Malcolm John

Abstract:

With high-energy collisions at the LHC imminent, this contribution describes the final commissioning of LHCb detector with comics and non-circulating beam. The status of each major sub-detector is reported, with particular attention paid to recent highlights. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-Non Commercial-ShareAlike Licence.

Abstract:

In this article we report on the use micro-focus synchrotron X-ray radiation and pion beams to compare the detection efficiencies and charge sharing properties of novel 3D detectors to that of the current planar technology. Detector substrates are bump-bonded to the Medipx2 and Timepix chips. 55μm square pixel maps of the detection efficiencies have been produced using X-ray and MIP beams. For X-rays, a drop of 3-4% detection efficiency over the pixel area was found due to the central electrode. The corner electrodes show no degradation in efficiency compared to that of the planar device. For MIPs a drop of 0.5% in efficiency due to the central electrode was observed. Evidence of a considerable reduction in charge sharing in the 3D detectors compared to the planar devices is also shown. ©2009 IEEE.

Abstract:

The Vertex Locator of the LHCb experiment has been used to fully reconstruct beam induced tracks at the LHC. A beam of protons was collided with a beam absorber during the LHC synchronisation test of the anti-clockwise beam on the weekend 22nd-24th August 2008. The resulting particles have been observed by the Vertex Locator. The LHCb Vertex Locator is a silicon micro-strip detector containing 21 planes of modules. Tracks were observed passing through up to 19 modules (38 silicon sensors). A total of over 700 tracks were reconstructed, and are being used to study the calibration and alignment of the detector. © 2009 Elsevier B.V. All rights reserved.

Abstract:

A series of tests in CERN’s North Area beam facility have been used to demonstrate the suitability of the Timepix chip, combined with a silicon sensor, as a particle tracking device. Specifically of interest is the potential of a successor to the current chip to be used in the context of an LHCb VELO upgrade. The 55µm square pixels, large active fraction and analogue information make the chip very attractive for forward, high precision tracking systems such as the VELO. In this contribution preliminary results are presented showing the resolution achieved by a Timepix assembly in a 120GeV π beam, over a wide range of incident angles. At the optimum angle the detector was able to provide an unbiased track residual of 5.5µm. The telescope constructed for these measurements contributed a track extrapolation error of 2.5µm. The plans for a future development of this telescope, also based on Timepix assemblies are discussed, with proposals for upgrading its spatial and timing resolution.