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Dreier, T., Krapohl, D., Maneuski, D., Lawal, N., Schöwerling, J. O., O'Shea, V. & Fröjdh, C. (2018). A USB 3.0 readout system for Timepix3 detectors with on-board processing capabilities. Paper presented at 20th International Workshop on Radiation Imaging Detectors, Sundsvall, Sweden, JUN 24-28, 2018. Journal of Instrumentation, 13, Article ID C11017.
Open this publication in new window or tab >>A USB 3.0 readout system for Timepix3 detectors with on-board processing capabilities
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2018 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 13, article id C11017Article in journal (Refereed) Published
Abstract [en]

Timepix3 is a high-speed hybrid pixel detector consisting of a 256 x 256 pixel matrix with a maximum data rate of up to 5.12 Gbps (80 MHit/s). The ASIC is equipped with eight data channels that are data driven and zero suppressed making it suitable for particle tracking and spectral imaging.

In this paper, we present a USB 3.0-based programmable readout system with online preprocessing capabilities. USB 3.0 is present on all modern computers and can, under real-world conditions, achieve around 320MB/s, which allows up to 40 MHit/s of raw pixel data. With on-line processing, the proposed readout system is capable of achieving higher transfer rate (approaching Timepix4) since only relevant information rather than raw data will be transmitted. The system is based on an Opal Kelly development board with a Spartan 6 FPGA providing a USB 3.0 interface between FPGA and PC via an FX3 chip. It connects to a CERN T imepix 3 chipboard with standard VHDCI connector via a custom designed mezzanine card. The firmware is structured into blocks such as detector interface, USB interface and system control and an interface for data pre-processing. On the PC side, a Qt/C++ multi-platformsoftware library is implemented to control the readout system, providing access to detector functions and handling high-speed USB 3.0 streaming of data from the detector.

We demonstrate equalisation, calibration and data acquisition using a Cadmium Telluride sensor and optimise imaging data using simultaneous ToT (Time-over-Threshold) and ToA (Timeof- Arrival) information. The presented readout system is capable of other on-line processing such as analysis and classification of nuclear particles with current or larger FPGAs.

Keywords
Data processing methods, Detector control systems (detector and experiment monitoring and slow-control systems, architecture, hardware, algorithms, databases), Front-end electronics for detector readout, X-ray detectors
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:miun:diva-34944 (URN)10.1088/1748-0221/13/11/C11017 (DOI)000450981800001 ()2-s2.0-85057630487 (Scopus ID)
Conference
20th International Workshop on Radiation Imaging Detectors, Sundsvall, Sweden, JUN 24-28, 2018
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2019-01-15Bibliographically approved
Fröjdh, C., Krapohl, D. & Thungström, G. (2016). Hard X-ray imaging and particle detection with TIMEPIX3. In: Proceedings of SPIE - The International Society for Optical Engineering: . Paper presented at SPIE Conference on Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII, AUG 29-31, 2016, San Diego, CA. SPIE - International Society for Optical Engineering, 9968, Article ID UNSP 99680T.
Open this publication in new window or tab >>Hard X-ray imaging and particle detection with TIMEPIX3
2016 (English)In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2016, Vol. 9968, article id UNSP 99680TConference paper, Published paper (Refereed)
Abstract [en]

CMOS pixel electronics open up for applications with single photon or particle processing. TIMEPIX3 is a readout chip in the MEDIPIX family with the ability to simultaneously determine energy and time of interaction in the pixel. The device is fully event driven, sending out data on each interaction at a maximum speed of about 40 Mhits/s. The concept allows for off-line processing to correct for charge sharing or to find the interaction point in multi pixel events. The timing resolution of 1.56 ns allows for three dimensional tracking of charged particles in a thick sensor due to the drift time for the charge in the sensor. The experiments in this presentation have been performed with silicon sensors bonded MEDIPIX family chips with special focus on TIMEPIX3. This presentation covers basic performance of the chip, spectral imaging with hard X-rays, detection and imaging with charged particles and neutrons. Cluster identification, centroiding and charge summing is extensively used to determine energy and position of the interaction. For neutron applications a converter layer was placed on top of the sensor.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2016
Series
Proceedings of SPIE, ISSN 0277-786X ; 9968
Keywords
charge sharing, particle identification, Pixel detector, single photon processing
National Category
Physical Sciences
Identifiers
urn:nbn:se:miun:diva-29806 (URN)10.1117/12.2238505 (DOI)000389506700013 ()2-s2.0-85007206718 (Scopus ID)STC (Local ID)978-1-5106-0327-1 (ISBN)978-1-5106-0328-8 (ISBN)STC (Archive number)STC (OAI)
Conference
SPIE Conference on Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVIII, AUG 29-31, 2016, San Diego, CA
Available from: 2017-01-02 Created: 2017-01-02 Last updated: 2017-06-30Bibliographically approved
Krapohl, D., Schubel, A., Fröjdh, E., Thungström, G. & Fröjdh, C. (2016). Validation of Geant4 Pixel Detector Simulation Framework by Measurements with the Medipix Family Detectors. IEEE Transactions on Nuclear Science, 63(3), 1874-1881, Article ID 7497723.
Open this publication in new window or tab >>Validation of Geant4 Pixel Detector Simulation Framework by Measurements with the Medipix Family Detectors
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2016 (English)In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 63, no 3, p. 1874-1881, article id 7497723Article in journal (Refereed) Published
Abstract [en]

Monte Carlo simulations are an extensively used tool for developingand understanding radiation detector systems. In this work, we usedresults of several chips and readout modes of the Medipix detector family to validatea Geant4 based pixel detector framework, developed in our group, thatis capable of simulating particle tracking, charge transport in thesensor material and different readout schemes. We experimentally verifiedthe simulation with different detector geometries in terms of pixelpitch and size as well as sensor material and sensor thickness. Thesingle pixel mode (SPM) and charge summing mode (CSM) in Medipix3 were evaluated with fluorescenceand synchrotron radiation. The integration of the charge sensitiveamplifier functionality in the simulation framework allowed to simulatethe time-over-threshold mode of the Timepix chip.Simulation and measurement have been compared in terms of spectralresolution using threshold scans in photon counting mode (Medipix3) and time over thresholdmode (Timepix). Furthercomparisons were done using X-ray tube spectra and beta decay to covera broad energy range. Additionally, TCAD simulations are performedas a comparison to a well-established simulation method. The resultsshow good agreement between simulation and measurement.

Keywords
Monte Carlo Simulation, Medipix, Timepix, photon counting detectors, x-ray, alpha-radiation
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:miun:diva-27746 (URN)10.1109/TNS.2016.2555958 (DOI)000382463600021 ()2-s2.0-84978249235 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Available from: 2016-05-20 Created: 2016-05-20 Last updated: 2017-06-30Bibliographically approved
Krapohl, D. (2015). Monte Carlo and Charge Transport Simulation of Pixel Detector Systems. (Doctoral dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Monte Carlo and Charge Transport Simulation of Pixel Detector Systems
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is about simulation of semiconductor X-ray and particledetectors. The simulation of a novel coating for solid state neutrondetectors is discussed as well as the implementation of a simulationframework for hybrid pixel detectors.Today’s most common thermal neutron detectors are proportionalcounters, that use 3He gas in large tubes or multi wire arrays. Globalnuclear disarmament and the increase in use for homeland securityapplications has created a shortage of the gas which poses a problemfor neutron spallation sources that require higher resolution and largersensors. In this thesis a novel material and clean room compatible pro-cess for neutron conversion are discussed. Simulations and fabricationhave been executed and analysed in measurements. It has been proventhat such a device can be fabricated and detect thermal neutrons.Spectral imaging hybrid pixel detectors like the Medipix chipare the most advanced imaging systems currently available. Thesechips are highly sophisticated with several hundreds of transistors perpixel to enable features like multiple thresholds for noise free photoncounting measurements, spectral imaging as well as time of arrivalmeasurements. To analyse and understand the behaviour of differentsensor materials bonded to the chip and to improve development offuture generations of the chip simulations are necessary. Generally, allparts of the detector system are simulated independently. However, itis favourable to have a simulation framework that is able to combineMonte Carlo particle transport, charge transport in the sensor as wellas analogue and digital response of the pixel read-out electronics. Thisthesis aims to develop such a system that has been developed withGeant4 and analytical semiconductor and electronics models. Further-more, it has been verified with data from measurements with severalMedipix and Timepix sensors as well as TCAD simulations.Results show that such a framework is feasible even for imagingsimulations. It shows great promise to be able to be extended withfuture pixel detector designs and semiconductor materials as well asneutron converters to aim for next generation imaging devices.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2015. p. 95
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 215
Keywords
Monte Carlo Simulation, TCAD, pixel detectors, Medipix, Timepix, Finite Element Simulation
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:miun:diva-24763 (URN)STC (Local ID)978-91-88025-06-7 (ISBN)STC (Archive number)STC (OAI)
Public defence
2015-04-08, M102, Mittuniversitetet, Holmgatan 10, Sundsvall, 10:00 (English)
Opponent
Supervisors
Available from: 2015-03-31 Created: 2015-03-31 Last updated: 2016-12-23Bibliographically approved
Norlin, B., Reza, S., Krapohl, D., Fröjdh, E. & Thungström, G. (2015). Readout cross-talk for alpha-particle measurements in a pixelated sensor system. Paper presented at 16th International Workshop on Radiation Imaging Detectors (IWORID2014). Journal of Instrumentation, 10, Article ID C05025.
Open this publication in new window or tab >>Readout cross-talk for alpha-particle measurements in a pixelated sensor system
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2015 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 10, article id C05025Article in journal (Refereed) Published
Abstract [en]

Simulations in Medici are performed to quantify crosstalk and charge sharing in a hybrid pixelated silicon detector. Crosstalk and charge sharing degrades the spatial and spectral resolution of single photon processing X-ray imaging systems. For typical medical X-ray imaging applications, the process is dominated by charge sharing between the pixels in the sensor. For heavier particles each impact generates a large amount of charge and the simulation seems to over predict the charge collection efficiency. This indicates that some type of non modelled degradation of the charge transport efficiency exists, like the plasma effect where the plasma might shield the generated charges from the electric field and hence distorts the charge transport process. Based on the simulations it can be reasoned that saturation of the amplifiers in the Timepix system might generate crosstalk that increases the charge spread measured from ion impact on the sensor.

Keywords
Charge transport and multiplication in solid media; Hybrid detectors; X-ray detec- tors; Imaging spectroscopy
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-24977 (URN)10.1088/1748-0221/10/05/C05025 (DOI)000357993300025 ()2-s2.0-84930958451 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
16th International Workshop on Radiation Imaging Detectors (IWORID2014)
Available from: 2015-05-25 Created: 2015-05-25 Last updated: 2017-12-04Bibliographically approved
Schübel, A., Krapohl, D., Fröjdh, E., Fröjdh, C. & Thungström, G. (2014). A Geant4 based framework for pixel detector simulation. Paper presented at 16th International Workshop on Radiation Imaging Detectors. Journal of Instrumentation, 9(12), Article ID C12018.
Open this publication in new window or tab >>A Geant4 based framework for pixel detector simulation
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2014 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 9, no 12, article id C12018Article in journal (Refereed) Published
Abstract [en]

The output from a hybrid pixel detector depends on the interaction of the radiation with the sensor material, the transport of the resulting charge in the sensor, the pulse processing in the readout circuit and processing of the resulting signal. In order to understand the full behaviour of the device and to predict the performance of future devices it is important to have a framework that can simulate the entire process in the detector system.Geant4 is a Monte Carlo based toolkit for simulation of particle interaction with matter which is developed and actively used for CERN experiments and detector development [1]. By extending the Monte Carlo code in Geant4 with a charge carrier transport model of the sensor material and basic amplifier functionality as well as read out logic, a simulation of the complete detector system is possible.The MEDIPIX is a state of the art hybrid pixel detector that allows bonding of a wide range of sensor materials [2,3]. Simulation models have been developed and tested for different chips from the MEDIPIX family. The simulation is defined using configuration files to set the geometry, sensor material properties, number of pixels, pixel pitch and chip properties. Source properties as well as filters and objects in the beam can be added for different experimental set-ups. The interaction of radiation with the sensor is taken into account in the transport of the charge carriers in the sensor material and a current induced in the pixel electrode that triggers an amplifier response. Simulation results have been verified with X-ray fluorescence and radioactive sources using MEDIPIX family chips. In this paper we present the developed simulation framework and first results.

Keywords
Performance of high energy physics detectors, Simulation methods and programs, Software architectures (event data models, frameworks and databases)
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:miun:diva-23708 (URN)10.1088/1748-0221/9/12/C12018 (DOI)000351342900002 ()2-s2.0-84918823479 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
16th International Workshop on Radiation Imaging Detectors
Available from: 2014-12-12 Created: 2014-12-12 Last updated: 2017-12-05Bibliographically approved
Thungström, G., Esebamen, O. X., Krapohl, D., Fröjdh, C., Nilsson, H.-E., Petersson, S. & Brenner, R. (2014). Fabrication, Characterization and Simulation of Channel Stop for n in p-Substrate Silicon Pixel Detectors. Journal of Instrumentation, 9(7), Art. no. C07013
Open this publication in new window or tab >>Fabrication, Characterization and Simulation of Channel Stop for n in p-Substrate Silicon Pixel Detectors
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2014 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 9, no 7, p. Art. no. C07013-Article in journal (Refereed) Published
Abstract [en]

Silicon detectors made on p-substrates are expected to have a better radiation hardness as compared todetectors made on n-substrates. However, the fixed positive oxide charges induce an inversion layer ofelectrons in the substrate, which connects the pixels. The common means of solving this problem isby using a p-spray, individual p-stops or a combination of the two. Here, we investigate the use offield plates to suppress the fixed positive charges and to prevent the formation of an inversion layer.The fabricated detector shows a high breakdown voltage and low interpixel leakage current for astructure using biased field plates with a width of 20 μm. By using a spice model for simulation of thepreamplifier, a cross talk of about 1.6 % is achieved with this detector structure. The cross talk iscaused by capacitive and resistive coupling between the pixels

Keywords
Electronic detector readout concepts (solid-state), Radiation-hard detectors, Solid state detectors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-22224 (URN)10.1088/1748-0221/9/07/C07013 (DOI)000340050700013 ()2-s2.0-84905165594 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Available from: 2014-06-19 Created: 2014-06-19 Last updated: 2017-12-05Bibliographically approved
Krapohl, D. (2013). Comparison of energy resolution spectra of CdTe TIMEPIX detector working in photon counting and time-over-threshold mode. In: IEEE Nuclear Science Symposium Conference Record: . Paper presented at 2013 60th IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2013; Seoul; South Korea; 27 October 2013 through 2 November 2013; Category numberCFP13NSS-ART; Code 106171 (pp. Art. no. 6829825).
Open this publication in new window or tab >>Comparison of energy resolution spectra of CdTe TIMEPIX detector working in photon counting and time-over-threshold mode
2013 (English)In: IEEE Nuclear Science Symposium Conference Record, 2013, p. Art. no. 6829825-Conference paper, Published paper (Other academic)
Abstract [en]

Hybrid pixel detectors like the Medipix andTIMEPIX developed by the Medipix collaboration combinedwith high-z materials are of growing interest. In particular theTIMEPIX detector can be operated in photon counting mode andtime-over-threshold mode (ToT) to obtain spectral information.Previous studies showed that 110 μm pixel sizes obtain a betterenergy resolution than 55 μm pixel sizes. Furthermore, thresholdscans obtained a better spectral resolution than operation in ToTmode. In this work the influence of noise sources in differentmeasurement approaches on the spectral response of a TIMEPIXchip bump-bonded to CdTe sensor are presented. Two 1mmthick CdTe sensors with pixel sizes of 55 μm and 110 μm,bump-bonded to a TIMEPIX readout chip, were evaluated atthe Diamond Light Source synchrotron. A finely collimated,perpendicular pencil beam with x-ray energies of 25 keV and79 keV was used to investigate single pixels. A small area of 10x10pixels was investigated in ToT-mode and compared to a thresholdscan of the same pixels on both detectors. The measurementsare compared to an analytical SPICE/Python simulation thatemulates photon counting and time-over-threshold mode.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:miun:diva-20809 (URN)10.1109/NSSMIC.2013.6829825 (DOI)000347163503197 ()2-s2.0-84904169444 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
2013 60th IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2013; Seoul; South Korea; 27 October 2013 through 2 November 2013; Category numberCFP13NSS-ART; Code 106171
Available from: 2013-12-19 Created: 2013-12-19 Last updated: 2016-10-20Bibliographically approved
Krapohl, D., Fröjdh, C., Fröjdh, E., Maneuski, D. & Nilsson, H.-E. (2013). Investigation of charge collection in a CdTe-Timepix detector. Paper presented at 14th International Workshop on Radiation Imaging Detectors (iWoRID 2012); 20-25 June 2012; Figueira da Foz, Portugal.. Journal of Instrumentation, 8(May), Art. no. C05003
Open this publication in new window or tab >>Investigation of charge collection in a CdTe-Timepix detector
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2013 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 8, no May, p. Art. no. C05003-Article in journal (Refereed) Published
Abstract [en]

Energy calibration of CdTe detectors is usually done using known reference sources disregarding the exact amount of charge that is collected in the pixels. However, to compare detector and detector model the quantity of charge collected is needed. We characterize the charge collection in a CdTe detector comparing test pulses, measured data and an improved TCAD simulation model [1]. The 1 mm thick detector is bump-bonded to a TIMEPIX chip and operating in Time-over-Threshold (ToT) mode. The resistivity in the simulation was adjusted to match the detector properties setting a deep intrinsic donor level [2]. This way it is possible to adjust properties like trap concentration, electron/hole lifetime and mobility in the simulation characterizing the detector close to measured data cite [3].

Keywords
Charge induction; solid state detectors; x-ray detectors; models and simulations
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:miun:diva-18946 (URN)10.1088/1748-0221/8/05/C05003 (DOI)000320726000003 ()2-s2.0-84878342633 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
14th International Workshop on Radiation Imaging Detectors (iWoRID 2012); 20-25 June 2012; Figueira da Foz, Portugal.
Available from: 2013-05-16 Created: 2013-05-16 Last updated: 2017-12-06Bibliographically approved
Thungström, G., Harrnsdorf, L., Norlin, B., Reza, S., Krapohl, D., Mattsson, S. & Gunnarsson, M. (2013). Measurement of the sensitive profile in a solid state silicon detector, irradiated by X-rays. Paper presented at 14th International Workshop on Radiation Imaging Detectors; 1-5 July 2012; Figueira da Foz, PORTUGAL. Journal of Instrumentation, 8(4), Art. no. C04004
Open this publication in new window or tab >>Measurement of the sensitive profile in a solid state silicon detector, irradiated by X-rays
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2013 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 8, no 4, p. Art. no. C04004-Article in journal (Refereed) Published
Abstract [en]

A newly constructed solid state silicon dose profile detector is characterized concerning its sensitive profile. The use of the MEDIPIX2 sensor system displays an excellent method to align an image of an X-ray slit to a sample under test. The scanning from front to reverse side of the detector, show a decrease in sensitivity of 20%, which indicates a minority charge carrier lifetime of 0.18 ms and a diffusion length of 460 μm. The influence of diced edges results in a volumetric efficiency of 59%, an active volume of 1.2 mm 2 of total 2.1 mm2.

Keywords
Computerized Tomography (CT) and Computed Radiography (CR); Dosimetry concepts and apparatus; Solid state detectors; X-ray detectors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-18741 (URN)10.1088/1748-0221/8/04/C04004 (DOI)000317462400004 ()2-s2.0-84877780840 (Scopus ID)STC (Local ID)STC (Archive number)STC (OAI)
Conference
14th International Workshop on Radiation Imaging Detectors; 1-5 July 2012; Figueira da Foz, PORTUGAL
Available from: 2013-04-12 Created: 2013-04-12 Last updated: 2017-12-06Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5619-409X

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