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SID-ALL  June 2017

SID-ALL June 2017

Subject:

Re: SiD Input for Staged Scenario discussion

From:

"Peskin, Michael E." <[log in to unmask]>

Reply-To:

General announcements to the Silicon Detector community <[log in to unmask]>

Date:

Sat, 17 Jun 2017 21:45:10 +0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (108 lines)

Folks,

I agree with Tom Rizzo.  It is only a small fraction of the overall cost to lengthen the tunnel to the full 31 km, and this ought to be our position in the discussions with the Japanese government.   But I think that our community needs to look deeply within itself at whether we will accept a solution that is 250 GeV in a 250 GeV tunnel.

My impression is that the considerations on the Japanese government side have less to do with saving money and more to do with maintaining control and limiting the future obligations of the ministries involved.  In the US, this is an attitude familiar to us.  Here we famously work under a system in which (1) no national laboratory is permanent, and any lab employee can be fired at any time due to lack of funding  (2) projects are approved only with an accounting of all project costs, including contingency and escalation over the full construction period, and (3) Congress can cancel any project in any year.   We remember that the SSC was cancelled after $2 B was spent.  

And yet, we are still here.  SLAC celebrated its 50th anniversary a few years ago, and Fermilab is celebrating its 50th this year.  Both labs are running programs for which both the technology and the physics motivation were unimaginable at the time that the laboratory started.  Both labs, at their 25-year point, were running energy frontier programs with center of mass energies more than 10 times greater than what was possible in their initial designs.

Based on this experience, I believe that the ILC lab will not be plowed under after a physics program of n ab-1 at 250 GeV.   There is a natural extension to 500 GeV, with strong physics motivation and the costs of the central region already paid out.   This is especially true if the luminosity upgrade, which is also needed for the 500 GeV program, can be done adiabatically during the 250 GeV run.  As long we have the (underground) real estate, it is possible to extend the energy to 1 TeV.   This will profit from expected improvements in superconducting RF technology over the next 20 years.  And, you have all heard me say, and I believe it is true, that the ILC tunnel will eventually host a 20 TeV e+e- collider based on some as yet undeveloped high-gradient technology. It needs only 1 GeV/m.  That accelerator will beat the FCC-hh, which may not even be ready on the same time scale.

If this is correct, our most important priority now is to get the initial ILC in the ground as soon as possible.    There is a minimum proposal, which is set by the fact that the physics case for the initial ILC must itself justify its cost without taking into account possible improvements from data at higher energies.    This means that 250 GeV and about 2000 fb-1 is the absolute minimum that we can put forward.  But I think that the physics of that machine is not only highly justified, it is the next logical step for the global high energy physics program in the light of what we have learned from LHC.

We will discuss all of this at the coming AWLC meeting at SLAC.  (Hint:  Be there!)   I hope that, after this meeting, we will be ready to go out and sell this philosophy to our LHC colleagues and the rest of the community.

Thanks for listening,

Michael 

-------------------------------------------------------------------------------------------
  Michael E. Peskin                           [log in to unmask]
  HEP Theory Group, MS 81                       -------
  SLAC National Accelerator Lab.        phone: 1-(650)-926-3250
  2575 Sand Hill Road                       fax:     1-(650)-926-2525
  Menlo Park, CA 94025 USA              www.slac.stanford.edu/~mpeskin/
---------------------------------------------------------------------------------------------
________________________________________
From: [log in to unmask] [[log in to unmask]] on behalf of Thomas G. Rizzo [[log in to unmask]]
Sent: Friday, June 16, 2017 11:38 PM
To: Marcel Stanitzki
Cc: sid-all
Subject: Re: [SID-ALL] SiD Input for Staged Scenario discussion

b ...but you will only get a



On Fri, 16 Jun 2017, Marcel Stanitzki wrote:

> Dear all
>
> As you may have heard, there are many discussions now ongoing on to start
> with
> an ILC at 250 GeV to lower the initial cost of the project.
> There seems to be quite some support for this scenario from Japanese
> Government circles.
>
> There are four distinct scenarios one could think about which involve both
> machine and tunnel options
>
> a) 250 GeV machine in a 250 GeV tunnel
>   Only build a tunnel suitable for 250 GeV machine, later updates will
> require major construction work
>
> b) 250 GeV machine in a 500 GeV tunnel
>   Only build a  250 GeV machine but drill the complete 31 km tunnel for 500
> GeV, later updates will only require installation of
>   Cryomodules, RF, etc. and can be adiabatic
>
>
> c) 250 GeV machine in a 350 GeV tunnel
>   Only build a  250 GeV machine but drill a tunnel suitable for 350 GeV
> machine
>   With a 10% increase in cavity gradient, this can later be still enough to
> get to 500 GeV. The cost increase for the 350 GeV tunnel will be a few %
>
> d) 500 GeV or bust
>   We need to start at 500 GeV, so go for the complete project as spec'ed in
> the TDR
>
> One should also point out, that the 250 GeV machine is not half-price, it is
> very roughly more like two-thirds of the 500 GeV machine, but detailed
> costing studies will be presented at the SLAC workshop
> Since this is really affecting the physics program and the associated
> timescales, we'd like to hear your input.
>
> Which option would you prefer, keeping the signals from Japan in mind ?
>
> Best wishes
>
> Andy & Marcel
>
> --
> Marcel Stanitzki
> DESY/ATLAS
> Notkestraße 85,       22607 Hamburg
> Geb.    : 1c/O1.338
> Tel.    : +49 40 8998 4930
> Cell    : +49 40 8998 9 4930
>
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