Common development of pixel tiles for the LHC upgrades

The world's largest scientific apparatus the 27 km long LHC is performing investigations into the fundamental building blocks of nature. For the second phase of the LHC improved detectors are needed that can cope with an increased number of particle collisions. The highest precision elements of the detectors that measure these collisions are known as pixel detectors. The UK has been at the forefront of vertex detector technology for over 20 years, and this proposal aims to retain this UK lead. This project aims to construct a small element of a pixel detector that will demonstrate the feasibility of making larger detectors for the LHC upgrade. This element, or pixel tile, can then be connected with others to produce the detector required for any of the new experiments at the LHC. The project is particularly aimed at two of these detectors, ATLAS - the largest detector at the LHC, searching for the direct production of new particles and LHCb - the LHC experiment studying anti-matter and rare processes to find physics effects from beyond the known standard model of particle physics.

This project will develop hybrid pixel tiles which can be connected to cover large areas. The development of these pixel tiles in particle physics is aimed at positioning the UK at the forefront of the highest technology developments for the upgrades of the LHC experiments. By investing in this technology the UK will retain and build upon its record as a world leader in vertex detectors within Particle Physics. The devices will be the enabling core of international projects, and provide a showcase for British technology within them.

However, the targeting of this technology by the applicants to be a major focus of future UK particle physics involvement is also due to its strategic advantage to the wider UK economy. These tiles will allow a wide range of fields to access hybrid pixel technology, fields where either the expertise would not have been available or access would not have not been financially viable. The tiles are an important development for markets where high resolution spatial and high speed temporal resolved imaging is required. Examples of specific areas with economic and societal benefit are described below.

UK semiconductor industry - the UK has a number of semiconductor companies with the necessary equipment and skills to produce pixel sensors. This project provides the potential to develop not only the sensors but to assemble them into bump-bonded detector assemblies. This adds significant extra commercial value by providing the opportunity to produce a finished product rather than an individual component. If UK companies were successful in bidding for the co-development of the pixel technologies this would put them in an excellent position to supply these devices worldwide to the markets described below.

Light Sources - the UK's own Diamond Light Source and other light sources around the world use beams of X-rays for investigations ranging from structural biology to environmental science. The hybrid pixel detectors conventionally used to image the samples are currently of lower resolution than those developed in this project.

Hadron therapy - Despite substantial uptake throughout much of the world the UK has lagged substantially behind in the treatment of cancer through the use of hadron therapy. The hybrid pixels would allow cheap, high precision, devices to be produced within the UK that would permit the calibration of the beam and, eventually, real time feedback to the control system to ensure the correct dose delivery. Together with other ongoing initiatives this will substantially enhance the quality of patient treatment available in the UK.

Medical Imaging - this area has arguably the broadest range of applications for high resolution low-noise imaging with X-rays. The devices have potential application in, for example, Computed Tomography (CT), digital readout for mammography and dental imaging.

Dosimetry - Personal dosimeters based on hybrid pixel devices have been investigated based on the chip technology utilized here, and are being considered for space based dosimetry.

Neutron Monitoring - Neutrons can be detected with high efficiency using silicon sensors coupled with a converter layer (of for example plastic). Neutron monitoring is of potential interest at nuclear power-plants and medical accelerators.

Education - The hybrid pixel devices are portable and easy to use with existing USB readout to connect them to a personal computer available for the family of chips utilised here. This allows alpha, beta and gamma radiation to be observed on-screen in real time and easily distinguished, and for simple computer data analysis to be performed.

Overall we consider that the involvement of the UK particle physics community in this technology area offers significant economic and societal impact, whilst positioning the UK at the forefront of future high profile fundamental scientific discoveries.