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The standard model characterizing the gamma-ray burst (GRB) spectrum invokes a four-parameter empirical function, the so-called the BAND model. An alternative model named cutoff power law (COMP) implements a power law with an exponential…

High Energy Physics - Phenomenology · Physics 2022-12-21 Liang Li

Gamma-Ray Bursts (GRBs), being observed at high redshift (z = 9.4), vital to cosmological studies and investigating Population III stars. To tackle these studies, we need correlations among relevant GRB variables with the requirement of…

High Energy Astrophysical Phenomena · Physics 2023-08-16 Maria G. Dainotti , Ritwik Sharma , Aditya Narendra , Delina Levine , Enrico Rinaldi , Agnieszka Pollo , Gopal Bhatta

Accurate beam modeling is important in many radio astronomy applications. In this paper, we focus on beam modeling for 21-cm intensity mapping experiments using radio interferometers, though the techniques also apply to single dish…

Instrumentation and Methods for Astrophysics · Physics 2025-09-16 Michael J. Wilensky , Philip Bull , Nicolas Fagnoni

Score-based diffusion models have significantly advanced generative deep learning for image processing. Measurement conditioned models have also been applied to inverse problems such as CT reconstruction. However, the conventional approach,…

Medical Physics · Physics 2025-02-24 Matthew Tivnan , Dufan Wu , Quanzheng Li

We propose a new approach to linear ill-posed inverse problems. Our algorithm alternates between enforcing two constraints: the measurements and the statistical correlation structure in some transformed space. We use a non-linear multiscale…

Computational Engineering, Finance, and Science · Computer Science 2018-12-04 Ivan Dokmanić , Joan Bruna , Stéphane Mallat , Maarten de Hoop

To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under…

Instrumentation and Detectors · Physics 2016-08-03 Jianguo Qin , Caifeng Lai , Rong Liu , Tonghua Zhu , Xinwei Zhang , Bangjiao Ye

Mathematical methods of step-by-step and combined shifts are proposed for experimental data processing to reconstruct the measuring system impulse response distorted by shift-invariant blur. Proposed methods base on direct non-blind…

Signal Processing · Electrical Eng. & Systems 2019-01-24 Andrey V. Novikov-Borodin

We compute burst spectra and time structures arising from synchrotron and inverse Compton scattering by non-thermal electrons accelerated in shocks which form during the interaction between a thin ultra-relativistic fireball and a…

Astrophysics · Physics 2009-10-30 A. Panaitescu , P. Meszaros

The Large Area Telescope (LAT) onboard the Fermi satellite is observing the gamma-ray sky in the high energy region, above 20 MeV. We have developed a method to reconstruct the energy spectra of the gamma-rays detected by the Fermi LAT…

Instrumentation and Methods for Astrophysics · Physics 2019-08-13 F. Loparco , M. N. Mazziotta

The Stark effect provides a powerful method to shift the spectra of molecules, atoms and electronic transitions in general, becoming one of the simplest and most straightforward way to tune the frequency of quantum emitters by means of a…

We calculate the synchrotron self-Compton emission from internal shocks occurring in relativistic winds as a source of gamma-ray bursts, with allowance for self-absorption. For plausible model parameters most pulses within a Gamma-Ray Burst…

Astrophysics · Physics 2009-10-31 A. Panaitescu , P. Meszaros

Ultrafast scattering using X-rays or electrons is an emerging method to obtain structure dynamics at the atomic length and time scales. However, directly resolving in real-space atomic motions is inherently limited by the finite detector…

Atomic Physics · Physics 2023-02-09 Adi Natan

The light we receive from distant astrophysical objects carries information about their origins and the physical mechanisms that power them. The study of these signals, however, is complicated by the fact that observations are often a…

Monte Carlo (MC) techniques are often used to estimate integrals of a multivariate function using randomly generated samples of the function. In light of the increasing interest in uncertainty quantification and robust design applications…

Machine Learning · Statistics 2011-08-25 Brendan Tracey , David Wolpert , Juan J. Alonso

The Rapid and accurate identification of Gamma-Ray Bursts (GRBs) is crucial for unraveling their origins. However, current burst search algorithms frequently miss low-threshold signals or lack universality for observations. In this study,…

High Energy Astrophysical Phenomena · Physics 2024-08-27 Peng Zhang , Bing Li , Ren-zhou Gui , Shao-lin Xiong , Yu Wang , Yan-qiu Zhang , Chen-wei Wang , Jia-cong Liu , Wang-chen Xue , Chao Zheng , Zheng-hang Yu , Wen-long Zhang

The Diffusion Monte Carlo method is devoted to the computation of electronic ground-state energies of molecules. In this paper, we focus on implementations of this method which consist in exploring the configuration space with a {\bf fixed}…

Numerical Analysis · Mathematics 2007-05-23 Tony Lelievre , Mohamed El Makrini , Benjamin Jourdain

A new method for correcting charged-particle spectra for thick target effects is described. Starting with a trial function, inverse response functions are found by an iterative procedure. The variances corresponding to the measured spectrum…

Nuclear Experiment · Physics 2009-11-11 S. Pomp , U. Tippawan

Relativistic shock models of gamma-ray bursts may be tested by comparison of their predicted low energy asymptotic spectral indices s to observations. Synchrotron radiation theory predicts that the instantaneous spectrum has s = - 1/3 and…

Astrophysics · Physics 2009-10-30 E. Cohen , J. I. Katz , T. Piran , R. Sari , R. D. Preece , D. L. Band

Improving resolution and sensitivity will widen possible medical applications of magnetic particle imaging. Pulsed excitation promises such benefits, at the cost of more complex hardware solutions and restrictions on drive field amplitude…

Low radio frequency spectral index measurements are a powerful tool to distinguish between different emission mechanisms and, in turn, to understand the nature of the sources. Besides the standard method of estimating the ``broadband"…

Instrumentation and Methods for Astrophysics · Physics 2024-05-30 Md Rashid , Nirupam Roy , J. D. Pandian , Prasun Dutta , R. Dokara , S. Vig , K. M. Menten