ILC NewsLine
China, Japan and U.S. Collaborate on Magnet Design and Production for ATF2

IHEP just completed the second batch of magnets, designed by KEK and SLAC for ATF2. They will be shipped to KEK next week.

The approximate number of magnets that the International Linear Collider will require: 17639.

The number of magnet styles that are needed in the ILC: 162.

Designing and building the perfect magnet system that produces high quality physics results: Priceless.

Scientists and magnet engineers in China, Japan and the United States recently collaborated together to design and build quadrupole magnets for the ATF2 project, which is currently under construction at KEK. A milestone for international collaboration on the International Linear Collider, KEK and SLAC designed the quadrupole magnets together and then worked closely with IHEP in Beijing, who managed the fabrication process in their shops.

In the late nineties, KEK built the Accelerator Test Facility (ATF) to create small emittance beams and succeeded in producing beam size values that almost met the requirements of the ILC. In order to maximize the number of electron-positron collisions in the ILC, and therefore produce the most physics results, the Beam Delivery Systems (BDS) must take the nanometer sized beams coming out of the linacs and deliver them to the interaction point while maintaining a stable beam. "In order to address the needed technologies, the ATF2 project was proposed and promoted under the international collaboration of institutions and universities in Asia, Europe and the US," said KEK's Ryuhei Sugahara, who is in charge of the magnet system for ATF2. "For the ATF2 beam line, we will need to produce four dipole magnets, 28 medium size quadrupole magnets, two doublet quadrupole magnets and 5 sextupole magnets."

In 2005, quadrupole magnet production for ATF2 began at IHEP. Located towards the end of the final focus line in ATF2, these magnets will mimic the conditions in the ILC at a much lower beam energy of 1.3 GeV. "We will study the way they work and affect the beam," said Cherrill Spencer, a magnet engineer at SLAC. "The ATF2 system will replicate how the beam will be affected by magnets in the real ILC."

In order for the ILC beams to be produced, focused and steered towards its two interaction points, the machine will use 17,639 magnets of 162 different styles. Any magnet is defined by three basic parameters, and there are many ways a magnet can be engineered to generate the required magnetic field. The 162 styles differ in their lengths, beam aperture or how much current they carry. The ATF2 has only about 10 styles of magnets, but in order to save time and cost, Spencer based the quadrupole on an existing design from KEK. ILC scientists and engineers are well experienced (and hence sleep deprived) in overcoming the difficulties of finding a common time zone for Asia, Europe and the US to have a conference call together, but this project faced an extra international hurdle of having three different sets of standards for the magnets.

"China, Japan and the U.S. all had different fabrication methods and standards, and it was a big challenge to figure out which set to use," Spencer said. "We needed to make sure that all of the parts would work together with other apparatus in the Japanese beamline."

In March 2006, IHEP delivered the first batch of the magnets to KEK. ATF2 is scheduled to come online in 2008, and collaboration members will meet at KEK next week to finalize the layout of the beam.

-- Elizabeth Clements