Physicist and engineer studying the response of a single cell ILC cavity in Pisa (INFN)

Small fraction of the ILC-Pisa group: front row: Left: Giorgio Bellettini, Right: Franco Bedeschi back row: From left to right: Roberto Carosi, Giovanni Martinelli, Stefano Galeotti

In Pisa, Italy, a team of physicists and engineers headed by Franco Bedeschi, who usually work on detectors, recently joined the ILC machine studies group. "The initial momentum came from Fermilab, a laboratory with which we used to collaborate for the CDF experiment", said senior physicist Giorgio Bellettini, the initiator of this ILC group. Presently, the group is still rather small but strongly motivated by the challenge. "We would like to contribute by obtaining the best quality for the bright beam we need for future ILC state-of-the-art detectors. We have limited our implication to restricted components, but we wanted to help early in the ILC process and we hope our initiative will be successful and useful for the global effort," he said.

The first part of the contribution aimed to take full advantage of the group's expertise in fast electronics controls, which they gained from CDF experiment, among others. Like several laboratories working on the ILC, the team dedicates part of their studies to beam stabilisation. "The contribution effort in this area is huge because the parameter is critical," said Bellettini. "We have to align electron and positron beams to a few nanometres while they run through over thousand 10 m long cryomodules which weigh tonnes." Engineers are trying to cancel two kinds of vibrations. The first are induced by the surroundings such as noise, tiny movements in the floor or a gradient of temperatures. The second are beam-induced vibrations and occur during operation. Electronics devices integrate the variations detected by cavity electric field sensors and beam positions monitors. If they are quick enough, fast electronics will be able to correct cavity vibrations between two bunches of particles, which is essential for keeping the beams aligned and their energies stable. Piezoelectric sensors and actuators that can be used to monitor and reduce these vibrations are also being studied by the Pisa group. Some electronic engineers come from the Virgo experiment, an interferometric gravitational wave detector sited near Pisa, for which an efficient damping of seismic noise is critical to achieve its extreme sensitivity.

Their second contribution on ILC machine studies relies on their mechanical expertise. They are working on modifications and improvements for ILC cryomodule design, which eventually could be included in the next generation (see NewsLine 11 May 2006). The Pisa group is simulating localised deformations and frequency response of the cryostat. They are also drafting the executive drawings and qualifying the compliance to international standards.

The group has been working on these subjects for more than half a year now. In Europe, it is unusual to see a detector group switch to accelerator activities. "We were very enthusiastic to start our work on the ILC with accelerator studies because one can not perform the ambitious physics programme of this project without nearly perfect beams," said Bellettini. Later, the group plans to join the ILC detector community and be part of one of the ILC experiments.

-- Perrine Royole-Degieux