Hi Markus,

Of course it should. Here's the evolution over the last few days:

Friday meeting:

The Snowmass study considered many other options for high-energy colliders that might be realized over a longer term.  These included linear and circular e+e- colliders, muon colliders, and photon colliders.  A longer term option with great promise is a 100 TeV hadron collider, which has unprecedented potential reach for new physics associated with electroweak symmetry breaking, naturalness, and dark matter. Further investigations of the physics and technical issues would be opportune at this time, leading to conceptual and technical design reports.

After Friday meeting:

The Snowmass study considered many other options for high-energy colliders that might be realized over a longer term.  These included higher energy linear colliders, circular e+e- colliders, muon colliders, and photon colliders. The study called out in particular the potential of a 100 TeV hadron collider for the exploration of electroweak symmetry breaking and dark matter and recommended more concerted work on its design and its physics capability. 

Saturday response:

The Snowmass study considered many other options for high-energy colliders that might be realized over a longer term.  These included higher energy linear colliders, circular e+e- colliders, muon colliders, and photon colliders and all merit continued study.  The Snowmass study called out in particular the potential of a 100 TeV hadron collider. While higher energy per se is always an advantage, this threshold seems to reach benchmarks suggested by questions about dark matter and naturalness.  Our conclusions call for renewed accelerator R&D and physics studies for such a machine over the next decade.

The question for me is what does the best job of being taken seriously. What the Friday language does, I decided, is say that we're urging consideration of every accelerator conceived - we always want more energy. And that we're putting the hardest one - politically hardest - at a level that's very far up there after 9 days of consideration: "with great promise" "unprecedented potential reach" "leading to conceptual and technical design reports." …. 

This puts it ahead of the muon collider, which is still a long way from CDR and TDR and suggests to me a reversal of their relative priorities. 

I do not believe that the "Saturday response" is "weakened yet again." On the contrary, I think it does what needs to be done and that is point out what was learned at Snowmass - because of your talk, primarily - that a high energy collider by itself is not what's of interest, but that the particular threshold of 100 Tev-ish is better than 33 TeV it's better than maybe 50 or 80…that 100 is qualitatively different. That's a fresh insight. It also calls, not for a TDR, but renewed R&D and physics studies which maybe there's the horsepower to do. Remember, again, there's not enough horsepower to do even muon collider studies at a level commensurate with its interest and technical promise.

It leaves out EWSB, I agree, and that could go back in.

So I'd like to argue that the "Saturday response" - which took Michael and me almost another whole day to hammer out! - is prudent and states what was in fact fresh on this subject out of snowmass.

You're talking to a VLHC guy. With Uli Baur I co-organized the 2001 snowmass VLHC group. Then I was appointed by the DG and the Fermilab director with Paris Sphicas, Uli, and Chris Hill to organize every-other-year workshops on VLHC. We did one and then it fizzled for lack of interest at the top and the "bottom." Actually, it led in part to Bill Foster's loud resignation as he was a large part of it. So I'm in your camp and pleased at the renewed interest, but I'm leery of going too far beyond what was newly understood in Minn.

best
Chip



On Aug 25, 2013, at 12:45 AM, Markus A. Luty <[log in to unmask]> wrote:

I am disappointed that the VLHC wording seems to have been weakened yet again. It is my understanding that the executive summary is supposed to reflect the conclusions of the working group reports. I felt that the previous version did but this one does not. The previous version was extensively discussed during the phone meeting, and seemed to have unanimous support. I request that the previous wording be reinstated.

Markus

On Saturday, August 24, 2013, Ashutosh Kotwal wrote:
On Aug 24, 2013, at 6:15 PM, "Graham W. Wilson" <[log in to unmask])">[log in to unmask]> wrote:

>
> Dear Chip, Michael and Ashutosh,
>
>     This looks reasonably OK within the confines of what has so far been discussed, but I do
> worry that not everybody will read it in the same informed spirit as Ashutosh. I do agree with points a and b.


hi Graham,
                        What we can do is lay out the logic in the longer part of the Summary in a little more detail so that people will read it in the informed spirit.



> I would however counsel against the explicit mention of accelerator R&D. The earlier wording about
> "more concerted work on its design and physics capability" seems to me to strike the right tone.


that would be OK too… but presumably accelerator R&D is referring to high field magnet R&D, which is a US strength we should not let go of…


> We should also all realize that current US accelerator R&D is already funding
> LARP, high-field magnets, MAP, but has cut back/zeroed out high-gradient
> super-conducting RF (ILC) and put on life-support other parts of the ILC R&D program.
> Getting the best science out of ILC will need US accelerator development efforts.


well, are you thinking that we should choose one or the other between SRF and high-field magnets?  I think that would be way too restrictive.

or are you saying we should mention something about ILC accelerator R&D also?

regards,
Ashutosh


>        regards
>               Graham

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