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Compact X-ray computed tomography system for non destructive characterization of nano materials

Final Report Summary - NANOXCT (Compact X-ray computed tomography system for non destructive characterization of nano materials)

Executive Summary:
1.1 Executive Summary
The NanoXCT project funded by the European Union’s FP7 programme developed a compact X-ray computed tomography system for laboratory use, which allows for non-destructive and fully three-dimensional characterizations of specimens and materials from micro to nanoscale. In this report we present the results achieved during the lifetime of the NanoXCT project between 01.05.2012 and 30.04.2015. NanoXCT put its main focus on implementing a novel technique to facilitate fully three dimensional and nondestructive structural and chemical characterizations of internal and external features at the nano-scale by applying a combination of two techniques: X-ray computed tomography for structural characterization and integrated chemical characterization through Multi Energy XCT and K-Edge absorptiometry. The main objectives of the project are found in the design, the development and finally the implementation of a compact X-ray computed tomography system for nondestructive chemical and structural characterization of nano-materials and components. A core requirement for the design of the NanoXCT system since the formation of the project idea was consequently avoiding expensive X-ray optical elements and not relying on a synchrotron source, which would both extend the costs and constrain the application areas of the targeted NanoXCT device. In this context the following goals were realized during the lifetime of the project:
• Development of a compact, laboratory scale demonstration system. The targeted specifications of this demonstration system, which may be individually reached in accordance to the application area are outlined in the list below:

Targeted NanoXCT demonstration system specifications
Scanning time: ~ 10 hours
Field of view: 1 mm
Specimen size: <= 1 mm³
Voxel size: 50 nm
Analysis modes: 3D structural and chemical analysis

• Development of a novel nano focus X-ray source specifically designed for nano-scale characterization.
• Development of a detection system which employs a novel wide field of view small pitch detector concept with photon counting and spectral information capabilities.
• Development of a precision manipulation system, which allows for alternative scanning geometries
• Facilitating nano-scale chemical characterizations by a combination of multi energy XCT and/or K-Edge absorptiometry.
• Design and implementation of NanoXCT reconstruction algorithms
• Design and implementation of specific algorithms to address qualitative and quantitative evaluation of nano scale structural and chemical characterization.

To summarize, the NanoXCT consortium successfully implemented the NanoXCT device demonstrator as specified and demonstrated it to be fully functional at the end of the NanoXCT project. Now the system undergoes a detailed testing and refinement phase to evaluate and enhance the potential of the system. In addition, all components are continuously advanced in order to transfer the generated results into a series of NanoXCT related products in near future.

Project Context and Objectives:
1.2 Summary description of project context and objectives
NanoXCT’s CONTEXT
Conventional material analytics for nano-scale characterization covers a wide spectrum of different techniques ranging from destructive methods (e.g. focused ion beam FIB), surface inspection methods (e.g. scanning electron microscope SEM, Atomic force microscopy AFM), to 2D methods (e.g. X-ray Diffraction Analysis XRDA). All these techniques share the fact, that they focus on individual aspects of materials characterization and consequently they are not intended to provide a comprehensive representation of a specimen including internal and external 3D-structure analysis as well as a chemical analysis without destroying the sample. In this respect nano-scale material analytics is now on the edge of a new era, which will be started by the results achieved in NanoXCT.
The NanoXCT project aimed to push the limits regarding the current state of the art in nanoscale analysis by developing a compact X-ray computed tomography system for non-destructive characterization of nano materials and components. Considering the state of the art at the time of the project start regarding conventional methods in nano-scale material analytics it was not possible to provide comprehensive representations of specimens including internal and external 3D-structure analysis as well as a chemical analysis without destroying the sample.

NanoXCT’s VISION
NanoXCT has put its main focus on implementing a novel technique to facilitate fully three dimensional and nondestructive structural and chemical characterizations of internal and external features at the nano-scale by applying a combination of two techniques: X-ray computed tomography for structural characterization and integrated chemical characterization through Multi Energy XCT and K-Edge absorptiometry. In this sense, a comprehensive representation of a specimen was facilitated including
• internal and external 3D-structure analysis as well as
• chemical analysis
• without destroying the sample.
The following goals and objectives have been defined in order to put this vision into reality.

NanoXCT’s GOALS and OBJECTIVES
The main focus of NanoXCT was put on a novel technique to facilitate a fully three dimensional and nondestructive structural and chemical characterization of internal and external features at the nano-scale. The main objective of the NanoXCT project was therefore to design, develop and implement a compact X-ray computed tomography system for non-destructive chemical and structural characterization of nano-materials and components. The technique should enable to be applied on widespread application areas and seamlessly extend the application areas of conventional sub-micro computed tomography. The targeted system should therefore avoid expensive X-ray optical elements and not rely on a synchrotron source, which would extend the costs and constrain the application areas of the aimed NanoXCT device at the same time. During the project lifetime the following goals were realized:
• Development of a compact, laboratory scale demonstration system. The targeted specifications of this demonstration system, which may be individually reached (in accordance to the application area), are outlined in Fehler! Verweisquelle konnte nicht gefunden werden..
• Development of a novel nano focus X-ray source specifically designed for nano-scale characterization.
• Development of a detection system which employs a novel wide field of view small pitch detector concept with photon counting and spectral information capabilities.
• Facilitating nano-scale chemical characterizations by a combination of multi energy XCT and/or K-Edge absorptiometry.
• Design and implementation of NanoXCT reconstruction algorithms
• Design and implementation of specific algorithms to address qualitative and quantitative evaluation of nano scale structural and chemical characterization.

Targeted NanoXCT demonstration system specifications:
Scanning time: ~ 10 hours
Field of view: 1 mm
Specimen size: <= 1 mm³
Voxel size: 50 nm
Analysis modes: 3D structural and chemical analysis

NanoXCT’s CONCEPT and IMPLEMENTATION
The NanoXCT consortium was setup in order to bring together the expertise of 2 universities, 2 research institutes, 4 technology providers as well as 2 industrial end users. At the time of initiating the project start and also at the time of writing this report, there was no group in Europe able to carry out the complete project on its own. The NanoXCT project was running from 05/2012 to 04/2015 in a total project lifetime of 36 months. NanoXCT was implemented using a total budget of 4,195 Mio EUR funded by the European Union’s FP7 programme within its FP7-NMP-2011-SME-5 call under the topic NMP.2011.1.4-3 Tools and methodologies for imaging structures and composition at the nanometer scale.

The targeted NanoXCT device shall enable a fully 3D, non-destructive, structural and chemical characterization of internal and external features at the nano-scale by applying a combination of two techniques: X-ray computed tomography and K-Edge-absorptiometry.

All components should be included in a laboratory scale NanoXCT demonstrator, which consists of a hardware demonstrator for the laboratory device demonstration system and a software demonstrator including all developed algorithms regarding the structural and chemical characterization of internal and external features. The 3D structural analysis should be facilitated in high detail using 3D X-ray computed tomography (XCT). The determination of chemical decomposition and material properties should be accomplished using multi energy XCT and/or K-Edge absorptiometry. Furthermore the technique should enable a wide application area to seamlessly extend the application areas of conventional sub-micro computed tomography. A core requirement for the design of the NanoXCT system, since the formation of the project idea was consequently avoiding expensive X-ray optical elements and not relying on a synchrotron source, which would both extend the costs and constrain the application areas of the targeted NanoXCT device.

Project Results:
(Note: All figures and tables are provided in the attached pdf Final Project Report.)
1.3 Description of the main results and foregrounds
1.3.1 WP 1 – Project management
The overall objective of WP1 Management comprises planning, organization, coordination and controlling of the NanoXCT project in order to accomplish the targeted goals. WP1 includes the management of the project’s resources regarding the deployment and manipulation of human resources, financial resources, technological resources, and natural resources.
WP1 involves the following objectives (according to the DoW):
• Supervision of the project vision and strategy as well as gender equality
• Management of resources
• Execution of relevant decisions
• Coordination of internal procedures and communication
Execution of administrative actions both internal and with Commission

Fulfilment of the project work plan
At the beginning of the project the management and communication structures in the project were fixed. In addition, the templates for reports, deliverables, time recording, dissemination activities and meeting minutes were created and distributed to the partners.
The fruitful collaboration within the NanoXCT project led to significant results in all work packages. The communication took place continuously using video or telephone conferences, as well as physical work package related meetings and lab visits. General assembly (GA) meeting were arranged in a six month’s cycle and took place with the participation of at least one representative per partner. The 8 NanoXCT GA meetings were hosted by the corresponding project partners at their site (FHW/AT, ST-Italy/IT, FHG/DE, KTH/SE, NTX/GR, VSG/FR, RAY/DE), in order to use the occasion for lab visits. Furthermore, work package meetings were scheduled together with the GA meetings whenever possible. The intermediate review meeting was held in Brussels at the commission’s premises together with the GA5 meeting.
For all GA meetings the agenda and participants lists were provided by the coordinator as well as the corresponding meeting minutes and protocols after the respective GA meetings. The protocol consisted of the meeting minutes and the collected presentations held during the meeting. To make communication more efficient a mailing list was set up which was updated regularly. Furthermore the coordinator conducted a continuous scientific and financial project monitoring, regarding the scientific project progress on a quarterly basis and regarding the financial development every six months.

Table 2: NanoXCT meetings

1.3.2 WP 2 – Detailed specifications

Fulfilment of the project work plan
The overall goal of WP2 was to establish and maintain interaction with end users and NanoXCT partners aiming at the detailed definition of the system’s requirements according to the specifications of the end user’s applications. This WP was divided in two Tasks (T2.1: Application specifications and T2.2: Detailed system requirements and definition interfaces) and the work progress is fully presented in three deliverables (D2.1: Application specification, D2.2: System requirements and interface definitions and D2.3: Refined system requirements and specifications).

Scientific and technical results
The objectives of the first task of WP2 were to clarify the nature of materials that are going to be characterized by the NanoXCT device, both by the end-users of the project and from an external industrial interest group. To achieve this, a questionnaire regarding materials properties and physical characteristics was created and delivered to the partners and members of the industrial interest group along with a publishable abstract of the project. The demands of the end users were grouped and presented analytically in Deliverable 2.1 while this work was continuously enhanced during the project.
The second task of WP2 was focused on the definition of the NanoXCT characteristics (both software and hardware) according to the applications specifications. For more, it was decided to split the deliverable of this Task in two, which analytically present the initial system requirements and the refined ones, which came up with the evolution of the project. The final specifications of each component was integrated according to the data provided by the responsible partners (i.e. data on X-ray source was provided by EXC, on detector by FHG, on CT system design, data analysis and visualization and interface definitions by RAY and VSG and for the XRF component by the XRD-tools). All these are presented in details to the deliverables 2.2 and 2.3.

Collaboration with other work packages
During the whole duration of the project there was a strong collaboration between all the WPs, since WP2 was the one defining the specifications of the applications needed from the end users, so as to adequately construct the NanoXCT device demonstrator. Apart from the end users, which were partners of the consortium, an external industrial interest group was established, which was continuously extended throughout the whole project.

1.3.3 WP 3 - Chemical analysis and nano structure characterization

Fulfilment of the project work plan
WP3 aims at chemical and nano structure evaluation of specially developed etalon specimens (also called NanoXCT Reference Materials in this report) using destructive methods, in order to verify the NanoXCT nondestructive methods. The main objectives are:
• Development and fabrication of NanoXCT Reference Materials and measurements for chemical analysis and nano structure characterization using advanced destructive methods and techniques;
• Determination of the essential parameters for evaluation;
• Collection of reference results and reporting;
• Verification and support on NanoXCT nondestructive methods and techniques development.
The WP3 was implemented according to DoW in Task 3.1. Sample preparation; Task 3.2. Nano-structure characterization; Task 3.3. Reference chemical evaluation and testing; and Task 3.4. Collecting reference results and support on NanoXCT methods. The work was successfully completed in close collaboration between the three WP3 partners - P3:BAS, P8:STM and P9:NTX. WP3 has completed the work on the 3 Deliverables and the three reports D3.1 D3.2 and D3.3 were submitted timely, according to DoW, as follows: (i) D3.1. Essential Nano Structure Parameters of Specimens - submitted to project coordinator (PC on 29.04.2013); (ii) D3.2. Reference chemical evaluation and testing –submitted to PC on 19.02.2014; (iii) D3.3. Report verifying the reference results and the results of NanoXCT methods – submitted to PC on 16.03.2015

Scientific and technical results
WP3 partners have developed 3 different Reference materials categories (8 etalon samples) for demonstration of the testing abilities of the NanoXCT device. Eight etalon samples were fully characterized by using the most advanced destructive structural and chemical test methods. Calibrated test equipment was used. The most essential parameters of interests for NanoXCT evaluation and verification were determined. The following results and achievements are obtained within the WP3:

1) Fabrication of NanoXCT Etalon Samples for Reference: The following NanoXCT etalon samples of 3 different reference materials categories were developed and fabricated:
• Reference Materials Category 1: Microelectronics with inside nanometric structures (3 etalon samples from STM);
• Reference Materials Category 2: Polymeric materials with nanofillers (3 etalon samples from BAS);
• Reference Materials Category 3: Carbon nanomaterials; Nanocomposites; Ceramic nanostructures (2 etalon samples from NTX);
• Samples from Industrial Interest Group: Borealis PP composites

2) Characterization of NanoXCT Etalon Samples: The following methods and techniques have been used for structural characterization at micro and nanoscale: 3D computed X-ray tomography (micro-XCT), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), atom force microscopy (AFM), focused ion beam plus TEM tomography (FIB) and Raman spectroscopy.
For chemical evaluation and elemental analysis have been used: X-ray fluorescence analysis (XRF), energy dispersive X-ray spectroscopy (EDX), electron diffraction spectroscopy (SEM-EDS), Fourier transform infra-red spectroscopy (FTIR), synchrotron near-edge X-ray absorption fine structure spectroscopy (NEXAFS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).
All the characterization techniques used for the evaluation of the etalon materials for NanoXCT project were periodically calibrated according to the procedures defined by the manufacturers of the instrumentation.

The obtained main results from structural and chemical characterization of the etalon samples are presented in the D3.1 D3.2 and D3.3 reports. All samples and data are available at the responsible partners: BAS, STM and NTX.
Table 3 summarizes the NanoXCT etalon samples developed and characterized in WP3 and provided for verification of NanoXCT device and methods
3. Essential Parameters of Interests for NanoXCT evaluation. For the NanoXCT etalon samples, the most essential parameters of interests for the NanoXCT evaluation and verification were determined. They are summarized in Table 3.

Table 3: NanoXCT etalon samples developed and characterised in WP3 for verification of the NanoXCT device and methods

4. Example Results for the Etalon Samples:
a) Materials Category 2 (BAS): Etalon sample - Bi-filler composite Epoxy resin/Clay/Gold

SEM, EDX and XCT results of Etalon Sample - Epoxy resin/Clay/Gold
Figure 3: Materials Category 2

b) Materials Category 3 (NTX): Etalon samples - NanoMembranes and Catalytic Metal Oxide Powder

SEM and EDX results of Nanomembranes and Catalytic metal oxide powder
Figure 4: Materials category 3

5. Procedure and Strategy for Verification of NanoXCT Results: The WP3 partners have elaborated procedures and strategy for the verification of NanoXCT results.
a) Results collection: Partners BAS, STM and NTX have collected the results on chemical evaluation and nanostructure characterization of their etalon materials. Samples and data are available at the responsible partners.
b) Proving and enhancing characterization: The WP3 partners have exchanged their etalon samples to be tested in between Laboratories for proving results and additional reference characterization by using specific testing equipment. This strategy has led to dissemination of the NanoXCT results in several conference presentations and a joint publication submitted to Express Polymer Letters.
c) Support to other WPs: During the NanoXCT project duration, the WP3 partners have provided regularly reference samples and test results to partners: VSG, FHW, FHG and RAY in order to support the NanoXCT software and device developments. Additionally, WP3 partners have supported with new samples and appropriate reference results: (i) the VSG to elaborate a tool for the software verification of reference results; (ii) the RAY was supported with reference samples and XCT results to enhance the test methods of the NanoXCT modules, CT and K-Edge.
d) Verification and reporting: The NanoXCT verification of the WP3 reference results are reported as showcases within the WP6 and WP9 at the 6th GA meeting in Patras, June 2014; 7th GA meeting in Bordeaux, Nov. 2014; and 8th GA in Meersburg 2015.

Collaboration with other work packages
Two Steps of interconnections were built in WP3:
1. Cooperation among the WP3 Partners: Strong cooperation was established between BAS, STM and NTX for successful implementation of WP3. Within the reporting period the NTX has sent to BAS their produced carbon nanotubes (NTX1 and NTX5) for preparation of epoxy based nanocomposites. Rheological characterization was performed also at BAS for evaluation of the degree of dispersion as varying the CNT functionalization. Then, BAS has sent the two etalon samples of Category 2 to NTX for Raman spectroscopy, as well as to STM for FIB, TEM and EDX analysis. NTX has sent the etalon samples Category 3 - nanomembranes and catalytic powders to STM for XCT analysis. As a result, several joint dissemination activities between the partners BAS, STM and NTX were possible, such as: 1 Joint Paper and 3 Joint Conference Communications.
2. Cooperation of WP3 partners with other WPs: The WP3 partners have worked in close cooperation with WP6, WP7 and WP8 partners, sending them etalon samples and characterization results for verification and improvement of the NanoXCT methodology and modulus. Thus, NTX has sent etalon catalytic samples and nanomembranes to: FHG, RAY and STM for verification of the CT module. BAS has prepared additional samples of Epoxy resin / Gold (agglomerated) and sent to RAY together with CT data obtained at BAS for improvement the CT module. The partners BAS, NTX and STM have sent SEM, TEM, XCT reference data to VSG for Software verification. Finally, the WP3 Partners have the possibility to inspect the system during GA 8 at RAY, in Meersburg, April 2015, to better target and compare the system performances according to their experience. As a result, the NanoXCT verification on the WP3 reference results was included in the WP9 and WP6 reports at the 7th and 8th GA meetings.

1.3.4 WP 4 - X-ray source

Fulfilment of the project work plan
WP 4 was led by Excillum and the main participating partners were Excillum and KTH spending 29 and 23 person months respectively on the various aspects of the X-ray source development. The objectives of the X-ray source work package was to develop a novel X-ray source with the main specifications as listed in Table 4. The process of work was that illustrated in Figure 5 where first simulations of the electron optics were performed as input to the design of a first source prototype. This first prototype was then, following procurement, assembled and evaluated. The evaluation of the first prototype fed into a redesign process leading to a second prototype that undergone final evaluation and then was delivered to Rayscan for integration in the complete nano-CT system.


Table 4: The main specification of the NanoXCT x-ray source that were all met by the final source prototype

Scientific and technical results
Reaching the small spot size required for the NanoXCT required using a very thin, 100-200 nm, thick tungsten anode deposited on a diamond substrate of roughly 100 µm thickness operating in the transmission geometry as illustrated in Figure 6. This is required to avoid broadening of the spot due to electron diffusion in the anode. Furthermore electron optics capable of achieving focal spots in the 100 nm region was developed.

Figure 6: The transmission anode concept of the nano-focus X-ray source

In addition, a mechanical design with a few key features as seen in Figure 7 were developed. Water cooling of the source head was incorporated from start and mounting features are present as close as possible to the anode for ultimate stability. Furthermore, the wedge shaped front of the X-ray tube allow for the use of sturdy cone shaped object holders.

Figure 7: The mechanical design of the nano-focus X-ray tube featured a few key features as shown in this picture of the second source prototype. Water cooling of the source head was incorporated from start to reach best mechanical stability, and mounting features are present as close as possible to the anode. Furthermore the wedge shaped front of the X-ray tube allow for the use of sturdy cone shaped object holders.

The first source prototype was assembled, and achieved first light in December 2013. This prototype could immediately resolve 0.7 µm lines and spaces as illustrated in Figure 8. This was, however, far from the ultimate specification and a design re-iteration was launched.

Figure 8 The first source prototype was able to resolve 0.7 µm lines and spaces shortly after “first light” in December 2013.

The second source prototype was then finally assembled in December 2014, and could resolve 150 nm lines and spaces as illustrated in Figure 9.

Figure 9 The second and final source prototype is able to resolve 150 nm lines and spaces as illustrated in this measurement performed in collaboration with project partner FHG.

Collaboration with other work packages
Project partners Fraunhofer Institute and Rayscan have been deeply involved in the source specifications and Fraunhofer Institute have supported in the definition of target materials and acceleration voltages.

1.3.5 WP 5 – Detector

Fulfilment of the project work plan
“WP5 focuses on the development and assembly of an X-ray detector according to the specifications of WP2. To achieve best possible image quality, direct converting photon counting sensors with high efficiency will be used.

It will be necessary to combine several detectors, ideally using a joint sensor layer and readout. For usability of the complete NanoXCT system, it will be necessary to develop a user-friendly software interface to the detector, which reduces the complexity of operating the detector as much as possible. The main objectives are:
• Development and assembly of a detector according to the specification of WP2
• Characterization and calibration of the detector
• Development and implementation of detector software, calibration and correction routines“ [1]

The specification of the detector is based on the results from D2.2 “System requirements and interface definitions” [2]. The general and actual requirements can be found in Table 5 and Table 6 respectively. The detector specification can be found in Table 7. Two concepts were evaluated, both meeting the requirements but based on different detector technologies. For evaluation a scoring system and a risk analysis was applied. With consideration of these factors, the concept based on photon counting Timepix hexa modules with direct converting silicon sensor layer with a pixel size of 55 µm was chosen. The final detector setup consists of four Timepix hexa modules in a row, each itself consisting of 3×2 Timepix chips, resulting in the total size of 3072×512 pixels.

Table 5: General requirements for the detector from the DoW (from D2.2 [2]).

Table 6: Actual requirements for the detector (from D2.2 [2]).

Table 7: NanoXCT X-ray detector specifications according to DoW (from D2.2 [2]).

Initially a prototype detector system was set up. The Timepix hexa modules were not yet delivered at this time, thus the Medipix2 Quad modules available at our facility were deployed for the prototype. Medipix2 and Timepix belong to the same family of detectors; they use the same interface and readout system and are identical in most other basic features. Using the prototype detector, the software interface as well as the calibration and characterization routines could be tested. After delivery of the first hexa modules, a second prototype using two hexa modules was set up and successfully used for first imaging and CT tests at Excillum in Stockholm. Meanwhile the head board containing a micro controller for controlling the high voltage and remote maintenance capability as well as the electrical interface (adapter board) between the Timepix hexa modules and the readout system was designed, assembled and tested. Due to delays of the detector module supplier, the assembly of the final detector was delayed accordingly.

The Timepix detectors offer a huge variety of settings and customization opportunities. Most of which are only necessary in special cases or for the maintenance or initial setup of the detector. For this reason the developed and implemented high level interface will not show all parameters of the detector but will restrict these settings to low-level maintenance, automatic calibration and equalization routines. The only parameters the end-user needs to set are standard imaging parameters (e.g. integration time) and the energy threshold. Figure 10 shows the architecture of the software interface. In order to ensure an optimal utilization of the detector, user-friendly automatic calibration and optimization routines, including a flat-flied threshold equalization and an energy calibration method using K-Lines, were implemented and evaluated. The detector calibration is performed by a tool, which is completely developed by FHG. This tool requires manual switching of the X-ray tube, but guides the user of the calibration software by the use of a wizard, which is a dialog based graphical user interface. The correction algorithms are integrated in our implementation, which provide both a corrected image and an uncorrected raw image for each acquisition. An algorithm for geometric calibration was also developed. It automatically detects the gaps between the detector modules and their respective positions on the detector and calculates the rotation and the position with respect to the detector coordinate. This needs to be done only once after the mechanical assembly of the detector modules.

Figure 10: Open detector with Timepix hexa modules.

After the final detector is set up, the detector needs to be calibrated and characterized. First off all, the detector threshold equalization was applied to compensate small pixel-to pixel deviations in the energy threshold due to manufacturing variations. After successful threshold equalization, both pixel-wise and chip-wise energy calibration were performed using the routines developed beforehand, using zirconium, molybdenum, silver and tin K fluorescence lines.
As the requirements on the alignment of detector modules are very demanding in high resolution computed tomography applications, the exact positions and rotations of the individual modules are calculated from an image of a regular rectangular mask of voids in a metal sheet. The knowledge of these exact positions and rotations allow the software correction of the positions subsequently.

Scientific and technical results
Requirements: To achieve the goals of the project, there are several requirements on the detector:
• Low noise especially at low photon flux that is typical for nano focus spot size
• Small pixel size for short focus object distance at given magnification
• Good spatial resolution at given pixel size
• Possibility to obtain spectral information from detector
• At least 3000 pixels wide; multiple modules if necessary
To meet these requirements, a detector working in photon counting mode is suitable, as it can provide low noise even at very low flux, a direct converting sensor layer for good spatial resolution and an energy threshold for obtaining spectral information. Different concepts and base tiles of photon counting detector types were evaluated.

Detector hardware and software implementation: The detector is based on four Timepix hexa detector modules. The hexa modules consist of 3×2 Timepix base tiles and have a total of 768×512 pixels with a pixel size of 55 µm. The resulting total detector size is 3072×512 pixels. It provides an adjustable energy threshold for spectral imaging capabilities. An adapter board connecting the Timepix hexa modules with the readout system was designed allowing the readout of all four hexa modules using only one Fitpix readout. As photon counting detectors provide different parameters to be controlled and set compared to standard digital detectors working in integrating mode, a new detector software interface was developed and implemented. To simplify the handling of the detector in routine applications, this interface will not allow access to all parameters to the user but instead restrict these settings to low-level maintenance, automatic calibration and equalization routines. Furthermore these calibration and equalization routines are described in the following section. The minimum achievable noise level, especially at very small focal spot size and resulting relatively low flux, is limited by quantum noise. Even at constant intensity in a classical point of view, the number of detected events N follows the Poisson distribution. At sufficiently large numbers, the standard deviation of the Poisson distribution can be approximated with the square root of that number, √N. At 40 kV we have detected approx. 2360 events per pixel in 5 minutes with a standard deviation between pixels of 50.3 counts. The standard deviation of the Poisson distribution for that number is 48.6 counts. So at this setup, the detector is within a few percent of the theoretical maximum of quantum statistics.

Detector calibration: Aside from a bad pixel selection and masking, routines for threshold equalization and energy calibration were developed and implemented. The Timepix device offers a special capability that allows compensating for production deviations of each pixel that lead to differences in counting characteristics, especially the energy threshold. An individual 4 bit value can be applied to each pixel to equalize the acquired image allowing a pixel wise threshold correction. For generation of the threshold equalization mask, a flat-field threshold equalization was implemented. It requires a homogeneous illumination of the detector, optimally by the X-ray spectrum which the detector will later be used with. An advantage of the flat-field threshold equalization is the relatively short acquisition time. Also, the equalization can be performed at any energy level above the noise edge and suited to the desired energy threshold. Furthermore, an energy calibration tool was implemented allowing both chip-wise and pixel-wise energy calibration using K-Lines of elements as e.g. copper, zinc, zirconium, molybdenum, silver and tin. The peaks of these emission lines are detected automatically from a threshold scan and linked to the respective threshold DAC register value. In reversion, this allows to set the threshold DAC value to a calibrated energy value. The detector consists of four Timepix Hexa modules while each Timepix Hexa consist of six (3×2) Timepix chips. Between these chips and between these modules there are dead gaps, without active pixels. The small pixel size of 55 µm of the detector requires a high precision geometric alignment of the detector modules, as CT reconstruction is very sensitive to detector misalignments. In particular, the distance between two modules is not known exactly and needs to be determined to be able to apply corrections. To ensure the necessary precision, the exact positions and rotations of the individual modules are calculated from an image of a regular rectangular mask of voids in a metal sheet

Collaboration with other work packages
There was close collaboration with work packages 4 (X-ray source), 6 (CT system development and integration), and 8 (Reconstruction + visualization + methods for structural and chemical analysis). In work package 4, close collaboration took place with RAY on development of the detector interface/software API, implementation of a TCP/IP server/client solution for data readout and on reconstruction/determination of alignment. Two measurement campaigns were performed in close collaboration and at the facilities of EXC in July and October 2014.

Figure 11: Detector concept

Figure 12: First prototype with one Medipix2 quad detector module

Figure 13: second prototype detector with two Timepix hexa modules

Figure 14: Adapter board

Figure 15: Components of the detector system. Three modules are in place, at the leftmost position one can see the heat transfer blocks and the control/supply board.

Figure 16: Open detector without Timepix hexa modules

Figure 17: Close up of the four Timepix modules mounted into the detector housing. The four reflecting metallic surfaces are the actual sensors.

Figure 18: Closed detector

Figure 19: Water cooling block attached to the rear side of the detector

Figure 20: software interface architecture

Table 8: Overview specifications of the detector

1.3.6 WP 6 – CT system development and integration

Fulfilment of the project work plan
In the NanoXCT project, the main objective of WP6 was to develop and build a CT system using the components developed and built by the other project partners in a mechanically and thermal stable design. For the integration of the components RAY had to define and provide proper interfaces in both hardware and software. Furthermore, it was the task of RAY to design an object manipulation system, a sample holder and a positioning device for moving, holding and placing a sample inside the measurement field of view such that a CT measurement becomes possible and easy to start. Finally the whole equipment was planned to be inside of a shielding cabinet that fulfills current laboratory safety standards.
In a very first design study we did some calculations and design experiments on the layout of a NanoXCT device. For that purpose we used the specification of the two main components – X-ray source and X-ray detector - available until that point. Based on these specsheets it became clear very soon that a nano positioning device with a specification as written in the top level specification is impossible to design. Main reason was the flat front end of the X-ray source. This flat front end would lead to a mechanically unstable sample holder design. After discussing alternative designs we agreed on modifying the X-ray tube front end such that a proper sample holder design was possible. Important criteria for selecting a proper object manipulation system were a small footprint of the stages, a very good accuracy but also a large enough travel range, all combined with highest demands on mechanical stability and thermal sensitivity. Finally we decided to use several nano positioners combined to a stack of stages. Whereat, a central design questions was, where to put the rotational stage: below or above the linear XY stages. Both positions have advantages and disadvantages. The final decision for the stack order was mainly driven by the demand for highest magnification combined with a free 360° rotation of the object. Since the stages have a rectangular footprint the only way was to mount the rotational stage on top of the stack without actually risking a collision with the X-ray tube. The NanoXCT device has a travel range of 50 mm in x-direction (magnification axis), 5 mm in y-direction (left-right) and 5 mm in z-direction (up-down). The rotation is 360° endless. Beside the object manipulation system the device has also a detector manipulation system. Here, also a set of axis was stacked in order to allow a flexible position of the detector such that demands concerning flux optimization and field of view could be met.
The design of the sample holder was influenced by demands which are similar to the demands on the manipulation system. The most important are: low thermal sensitivity, high mechanical strength, low X ray scattering and attenuating, low cost, easy to machine and easy to use as well as detachable. The final sample holder consists of two elements: One holder base made of brass and one sample holder made of aluminum. While the brass part is mounted to the positioners the aluminum body can be detached and removed from the system for the purpose of sample preparation. The process of placing a sample on top of the sample holder pin was extremely difficult in the beginning. Very soon it turned out that gluing the sample to the sample holder with an easy to remove glue is the best solution.
Initially, it was planned to build the system based on granite in order to reach highest precision. Nevertheless, the NanoXCT device was planned to be a prototype and therefore it had to be as flexible as possible. Since the granite is manufactured on purpose, all connections like screws, drill holes, etc. have to be foreseen. For the sake of flexibility we decided to build the CT system based on an optical table which also fulfills very high demands on accuracy and mechanical stability but is far more flexible than a granite base.
On top of the optical table the shielding cabinet is placed which is based on an aluminum frame encased by steel-lead planks. The front door can be opened vertically and allows complete access to the components inside. On the back side there are two labyrinths giving plenty of space for cables, sensors and other equipment.
All peripherals like the electrical installation, controllers for the X-ray source and the manipulation system as well as the water cooling system are installed in a 19” control rack. This rack is the control center of the system. Inside the control rack is a control PC which is connected via TCP/IP and USB to the several controllers.
The source was placed on top of a sliding mechanism which keeps the X-ray tube in position by a mechanical stop near the tube front end. Thermal expansions of the whole X-ray source system will be pushed backwards in order to keep the focal spot in position. The sliding mechanism itself is placed on top of a manual tilt platform in order to manually adjust the central X-ray beam parallel to the optical axis. The object and detector manipulation systems are combined with manual shift and tilt platforms for alignment purposes.
Controls for all components (X-ray Source, X-ray detector and all manipulators) are integrated into a NanoXCT Software. The user front end was implemented as a graphical user interface (GUI) which allows controlling all components separately as well as preparing and starting measurements. This also included preoperational steps like calibrations of the detector and the positioners but also a first impression of the most recent projection image taken by the detector.
Although, the system is calibrated by mechanical equipment as good as possible, there are still some remaining static and also non-static misalignments, which become relevant at very high magnifications. Therefore additional software-based correction methods have been developed.
An initial XCT scan with a low number of projection images is used to compensate for movements of device components during the actual XCT scan. Such movements are mainly caused by thermal drifts and effects within the X-ray tube, both with long time constants.
Besides that, a special phantom with high density structures giving high contrast has been developed that allows the determination of static and reproducible angle-dependent rotary stage errors as well as detector misalignments. This is achieved by comparing actual and nominal particle tracks during an XCT scan of this phantom. The determined misalignments are corrected before the CT reconstruction is started.

Scientific and technical results
With NanoXCT Computed tomography system exploring the nano world is possible. The NanoXCT device is a powerful tool for fully 3D, nondestructive, structural and chemical characterization with highest spatial resolution. It is perfectly suited for the development, characterization and control of new materials and their manufacturing processes in nanometer scale, e.g. integrated circuits and chips or bio-engineering. But also for classical metallurgy measurements and characterizations this system provides significantly improved results compared to recently available CT products.
In total the project was a success since it is the very first CT system which combines a new generation of X-ray tubes and X-ray detectors together with a high accuracy manipulation system based on a very flexible platform. The very first and also the latest results show that a huge step deep into the sub-micrometer range is possible now.
Regarding the fulfillment of the top-level specification the performance of the system couldn’t be tested completely. Due to delays and uncertainties during the project the time for the final testing period was reduced down to some weeks. A full specification of the system will be available shortly after the project.
After the NanoXCT project RayScan intends to use the gained experience with the prototype for developing a commercially available product – the RayScan Nano.

Collaboration with other work packages
There was a very close cooperation with the other hardware partners. Since the components were developed within the project as well an overall compromise had to be found. This cooperation was very fruitful and based on trust and respect. Also with the other work packages we collaborated in order to select reference samples, exchange measurement data and help in hardware questions.

1.3.7 WP 7 – X-ray fluorescence and K-edge analysis

Fulfilment of the project work plan
The main objective of the WP7 is to provide the technology for integrated chemical characterization of the specimen using XRF and/or MECT and/or KEA. The XRF part will be developed as an individual component to be integrated in software in the NanoXCT laboratory device demonstrator. The XRF component is one technique for chemical analysis of the specimen besides multi energy XCT and K-edge absorptiometry. Together with the data evaluation and visualization work package, the 3D material information will be combined with the structural analysis in the software demonstrator, to provide a meaningful visualization of the specimen regarding structural and chemical decomposition. As a supplemental method for elemental analysis, a method based on K-edge absorptiometry will be developed, evaluated and demonstrated.

In order to fulfill the goals of this project regarding the chemical analysis features, different approaches were studied. As the concepts generated for the XRF component were evaluated by the NanoXCT as not promising for NanoXCT and the required specifications, the NanoXCT general assembly decided to refocus of WP7 in order to integrate K-edge absorptiometry in the final NanoXCT demonstration device. Therefore, K-edge absorptiometry was developed, evaluated and successfully demonstrated at the final meeting.
The method of K-edge imaging was chosen in favor of fluorescence pin-hole imaging, confocal fluorescence imaging for the reasons summarized in Table 9.

Table 9: Pros (green) and cons (red) of the three approaches of chemical analysis

The proposed solution combines different aspects of the above mentioned approaches and goes beyond the current state of the art, by acquiring spectroscopic data with a 2-D imaging detector, that is then analyzed for K-edges (position in the spectrum, amplitude) to identify and quantify the material composition of the penetrated object, all in the context of micro-scale imaging.
The energy calibration of the detector was done not only chip-wise, but also pixel-by-pixel. The distribution of the parameter of the calibration characteristic line was analyzed as a figure of merit for the detectors suitability for spectral imaging which is a condition for K-edge imaging.
As calculated absolute values are generally not quantitatively correct, they need a calibration to remove a possible offset. An approach using actual measurement data of sample materials was used. This calibration implicitly covers the detector response function that otherwise would have to be covered by deconvolution with the detector response function explicitly. By choosing the reference material based calibration approach, the disadvantages of a deconvolution based approach that typically introduces numerical instability and additional noise, are also avoided.
An algorithm for quantitative K- and L-edge analysis was developed based on previously mentioned calibration of reference materials. This calibration step includes the analysis of different calibration foils of known material and thickness.
The K-edge absorptiometry component was designed in a way that not only the existing hardware of the NanoXCT system can be used, but also no additional hardware is required on the system side. A measurement workflow was prepared and tested. Sub-micro meter resolution could be demonstrated with a voxel size of approx. 250 nm on the MEMS gyro device sample from STM, where the gold contact stripe could be highlighted using L-edge absorptiometry.

Scientific and technical results
Tomographic reconstruction of K-edge projection images: The images obtained from the K-edge algorithm represent the areal density of the respective element. The areal density of the element with the k-edge under investigation aK is the projection of the partial density of the respective element in the object volume. Thus, it can be reconstructed directly using a standard CT reconstruction algorithm with minor adaptions. For example, a filtered back projection (FBP) can be employed and yields a 3-D image representing the spatial distribution of the density of the respective element.

Results of K-edge imaging: The first step in the K-edge method developed in the scope of this project is the analysis of the 2-D projection image data. The 2-D image data resulting from this step represent the areal density of the K-edge material in one image and the areal density of the residual material in a second image. From the areal density images the 3-D tomographic images can be calculated using a CT reconstruction algorithm as described in the previous section.
The first measurements of projections were done with a PMMA (Poly(methyl methacrylate)) cylinder with a bore hole filled with iodine solution (aqueous solution with 10% wt povidone-iodine). The diameter of the cylinder is 15 mm and the diameter of the bore hole is 3 mm. It has an additional 2 mm bore hole that is empty for these measurements. The K-edge of iodine is at 33.2 keV, thus the energy bins were set to [29.2 keV; 31.2 keV] and [35.2 keV; 37.2 keV]. The raw transmission images can be seen in Figure 23, the left images shows the low energy bin and the right the high energy bin. In the images, the iodine filled hole is on the right. To reduce noise, a 5x5 median filter kernel has been applied to the images before the K-edge analysis.
The resulting 2-D images of the areal density are shown in Figure 24. On the left, the areal density of the residual material is shown; iodine is not visible at all in this image. The right image represents the K-edge element (in this case iodine) and depicts the areal density of iodine in this projection image. Furthermore silver (Ag) and molybdenum (Mo) wire with a diameter of 50 µm were imaged. In the resulting K-edge images both materials are clearly separated (Figure 25).

Figure 23: Raw transmission images of the iodine sample. Low energy bin [29keV; 31keV] (left) and high energy bin [35keV; 37keV] (right)

Figure 24: K-edge images of the iodine sample showing the respective areal density: the residual material (left) and K-edge material (right)

Figure 25: Basic transmission images and resulting K-edge images of of Ag and Mo wires with 700 nm pixel size

L-edge imaging: K-edge imaging can only be used for elements with the K-edge energy significantly below the acceleration voltage of the tube. When using 60 kV acceleration voltage, this is given for elements with an atomic number smaller than 64 (Gadolinium). In addition to K-edge imaging, edge imaging using the L-edge was applied for high-Z materials as Gold (Z=79). An example of Gold-L-edge imaging can be seen in Figure 26 and Figure 27. It is a high magnification image (200×) with a resulting pixel size of approx. 250 nm of the gold contact layer of a MEMS gyroscope device (sample from STM). The gold stripe is approx. 70 µm wide and 4 µm thick. Figure 26 shows low energy bin of the transmission image (9-11 keV), the energy of the high energy bin was 14-17 keV. Figure 27 shows the L-edge image obtained using the K-edge method.

Figure 26 Gold contact part of the MEMS gyroscope device from STM. Low energy bin. The gold stripe shows relatively low contrast

Figure 27: L-edge image of Gold showing just the gold contact stripe (70 µm wide and 4 µm thick)

Reconstruction
The last step is to apply the previous operations to gain K- or L-edge images to all projection images of a CT measurement. The resulting areal density images can be reconstructed a described in section “Tomographic reconstruction of K-edge projection images” yielding the K-edge element specific 3-D data set of the sample.

Collaboration with other work packages (FHG)
In WP7 there was a close collaboration with WP3 and WP5; Regarding WP3, requirements were discussed and samples were provided by BAS, NTX and STM. Detector requirements were synchronized with WP5. Furthermore collaboration with WP6 regarding integration of K-edge absorptiometry took place with RAY. In addition in the final phase WP7 collaborated also with WP8 regarding software development and also with WP9 regarding demonstration.

1.3.8 WP 8 – Reconstruction, visualization and methods development for structural and chemical analysis

Fulfilment of the project work plan
WP8 designed application specific software routines for NanoXCT. The specific acquisition methods of this system produce images having particular properties and artifacts different from classical scanning devices. Images need have to be filtered taking into account the physical properties of the sample. 3D reconstruction methods had to be adapted to these specificities. Quantification methods needed to take into account the chemical properties detected by the NanoXCT. Finally, the amount of data to be handled by the system will require specific out-of-core algorithms from the acquisition to the visualization.
WP8 started at M5 and relied on WP2 application specification work (D2.2 System Requirements and Interface Definitions) for starting to design NanoXCT reconstruction, data analysis and quantification, and visualization of structural and chemical analysis. WP8 started using results of WP3 (D3.1 Report on essential nano structure parameters) for defining measure and analysis actually required. WP8 was expected to use work in progress of WP7 (XRF components) for integrating analysis of XRF data. Since actual relevant XRF data were not available, simulated data have been be used when possible to progress in software design and implementation, for instance data from reconstruction by FHG, for limiting risk in WP8 at the very end of production chain. Synchronization with WP6 (CT system) must also be ensured regarding software components integration (deliverable D6.1 CT system study). The integration phase of the developed techniques into the Avizo software platform started in Q4 with initial trainings, and feasibility study prototyping, and has been continued with closer integration of development in demonstrator. Avizo has been extended to facilitate such integration.
WP8 was proceeding essentially according to plan throughout the project. FHG finalized study and implementation for reconstruction, and generates multi-resolution format from reconstruction engine. VSG has analysed requirements from D3.1 for specifying analysis/visualization workflows with FHW. A number of enhancements are integrated in Avizo to better address analysis tasks. FHW continued developing specific visualization techniques to be integrated in Avizo. A prototype integrating Avizo from VSG with the InSpectr framework from FHW has been implemented.

Scientific and technical results
A software environment was implemented to address NanoXCT data analysis requirements:
• Specialized data reconstruction, including reconstruction of compositional information from Multi Energy XCT and K-Edge absorptiometry;
• Large high-resolution data handling
• Characterization of complex nanomaterials
• Visual and quantitative integration of structural and chemical information

The integration platform for NanoXCT data visualization and analysis is the software Avizo, dedicated to materials science, digital rock analysis and industrial inspection. A set of extended tools and workflows address image filtering, noise reduction, segmentation, features extraction and measurements. In particular, a new workroom integrates the InSpectr module for spectral and composition data. InSpectr offers a number of techniques for visualization and data analysis of the generated XCT data in combination with spectral data as well as element maps of the same specimen. The implemented techniques within NanoXCT may be subdivided with regard to the following three analysis tasks: Global material composition analysis, local material composition analysis, and analysis of unknown and foreign materials.
Addressing the task of global material composition analysis, the InSpectr module provides information on the elements which are contained in the specimen as well as in which quantity those elements are contained. For this purpose various techniques have been implemented such as calculating and visualizing aggregated spectra as well as histograms of spectral data, overlaying the characteristic energy lines for elements of interest and finally spectral functional boxplots, which adopt the visual metaphor of boxplots to visualize the five important statistical characteristics of numerical datasets: median, first and third quartile, and minimum and maximum values.
Regarding the local material decomposition analysis magic lenses have been implemented, which allow to peek into spectral data or elemental maps given the context information of XCT data in the slice views. Together with the spectral color image as well as the element maps both slicer and the 3D view allow for a fast and easy localization of elements of interest. In addition, the InSpectr module allows for adjusting the transparency of the spectral data or elemental map overlays. Brushing in the spectrum view highlights the regions with spectra leading through the selected region in the XCT slice. Spectrum and concentration probing links information on the local spectrum and composition to the XCT slice view.
Regarding the task of analyzing unknown and foreign materials, the InSpectr module allows to display reference spectra in the spectrum view. When hovering with the mouse over the periodic table the corresponding reference spectra as well as the characteristic energy lines an element of interest is shown.

Figure 28: The InSpectr interface contains an XCT slice view, a pie chart and periodic table view showing the element concentration at the current mouse position in the slice view, a reference spectra list and the spectrum view.

When hovering over the slice view, the corresponding spectrum is displayed and the local material decomposition is shown in the centration view. Also the periodic table view allows to locally identifying materials. Using these functionalities an easy identification of an element of interest is facilitated. An overview of the InSpectr interface fully integrated in Avizo is shown in Figure 28.
In order to fulfill the goals regarding the chemical analysis features, different approaches were studied, namely fluorescence pin-hole imaging, confocal fluorescence imaging and K-edge imaging. The method of K-edge imaging was chosen because it provides a number of advantages, especially that no additional hardware is required. Our solution combines different aspects of the above mentioned approaches and goes beyond the current state of the art, by acquiring spectroscopic data with a 2D imaging detector, that is then analyzed for K-edges (position in the spectrum, amplitude) to identify and quantify the material composition of the penetrated object, all in the context of micro-scale imaging. The images obtained from the K-edge algorithm represent the areal density of the respective element. The areal density of the element with the K-edge under investigation is the projection of the partial density of the respective element in the object volume. The 2D image data resulting from this step represent the areal density of the K-edge material in one image and the areal density of the residual material in a second image. From the areal density images the 3D tomographic images can be calculated using a CT reconstruction algorithm. As an example silver (Ag) and molybdenum (Mo) wire with a diameter of 50 µm were imaged. In the resulting K-edge images both materials are clearly separated (Figure 25). Elemental maps as generated by K-edge imaging may be analyzed in the InSpectr framework, e.g. using magic lenses, overlays etc.

Collaboration with other work packages
WP8 is as other WPs an interface work package which required strong collaboration with the most other work packages. Based on the work done for testing detectors, FHG has worked on techniques for stitching the acquired images and for removing acquisition artifacts. In this sense there was a strong collaboration between WP4, WP5, WP6 and WP7. FHW has worked on visualization and analysis techniques for complex materials as fiber materials and for XRF data sets. Based on the requirements of WP2 techniques and methods have been to cover all tasks set. In order to finalize the software demonstrator the developed techniques have been integrated in the common software platform Avizo. VSG has been investigating techniques for segmentation and quantification workflows of compositional information for XRF or DECT analysis

1.3.9 WP 9 – Demonstration

Fulfilment of the project work plan
WP9 focused on the demonstration of the achieved project results from HW and SW point of view of both NanoXCT tool properly said and of the complementary K-edge absorption one for elemental analysis. That included the laboratory device demonstrator integrating all developed components in a fully functional prototype device. Software demonstrator consisted in all developed methods for reconstruction together with visualization, structural and chemical analysis. The capabilities of the complete demonstration system have been demonstrated on the selected showcases provided through the project years by the end-users.

According to the showcases prepared during WP3 activity in fact, the following ones were evaluated:
• Reference material 1: Microelectronics structures (STM);
• Reference material 2: Polymeric materials with nanofillers (BAS);
• Reference material 3: Carbon nanomaterials, Nanocomposites and Ceramic nanostructures (NTX) ;
• Samples from Industrial Interest Group: PP and PE enhanced with Talk, Chalk, Carbon Black, Carbon Nanotubes and Natural fibers (Borealis).

Scientific and technical results
The demonstration apparatus has been installed and built at RAY (leader of WP6 CT system development and integration) with developed Excillum X-ray source and the detector developer by the Fraunhofer IIS institute in Furth. Besides the demonstration of the aimed at laboratory device demonstrator, the capabilities on test patterns and a demonstration on showcases were carried out. This task was performed by RAY, FHG and EXC. During the project, to make the project successful, it was necessary to substitute the originally planned XRF equipment with a K-edge absorption tool developed by FHG. The source is able to reach an electron beam spot size down to < 150 nm and an X-ray spot size of the order of 100 nm. The special operational range allows for additional measurement modalities like K/L-edge imaging and an extended set of samples to be analyzed with reasonable exposure times using a single X-ray tube. The conical rotating sample holder is able to lodge specimens down to 0.150 mm, at minimum distance with respect to source output orifice. Thanks to its needle tip ending, with simple gluing, satisfactory alignment can be reached mounting the showcases under classical metallurgical microscopes or inside a FIB chamber equipped with micro-manipulators. As far as the detector architecture is concerned, six Timepix chips are mounted on each of the four sensor boards which are connected to a voltage regulation and control board. The sensor board contains the attachments for the sensor ASICs and an electrical interface to the voltage regulation and control board. In the detectors a semi-conductor sensor layer is bonded onto an electronics layer. The sensor layer is a semiconductor in which the incident radiation makes an electron/hole cloud. The charge is then collected to pixel electrodes and conducted to the CMOS electronics layer, enabling thus, through scansion, full spectroscopic X-ray imaging. Through multi-energy XCT technique, it was also possible to equip the NanoXCT tool with a ’K-edge’ absorption spectroscopy system, which resolved spectra and elemental analysis, by FEI-VSG InSpectr software, was made possible by. Figure 22 reports on a NanoXCT measurement taken on a Mosquito, suitably prepared for the analysis with thin metallic film deposition, is reconstructed and depicted by NanoXCT.
K- and L-edge imaging allowed identifying elements by their edges in the attenuation spectrum. K-edge images for 50 µm in diameter Ag and Mo wires were obtained in the energy bins [18;19] keV and [21;22] keV. As far as ‘K-edge’ absorption tool development was concerned (FHG), the newly developed algorithm on K-edge image decomposition performed successfully on projection data. As the K-edge of gold cannot be imaged with this system, the ‘L-edge’ absorption technique was instead used on the NanoXCT tool to reveal gold in a 70 µm stripe, wafer to wafer mechanically bonded through thermo compression.
As far as the demonstration of the NanoXCT software for reconstruction, visualization, structural, and chemical analysis are concerned it was experimentally tested on the analyzed selected showcases provided by project partners and end-users. It was developed by Partner FEI-VSG and integrates algorithms for reconstruction, visualization and methods developed for structural and chemical analysis. The project participants verified the fulfilment of the specifications and requirements, user-friendly acquisition and elaboration methods, applicability of the set up techniques, the integration of such methods and algorithms can be integrated into standard procedures. The NanoXCT software components can be distinguished as on-line (acquisition) and off-line (data analysis) components. On-line components directly control and follow the acquisition to build the raw 3D image results:
• Data acquisition control software (described in deliverable D6.3)
• Tomographic reconstruction (specialized reconstruction for NanoXCT device)
• Calculation of k-edge decomposition maps.
The off-line software Avizo with InSpectr package provides nano-structure visualization and elemental analysis of K-edge absorption system and multi-energy XCT. The K-edge calculation can also be run standalone. Both steps could be eventually triggered from the analysis software using a convenience Tcl of MATLAB script module. The positive results of image manipulation and reconstruction obtained onto Logic and MEMS Integrated Circuits, Epoxy / Clay / Gold, PP / MWCNT Gold, Epoxy / Gold composite, Gold composite, Epoxy / Clay / Gold project partner’s showcases have been also reported.

Collaboration with other work packages
WP9 saw a tight collaboration with WP3 to prepare and finally chose the most suitable showcases for XCT structural and K-edge elemental analyses used in the final demonstration. Continuous information and datum sharing were necessary, both from the HW and SW point of views, between the two work packages to demonstrate NanoXCT tool capabilities and potentialities.

1.3.10 WP 10 – Dissemination and Exploitation

WP10 focused on the broad dissemination and exploitation of NanoXCT project results, under consideration of the IPR of the partners. Dissemination and exploitation activities were carried out continuously during the project and will be carried out beyond the project lifetime due to the delay of the finalization of the NanoXCT device demonstrator. The main objectives of WP10 are:
• effective and sustainable dissemination of knowledge among and beyond the members of the consortium (beyond the life time of the project)
• coordination of knowledge management and other innovation-related activities
• promotion of the exploitation of the NanoXCT results
• providing adequate and effective protection of knowledge created in the NanoXCT project, having due regard to the legitimate interests of the contractors concerned
• reporting about these activities
• supervision of external activities
• coordination of exploitation of project results
• relation to state of the art and interaction with developers, contact to related projects, international associations and standardization organizations

Note: As the exploitation results are all confidential and this report has the dissemination level public, no information can be given in here.

Fulfilment of the project work plan
As shown in the analysis given in Figure 29 most of the dissemination activities have been conference participations such as paper or poster presentations. A further important point regarding the dissemination of NanoXCT’s results was the creation of newsletters as well as a NanoXCT poster. In addition, several success stories were published and available for a broad audience. Furthermore a master thesis was done based on the research within the NanoXCT project at Fraunhofer EZRT. For a lot of the dissemination activities carried out, the NanoXCT flyers were used as give-away for interested people. The most important activities regarding dissemination were hosting a special session on the NanoXCT project at the iCT 2014 conference in Austria and the presentation of the project at AAAS2015 conference. Furthermore an industrial interest group was established and expanded through the project lifetime. Related projects were also integrated to the industrial interest group.

Figure 29: Distribution of Dissemination activities

Figure 30 reports on the publishers of NanoXCT’s publications. As shown in Figure 30, a lot of the scientific publications were published in form of proceedings of conferences, such as iCT, EuroVis, FFH, SPIE etc. The peer reviewed publications were published in journals such as Nanoscience & Nanotechnologies Letters, Lecture Notes in Computer Sciences, Polymer Composites, Composites Science and Technology or the Journal of Theoretical and Applied Mechanics.

Figure 30: Distribution of publisher for scientific publications

Scientific and technical results
Dissemination and exploitation activities have been carried out continuously during the project since the first results in form of the NanoXCT homepage, the NanoXCT poster and the NanoXCT folder were available. Right after the start of the project, a success story has been published and 2 further success stories followed during the projects lifetime. 23 scientific publications were created, both individually per partner and as joint publications of several partners. Those papers were submitted to relevant workshops, conferences and journals in the field. Beyond the project’s lifetime there will be further NanoXCT presentations of the partners at conferences, where the corresponding contributions have already been approved but the conference date is after the project end. Furthermore, 3 newsletters were sent to the NanoXCT IIG and another one will be published after the project end based on the final report of the NanoXCT project. Figure 31 shows a collection conferences and journals, where NanoXCT publications have been published.

Figure 31: Conferences, journals etc. where NanoXCT contributions have been published

Collaboration with other work packages
The dissemination and exploitation activities of NanoXCT project results were coordinated by the dissemination manager and the exploitation manager respectively. All dissemination and exploitation activities were regularly updated in dissemination and exploitation plans. Regarding dissemination, potential conferences to present NanoXCT’s results have been announced at each meeting. A formal mechanism for exploiting all technologies and capabilities is outlined below:
• Interaction between consortium members enabled the exploitation of specific technologies through the leading industrial participants by incorporating new technology into future products.
• The Intellectual Property Rights (IPR) were defined in the Consortium Agreement and signed by all partners before the project start.
• The partners actively submitted (joint) publications to scientific journals, relevant international and national conferences as well as EU funded workshops.
• Regularly newsletters updated the NanoXCT Industrial Interest Group about the progress and achievements within the project.
• The industrial partners contributed to exhibitions and business fares to promote their developed part of the NanoXCT system and their participation to the NanoXCT project.

Potential Impact:
1.4 Impact
NanoXCT implemented a demonstration system which shows a breakthrough compared to current conventional inspection techniques regarding the structural characterization of buried nano-scale features and defects of specimens in a nondestructive way. NanoXCT is expected to generate significant advantages in international competition by achieving the technology leadership in nano scale characterization not only on European scale but worldwide. In particular, the project developed a technique based on X-ray computed tomography, facilitating nondestructive, and three dimensional structural and chemical characterizations of nano-scale features. The achievements of the project will have an impact on various application areas ranging from but not limited to nano electronics, nano materials, nano composites, nano medicine, nano biology, nano photonics, nanorobotics and NEMS, nano coatings and adhesives.

1.4.1 Impact on partner level (as made public available):

FH OÖ Forschungs & Entwicklungs GmbH
Through the participation in NanoXCT FHW could further improve its R&D-competence in the fields of nano characterization of materials, nano components as well as nondestructive evaluation using highly advanced techniques of computed tomography. For FHW the NanoXCT project and its results symbolize a big leap in nano-scale characterization which FHW as university for applied sciences envisages to make available to regional partners. So FHW will follow its major aim of transferring cutting edge research to local small and medium enterprises, in order to strengthen the region of Upper Austria and beyond as high-tech business location.

Institute of Mechanics, Bulgarian Academy of Science
The participation of BAS in implementation of the NanoXCT project has an impact on improving of our competence in non-destructive testing and data answering using the NanoXCT software. Also help in better understanding the materials properties at micro and nanoscale by combining the 3D structural and the chemical evaluation results. The impact is also envisaged in the transfer of obtained knowledge within the Nanoscience community and other potential end users (SMEs) at national level. It was published of 7 papers in peer review journals, acknowledging the NanoXCT project, including 1 joint paper with other WP3 partners.

Excillum A.B.
It is the intention of project partner Excillum to exploit the nano-focus X-ray tube through a product under development, partly based on the foreground developed under the project. All WP4 foreground is owned by Excillum through transfer of ownership agreement with KTH. Remaining steps in the product development process include:
• Final development of basic technology
• Transfer from R&D to production
• Compliance and Certification (CE)
• Manuals
• Etc.
After design and launch of the first nano-focus X-ray source, it is Excillum’s intention to let the design grow into a family of transmission-tube X-ray tubes.

ST Microelectronics Italy
The participation to NanoXCT project allowed to develop and perform specific preparative testing on chosen specimens, using for instance plasma-FIB technique to prepare samples down to 150x150x200 µm3 in size and mounted on special glass needles to be better supported by NanoXCT tool sample holder.
In seek of comparison and according to the program, another new finding was constituted by the achievement of 300 nm pixel size with commercial XCT tools available in ST labs, whereas NanoXCT project target is even more pushed till to 50 nm voxel.
Moreover it was possible to reveal interface metallic bonding quality of selected specimens.
But beyond the results obtained during preparative phase, the developed NanoXCT tool paves the way for real nano-electronics feature imaging and elemental analyses. In fact that will be possible with elemental techniques like the obtained “k-edge” absorption multi-energy tool, the VSG image reconstruction SW (Avizo) and the elemental analysis one (InSpectr) methods.
Impact for the non-destructive NanoXCT analysis concerns:
• Nano-electronics structure 3D tomographic visualization in ULSI technology, like mass data storage Non Volatile Memories and Logics;
• IC construction analysis;
• IC reverse engineering;
• IC failure analysis, both BEOL and FEOL ones, especially important where the certainty not having manipulated the sample through preparation is provided by the non-destructive method; moreover the analysis output has in that way an added value in terms of quality and completeness.
• IC sampling quality check and monitoring;
• Speeding up visualization analysis cycle time because in principle NanoXCT does not need specific sample preparation, but only its mounting on the sample holder, and acquisition time not assisted by operator, decreasing so costs and, on large scale, decreasing development time and time to market, providing to end-user strategic advantage.
• Basic study on interconnections of nano-electronics devices using graphene.
ST as microelectronics manufacturer and not as system one, cannot receive obviously direct advantage from NanoXCT commercialization, but an indirect one obtained by participating directly to the project, creating an NanoXCT network and getting knowledge since the beginning of the potentialities of the developed tool, which will reach its top in combination with an XRF one, integrated or not, to detect also “light” elements and able to perform elemental analysis at nano-scale.

Nanothinx S.A.
The participation of Nanothinx on the realization of the NanoXCT project had a positive impact on several fields of the evolution of the company. First of all, the development for the demands of the project nanomaterials with specific external dimensions was a challenge, which was successfully achieved.
The development of the NanoXCT device and the characterization of the catalytic substrates was a first step on the definition of the production mechanism of the specific Carbon Nanotubes. Moreover, the study of the influence of the addition of carbon nanotubes in the porous network of membranes was proved to be a key point on the optimization of nanofiltration membranes.
The company, was also influenced positively from the dissemination activities from the cooperation developed through the project, while the results obtained through it, are going to have an indirect profit on the market share of the company, through the optimization of current available products (CNTs) and the addition of new (nanomebranes).

1.4.2 Impact on European Industry
To see inside specimens in order to analyze materials at the nanometer scale, without influencing further applications and without shape modification - in short nondestructive - is a very common request of various fields of industry. One of the most prominent fields is materials science, aiming at the development of novel materials with previously unthinkable characteristics. Using the techniques developed in NanoXCT, not only surface based features may be characterized, but also a detailed volumetric insight is given in the matter and its surrounding, without destroying the specimen. Markets which are benefitting from NanoXCTs results are therefore found in the area of the characterization of novel high tech materials in the following industries and beyond:
• Plastics industry
• Aluminum industry
• Ceramics industry
• Medical industry
• Pharmaceutics industry
• Biology
• Life sciences
• etc.

1.4.3 Impact on research
Besides the impact on industry also the impact of NanoXCT on universities and research institutes may not be neglected. Research fields, which directly profit from NanoXCT’s results, are strongly related to the industries. The areas of nano electronics, nano material, nano composites, nano medicine, nano biology, nano photonics, nanorobotics and NEMS, nano coatings and nano adhesives will be offered a unique device, which integrates nano computed tomography and X-ray fluorescence in a piece of equipment which is affordable and scales to their needs. NanoXCT provides highly detailed results within reasonable time for characterizations the research institutes usually needed two individual devices and twice the time for data evaluation. Additionally the expected quality and comprehensiveness of the scanning results generated by NanoXCT, will not be achieved in single devices within the regular development cycles as seen in the last 10 years. Even a more wide spread impact will be generated, considering the novel research results generated using NanoXCT.

1.4.4 Impact on Industrial interest group
A major goal of the NanoXCT was the industrial promotion of the projects achievements, in order to inform end users and other stakeholders about the technology and the potential of NanoXCT, but also the limitations regarding an efficient use of the project outcomes. The industrial interest group was formed as forum for industry and end users that might benefit from the efforts done in NanoXCT. As the main instrument for industrial promotion, it ensured a seamless dissemination of results on the stake holders regarding the European instrumentation industry, end-users for nano scale characterizations, as well as RTD and other institutions. Members of the industrial interest group were not limited to a specific area. X-ray source manufacturers, detector manufacturers, specialists for XRF, system integrators, software developers, distribution network operators and research institutes were invited as their input was be highly valued. Furthermore a strong focus was put on integrating SMEs in the industrial interest group. Companies with an interest in the NanoXCT technology were continuously invited to the industrial interest group

1.4.5 Impact on Knowledge, Technology Transfer and Teaching
All partners improved competences in non-destructive testing using NanoXCT. Furthermore FHW, BAS aim to transfer the gained knowledge to local small and medium enterprises. In addition, the hardware and software partners trained new employees in NanoXCT and related techniques. Also the research partners integrated the generated results in lectures and exercise courses.

List of Websites:
Dr. Christoph Heinzl
FH OÖ Forschungs & Entwicklungs GmbH
(University of Applied Sciences Upper Austria)
Stelzhamerstraße 23, 4600 Wels, Austria
Tel: +43-50804-44406
Fax: +43-50804-944406
E-mail: c.heinzl@fh-wels.at

Project website: www.nanoxct.eu