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Kernel density estimation of a multidimensional efficiency profile

JOURNAL OF INSTRUMENTATION 2015年第2期10卷 P02011-P02011页

作者： Poluektov, A. Univ Warwick Coventry CV4 7AL W Midlands England Budker Inst Nucl Phys Novosibirsk 630090 Russia

Kernel density estimation is a convenient way to estimate the probability density of a distribution given the sample of data points. However, it has certain drawbacks: proper description of the density using narrow kernels needs large data samples, whereas if the kernel width is large, boundaries and narrow structures tend to be smeared. Here, an approach to correct for such effects, is proposed that uses an approximate density to describe narrow structures and boundaries. The approach is shown to be well suited for the description of the efficiency shape over a multidimensional phase space in a typical particle physics analysis. An example is given for the five-dimensional phase space of the Lambda(0)(b) -> D(0)p pi(-) decay.

关键词： Analysis and statistical methods data processing methods

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Development of a plastic scintillation detector for muon scattering imaging

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JOURNAL OF INSTRUMENTATION 2020年第11期15卷

作者： Hu, T. Q. Liang, Z. Li, X. Li, C. Tang, Z. B. Wu, Y. T. Univ Sci & Technol China State Key Lab Particle Detect & Elect Hefei 230026 Peoples R China Univ Sci & Technol China Dept Modern Phys Hefei 230026 Peoples R China

To develop a device of large-area cosmic ray imaging in complex measurement environments, we design a muon scattering imaging detector composed of triangular scintillators, with a new type of photodetector (SiPM) as readout. A 500 mm x 500 mm imaging detector composed of multiple scintillator bars is presented in this paper. GEANT4 simulation shows that its intrinsic position resolution can be improved by the incidence angle and air gap corrections. To optimize its imaging performance, the reconstruction and correction methods of hit position are discussed in detail and compared with the experimental results.

关键词： Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc) Particle tracking detectors Simulation methods and programs data processing methods

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Temperature fitting of partially resolved rotational spectra

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JOURNAL OF INSTRUMENTATION 2012年第02期7卷 C02054-C02054页

作者： van Gessel, A. F. H. Hrycak, B. Jasinski, M. Mizeraczyk, J. van der Mullen, J. J. A. M. Bruggeman, P. J. Eindhoven Univ Technol Dept Appl Phys NL-5600 MB Eindhoven Netherlands Polish Acad Sci Szewalski Inst Fluid Flow Machinery Ctr Plasma & Laser Engn PL-80231 Gdansk Poland

In this paper we present a method to automatically fit the temperature of a rotational spectrum. It is shown that this fitting method yields similar results as the traditional Boltzmann plot, but is applicable in situations where lines of the spectrum overlap. The method is demonstrated on rotational spectra of nitric oxide from an atmospheric pressure microwave plasma jet operated with a flow of helium and air, obtained with two different methods: laser induced fluorescence and optical emission spectroscopy. Axial profiles of the rotational temperatures are presented for the ground NO X state and the excited NO A state.

关键词： data processing methods Plasma diagnostics - interferometry, spectroscopy and imaging

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A new approach to theoretical investigations of high harmonics generation by means of fs laser interaction with overdense plasma layers. Combining particle-in-cell simulations with machine learning.

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JOURNAL OF INSTRUMENTATION 2016年第12期11卷 C12004-C12004页

作者： Mihailescu, A. Natl Inst Laser Plasma & Radiat Phys POB MG 36 Magurele 077125 Romania

Within the past decade, various experimental and theoretical investigations have been performed in the field of high-order harmonics generation (HHG) by means of femtosecond (fs) laser pulses interacting with laser produced plasmas. Numerous potential future applications thus arise. Beyond achieving higher conversion efficiency for higher harmonic orders and hence harmonic power and brilliance, there are more ambitious scientific goals such as attaining shorter harmonic wavelengths or reducing harmonic pulse durations towards the attosecond and even the zeptosecond range. High order harmonics are also an attractive diagnostic tool for the laser-plasma interaction process itself. Particle-in-Cell (PIC) simulations are known to be one of the most important numerical instruments employed in plasma physics and in laser-plasma interaction investigations. The novelty brought by this paper consists in combining the PIC method with several machine learning approaches. For predictive modelling purposes, a universal functional approximator is used, namely a multi-layer perceptron (MLP), in conjunction with a self-organizing map (SOM). The training sets have been retrieved from the PIC simulations and also from the available literature in the field. The results demonstrate the potential utility of machine learning in predicting optimal interaction scenarios for gaining higher order harmonics or harmonics with particular features such as a particular wavelength range, a particular harmonic pulse duration or a certain intensity. Furthermore, the author will show how machine learning can be used for estimations of electronic temperatures, proving that it can be a reliable tool for obtaining better insights into the fs laser interaction physics.

关键词： data processing methods Pattern recognition cluster finding calibration and fitting methods Analysis and statistical methods Simulation methods and programs

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A new fast scanning system for the measurement of large angle tracks in nuclear emulsions

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JOURNAL OF INSTRUMENTATION 2015年第11期10卷 P11006-P11006页

作者： Alexandrov, A. Buonaura, A. Consiglio, L. D'Ambrosio, N. De Lellis, G. Di Crescenzo, A. Di Marco, N. Galati, G. Lauria, A. Montesi, M. C. Pupilli, F. Shchedrina, T. Tioukova, V. Vladymyrov, M. Ist Nazl Fis Nucl Sez Napoli I-80125 Naples Italy Russian Acad Sci LPI RUS-119991 Moscow Russia Ist Nazl Fis Nucl LNGS I-67100 Laquila Italy Univ Naples Federico II I-80125 Naples Italy Ist Nazl Fis Nucl LNF I-00044 Frascati Italy

Nuclear emulsions have been widely used in particle physics to identify new particles through the observation of their decays thanks to their unique spatial resolution. Nevertheless, before the advent of automatic scanning systems, the emulsion analysis was very demanding in terms of well trained manpower. Due to this reason, they were gradually replaced by electronic detectors, until the '90s, when automatic microscopes started to be developed in Japan and in Europe. Automatic scanning was essential to conceive large scale emulsion-based neutrino experiments like CHORUS, DONUT and OPERA. Standard scanning systems have been initially designed to recognize tracks within a limited angular acceptance (theta less than or similar to 30 degrees) where theta is the track angle with respect to a line perpendicular to the emulsion plane. In this paper we describe the implementation of a novel fast automatic scanning system aimed at extending the track recognition to the full angular range and improving the present scanning speed. Indeed, nuclear emulsions do not have any intrinsic limit to detect particle direction. Such improvement opens new perspectives to use nuclear emulsions in several fields in addition to large scale neutrino experiments, like muon radiography, medical applications and dark matter directional detection.

关键词： data processing methods Pattern recognition cluster finding calibration and fitting methods data acquisition concepts Performance of High Energy Physics Detectors

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Simulation and reconstruction of the PANDA Barrel DIRC detector

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JOURNAL OF INSTRUMENTATION 2011年第11期6卷

作者： Patsyuk, M. Schwarz, C. Dutta, D. Goetzen, K. Peters, K. Schwiening, J. GSI Helmholtzzentrum Schwerionenforschung GmbH D-64291 Darmstadt Germany Goethe Univ Frankfurt D-60325 Frankfurt Germany Bhabha Atom Res Ctr Div Nucl Phys Bombay 400085 Maharashtra India

The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt, aims at studying the strong interacting matter by precision spectroscopy. A detector system with excellent particle identification over a large range of solid angle and momentum is therefore mandatory. Charged hadron identification in the barrel region will be performed by a compact ring imaging Cherenkov detector based on the DIRC principle (Detection of Internally Reflected Cherenkov light), designed to separate pions from kaons with at least 3 standard deviations in the momentum range from 0.5 GeV/c to 3.5 GeV/c. We present details of the simulation of the PANDA Barrel DIRC and a study of the detector performance using a fast reconstruction algorithm to determine the single photon Cherenkov angle resolution and photon yield for several design options.

关键词： data processing methods Particle identification methods Cherenkov detectors Cherenkov and transition radiation

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Performance measurements of a depth-encoding TraPET detector module

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JOURNAL OF INSTRUMENTATION 2011年第11期6卷

作者： Chung, Y. H. Lee, C. Y. Baek, C. -H. An, S. J. Kim, H. Il Choi, Y. Kang, J. Hu, W. Yonsei Univ Coll Hlth Sci Dept Radiol Sci Wonju 220710 Kangwon Do South Korea Yonsei Univ Inst Hlth Sci Wonju 220710 Kangwon Do South Korea Sogang Univ Dept Elect Engn Seoul 121742 South Korea Sungkyunkwan Univ Sch Med Samsung Med Ctr Dept Nucl Med Seoul 135710 South Korea

The new method to correct a parallax error and the loss of coincidence counts caused by the gap between modules was developed for a small animal PET scanner. We proposed the TraPET scanner composed of 6 dual-layer phoswich detector modules. Each detector module consists of a 5.0 mm-thick trapezoidal-shaped monolithic LSO crystal and a 23 x 23 array of GSO crystal. The layer of interaction is identified by the pulse shape discrimination method. One detector module was built and the algorithm for layer identification was optimized. The dual-layer crystals were optically coupled to a Hamamatsu H8500 position-sensitive PMT and a resistive charge divider was used to multiplex 64-channel anode outputs into 4-channel position signals. The 4 signals have been sampled continuously by 14-bit ADC at a sampling rate of 105 MHz and the pulse shape discrimination algorithm was achieved through FPGA programming. The detector module was irradiated with a Na-22 point source from the side of the crystals to obtain flood images of each layer and two layers were clearly identified, thus verifying the DOI capability. The TraPET detector proved to be a reliable design for correcting the parallax error and improving the sensitivity simultaneously in the small animal PET.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) data processing methods Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc) Front-end electronics for detector readout

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Enhancing spatial resolution in MONCH for electron microscopy via deep learning

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JOURNAL OF INSTRUMENTATION 2024年第1期19卷 C01020页

作者： Xie, X. Flores, L. Barba Haro, B. Bejar Bergamaschi, A. Frojdh, E. Muller, E. Paton, K. A. Poghosyana, E. Remlinger, C. Paul Scherrer Inst CH-5232 Villigen Switzerland Swiss Data Sci Ctr SDSC Hub PSI CH-5232 Villigen Switzerland Swiss Data Sci Ctr CH-1015 Lausanne Switzerland

Hybrid Pixel Detectors (HPDs) are highly suitable in diffraction -based electron microscopy due to their high frame rates (> 1 kHz), high dynamic range, and good radiation hardness. However, their use in imaging applications has been limited by their relatively large pixel size (>= 55 mu m) and high-energy (> 80 keV) electrons scattering over multiple pixels in the sensor layer. To realize the full potential of fast, radiation -hard HPDs across electron microscopy modalities, we developed deep learning techniques to precisely localize the impact point of incident electrons in MUNCH, a charge integrating HPD with 25 mu m pixel size. With neural network models trained using labeled data via simulations and experimental measurements, the best spatial resolution obtained, defined in terms of the root mean squared error, was 0.60 pixels for 200 keV electrons, a three -fold improvement over a simple charge centroid method. This article presents the training sample generation, deep learning model design, training results, and imaging outcomes for a sample containing gold nanoparticles.

关键词： data processing methods Hybrid detectors Pixelated detectors and associated VLSI electronics

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Spectral X-ray computed tomography image denoising using weighted local regression and noise-insensitive feature dimensionality reduction

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JOURNAL OF INSTRUMENTATION 2024年第8期19卷 P08020页

作者： Hotta, T. Yatagawa, T. Ohtake, Y. Matsukawa, M. Suzuki, H. Aoki, T. Shizuoka Univ Grad Sch Med Photon 3-5-1 JohokuChuo Ku Hamamatsu Shizuoka 4328011 Japan Hitotsubashi Univ Sch Social Data Sci 2-1 Naka Kunitachi Tokyo 1868601 Japan Univ Tokyo Dept Precis Engn 7-3-1 Hongo Bunkyo City Tokyo 1138654 Japan Zodiac Inc 145-1 TokiwachoChuo Ku Hamamatsu Shizuoka 4300917 Japan

This study introduces a novel denoising method for spectral X-ray computed tomography (CT) images using weighted local regression (WLR). The proposed method exploits the common structural information present across different energy bins. Denoised pixel intensities of a certain energy bin are estimated using the intensities of the other energy bins via WLR. Denoising is achieved by applying a WLR model to the noisy pixel intensities of all energy bins, excluding the target bin, which obtains approximate noise-free intensities for the target energy bin. The performance of our approach was assessed using synthetic spectral X-ray CT images produced using a Monte Carlo photon simulator called the Electron Gamma Shower 5 (EGS5). Both qualitative and quantitative evaluations demonstrated that our approach effectively reduced noise across all energy bins while maintaining image sharpness. Comparisons with common denoising methods demonstrate the effectiveness of the proposed method.

关键词： Analysis and statistical methods Computerized Tomography (CT) and Computed Radiography (CR) data processing methods Image filtering

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Automated detection of arterial input function in DSC perfusion MRI in a stroke rat model

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JOURNAL OF INSTRUMENTATION 2009年第5期4卷 P05021-P05021页

作者： Yeh, M. -Y. Lee, T. -H. Yang, S. -T. Kuo, H. -H. Chyi, T. -K. Liu, H. -L. Chang Gung Univ Grad Inst Med Phys & Imaging Sci Tao Yuan Taiwan Chang Gung Mem Hosp MRI Ctr Tao Yuan Taiwan Chang Gung Mem Hosp Stroke Sect Dept Neurol Tao Yuan Taiwan Chang Gung Mem Hosp Mol Imaging Ctr Tao Yuan Taiwan

Quantitative cerebral blood flow (CBF) estimation requires deconvolution of the tissue concentration time curves with an arterial input function (AIF). However, image-based determination of AIF in rodent is challenged due to limited spatial resolution. We evaluated the feasibility of quantitative analysis using automated AIF detection and compared the results with commonly applied semi-quantitative analysis. Permanent occlusion of bilateral or unilateral common carotid artery was used to induce cerebral ischemia in rats. The image using dynamic susceptibility contrast method was performed on a 3-T magnetic resonance scanner with a spin-echo echo-planar-image sequence (TR/TE= 700/80 ms, FOV=41 mm, matrix=64, 3 slices, SW=2 mm), starting from 7 s prior to contrast injection (1.2ml/kg) at four different time points. For quantitative analysis, CBF was calculated by the AIF which was obtained from 10 voxels with greatest contrast enhancement after deconvolution. For semi-quantitative analysis, relative CBF was estimated by the integral divided by the first moment of the relaxivity time curves. We observed if the AIFs obtained in the three different ROIs (whole brain, hemisphere without lesion and hemisphere with lesion) were similar, the CBF ratios (lesion/normal) between quantitative and semi-quantitative analyses might have a similar trend at different operative time points. If the AIFs were different, the CBF ratios might be different. We concluded that using local maximum one can define proper AIF without knowing the anatomical location of arteries in a stroke rat model.

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

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