ROOT - A C++ Framework for Petabyte Data Storage, Statistical Analysis and Visualization

ROOT is an object-oriented C++ framework conceived in the high-energy physics (HEP) community, designed for storing and analyzing petabytes of data in an efficient way. Any instance of a C++ class can be stored into a ROOT file in a machine-independent compressed binary format. In ROOT the TTree object container is optimized for statistical data analysis over very large data sets by using vertical data storage techniques. These containers can span a large number of files on local disks, the web, or a number of different shared file systems. In order to analyze this data, the user can chose out of a wide set of mathematical and statistical functions, including linear algebra classes, numerical algorithms such as integration and minimization, and various methods for performing regression analysis (fitting). In particular, ROOT offers packages for complex data modeling and fitting, as well as multivariate classification based on machine learning techniques. A central piece in these analysis tools are the histogram classes which provide binning of one- and multi-dimensional data. Results can be saved in high-quality graphical formats like Postscript and PDF or in bitmap formats like JPG or GIF. The result can also be stored into ROOT macros that allow a full recreation and rework of the graphics. Users typically create their analysis macros step by step, making use of the interactive C++ interpreter CINT, while running over small data samples. Once the development is finished, they can run these macros at full compiled speed over large data sets, using on-the-fly compilation, or by creating a stand-alone batch program. Finally, if processing farms are available, the user can reduce the execution time of intrinsically parallel tasks - e.g. data mining in HEP - by using PROOF, which will take care of optimally distributing the work over the available resources in a transparent way

Choice and use of mathematical methods to determine the technological parameters of radiation-shielding materials

В статье обоснован выбор программного комплекса для проведения численного моделирования прохождения ионизирующего излучения через вещество, приведено обоснование выбора корректного метода расчета дозы и мощности дозы при проведение численного моделирования прохождения ионизирующего излучения через вещество. Предложена методика подбора аппроксимирующей кусочно-непрерывной функции для расчета массового коэффициента ослабления гамма-излучения, необходимого при расчете поглощенной и эквивалентной доз.Ionization radiation is everywhere: cosmic rays, nuclear energy, medicine and etc. One of the main tasks during work with the ionization radiation – human safety. There are a lot of radiation protected clothes. To define their protective characteristics two way are possible: experimental and simulation. The numerical simulation allows to speed up experiments and cheapen them.There are a lot of software toolkit for ionization radiation pass through the matter simulation. The article is devoted to following tasks: selection of software toolkit for numerical simulation of ionization irradiation passage through the matter; correct way of dose and dose ray calculation as dose rate should be calculated at the point; correct way of mass energy-absorption coefficient approximation by piecwise continuous function. For numerical simulation GEANT4 software toolkit was chosen. The GEANT4 is written in modern programming language: C++. GEANT4 is well documented, has a good supprot and free open software. To calculate dose and dose rate calculation should be made for the point. The absorbed dose calculaation method which is used in GEANT4 can not be used for dose rate calculation. Proper mathematical method for absorbed dose calculation was chosen and was described in the articl

Calculation method of the absorbed (equivalent) dose and absorbed (equivalent) dose rate of the ionizing radiation

В статье предложен метод расчета поглощенной (эквивалентной) дозы и мощности поглощенной (эквивалентной) дозы ионизирующего излучения (гамма-, нейтронное и электронное излучение) в точке. Предложены аппроксимирующие функции и рассчитаны соответствующие коэффициенты. Приведены графики зависимостей коэффициентов перевода флюенса частиц и флюенса энергии частиц в поглощенную (эквивалентную) дозу в зависимости от энергии частиц.One of the perspective way to calculate absorbed (equivalent) dose and their rate is numerical simulation. GEANT4 is one of the software toolkit for the simulation of the passage of particles through matter.The article is devoted to define correct way of dose and dose rate calculation as dose rate should be calculated at the point; correct way of dose conversion coefficient approximation by piecwise continuous function. Calculation method of the absorbed (equivalent) dose and absorbed (equivalent) dose rate of ionizing radiation (gamma, neutron andelectron radiation) at the point is proposed in the article. Approximating functions are proposed and the corresponding coefficients are calculated. Figures with coefficients dependencies of particles fluence and particle fluence energy depending on the energy of the particles are given. These coefficients are needed for calculations of absorbed (equivalent) dose. The absorbed dose rate calculation method which is used in GEANT4 can not beused for dose rate calculation. Proper mathematical method for absorbed dose rate calculation was chosen and was described in the article. Also, the method of absorbed (equivalent) dose rate calculation are given. Proposed calculation method of the absorbed (equivalent) dose and absorbed (equivalent) dose rate of the ionizing radiation may be used for numerical simulation of ionization radiation passage through the matter, for example, with the use of GEANT4

Data analysis with R in an experimental physics environment

A software package has been developed to bridge the R analysis model with the conceptual analysis environment typical of radiation physics experiments. The new package has been used in the context of a project for the validation of simulation models, where it has demonstrated its capability to satisfy typical requirements pertinent to the problem domain.Comment: IEEE Nuclear Science Symposium 201

Study of the resonance α+13C interaction at low energies: Optimization of parameters of the beam shape

About half of all elements heavier than iron are produced in a stellar environment through the s process, which involves a series of subsequent neutron captures and α decays. The reaction 13C(α,n)16O is considered to be the main source of neutrons for the s process at low temperatures in low mass stars in the asymptotic giant branch (AGB). In order to understand better creation of such elements we need to imrove the understanding of creation of such elements, that is to obtain the excitation functions of the 13C (α, α)17O elastic scattering at the initial beam energy 13C from 1.7Mev/A till energies close to zero by using the Thick Target Inverse Kinematics method (TTIK) [1]. The experiment will be conducted in Astana, KZ by using a new heavy ion accelerator DC-60 that provides ion beam with the energy 1.75 MeV/nucleon [1]. To improve the results and reduce errors, the profiling of the beam within the experimental camera is required. In this article, the detailed preparations for this measurement are described

Study of the resonance α+13C interaction at low energies: Optimization of parameters of the beam shape

About half of all elements heavier than iron are produced in a stellar environment through the s process, which involves a series of subsequent neutron captures and α decays. The reaction 13C(α,n)16O is considered to be the main source of neutrons for the s process at low temperatures in low mass stars in the asymptotic giant branch (AGB). In order to understand better creation of such elements we need to imrove the understanding of creation of such elements, that is to obtain the excitation functions of the 13C (α, α)17O elastic scattering at the initial beam energy 13C from 1.7Mev/A till energies close to zero by using the Thick Target Inverse Kinematics method (TTIK) [1]. The experiment will be conducted in Astana, KZ by using a new heavy ion accelerator DC-60 that provides ion beam with the energy 1.75 MeV/nucleon [1]. To improve the results and reduce errors, the profiling of the beam within the experimental camera is required. In this article, the detailed preparations for this measurement are described

Refining light stop exclusion limits with W+W−W^+W^- cross sections

If light supersymmetric top (stop) quarks are produced at the LHC and decay via on- or off-shell $W$-bosons they can be expected to contribute to a precision $W^+W^-$ cross section measurement. Using the latest results of the CMS experiment, we revisit constraints on the stop quark production and find that this measurement can exclude portions of the parameter space not probed by dedicated searches. In particular we can exclude light top squarks up to 230~GeV along the line separating three- and four-body decays, $\tilde{t}_1 \to \tilde{\chi}_1^0 W^{(*)} b$. We also study the exclusion limits in the case when the branching ratio for these decays is reduced and we show significant improvement over previously existing limits.Comment: 5 pages, 2 figures; references updated, minor changes; to appear in Phys. Lett.

Efficient HTTP based I/O on very large datasets for high performance computing with the libdavix library

Remote data access for data analysis in high performance computing is commonly done with specialized data access protocols and storage systems. These protocols are highly optimized for high throughput on very large datasets, multi-streams, high availability, low latency and efficient parallel I/O. The purpose of this paper is to describe how we have adapted a generic protocol, the Hyper Text Transport Protocol (HTTP) to make it a competitive alternative for high performance I/O and data analysis applications in a global computing grid: the Worldwide LHC Computing Grid. In this work, we first analyze the design differences between the HTTP protocol and the most common high performance I/O protocols, pointing out the main performance weaknesses of HTTP. Then, we describe in detail how we solved these issues. Our solutions have been implemented in a toolkit called davix, available through several recent Linux distributions. Finally, we describe the results of our benchmarks where we compare the performance of davix against a HPC specific protocol for a data analysis use case.Comment: Presented at: Very large Data Bases (VLDB) 2014, Hangzho