Charge Transfer and Charge Broadening of GEM Structures in High Magnetic Fields

We report on measurements of charge transfer in GEM structures in high magnetic fields. These were performed in the framework of the R&D work for a Time Projection Chamber at a future Linear Collider. A small test chamber has been installed into the aperture of a superconducting magnet with the GEM structures mounted perpendicular to the B field direction. The charge transfer is derived from the electrical currents monitored during irradiation with an ${}^{55}$Fe source. No severe loss of primary ionisation charge is observed, but an improved ion feedback suppression is achieved for high magnetic fields. Additionally, the width of the charge cloud released by individual ${}^{55}$Fe photons is measured using a finely segmented strip readout after the triple GEM structure. Charge widths between 0.3 and 0.5 mm RMS are observed, which originate from the charge broadening inside the GEM readout. This charge broadening is only partly suppressed at high magnetic fields.Comment: 11 pages, 9 figure

Modelling and Measurement of Charge Transfer in Multiple GEM Structures

Measurements and numerical simulations on the charge transfer in Gas Electron Multiplier (GEM) foils are presented and their implications for the usage of GEM foils in Time Projection Chambers are discussed. A small test chamber has been constructed and operated with up to three GEM foils. The charge transfer parameters derived from the electrical currents monitored during the irradiation with an Fe-55 source are compared with numerical simulations. The performance in magnetic fields up to 2 T is also investigated.Comment: 21 pages, 16 figures, submitted to NIM-

Development of a Time Projection Chamber Using Gas Electron Multipliers (GEM-TPC)

We developed a prototype time projection chamber using gas electron multipliers (GEM-TPC) for high energy heavy ion collision experiments. To investigate its performance, we conducted a beam test with 3 kinds of gases (Ar(90%)-CH4(10%), Ar(70%)-C2H6(30%) and CF4). Detection efficiency of 99%, and spatial resolution of 79 $\mu$m in the pad-row direction and 313 $\mu$m in the drift direction were achieved. The test results show that the GEM-TPC meets the requirements for high energy heavy ion collision experiments. The configuration and performance of the GEM-TPC are described.Comment: 18 pages, 12 figures, published online in Nucl. Instr. and Meth.

How leaders benefit from engaging in high-quality leader-member exchanges : a daily diary study

Purpose Drawing from the conservation of resources theory and the success resource model of job stress, the authors investigated the role of leader behaviours in the context of leader-member exchanges (LMXs) as a driver of leaders' job-related well-being and recovery. Specifically, they hypothesised positive affect and perceived competence as potential mechanisms enhancing leaders' job satisfaction and psychological detachment. Design/methodology/approach Daily diary data were collected from 85 leaders over five consecutive working days (376 daily observations) and analysed using multilevel path analyses. Findings Leader LMX behaviours were positively associated with leaders' positive affect and perceived competence at work at the person and day levels. Additionally, results provided support for most of the assumed indirect effects of leader LMX behaviours on leaders' job satisfaction and psychological detachment via positive affect and perceived competence. Practical implications Leadership development activities should raise leaders' awareness of the relevance of resourceful interactions with followers for leaders' own well-being. Organisations should create a working environment that facilitates high-quality exchanges amongst their members. The current trend towards increasing digital and less face-to-face collaboration may pose a risk to this important resource source for leaders. Originality/value These findings emphasise the day-to-day variation in leadership behaviours and that leaders' engagement in high-quality leader-follower interactions has the potential to stimulate a resource-building process for the benefit of leaders themselves

A Time Projection Chamber with GEM-Based Readout

For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1 T solenoidal field and read out with three independent GEM-based readout modules, are reported. The TPC was exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.Comment: 22 pages, 19 figure

Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter

We present a study of showers initiated by electrons, pions, kaons, and protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE scintillator-tungsten analogue hadronic calorimeter. The data were recorded at the CERN Super Proton Synchrotron in 2011. The analysis includes measurements of the calorimeter response to each particle type as well as measurements of the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to Geant4 simulations (version 9.6.p02). In the study of the energy resolution we include previously published data with beam momenta from 1 GeV to 10 GeV recorded at the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table

The Time Structure of Hadronic Showers in highly granular Calorimeters with Tungsten and Steel Absorbers

The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.Comment: 24 pages including author list, 9 figures, published in JINS

Infrastructure for Detector Research and Development towards the International Linear Collider

The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

Schlussbericht - Projektförderung im Rahmen des Programms "KMU-innovativ - Verbundvorhaben Ressourceneffizienz"

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