Ralf Diener

A Lightweight Field Cage for a Large TPC Prototype for the ILC

We have developed and constructed the field cage of a prototype Time Projection Chamber for research and development studies for a detector at the International Linear Collider. This prototype has an inner diameter of 72 cm and a length of 61 cm. The design of the field cage wall was optimized for a low material budget of 1.21% of a radiation length and a drift field homogeneity of ΔE/E10−4. Since November 2008 the prototype has been part of a comprehensive test beam setup at DESY and used as a test chamber for the development of Micro Pattern Gas Detector based readout devices.

Characterization of CdTe detector for use in PET

CdTe diode detectors with Schottky contact have been characterized in terms of energy resolution and time of response. A resolution of 0.98% at 511keV has been achieved with a 4 mm × 4 mm × 2 mm detector at 900 V/mm and −7 °C. At the same bias and temperature conditions, two identical CdTe detectors show a coincidence time FWHM of 25 ns. Additionally, the effect of a strong magnetic field on the charge sharing has been studied for a 9-pixel array detector of 55 µm × 55 µm × 800 µm pixel size connected to MediPix2 front end electronics. No effect on the charge sharing distribution has been observed up to 4 T. These results show that CdTe Schottky diodes are excellent candidates for the development of next generation nuclear medical imaging devices such as PET, Compton gamma camera, and especially PET-MRI when used in a magnetic field immune configuration.

MarlinTPC: A common software framework for TPC development

MarlinTPC is a simulation, digitisation, reconstruction and analysis package for research and development on Time Projection Chambers. It is based on the modular Marlin framework for ILC detector development and on the LCIO event data model. The MarlinTPC package consists of more than 50 software modules, providing a flexible tool box for a large variety of TPC applications. It is designed to simulate and reconstruct data from TPCs equipped with conventional pad readout and different kinds of electronics (ADCs and TDCs), taking into account the particularities of micro pattern gas amplification (GEMs and Micromegas). Also upcoming pixellated readouts as the Timepix chip are supported.

A novel self-supporting GEM-based amplification structure for a Time Projection Chamber at the ILC

Modern Time Projection Chambers are increasingly based on micro-pattern gas detector readout systems. In this paper a self-supporting method used to mount Gas Electron Multiplier foils is presented. It is based on light weight ceramic grids, and promises to cover large readout areas with minimum dead zones and material, while ensuring a flat and mechanically stable mounting. The structure has been tested in a Time Projection Chamber prototype, using cosmic muon tracks. The impact of the mounting structure on the charge measurement, the track reconstruction and the single point resolution is quantified.