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The pursuit of polarised positrons

The sixth POSIPOL workshop held at IHEP, Beijing

| 8 September 2011

Participants of the POSIPOL 2011 workshop

The POSIPOL 2011 workshop was held from 28 to 30 August at the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences in Beijing. It was the sixth in the POSIPOL series of workshops coupling the polarised positron source R&D efforts of next-generation electron-positron colliders such as the ILC and the Compact Linear Collider (CLIC) Study to more general polarised-positron community.

More than 30 scientists from Asia, Europe and the US attended the workshop, including some via videoconference. “The main goal of this workshop is to speed up the steps for realising required polarised positron beams for ILC, CLIC, SuperB [a future electron-positron collider in Italy], and inverse Compton scattering sources in general,” said Jie Gao, chair of POSIPOL 2011 and of the Asian linear collider steering committee. In total, 25 talks were given during the workshop, including talks on physics, colliders, gamma ray generation, targets, conventional positron sources, polarimeter, capture section, spin tracking and Compton scattering X-rays.

Jie Gao gives a summary talk at the workshop

Researchers said that much progress has been made since the POSIPOL 2010 workshop held at KEK in Japan. As for the ILC, scientists held in-depth discussions on collimator studies for the undulator-based positron source, targets, and gamma ray generation at the Accelerator Test Facility (ATF). Concerning CLIC, studies on hybrid targets with a non-polarised positron source, a capture section study, and a proposal on polarised positron Compton ring, which is superconducting stacking-ring-based, were discussed.

The workshop banquet was held at a western-style restaurant at Beijing 798 Art Zone. Diners talk, laugh and make faces for the camera.

Looking forward, there are many studies still to be carried out. A group at Lawrence Livermore National Laboratory in the US will work on prototype of flux concentrator for the ILC, and will begin designing a collimator. A positron target unit material experiment will be carried out at DESY. Gamma ray experiments with four mirror cavities at ATF will continue. Further evaluation on target stress and optimisation of capture parameters are needed; remote handling study will start. For the CLIC non-polarised positron source, “it is crucial to implement test facilities, and the SuperB experiment is the only one currently existing, which is an important step forward for the positron source,” said Gao in his summary talk.

Participants paid a visit to the National Art Museum of China and enjoyed a banquet at Beijing 798 Art Zone. “The combination of the classical and modernism of these two places impressed me a lot,” said Kaoru Yokoya, Global Design Effort Asian regional director.

The POSIPOL 2012 workshop will be held at DESY in Zeuthen, Germany.

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