxes and cross-sections. With proper focusing, the current density from e+/e- is smaller than for hadrons. Then the cross sections kill your statistics: for point-like particles, they fall like 1/s, as opposed to hadronic cross sections that rise like s. This latter problem is an issue for either linear or circular colliders.

Not that I’m prejudiced against e+/e-. I did my doctoral thesis at such a collider and spent a couple years on an ILC (International Linear Collider) task force in the 1990s. The clean-ness of e+/e- was a compelling argument in favor. See various Web articles about the ILC, which has been floating around in proposal form for about 25 years.