Eric Doyle

Advanced collimator engineering for the nlc

The high beam intensities in the Next Linear Collider can damage the collimation system jaws if a failure of the electronic machine protection system allows the acceleration of a mis-launched pulse. We are developing a prototype collimator that will allow a new jaw surface to be moved into place after beam damage. We are also developing a prototype collimator based on continuously reforming the collimator jaws out of liquid metal. This second system would allow the use of smaller beam sizes, and thereby shorter beam line lengths in the collimation system. The status of both prototypes is presented.

Inertial sensor development for active vibration stabilization

Future Linear Colliders require nanometer stability of the beams at the interaction point. One approach to stabilising the beams is to use feedback based on inertial sensors (accelerometers/seismometers) to control the positions of the final focus magnets. Commercial seismometers developed for geo-science applications have sufficient noise performance (nanometer noise down to a fraction of a hertz), but due to their large size and magnetic sensitivity are unsuitable for use in a linear collider detector. We report on the development of a high sensitivity, compact, non-magnetic inertial sensor for this application. In addition to its use in linear colliders, the sensor is also expected to have application in vibration measurement and control in synchrotron light sources.

Advanced collimator prototype results for the NLC

The Next Linear Collider accelerator will include a large (kilometer scale) and complex collimation system. The size and complexity of this system could be reduced if the collimator jaws could be made immune to damage from the electron beam. We describe two collimation systems currently under development. Construction of a prototype system which uses wheels that can be moved to a new position after damage is underway. The second system, currently in the R+D phase, uses rotors which are continuously reformed from a bath of liquid metal as the collimation surface. This second system allows operation at beam intensities which damage the jaws on every pulse. We describe results of tests on both systems.

Prototype Testing for a Copper Rotatable Collimator for the LHC Collimation Upgrade

The Phase II upgrade to the LHC collimation system calls for complementing the robust Phase I graphite collimators with high Z Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and testing of this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A prototype collimator jaw referred to as RC0 has been tested for both mechanical and thermal compliance with the design goals. Thermal expansion bench-top tests are compared to ANSYS simulation results. The prototype has also been tested in vacuum bake-out to confirm compliance with the LHC vacuum spec. CMM equipment has been used to verify the flatness of the jaw surface after heat tests and bake-out.