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

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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Single event imaging for electron microscopy using MAPS detectors

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JOURNAL OF INSTRUMENTATION 2011年第4期6卷 C04001-C04001页

作者： McMullan, G. Turchetta, R. Faruqi, A. R. MRC Mol Biol Lab Cambridge CB2 0QH England STFC Rutherford Appleton Lab Didcot OX11 0QX Oxon England

Monolithic active pixel sensors, MAPS, combine sensitivity to individual incident electrons with fast readout. This combination allows single event imaging, in which the final image is assembled from the information in the images of individual incident electrons to be implemented. This mode of imaging offers higher detective quantum efficiency and increased lifetime of the detector. Problems faced in processing the single electron events are discussed. It is proposed that the individual electron contributions should be accumulated into a final image with a probability distribution representing the uncertainty of their arrival position due to scattering. The use of a shadow image of a grid is advocated as a way to compare different methods for processing single electron events. Finally an example of a single event image is presented.

关键词： data processing methods Solid state detectors data acquisition concepts

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Improvement of a spectrum-to-dose conversion function for electronic personal dosimeters

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JOURNAL OF INSTRUMENTATION 2020年第2期15卷

作者： Park, K. Kim, J. Lim, K. T. Kim, G. Lee, M. Kim, H. Cho, G. Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn 291 Daehak Ro Daejeon 34141 South Korea IRIS Co Ltd 193 Munji Ro Daejeon 34051 South Korea

For electronic personal dosimeters (EPDs) based on a spectroscopy system, it is necessary to accurately measure the dose in real-time from the gamma energy spectra. The method of spectrum-to-dose conversion is being used instead of the method of count-to-dose conversion. The G(E) function, a typical method of spectrum-to-dose conversion has been applied to various instruments due to its good dose measurement performance and the advantage of real-time measurements. In this manuscript, we present a method to increase the accuracy of G(E) function for the EPD consisting of a 3 x 3 mm(2) PIN diode coupled with a 3 x 3 x 3 mm(3) CsI(Tl) scintillator. The new G(E) function was calculated using the adaptive moment estimation (ADAM) method based on Monte Carlo simulation. The proposed G(E) function is verified by comparison with the least-square method (LSM), which is the conventional method for calculating the G(E) function and with the gradient-descent method (GDM), which is the basis for the ADAM. The relative difference was acquired to compare the converted dose value using each G(E) function by using Am-241, Co-57, Na-22, Cs-137, Mn-54 and Co-60 radioisotopes. In addition, the energy response to Cs-137 of each G(E) function was obtained. The relative difference of G(E) function according to LSM, GDM, and ADAM was in the range of +/- 28.54, +/- 12.59, and +/- 9.9%, respectively, and the energy response to Cs-137 was 0.71 to 1, 0.87 to 1.02, and 0.9 to 1.03, respectively.

关键词： Dosimetry concepts and apparatus Analysis and statistical methods data processing methods Models and simulations

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Study of neutron-rich isotopes near N=152 shell closure using Timepix type detectors integrated into the mass separator MASHA

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JOURNAL OF INSTRUMENTATION 2020年第2期15卷

作者： Broulim, J. Chernysheva, E. V. Gulyaev, S. N. Gulyaeva, A. V. Holik, M. Kamas, D. Kliman, J. Komarov, A. B. Krupa, L. Mora, Y. Novoselov, A. S. Opichal, A. Pechousek, J. Podshibyakin, A. V. Rodin, A. M. Salamatin, V. S. Stepantsov, S. V. Vedeneev, V. Yu. Yukhimchuk, S. A. Joint Inst Nucl Res Flerov Lab Nucl React Joliot Curie 6 Dubna 141980 Moscow Region Russia Slovak Acad Sci Inst Phys Dubravska Cesta 9 Bratislava 84228 Slovakia Czech Tech Univ Inst Expt & Appl Phys Husova 240-5 Prague 11000 1 Czech Republic Palacky Univ Olomouc Fac Sci 17 Listopadu 1192-12 Olomouc 77900 Czech Republic Univ West Bohemia Pilsen Fac Elect Engn Univ 26 Plzen 30100 Czech Republic

The MASHA facility [1-3] was developed as a high precision mass-spectrometer for heavy and super heavy elements with masses up to 450 a.m.u. It uses ISOL (Isotope Separation On-Line) method. Its unique properties opens great prospective for the investigation of neutron-rich nuclei produced in multinucleon transfer reactions. Mainly nuclei near the neutron N = 126 and N = 152 shell closures are of great interest. This region of nuclei is not so far thoroughly enough investigated while its research has direct relation to the synthesis of super heavy elements. As is known the island of stability close to super heavy elements (Z = 112-118) exists due to the shell effects in nuclei. More detailed investigation of these shell effects can greatly help in the synthesis of next super heavy elements. Heavy neutron rich radon isotopes were produced in the multinucleon transfer reaction Ar-40 + Th-232 at Flerov Laboratory of Nuclear Reactions, Dubna. Radon isotopes with given masses were detected using two types of detectors: a multi-strip well-type detector (made in Canberra) and a position-sensitive quantum counting hybrid pixel detector of the Timepix type [4]. The latter detector has an array of 256x256 square pixels each with a pitch size of 55 mu m for the full sensitive area 14x14mm(2). Radon isotopes implanted into the detector emit then alpha and beta particles until they reach the stable or long-lived isotopes at the end of their decay chains. The positions of radon isotopes, the tracks, times and energies of the beta particles were measured and analyzed. New software for the particle recognition and data analysis of the results obtained from the experiment was developed and used. It has been proven that MASHA + Timepix setup is a powerful instrument for investigation of neutron-rich isotopes far from stability limits.

关键词： Particle identification methods Particle tracking detectors data processing methods data acquisition concepts

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Polar-coordinate-based data analysis scheme for high-voltage measurement system using the Pockels electro-optic effect

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JOURNAL OF INSTRUMENTATION 2020年第3期15卷

作者： Choi, S. Sugianto, A. A. Lee, D-G Woo, H. J. Hong, S. H. Ghim, Y-C Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn Daejeon South Korea Korea Adv Inst Sci & Technol Dept Phys Daejeon South Korea Agcy Def Dev Daejeon South Korea Hanyang Univ Dept Elect & Engn Seoul South Korea

A voltage measurement system based on the Pockels electro-optic effect typically has, due to a half-wave voltage V-pi of a Pockels cell, a limitation on the unambiguous measurable range. To overcome such a limitation, we develop a polar-coordinate-based data analysis scheme with a simultaneous measurement of cos (pi V/V-pi) and sin (pi V/V-pi), where V is the voltage the Pockels cell experiences, i.e., the voltage we wish to measure. The developed data analysis scheme also corrects, without knowledge of V-pi, a misalignment of the Pockels cell and an imbalanced transmittance of a beam splitter between the horizontal and vertical components of the polarized laser beam. Thus, increased accuracy of not only the V-pi measurement during calibration procedure but also the voltage measurement itself is also achieved.

关键词： data processing methods Analysis and statistical methods Detector alignment and calibration methods (lasers, sources, particle-beams)

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Development of correction methods for variable pinhole single-photon emission computed tomography

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JOURNAL OF INSTRUMENTATION 2016年第2期11卷 C02060-C02060页

作者： Bae, S. Bae, J. Lee, H. Lee, K. Korea Univ Dept Bioconvergence Engn 145 Anam Ro Seoul South Korea Korea Univ Res Inst Global Hlth Technol 145 Anam Ro Seoul South Korea Korea Univ Sch Biomed Engn 145 Anam Ro Seoul South Korea

We propose a novel pinhole collimator in which the pinhole shape can be changed in real-time, and a new single-photon emission computed tomography (SPECT) system that utilizes this variable pinhole (VP) collimator. The acceptance angle and distance between the collimator and the object of VP SPECT are varied so that the optimum value of the region-of-interest (ROI) can be obtained for each rotation angle. Because of these geometrical variations, new correction methods are required for image reconstruction. In this study, we developed two correction methods. The first is the sensitivity-correction algorithm, which minimizes the variation of a system matrix caused by varying the acceptance angle for each rotation angle. The second is the acquisition-time-correction method, which reduces the variation of uniformity caused by varying the distance between the collimator and the object for each rotation angle. A 3D maximum likelihood expectation maximization (MLEM) algorithm was applied to image reconstruction, and two digital phantoms were studied to evaluate the resolution and sensitivity of the images obtained using the proposed methods. The images obtained by using the proposed correction methods show higher uniformity and resolution than those obtained without using these methods. In particular, the results of the resolution phantom study show that hot rods (0.8-mm-diameter) can be clearly distinguished using the proposed correction methods. A quantitative analysis of the ROI phantom revealed that the mean square error (MSE) was 0.42 without the acquisition-time-correction method, and 0.04 with the acquisition-time-correction method. The MSEs of the resolution phantom without and with the acquisition-time-correction method were calculated as 55.14 and 14.69, respectively.

关键词： data processing methods Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) Medical-image reconstruction methods and algorithms, computer-aided software

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Extra dimensions: 3D and time in PDF documentation

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JOURNAL OF INSTRUMENTATION 2011年第1期6卷 C01053-C01053页

作者： Graf, N. A. SLAC Natl Accelerator Lab Menlo Pk CA USA

Experimental science is replete with multi-dimensional information which is often poorly represented by the two dimensions of presentation slides and print media. Past efforts to disseminate such information to a wider audience have failed for a number of reasons, including a lack of standards which are easy to implement and have broad support. Adobe's Portable Document Format (PDF) has in recent years become the de facto standard for secure, dependable electronic information exchange. It has done so by creating an open format, providing support for multiple platforms and being reliable and extensible. By providing support for the ECMA standard Universal 3D (U3D) file format in its free Adobe Reader software, Adobe has made it easy to distribute and interact with 3D content. By providing support for scripting and animation, temporal data can also be easily distributed to a wide, non-technical audience. We discuss how the field of radiation imaging could benefit from incorporating full 3D information about not only the detectors, but also the results of the experimental analyses, in its electronic publications. In this article, we present examples drawn from high-energy physics, mathematics and molecular biology which take advantage of this functionality. We demonstrate how 3D detector elements can be documented, using either CAD drawings or other sources such as GEANT visualizations as input.

关键词： data processing methods Simulation methods and programs Large detector systems for particle and astroparticle physics Computing (architecture, farms, GRID for recording, storage, archiving, and distribution of data)

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A neural network based algorithm for MRPC position reconstruction

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JOURNAL OF INSTRUMENTATION 2020年第10期15卷

作者： Yu, Y. Chen, X. Wang, Y. Han, D. Guo, B. Wang, F. Shen, C. Zhang, Q. Li, Y. Tsinghua Univ Dept Engn Phys Key Lab Particle & Radiat Imaging Beijing 100084 Peoples R China

Over the last ten years, muon imaging has attracted much attention due to its possible applications to detect high-Z materials in shipping containers or image very large objects such as volcanoes and large buildings. Precise measurements of the incident and outgoing angles of the cosmic muons are mandatory in this application. Large size (M)RPC detector with sub-millimetre position resolution should be an ideal candidate for the detector system. Prior work on improving the position resolution of MRPC mainly focuses on adjusting read-out panel and the detector geometry, while little work has been done on improving the position reconstruction algorithm. This paper proposes a new position reconstruction algorithm based on the neural networks which has no systematic error and gives better results than the center of gravity algorithm.

关键词： data processing methods Detector modelling and simulations II (electric fields, charge transport, multiplication and induction, pulse formation, electron emission, etc) Particle tracking detectors (Gaseous detectors) Resistive-plate chambers

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Toward clinical differential phase contrast mammography: preliminary evaluations and image processing schemes

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JOURNAL OF INSTRUMENTATION 2013年第5期8卷 C05009-C05009页

作者： Stampanoni, M. Wang, Z. Thuering, T. David, C. Roessl, E. van Stevendaal, U. Koehler, T. Trippel, M. Singer, G. Kubik-Huch, R. A. Hohl, M. K. Hauser, N. Paul Scherrer Inst Swiss Light Source CH-5232 Villigen Switzerland Univ Zurich Inst Biomed Engn Zurich Switzerland Swiss Fed Inst Technol Zurich Switzerland Paul Scherrer Inst Lab Micro & Nanotechnol CH-5232 Villigen Switzerland Philips Technol GmbH Hamburg Germany Kantonsspital Baden Inst Pathol CH-5404 Baden Switzerland Kantonsspital Baden Dept Radiol CH-5404 Baden Switzerland Kantonsspital Baden Interdisciplinary Breast Ctr Baden Dept Gynecol & Obstet CH-5404 Baden Switzerland

Phase contrast and scattering-based X-ray imaging are very promising tools for medical diagnostics because they are able to provide additional and complementary information to traditional absorption-based methods. In this work, we discuss the investigation of three native breast samples with a grating interferometer equipped with a conventional X-ray tube, the full study being published in ref. [1]. We briefly introduce a method to fuse absorption, differential phase and scattering signals into a unique image with improved diagnostic contents. Our approach yields complementary and inaccessible information on the electron density distribution and the small-angle scattering power of the sample which could potentially answer clinically relevant, yet unresolved questions such as the capability to unequivocally discern between (pre-) malignant changes and post-operative scars or to distinguish cancer-invaded regions within healthy tissue.

关键词： X-ray mammography and scinto- and MRI-mammography Image filtering data processing methods Medical-image reconstruction methods and algorithms computer-aided so

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