NSRRC celebrates 10th anniversary of beamlines at SPring-8

When the Taiwan Light Source (TLS) started up at the National Synchrotron Radiation Research Center (NSRRC) in 1993, it was clear that the need for a complementary high-energy photon flux would become increasingly urgent. The only realistic possibility pointed to the SPring-8 third-generation synchrotron-radiation facility of the Japan Synchrotron Radiation Research Institute (JASRI).

Chien-Te Chen, director of NSRRC from 1998 to 2005, the NSRRC management and governmental officials put together a proposal to build the Taiwan Beamlines (TW-BLs) at SPring-8 at a cost of $9 million. This led to a memorandum for JASRI and the Asia and Pacific Council for Science and Technology (APCST), which was followed by agreements between APCST and NSRRC. These were signed on 18 December 1998, giving NSRRC control of 75–80% of the beam time, with the remaining time managed by SPring-8 for general users.

The first TW-BL (12B2), designed to provide time-resolved protein crystallography, was completed in 2000; the second (12XU) in 2002 was for inelastic X-ray scattering; and a side line (12XU) for hard X-ray photoemission spectroscopy started up in 2009.

On 22 December 2010, a celebration of the 10th anniversary of the TW-BLs was organized at SPring-8 by Di-Jing Huang, the deputy director, and hosted by Wen-Chang Chang, chair of the Board of Trustees, and Shih-Lin Chang, the director of NSRRC. The event gathered current and former staff from both facilities to reaffirm the long-lasting friendship and the effort to pursue further scientific collaboration.

ECFA extends its linear collider study for another three years

The European Committee for Future Accelerators (ECFA) has extended the mandate of its Study of Physics and Detectors for a Linear Collider for another three years, from January 2011 to the end of 2013. The committee has also appointed a new chair to lead the study. Juan Fuster of Valencia has taken over from François Richard of the Laboratoire de l’Accélérateur Linéaire, Orsay, who was in charge from 2005. Fuster was responsible for high-energy physics funding in Spain during the period 2007–2010. A member of the ATLAS collaboration, he has been involved in the organization of ECFA workshops for this study for many years.

The ECFA study began in 1996 as the first Joint ECFA/DESY Study on Physics and Detectors for a Linear Collider, which held several workshops and reported the following year. A second joint study began in 1998 and was extended until 2003 (CERN Courier July/August 2001 p11). Since then, the study has continued as the ECFA study with regular workshops during two mandates, 2003–2005 and 2005–2010.

What has happened during the most recent period? The physics case for a light Higgs scenario has been studied to a high degree of realism using two detector concepts – named SiD and ILD – developed by international collaborations. This work demonstrated that by using the channel e+e → ZH, precise measurements can be achieved for the mass (to <100 MeV), cross-section (a few per cent) and branching ratios (a few per cent for all fermionic modes) of a Higgs particle with a mass of around 120 GeV, as predicted by theory and suggested from precision electroweak data. The case for top physics has also received growing attention because a linear collider allows precise and unique measurements of the mass (<100 MeV) and electroweak couplings (fraction of a per cent), giving a sensitive test for theories beyond the Standard Model. Searches for physics beyond the Standard Model have also been studied for a large variety of scenarios and have confirmed the potential of a linear collider for discovery and precision measurements.

Detector studies for a linear collider have received a considerable boost during this period, with the support of EU contracts (previously EUDET and now AIDA) and the creation of international collaborations such as CALICE, LC-TPC and others. These collaborations aim to develop ambitious subdetectors for both SiD and ILD, so as to achieve unprecedented performances for the tagging of flavours, momentum resolution and jet-energy reconstruction. The teams have built large prototypes and tested them at CERN, DESY, Fermilab, KEK and SLAC. Remarkably, these detectors – developed for the International Linear Collider (ILC) project operating at up to 1 TeV – are also able to satisfy the needs of a multi-tera-electron-volt collider, such as the Compact Linear Collider (CLIC) concept.

The regional studies (ECFA, ACFA in Asia and ALCPG in the Americas) are now co-operating more closely, with the installation of a research directorate for ILC detectors in 2007. This co-operation is also visible in the publication of the letters of intent from the detector groups in 2008, resulting in the approval of the ILD and SiD concepts.

The ECFA workshop in Valencia in 2006, with more than 400 participants, was for the first time a common meeting on activities for machine, detectors and physics. The Global Design Effort, in charge of preparing the technical design report for the ILC, has joined forces with the detector part, allowing the community to define better the requirements for the machine and in particular to strengthen activities at the "machine-detector interface", which are extremely important for a linear collider. A big challenge in this context was the decision to plan the ILC with only one interaction region, but serving two detectors in a so-called "push–pull" scheme.

Recognizing the need for a truly global approach towards the timely realization of a linear collider, the decision was made to have a common meeting under ECFA between CLIC and ILC at CERN in 2010. The resulting International Workshop on Linear Colliders (IWLC2010) was held in October, attracting around 500 participants (CERN Courier November 2010 p7). Building on its success, from now on there will be an annual common meeting among all linear-collider concepts organized in a global context. The next such meeting will take place this year in Granada on 26–30 September.

What are the prospects for these studies? As Rolf Heuer, CERN’s director-general, pointed out during IWLC2010, the future relies on the successful start of the LHC and discoveries there. This implies that the international linear-collider community should be ready by 2012 to propose a viable project for a machine with two detectors. CLIC will produce a Conceptual Design Report in 2011 based on modified SiD and ILD concepts, with the active participation of contributors from the ILC. By the end of 2012, the ILC will have both a Technical Design Report, for the machine, and a Detailed Baseline Design, for the two detectors.

• For more about the ECFA Study of Physics and Detectors for a Linear Collider, see www.desy.de/conferences/ecfa-lc-study.html.