Performance of a GridPix detector based on the Timepix3 chip

A GridPix readout for a TPC based on the Timepix3 chip is developed for future applications at a linear collider. The GridPix detector consists of a gaseous drift volume read out by a single Timepix3 chip with an integrated amplification grid. Its performance is studied in a test beam with 2.5 GeV electrons. The GridPix detector detects single ionization electrons with high efficiency. The Timepix3 chip allowed for high sample rates and time walk corrections. Diffusion is found to be the dominating error on the track position measurement both in the pixel plane and in the drift direction, and systematic distortions in the pixel plane are below 10 $\mu$m. Using a truncated sum, an energy loss (dE/dx) resolution of 4.1% is found for an effective track length of 1 m.Comment: To be published in Nuclear Instruments and Methods in Physics Research Section

The performance of GridPix detectors

A GridPix detector is a gaseous detector capable of detecting individual single primary electrons from ionizing particles. Such a detector consists of a pixel chip as active anode covered with a thin layer of silicon rich silicon nitride (SiRN) for protection against discharges, an integrated amplification grid (InGrid), applied on top of the chip by wafer post processing techniques, and a cathode plane. The drift region is between the grid and cathode while the gas gain occurs between the chip and the grid. The discharge quenching properties of the SiRN layer have been determined as well as the relation on grid capacitance, grid voltage and gas mixture. Part of the detectors in this report were of the type Gossip, a GridPix detector with a drift gap of ∼1 mm. Using such thin drift layer, one may consider this detector as a replacement for a silicon pixel detector. The performance of three Gossip detectors has been investigated by measurements in a test beam at CERN

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

Reliable cool-down of GridPix detectors for cryogenic applications

In this paper we present thermal cycling experiments of GridPix radiation imaging detectors, in view of a potential application in a cryogenic experiment. The robustness of the GridPix detector is studied for various grid designs, as well as various mechanical and thermal surroundings. The grid design variations had insignificant effect on the grid strength. A low cool-down rate as well as good thermal contact are crucial for the durability of the grid. Further, additional strengthening at the grid edges proved necessary to maintain the integrity of the structure during thermal cycling, which was done using globtop adhesive. The combination of these measures led to 100% survival rate after thermal cycling down to −130 °C

Twingrid: a wafer post-processed multistage micro patterned gaseous detector

This paper presents a new multistage Micro Patterned Gaseous Detector (MPGD) made by wafer post-processing. The device consists of a double metal grid supported by SU-8 structures on top of a Timepix chip. The detector has been operated with He/iC4H10 and Ar/iC4H10 gas mixtures. Cosmic rays as well as 55Fe decay events have been recorded using the Timepix chip in 2D and 3D readout modes. The detector can be operated like a Micromegas (high field close to the chip) or like a GEM (amplification stage followed by a low extraction field). This approach for manufacturing GEM-like radiation imaging detectors allows for precise dimensional control and considerable geometrical design freedom

GEMGrid: a wafer post-processed GEM-like radiation detector

This paper presents a new wafer post-processed micropatterned gaseous radiation detector called GEMGrid.The device consists of a GEM-like structure fabricated with SU-8 photo resist directly on top of a Timepix chip with zero gap distance.\ud The detector characteristics have been studied in several gas mixtures. The device is capable of tracking minimum ionizing particles and exhibits good energy resolution on 55Fe decays.\ud We further show a strongly improved mechanical robustness of these GEM-like structures as compared to a pillar-supported integrated Micromegas.\u

Potential applications of electron emission membranes in medicine

With a miniaturised stack of transmission dynodes, a noise free amplifier is being developed for the detection of single free electrons, with excellent time- and 2D spatial resolution and efficiency. With this generic technology, a new family of detectors for individual elementary particles may become possible. Potential applications of such electron emission membranes in medicine are discussed

Charge protection characterisation and drift time resolution improvement for GridPix

A GridPix detector is a gaseous detector capable of detecting single primary electrons from ionising particles. Such a detector consists of a pixel chip as active anode covered with a thin layer of silicon rich silicon nitride (SiRN) for protection against discharges. A layer of 8 JlIl1 SiRN, and according recent tests even 4 JlIl1, is sufficient to protect against discharges. The effect of the thickness of the SiRN layer on the operation of a detector has been determined. Time walk effects due to pixel electronics response time and gas gain statistics cause errors in drift time measurements thereby worsening the resolution in the drift direction. Simulations and measurements have been performed to determine how much time walk can be compensated for. GridPix detectors are high resolution low mass detectors that measures track segments in 3D. Very recently we performed first tests in a 250 Me V proton beam, in order to investigate the application of GridPix in Proton therapy and results are promising

Spark protection layers for CMOS pixel anode chips in MPGDs

In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs).When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A signal reduction is expected when the layers are too thick; simulations presented in this paper indicate that layer supto 10 mm thick can be applied without significantly degrading the detector performance. Layers of amorphous silicon and silicon-rich nitride have been deposited on top of Timepix and Medipix 2chips in GridPix detectors; with this, chips survive naturally occurring as well as intentionally produced discharges