Hi Marcel,
These are interesting options.
My personal uneducated opinion is to go for the 500 GeV tunnel right away.
As you point out, additional installations can happen adiabatically, while digging more tunnel will require a large lump sum of money, which may be harder to get.
It seems that the scenario with a 350 GeV tunnel will be the most difficult to argue for a tunnel extension, so my concern would be that this is all the tunnel we'd ever get.
So in order of decreasing preference, I'd rank the scenarios
b) a) c) d)
Cheers,
Jan
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Technical Team Lead
Fundamental Particle Physics at Accelerators
Pacific Northwest National Laboratory
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-----Original Message-----
From: <[log in to unmask]> on behalf of Marcel Stanitzki <[log in to unmask]>
Date: Friday, June 16, 2017 at 14:07
To: "[log in to unmask]" <[log in to unmask]>
Subject: [SID-ALL] SiD Input for Staged Scenario discussion
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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