Director's Corner

Le roi est mort, vive le roi ! (*)

| 4 April 2013

The European Approach to succession planning (the battle of Trafalgar).

The Global Design Effort (GDE) has successfully completed the R&D programme outlined back in 2006, and with the Technical Design Report (TDR) effectively complete and a cost estimate based on the TDR design done, the future programme must be addressed. The major new factor is the very real possibility that Japan may proceed with a bid to host the ILC. Indeed recent activities in Japan are so promising that we are plan the upcoming ILC programme based on this prospect. An early item of business will be that of site selection. Japan’s timeline indicates that a possible site could be named by the summertime. This would allow the TDR generic site design to be modified as required for a real site, the first step in the evolution towards an engineering design.

Cavity production was a great success of the GDE global programme, but for a complete cryomodule there was only a proof-of-principle result during the S1 global programme. Cryomodules are expensive and a full-scale production demonstration will only be possible with a construction project. Fortunately for us we have one of those about to start: the European XFEL. In a few short months the cryomodule production line at Saclay, France, will start to turn. While Europen-XFEL cryomodules are not identical to ILC ones, they are sufficiently similar, meaning that the fabrication process will be of immense value to ILC planning. How we maximise the benefit to the ILC of the complete European XFEL project is a opportunity we cannot afford to miss.

The present Japanese thinking towards ILC construction favours a phased approach to a 500 GeV centre-of-mass energy, with an initial phase of around 250 GeV for a Higgs-factory scenario. The TDR, of course features a 500-GeV baseline with options towards higher energies. We will need to carefully evaluate the impact of this plan for lower-energy operation. The initial facility will be cheaper of course: it will reduce the required cryomodule production rate, hopefully decrease the project construction time, and introduce options on machine and tunnel layout not considered in the TDR baseline. We will need to carefully analyse the facts in order to understand how best to use the flexibility of a phased construction project and to what end.

Linear colliders are by definition single-pass devices and are inherently power hungry as the energy and luminosity are pushed ever higher. The CLIC Conceptual Design Report study looked to mitigate power consumption in several ways, and one of the more intriguing ideas was that of load balancing. Based on the observation that not all power is created equal (power at 3 am is less in demand than at 6 pm) the CLIC team looked at the possibility of rapid site power reduction in periods of high demand and equally rapid resumption of the physics operation.  While cryogenic objects, such as the ILC, do not turn off as gracefully as the normal conducting CLIC, power consumption mitigation strategies will need a better evaluation in the future.

The prospect of a construction project in the foreseeable future brings to the surface not only the issues I have outlined above but many others as well (e.g. value engineering, configuration control). How do we choose and prioritise the programme for the near future? To answer these (and other) questions I have asked several people to serve on a new entity; the ILC Technical Board (TB).  In addition to myself the TB will comprise of Hitoshi Hayano, as my deputy, Olivier Napoly (CEA/Saclay), Marc Ross (SLAC), Nikolay Solyak (Fermilab), Nobuhiro Terunuma (KEK), Nick Walker (DESY), “Kirk” Yamamoto (KEK) and ex officio in his role as Head of the KEK LC Project Office, Akira Yamamoto. This group will determine the ILC programme for the next three years that will be submitted to the Linear Collider Directorate and the Linear Collider Board for ratification. Initially the programme will be defined on the basis of constant global effort for the next few years.  Indicating where additional effort would be useful will also be part of their mission. I hope we have something to report by LC2013 in Hamburg.

So there we have it. Deciding the path forward for the ILC programme, while important, does not have quite the same romance as trying to eviscerate ones antagonists with a cannon ball on a triple-masted frigate. Global projects back then were a lot smaller, but what they lacked in scope they appeared to make up for with enthusiasm. I hope we can demonstrate that we have a similar level of purpose.

(*) The king is dead, long live the king!

Mike Harrison

Mike Harrison is Associate Director for the International Linear Collider in the Linear Collider Collaboration.
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