A TPC field cage, produced by Max Planck Institute, being installed into a Japanese superconducting solenoid at KEK.

ILC NewsLine recently provided an overview of the four detector concepts for the International Linear Collider. This week's issue takes a closer look at the Global Large Detector. Stay tuned to ILC NewsLine for future stories about the Large Detector Concept (LDC), Silicon detector (SiD) and the fourth detector concept.

Of the four proposed detector concepts for the International Linear Collider, three of them are based on "particle flow" – a method of precisely measuring the energy of jets. Particle flow algorithms are meant to link the hits in the calorimeter to both charged and neutral particles – just like putting a very complicated puzzle together. Inside the detector the particle showers tend to be repeated and contiguous. Scientists must therefore focus on clearly separating the shower clusters so that the matching of tracks with the clusters can be done unambiguously.

The Global Large Detector (GLD) has the largest calorimeter of 2.1 metres. "The GLD is designed for fine segmentation and optimised for Particle Flow Algorithm (PFA)", said Histoshi Yamamoto of Tohoku University. For a tracker, the GLD uses a Time Projection Chamber (TPC) and for a micro vertex detector, it uses FPCCD, which is based on CCD with super-fine pixels. "The GLD aims to develop a large-scale detector and a detector element of cost effectiveness as an optimisation for the reconfiguration of quark energy," Yamamoto said.

The history of the GLD dates back to the Japan Large Detector (JLD). Similar to the GLD, the JLD has a large inner radius. Based on their experiences with the JLD, the Japanese group thought that a large inner radius would benefit the ILC detector. The GLD detector concept research group based their design on the JLD and optimised detector components for the ILC in internationalising the effort.

About 220 people from 16 countries, 77 universities and research facilities in the world now participate in the GLD. In addition to the Asian countries, the GLD is supported from a large-scale TPC prototype from EUDET that is designed to fit within the superconducitng magnets supplied by KEK. The GLD group also collaborates with CALICE, an international joint research organisation for calorimeters. The GLD is an Asian-based concept but continues to move toward an international framework with two contact persons in Asia, Europe, and the U.S.

The GLD R&D has funding from JPS for the next five years, mainly focusing on the vertex detector, TPC particle track detector, and calorimeter. "It is impossible that all of the present detector concepts will be realised," Yamamoto said for the future of the four ILC detector concepts. "Concept reorganisation will begin in few years, and then it will narrow down to one or two, so we'd better be in close collaboration sooner than later."

-- Nobuko Kobayashi