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Investigation of thickness uniformity of thin metal films by using α-particle energy loss method and successive scanning measurements

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JOURNAL OF INSTRUMENTATION 2017年第3期12卷 T03001-T03001页

作者： Li, Gang Xu, Jiayun Bai, Lixin Sichuan Univ Dept Nucl Engn & Technol Coll Phys Sci & Technol Chengdu 610064 Sichuan Peoples R China

The metal films are widely used in the Inertial Confinement Fusion (ICF) experiments to obtain the radiation opacity, and the accuracy of the measuring results mainly depends on the accuracy of the film thickness and thickness uniformity. The traditional used measuring methods all have various disadvantages, the optical method and stylus method cannot provide mass thickness which reflects the internal density distribution of the films, and the weighing method cannot provide the uniformity of the thickness distribution. This paper describes a new method which combines the alpha-particle energy loss (AEL) method and the successive scanning measurements to obtain the film thickness and thickness uniformity. The measuring system was partly installed in the vacuum chamber, and the relationship of chamber pressure and energy loss caused by the residual air in the vacuum chamber was studied for the source-to-detector distance ranging from 1 to 5 cm. The results show that the chamber pressure should be less than 10 Pa for the present measuring system. In the process of measurement, the energy spectrum of alpha-particles transmitted through each different measuring point were obtained, and then recorded automatically by a self-developed multi-channel analysis software. At the same time, the central channel numbers of the spectrum (CH) were also saved in a text form document. In order to realize the automation of data processing and represent the thickness uniformity visually in a graphic 3D plot, a software package was developed to convert the CH values into film thickness and thickness uniformity. The results obtained in this paper make the film thickness uniformity measurements more accurate and efficient in the ICF experiments.

关键词： Analysis and statistical methods data processing methods Spectrometers

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Polaris: a general-purpose, modular data acquisition framework

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JOURNAL OF INSTRUMENTATION 2018年第12期13卷

作者： Suerfu, B. Princeton Univ Dept Phys Jadwin Hall Princeton NJ 08544 USA

data acquisition (DAQ) plays a key role in most, if not all, experimental sciences. However, developing DAQ software is difficult and time-consuming. Polaris is a general-purpose, modular, open-source framework written in C++ that can meet a wide range of DAQ requirements, from laboratory measurements to mid-scale nuclear and particle physics experiments. This is achieved by decoupling application-specific requirements from common features of DAQ software. This article focuses on the design philosophy and features of Polaris and describes real-world applications of the Polaris framework.

关键词： data acquisition concepts Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data) Detector control systems (detector and experiment monitoring and slow-control systems, architecture, hardware, algorithms, databases) data processing methods

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Tests of UFXC32k chip with CdTe pixel detector

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JOURNAL OF INSTRUMENTATION 2018年第2期13卷 C02014-C02014页

作者： Maj, P. Taguchi, T. Nakaye, Y. AGH Univ Sci & Technol Dept Measurement & Instrumentat Krakow Poland Rigaku Corp XRD Design & Engn Dept 3-9-12 Matsubara Cho Akishima Tokyo Japan

The paper presents the performance of the UFXC32K - a hybrid pixel detector readout chip working with CdTe detectors. The UFXC32K has a pixel pitch of 75 mu m and can cope with both input signal polarities. This functionality allows operating with widely used silicon sensors collecting holes and CdTe sensors collecting electrons. This article describes the chip focusing on solving the issues connected to high-Z sensor material, namely high leakage currents, slow charge collection time and thick material resulting in increased charge-sharring effects. The measurements were conducted with higher X-ray energies including 17.4 keV from molybdenum. Conclusions drawn inside the paper show the UFXC32K's usability for CdTe sensors in high X-ray energy applications.

关键词： Analogue electronic circuits data processing methods VLSI circuits X-ray detectors

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Direct measurement of the position accuracy for low energy X-ray photons with a pnCCD

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JOURNAL OF INSTRUMENTATION 2017年第2期12卷 P02005-P02005页

作者： Ihle, S. Holl, P. Kalok, D. Hartmann, R. Ryll, H. Steigenhoefer, D. Strueder, L. PNSensor GmbH Otto Hahn Ring 6 D-81739 Munich Germany Univ Siegen Dept Phys Walter Flex Str 3 D-57068 Siegen Germany

We undertook a comparative study on optimizing the position accuracy of pnCCDs for single X-ray photon measurements. Various methods were analyzed by Monte Carlo simulations and related to experimental data obtained with a focused X-ray beam. Even with low energy photons of 1320 eV, a position accuracy much smaller than the actual pixel size of 48 mu m X 48 mu m can be achieved. This is possible since signal charges from a single photon interaction spread into more than one pixel, allowing a reconstruction of the original point of interaction. We found that a) making a decision on which pixels to use for the reconstruction and b) choosing a centroiding algorithm for carrying out the reconstruction were particularly crucial. For a) we introduce a new and superior method using a two step analysis with an adaptive pattern. It is compared to using a threshold or a fixed pattern. For b) we present a Center-of-Gravity method with a Gaussian correction taking into account the shape of the signal charge cloud. Both methods are also optimized for fast execution by implementing lookup tables rather than time consuming calculations. Our results show that with the appropriate analysis an uncertainty of the position measurement of better than 3 : 0 mu m rms for 1320 eV photons is possible.

关键词： data processing methods X-ray detectors Simulation methods and programs

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After-pulsing and cross-talk comparison for PM1125NS-SB0 (KETEK), S10362-11-100C (HAMAMATSU) and S13360-3050CS (HAMAMATSU)

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JOURNAL OF INSTRUMENTATION 2017年第6期12卷 C06046-C06046页

作者： Oleynikov, V. Porosev, V. Budker Inst Nucl Phys Lavrentiev Ave 11 Novosibirsk 630090 Russia

Silicon photomultipliers (SiPMs) are extensively used in different fields now. They exceed photomultiplier tubes in the quantum efficiency, size and resistance to magnetic field. However, because of structure features, their dark noise rate is higher and they have additional sources of noise: cross-talk and after-pulsing. In addition, these parameters may be temperature dependent. In this article we present results of an evaluation of the dark noise rate, probabilities of cross-talk and after-pulses at different voltages and temperatures for two modern SiPMs: S13360-3050CS(HAMAMATSU) and PM1125NS-SB0 (KETEK). For comparison, the data for a previous-generation SiPM, S10362-11-100C (HAMAMATSU), are presented. To find these parameters, we performed a waveform analysis to determine the amplitude and time distributions of the pulses generated by a SiPM without an external light source. We evaluated the temperature and voltage dependences of these parameters. The measured cross-talk probability for PM1125NS-SB0 and S13360-3050CS at their optimal operating voltage is about 6%. It is two times smaller than that for S10362-11-100C. The fast component of the after-pulsing probability for PM1125NS-SB0 and S13360-3050CS is about 10%, which is also almost 2 times smaller than the sum of the fast and slow components of the after-pulsing probability for S10362-11-100C. The dark noise rate for S13360-3050CS at 20 degrees C is just 45 kHz/mm(2) in comparison with 60 kHz/mm(2) for PM1125NS-SB0.

关键词： Analysis and statistical methods data processing methods Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc)

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A USB 3.0 readout system for Timepix3 detectors with on-board processing capabilities

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JOURNAL OF INSTRUMENTATION 2018年第11期13卷

作者： Dreier, T. Krapohl, D. Maneuski, D. Lawal, N. Schoewerling, J. O. O'Shea, V. Frojdh, C. Mid Sweden Univ Sundsvall Sweden Univ Glasgow Glasgow Lanark Scotland Osnabruck Univ Appl Sci Osnabruck Germany

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.

关键词： 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

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Quantitative ptychographic reconstruction by applying a probe constraint

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JOURNAL OF INSTRUMENTATION 2018年第4期13卷 C04016-C04016页

作者： Reinhardt, J. Schroer, C. G. La Trobe Univ ARC Ctr Excellence Adv Mol Imaging Dept Chem & Phys La Trobe Inst Mol Sci Plenty Rd Bundoora Vic Australia Australian Synchrotron 800 Blackburn Rd Clayton Vic Australia DESY Notkestr 85 Hamburg Germany Univ Hamburg Dept Phys Luruper Chaussee 149 Hamburg Germany

The coherent scanning technique X-ray ptychography has become a routine tool for high-resolution imaging and nanoanalysis in various fields of research such as chemistry, biology or materials science. Often the ptychographic reconstruction results are analysed in order to yield absolute quantitative values for the object transmission and illuminating probe function. In this work, we address a common ambiguity encountered in scaling the object transmission and probe intensity via the application of an additional constraint to the reconstruction algorithm. A ptychographic measurement of a model sample containing nanoparticles is used as a test data set against which to benchmark in the reconstruction results depending on the type of constraint used. Achieving quantitative absolute values for the reconstructed object transmission is essential for advanced investigation of samples that are changing over time, e.g., during in-situ experiments or in general when different data sets are compared.

关键词： Analysis and statistical methods data processing methods

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Compression and information recovery in ptychography

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JOURNAL OF INSTRUMENTATION 2018年第4期13卷 C04019-C04019页

作者： Loetgering, L. Treffer, D. Wilhein, T. Inst X Opt RheinAhrCampus RemagenJoseph Rovan Allee 2 D-53424 Remagen Germany

Ptychographic coherent diffraction imaging (PCDI) is a scanning microscopy modality that allows for simultaneous recovery of object and illumination information. This ability renders PCDI a suitable technique for x-ray lensless imaging and optics characterization. Its potential for information recovery typically relies on large amounts of data redundancy. However, the field of view in ptychography is practically limited by the memory and the computational facilities available. We describe techniques that achieve robust ptychographic information recovery at high compression rates. The techniques are compared and tested with experimental data.

关键词： data reduction methods data processing methods Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data)

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Biased bootstrap sampling for efficient two-sample testing

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JOURNAL OF INSTRUMENTATION 2018年第12期13卷 P12014-P12014页

作者： Gillam, T. P. S. Lester, C. G. GAM Systemat Cantab Hills Rd Cambridge England Univ Cambridge Dept Phys JJ Thomson Ave Cambridge England

The so-called 'energy test' is a frequentist technique used in experimental particle physics to decide whether two samples are drawn from the same distribution. Its usage requires a good understanding of the distribution of the test statistic, T, under the null hypothesis. We propose a technique which allows the extreme tails of the T-distribution to be determined more efficiently than possible with present methods. This allows quick evaluation of (for example) 5-sigma confidence intervals that otherwise would have required prohibitively costly computation times or approximations to have been made. Furthermore, we comment on other ways that T computations could be sped up using established results from the statistics community. Beyond two-sample testing, the proposed biased bootstrap method may provide benefit anywhere extreme values are currently obtained with bootstrap sampling.

关键词： Analysis and statistical methods data processing methods

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Assessing denoising strategies to increase signal to noise ratio in spinal cord and in brain cortical and subcortical regions

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JOURNAL OF INSTRUMENTATION 2018年第2期13卷 C02028-C02028页

作者： Maugeri, L. Moraschi, M. Summers, P. Favilla, S. Mascali, D. Cedola, A. Porro, C. A. Giove, F. Fratini, M. IRCCS Fdn Santa Lucia Via Ardeatina 306-354 I-00179 Rome Italy Ctr Fermi Museo Storico Fis Piazza Viminale 1 I-00184 Rome Italy Ctr Studi & Ric Enrico Fermi Piazza Viminale 1 I-00184 Rome Italy Univ Modena & Reggio Emilia Dept Biomed Metab & Neural Sci Via Giuseppe Campi 287 I-41125 Modena Italy CNR NANOTEC Piazzale Aldo Moro 2 I-00185 Rome Italy

Functional Magnetic Resonance Imaging (fMRI) based on Blood Oxygenation Level Dependent (BOLD) contrast has become one of the most powerful tools in neuroscience research. On the other hand, fMRI approaches have seen limited use in the study of spinal cord and subcortical brain regions (such as the brainstem and portions of the diencephalon). Indeed obtaining good BOLD signal in these areas still represents a technical and scientific challenge, due to poor control of physiological noise and to a limited overall quality of the functional series. A solution can be found in the combination of optimized experimental procedures at acquisition stage, and well-adapted artifact mitigation procedures in the data processing. In this framework, we studied two different data processing strategies to reduce physiological noise in cortical and subcortical brain regions and in the spinal cord, based on the aCompCor and RETROICOR denoising tools respectively. The study, performed in healthy subjects, was carried out using an ad hoc isometric motor task. We observed an increased signal to noise ratio in the denoised functional time series in the spinal cord and in the subcortical brain region.

关键词： data processing methods MRI (whole body, cardiovascular, breast, others), MR-angiography (MRA)

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