T2K experiment began in 2008. It sends the world’s most intense neutrino beam from the JPARC facility at Tokai in the east of Japan 295 km through the earth to the Super Kamiokande neutrino detector in the west of the country, with the aim of studying the properties of these tiny, weakly interacting particles.
We are responsible for the
Neutrino Production Target
We are responsible for the T2K neutrino production target which converts the high power proton beam into neutrinos. It is a 1 metre long graphite rod encased in a titanium container cooled with helium. We designed and optimised the target for mechanical and thermal stresses using ANSYS Finite Element Analysis (FEA) code and the flow using ANSYS CFX Computational Fluid Dynamics (CFD). The target is designed to cope with a proton beam power of 750kW and work is currently underway to upgrade it so the power can be increased to 1.3MW.
Target exchange mechanism
We designed and developed a remote exchange system which permits highly radioactive failed targets to be safely and quickly replaced using master-slave manipulators in a remote maintenance area. This allows the large and expensive magnetic horn in which the target is installed to be reused saving money and reducing radioactive waste. This is a challenging task as the clearance between the target and horn bore is only 3mm and the target is 1 metre long and contains delicate graphite components.
Vacuum-to-air beam window
The T2K beam window separates the accelerator vacuum from the target station helium volume at atmospheric pressure. The window consists of two thin partially spherical domes of titanium alloy cooled by helium to remove the heat generated by the passage of the proton beam. It is remotely replaceable and seals to mirror flanges using inflatable metal seals.
The T2K baffle/collimator is situated between the beam window and target. The main functions of the this component are:
- To protect the target, magnetic horns and hadron absorber from damage due to a mis-steered proton beam;
- To reduce activation and damage of components upstream of the target.
The core of the baffle consists of a large block graphite. The graphite block has a 30mm bore for the proton beam to pass through under normal conditions. To protect the graphite and reduce future radiological contamination the graphite is clad in zinc coated steel plates. The baffle incorporates thick steel shielding blocks which fit into the target station shielding to create a labyrinth seal and reduce radiation backscattering from the target to the final focusing section magnets. To keep the assembly cool during operation it has cooling pipes embedded in the outer edges of the graphite.
The hadron absorber is a large assembly of graphite blocks that must absorb the remnant hadrons some 100 metres downstream of the production target. It is cooled by aluminium cooling modules connected to the ends of the graphite block. The hadron absorber is not replaceable or upgradable so it has been designed to cope with 3MW beam power.
Contact: High Power Targets Group
Tel: 01235 446273