Showing 1–50 of 79 results for author: Vasilyev, I

Norm bounds on Fourier series with polynomial spectra and constrained coefficients

Authors: Ioann Vasilyev

Abstract: The goal of this paper is to prove an upper bound for the $L^4$ norm of a trigonometric polynomial whose spectrum is a nontrivial strictly monotone polynomial with integer coefficients of degree three and higher, via its $L^2$ norm. Our condition on the coefficients of the trigonometric polynomial in question is that they form a complex sequence whose modulus is decreasing. Second, we obtain a sim… ▽ More The goal of this paper is to prove an upper bound for the $L^4$ norm of a trigonometric polynomial whose spectrum is a nontrivial strictly monotone polynomial with integer coefficients of degree three and higher, via its $L^2$ norm. Our condition on the coefficients of the trigonometric polynomial in question is that they form a complex sequence whose modulus is decreasing. Second, we obtain a similar result in the case where the spectrum is formed by perfect squares, under a more strict condition on the coefficients. Our results strengthen and complement those by S. Bochkarev and A. Córdoba. We also give an answer to a conjecture of Eceizabarrena and Da Rocha and determine the sharp order of growth of the $L^4$ norm of the trigonometric polynomial in this conjecture. △ Less

Submitted 19 August, 2026; originally announced August 2026.

Comments: 11 pages, no pictures. Comments are welcome!

MSC Class: 42A05; 11A05

SLAI T-Rex: Full-Parameter Post-training of the DeepSeek-V4 Family on Ascend SuperPOD

Authors: Dongfang Li, Xiaodong Luo, Ruoyu Sun, Xuhui Chen, Linyuan Qiu, Jian Meng, Zhengxuan Lu, Yiting Wang, Yucheng Xie, Tao Guo, Tianxiang Fang, Jing Li, Sihang Chen, Shihao Hong, Chang Liu, Weihua Dai, Zirong Zeng, Ziwei Zhu, Zhuohan Wang, Zhengjun Yue, Igor Vasilyev, Min Liu, Weijian Sun, Xin Chen, Yingmeng Gao , et al. (40 additional authors not shown)

Abstract: Full-parameter post-training of trillion-parameter-scale MoE models introduces substantial system-level challenges for large-scale distributed training, including severe memory pressure, non-overlapped communication overhead, and inefficient kernel execution. While most large-scale LLM training systems are built around GPU-based clusters, this report presents an end-to-end optimization practice on… ▽ More Full-parameter post-training of trillion-parameter-scale MoE models introduces substantial system-level challenges for large-scale distributed training, including severe memory pressure, non-overlapped communication overhead, and inefficient kernel execution. While most large-scale LLM training systems are built around GPU-based clusters, this report presents an end-to-end optimization practice on the Ascend NPU SuperPOD. Using the DeepSeek-V4 model family as the target workload, we develop a hierarchical optimization framework spanning model-level parallelism, computation-communication orchestration, and low-level kernel execution. The resulting system achieves 34.22% Model FLOPs Utilization (MFU) with a 2.93x improvement over the open-source baseline recipe while maintaining training stability. Building on this optimized infrastructure, we further establish a CPT and SFT workflow for complex Operations Research (OR) tasks. We refer to the integrated framework as SLAI T-Rex. Using DeepSeek-V4-Flash, we develop OR-oriented CPT and SFT data pipelines that combine collected domain resources with solver-verified synthetic optimization documents. The resulting dataset contains 10K high-quality SFT samples spanning four task categories and three problem representations. The specialized model achieves the highest average zero-shot Pass@1 score among the evaluated models, reaching 71.81% and outperforming GPT-5.4-Mini and the base DeepSeek-V4-Flash model by 3.98 and 11.27 percentage points, respectively. Overall, this work demonstrates a full-stack pathway from efficient trillion-parameter model post-training on Ascend infra to domain-specialized Flash models for solver-grounded mathematical modeling, advancing frontier-model systems for complex reasoning. △ Less

Submitted 19 August, 2026; v1 submitted 22 July, 2026; originally announced July 2026.

Comments: 73 pages, 22 figures, 20 tables

Signal selection and model-independent extraction of pionless charged-current muon neutrino cross section using double-differential kinematic imbalance observables on carbon and oxygen with the T2K experiment

Authors: K. Abe, S. Abe, H. Adhikary, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Asami, Y. Asaoka, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak , et al. (380 additional authors not shown)

Abstract: We present the first joint measurement of muon neutrino CC$0πNp$ interactions on carbon and oxygen targets, in two double-differential kinematic imbalance (KI) observable spaces, $δp_{T}$-$δα_{T}$ and $p_{N}$-$\cosθ_μ$. The measurement employs the ND280 detector of the T2K experiment and includes a detailed description of the event selection used to define signal and control regions, the evaluatio… ▽ More We present the first joint measurement of muon neutrino CC$0πNp$ interactions on carbon and oxygen targets, in two double-differential kinematic imbalance (KI) observable spaces, $δp_{T}$-$δα_{T}$ and $p_{N}$-$\cosθ_μ$. The measurement employs the ND280 detector of the T2K experiment and includes a detailed description of the event selection used to define signal and control regions, the evaluation of systematic uncertainties, and the signal extraction procedure, together with validation studies supporting a robust cross-section measurement. The results of this analysis indicate that current neutrino-nucleus interaction models do not adequately describe the data, and demonstrate the strong discriminating power of KI observables. This measurement highlights the need for improved theoretical nuclear modeling within neutrino interaction generators to achieve increased precision in neutrino oscillation measurements. △ Less

Submitted 12 July, 2026; originally announced July 2026.

First double-differential measurement of pionless charged-current muon neutrino interactions using kinematic imbalance observables on carbon and oxygen with the T2K experiment

Authors: K. Abe, S. Abe, H. Adhikary, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Asami, Y. Asaoka, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak , et al. (380 additional authors not shown)

Abstract: We report the first measurement of muon-neutrino charged-current cross section as a function of kinematic imbalance (KI) observables on oxygen with no pions and at least one proton in the final state, using the T2K ND280 detector. The cross section is extracted simultaneously for carbon and oxygen targets and double-differentially as a function of several KI observables, providing new insight into… ▽ More We report the first measurement of muon-neutrino charged-current cross section as a function of kinematic imbalance (KI) observables on oxygen with no pions and at least one proton in the final state, using the T2K ND280 detector. The cross section is extracted simultaneously for carbon and oxygen targets and double-differentially as a function of several KI observables, providing new insight into the modeling of nuclear effects. This joint measurement offers direct sensitivity to the correlations between two targets, a key ingredient for reducing systematic uncertainties in neutrino oscillation experiments that employ multiple target nuclei, such as T2K and Hyper-Kamiokande. Comparisons with predictions from widely used neutrino event generators show that none of the models fully describe the data across all regions of measured phase space. These results highlight possible directions where improvements in neutrino-nucleus interaction modeling are needed for current and future neutrino oscillation experiments. △ Less

Submitted 14 July, 2026; v1 submitted 12 July, 2026; originally announced July 2026.

Comments: Added cross reference to arXiv:2607.10644

Constraining Neutrino Interaction Uncertainties for Neutrino Oscillation Measurements at the T2K Experiment

Authors: K. Abe, S. Abe, H. Adhikary, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Asami, Y. Asaoka, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak , et al. (417 additional authors not shown)

Abstract: In the context of neutrino oscillation measurements from the T2K experiment, the off-axis near detector ND280 plays a crucial role in constraining the incoming neutrino flux and neutrino-nucleus interaction cross sections. The result is a robust control over systematic uncertainties in the fit of neutrino oscillation parameters to the data at the T2K far detector, Super-Kamiokande. This paper deta… ▽ More In the context of neutrino oscillation measurements from the T2K experiment, the off-axis near detector ND280 plays a crucial role in constraining the incoming neutrino flux and neutrino-nucleus interaction cross sections. The result is a robust control over systematic uncertainties in the fit of neutrino oscillation parameters to the data at the T2K far detector, Super-Kamiokande. This paper details the methodology and results of these constraints in the context of the latest neutrino oscillation analysis from T2K. It describes how a new neutrino cross-section model and refined flux prediction are parameterized and fit to data in new ND280 event selections. Additionally, this work reports the results of extensive robustness studies, including fits with alternative interaction models, consistency checks against publicly available cross-section measurements, and \textit{p}-value evaluations, to demonstrate the reliability and robustness of our methodology. Finally, we present a sensitivity study demonstrating that the upgraded ND280, with improved acceptance and a lower hadron threshold, may enhance future constraints and further reduce systematic uncertainties in oscillation measurements. △ Less

Submitted 11 June, 2026; originally announced June 2026.

The Super Fine-Grained Detector for the T2K neutrino oscillation experiment

Authors: S. Abe, H. Alarakia-Charles, I. Alekseev, T. Arai, T. Arihara, S. Arimoto, A. M. Artikov, Y. Awataguchi, N. Babu, V. Baranov, G. Barr, D. Barrow, L. Bartoszek, A. Beliakova, L. Bernardi, L. Berns, S. Bhattacharjee, A. V. Boikov, A. Blondel, A. Bonnemaison, F. Cadoux, S. Cap, A. Cauchois, J. Chakrani, P. S. Chong , et al. (147 additional authors not shown)

Abstract: The magnetised near detector ND280 of the long-baseline neutrino experiment T2K has been upgraded to improve its detection performance and, consequently, enhance our understanding of neutrino-nucleus interactions, reducing the systematic uncertainties in measurements of the neutrino oscillation parameters. A key component of the upgrade is a novel segmented plastic scintillator detector, called th… ▽ More The magnetised near detector ND280 of the long-baseline neutrino experiment T2K has been upgraded to improve its detection performance and, consequently, enhance our understanding of neutrino-nucleus interactions, reducing the systematic uncertainties in measurements of the neutrino oscillation parameters. A key component of the upgrade is a novel segmented plastic scintillator detector, called the Super Fine-Grained Detector (SuperFGD), made of approximately 2 million optically isolated 1 cm$^3$ cubes read out by three orthogonal wavelength-shifting (WLS) fibres. Scintillation photons are detected by 55,888 Hamamatsu Multi-Pixel Photon Counters (MPPCs). The SuperFGD provides 3D images of neutrino interactions by tracking the final-state charged particles produced isotropically, including protons down to a threshold of around 330 MeV/$c$. The high light yield of SuperFGD greatly improves particle identification and the sub-nanosecond time resolution provides an excellent identification of Michel electrons. The SuperFGD is also able to detect neutrons from neutrino interactions and, for the first time in a neutrino experiment, to reconstruct their kinetic energy using a fine detector segmentation and by measuring the time-of-flight with sub-nanosecond precision. In this article the details of the detector design, construction and performance are described. The detector was installed in ND280 and successfully commissioned with cosmic data in 2023 and, later, with the T2K neutrino beam. The detector response has been characterised with the 2023 and 2024 data and the results are reported in this article. △ Less

Submitted 16 March, 2026; originally announced March 2026.

Weighted Chui's conjecture

Authors: Evgueni Doubtsov, Anton Tselishchev, Ioann Vasilyev

Abstract: The goals of this paper are threefold. First, we show that a counterpart of the Newman bound related to the Chui conjecture is valid in the case where the gradient of Coulomb potential is generated by arbitrary positive charges placed at the boundary of a unit ball. Second, we prove that our bound is sharp in the two-dimensional case. Finally, we discuss a related problem, where the unit charges a… ▽ More The goals of this paper are threefold. First, we show that a counterpart of the Newman bound related to the Chui conjecture is valid in the case where the gradient of Coulomb potential is generated by arbitrary positive charges placed at the boundary of a unit ball. Second, we prove that our bound is sharp in the two-dimensional case. Finally, we discuss a related problem, where the unit charges are placed in the unit disc. △ Less

Submitted 11 May, 2026; v1 submitted 5 March, 2026; originally announced March 2026.

Comments: Comments are welcome! v2: minor corrections

MSC Class: 30E20

Joint neutrino oscillation analysis from the T2K and NOvA experiments

Authors: NOvA, T2K Collaborations, :, K. Abe, S. Abe, S. Abubakar, M. A. Acero, B. Acharya, P. Adamson, H. Adhkary, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, N. Anfimov, L. Anthony, A. Antoshkin, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, E. Arrieta-Diaz, Y. Ashida, L. Asquith , et al. (577 additional authors not shown)

Abstract: The landmark discovery that neutrinos have mass and can change type (or "flavor") as they propagate -- a process called neutrino oscillation -- has opened up a rich array of theoretical and experimental questions being actively pursued today. Neutrino oscillation remains the most powerful experimental tool for addressing many of these questions, including whether neutrinos violate charge-parity (C… ▽ More The landmark discovery that neutrinos have mass and can change type (or "flavor") as they propagate -- a process called neutrino oscillation -- has opened up a rich array of theoretical and experimental questions being actively pursued today. Neutrino oscillation remains the most powerful experimental tool for addressing many of these questions, including whether neutrinos violate charge-parity (CP) symmetry, which has possible connections to the unexplained preponderance of matter over antimatter in the universe. Oscillation measurements also probe the mass-squared differences between the different neutrino mass states ($Δm^2$), whether there are two light states and a heavier one (normal ordering) or vice versa (inverted ordering), and the structure of neutrino mass and flavor mixing. Here, we carry out the first joint analysis of data sets from NOvA and T2K, the two currently operating long-baseline neutrino oscillation experiments (hundreds of kilometers of neutrino travel distance), taking advantage of our complementary experimental designs and setting new constraints on several neutrino sector parameters. This analysis provides new precision on the $Δm^2_{32}$ mass difference, finding $2.43^{+0.04}_{-0.03}\ \left(-2.48^{+0.03}_{-0.04}\right)\times 10^{-3}~\mathrm{eV}^2$ in the normal (inverted) ordering, as well as a $3σ$ interval on $δ_{\rm CP}$ of $[-1.38π,\ 0.30π]$ $\left([-0.92π,\ -0.04π]\right)$ in the normal (inverted) ordering. The data show no strong preference for either mass ordering, but notably if inverted ordering were assumed true within the three-flavor mixing paradigm, then our results would provide evidence of CP symmetry violation in the lepton sector. △ Less

Submitted 24 October, 2025; v1 submitted 22 October, 2025; originally announced October 2025.

Comments: 25 pages, 13 figures

Journal ref: Nature 646, 818-824 (2025)

Measurement of muon neutrino induced charged current interactions without charged pions in the final state using a new T2K off-axis near detector WAGASCI-BabyMIND

Authors: K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi, L. Berns , et al. (377 additional authors not shown)

Abstract: We report a flux-integrated cross section measurement of muon neutrino interactions on water and hydrocarbon via charged current reactions without charged pions in the final state with the WAGASCI-BabyMIND detector which was installed in the T2K near detector hall in 2018. The detector is located 1.5$^\circ$ off-axis and is exposed to a more energetic neutrino flux than ND280, another T2K near det… ▽ More We report a flux-integrated cross section measurement of muon neutrino interactions on water and hydrocarbon via charged current reactions without charged pions in the final state with the WAGASCI-BabyMIND detector which was installed in the T2K near detector hall in 2018. The detector is located 1.5$^\circ$ off-axis and is exposed to a more energetic neutrino flux than ND280, another T2K near detector, which is located at a different off-axis position. The total flux-integrated cross section is measured to be $1.26 \pm 0.18\,(stat.+syst.) \times 10^{-39} $ $\mathrm{cm^{2}/nucleon}$ on CH and $1.44 \pm 0.21\,(stat.+syst.) \times 10^{-39} $ $\mathrm{cm^{2}/nucleon}$ on H$_{2}$O. These results are compared to model predictions provided by the NEUT v5.3.2 and GENIE v2.8.0 MC generators and the measurements are compatible with these models. Differential cross sections in muon momentum and cosine of the muon scattering angle are also reported. This is the first such measurement reported with the WAGASCI-BabyMIND detector and utilizes the 2020 and 2021 datasets. △ Less

Submitted 6 January, 2026; v1 submitted 9 September, 2025; originally announced September 2025.

Journal ref: Phys. Rev. D 112, 112020 (2025)

Introducing a Markov Chain-Based Time Calibration Procedure for Multi-Channel Particle Detectors: Application to the SuperFGD and ToF Detectors of the T2K Experiment

Authors: S. Abe, H. Alarakia-Charles, I. Alekseev, C. Alt, T. Arai, T. Arihara, S. Arimoto, A. M. Artikov, Y. Awataguchi, N. Babu, V. Baranov, G. Barr, D. Barrow, L. Bartoszek, L. Bernardi, L. Berns, S. Bhattacharjee, A. V. Boikov, A. Blanchet, A. Blondel, A. Bonnemaison, S. Bordoni, M. H. Bui, T. H. Bui, F. Cadoux , et al. (168 additional authors not shown)

Abstract: Inter-channel mis-synchronisation can be a limiting factor to the time resolution of high performance timing detectors with multiple readout channels and independent electronics units. In these systems, time calibration methods employed must be able to efficiently correct for minimal mis-synchronisation between channels and achieve the best detector performance. We present an iterative time calibr… ▽ More Inter-channel mis-synchronisation can be a limiting factor to the time resolution of high performance timing detectors with multiple readout channels and independent electronics units. In these systems, time calibration methods employed must be able to efficiently correct for minimal mis-synchronisation between channels and achieve the best detector performance. We present an iterative time calibration method based on Markov Chains, suitable for detector systems with multiple readout channels. Starting from correlated hit pairs alone, and without requiring an external reference time measurement, the method solves for fixed per-channel offsets, with precision limited only by the intrinsic single-channel resolution. A mathematical proof that the method is able to find the correct time offsets to be assigned to each detector channel in order to achieve inter-channel synchronisation is given, and it is shown that the number of iterations to reach convergence within the desired precision is controllable with a single parameter. Numerical studies are used to confirm unbiased recovery of true offsets. Finally, the application of the calibration method to the Super Fine-Grained Detector (SuperFGD) and the Time of Flight (TOF) detector at the upgraded T2K near detector (ND280) shows good improvement in overall timing resolution, demonstrating the effectiveness in a real-world scenario and scalability. △ Less

Submitted 19 September, 2025; v1 submitted 11 August, 2025; originally announced August 2025.

Comments: 25 pages, 17 figures - Small improvement of plots aesthetics after JINST minor revision

Testing T2K's Bayesian constraints with priors in alternate parameterisations

Authors: The T2K Collaboration, K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi , et al. (379 additional authors not shown)

Abstract: Bayesian analysis results require a choice of prior distribution. In long-baseline neutrino oscillation physics, the usual parameterisation of the mixing matrix induces a prior that privileges certain neutrino mass and flavour state symmetries. Here we study the effect of privileging alternate symmetries on the results of the T2K experiment. We find that constraints on the level of CP violation (a… ▽ More Bayesian analysis results require a choice of prior distribution. In long-baseline neutrino oscillation physics, the usual parameterisation of the mixing matrix induces a prior that privileges certain neutrino mass and flavour state symmetries. Here we study the effect of privileging alternate symmetries on the results of the T2K experiment. We find that constraints on the level of CP violation (as given by the Jarlskog invariant) are robust under the choices of prior considered in the analysis. On the other hand, the degree of octant preference for the atmospheric angle depends on which symmetry has been privileged. △ Less

Submitted 2 July, 2025; originally announced July 2025.

Journal ref: Eur.Phys.J.C 85 (2025) 12, 1414

On the zero sets of harmonic polynomials

Authors: Ioann Vasilyev

Abstract: In this paper we consider nonzero harmonic functions vanishing on some subsets of $\mathbb R^n$. We give a positive solution to Problem 151 from the Scottish Book posed by R. Wavre in 1936. In more detail, we construct a nonzero harmonic polynomial that vanishes on the edges of the unit cube. Moreover, using harmonic morphisms we build new nontrivial families of harmonic polynomials that vanish at… ▽ More In this paper we consider nonzero harmonic functions vanishing on some subsets of $\mathbb R^n$. We give a positive solution to Problem 151 from the Scottish Book posed by R. Wavre in 1936. In more detail, we construct a nonzero harmonic polynomial that vanishes on the edges of the unit cube. Moreover, using harmonic morphisms we build new nontrivial families of harmonic polynomials that vanish at the same set in the unit ball in $\mathbb R^n$ for all $n \geq 4$. This extends certain results by Logunov and Malinnikova. We also present new results on harmonic functions in the space whose zero sets are unions of affine codimension two subspaces. △ Less

Submitted 30 December, 2025; v1 submitted 30 June, 2025; originally announced June 2025.

Comments: 11 pages, no figures. Comments are welcome ! Some minor changes. Some typos corrected. Referee's remarks incorporated

MSC Class: 31B05; 58E20

Results from the T2K experiment on neutrino mixing including a new far detector $μ$-like sample

Authors: The T2K Collaboration, K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi , et al. (383 additional authors not shown)

Abstract: We have made improved measurements of three-flavor neutrino mixing with 19.7(16.3)$\times 10^{20}$ protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, as well as new proton and photon-tagged samples at the near detector. Significant improvements have been made to the flux and neutrino interaction model… ▽ More We have made improved measurements of three-flavor neutrino mixing with 19.7(16.3)$\times 10^{20}$ protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, as well as new proton and photon-tagged samples at the near detector. Significant improvements have been made to the flux and neutrino interaction modeling. T2K data continue to prefer the normal mass ordering and upper octant of $\sin^2θ_{23}$ with a near-maximal value of the charge-parity violating phase with best-fit values in the normal ordering of $δ_{\scriptscriptstyle\mathrm{CP}}=-2.18\substack{+1.22 \\ -0.47}$, $\sin^2θ_{23}=0.559\substack{+0.018 \\ -0.078}$ and $Δm^2_{32}=(+2.506\substack{+0.039 \\ -0.052})\times 10^{-3}$ eV$^{2}$. △ Less

Submitted 30 December, 2025; v1 submitted 6 June, 2025; originally announced June 2025.

Comments: Version accepted for publication by PRL

Journal ref: Phys. Rev. Lett. 135, 261801 (2025)

First Measurement of the Electron Neutrino Charged-Current Pion Production Cross Section on Carbon with the T2K Near Detector

Authors: K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi, L. Berns, S. Bhattacharjee , et al. (371 additional authors not shown)

Abstract: The T2K Collaboration presents the first measurement of electron neutrino-induced charged-current pion production on carbon in a restricted kinematical phase space. This is performed using data from the 2.5$^°$ off-axis near detector, ND280. The differential cross sections with respect to the outgoing electron and pion kinematics, in addition to the total flux-integrated cross section, are obtai… ▽ More The T2K Collaboration presents the first measurement of electron neutrino-induced charged-current pion production on carbon in a restricted kinematical phase space. This is performed using data from the 2.5$^°$ off-axis near detector, ND280. The differential cross sections with respect to the outgoing electron and pion kinematics, in addition to the total flux-integrated cross section, are obtained. Comparisons between the measured and predicted cross section results using the Neut, Genie and NuWro Monte Carlo event generators are presented. The measured total flux-integrated cross section is [2.52 $\pm$ 0.52 (stat) $\pm$ 0.30 (sys)] x $10^{-39}$ cm$^2$ nucleon$^{-1}$, which is lower than the event generator predictions. △ Less

Submitted 1 May, 2025; originally announced May 2025.

Comments: 8 pages, 2 figures. Data release: https://zenodo.org/records/15316318

First differential measurement of the single $\mathbfπ^+$ production cross section in neutrino neutral-current scattering

Authors: K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi, L. Berns , et al. (357 additional authors not shown)

Abstract: Since its first observation in the 1970s, neutrino-induced neutral-current single positive pion production (NC1$π^+$) has remained an elusive and poorly understood interaction channel. This process is a significant background in neutrino oscillation experiments and studying it further is critical for the physics program of next-generation accelerator-based neutrino oscillation experiments. In this… ▽ More Since its first observation in the 1970s, neutrino-induced neutral-current single positive pion production (NC1$π^+$) has remained an elusive and poorly understood interaction channel. This process is a significant background in neutrino oscillation experiments and studying it further is critical for the physics program of next-generation accelerator-based neutrino oscillation experiments. In this Letter we present the first double-differential cross-section measurement of NC1$π^+$ interactions using data from the ND280 detector of the T2K experiment collected in $ν$-beam mode. The measured flux-averaged integrated cross-section is $ σ= (6.07 \pm 1.22 )\times 10^{-41} \,\, \text{cm}^2/\text{nucleon}$. We compare the results on a hydrocarbon target to the predictions of several neutrino interaction generators and final-state interaction models. While model predictions agree with the differential results, the data shows a weak preference for a cross-section normalization approximately 30\% higher than predicted by most models studied in this Letter. △ Less

Submitted 1 July, 2025; v1 submitted 9 March, 2025; originally announced March 2025.

Signal selection and model-independent extraction of the neutrino neutral-current single $π^+$ cross section with the T2K experiment

Authors: K. Abe, S. Abe, R. Akutsu, H. Alarakia-Charles, Y. I. Alj Hakim, S. Alonso Monsalve, L. Anthony, S. Aoki, K. A. Apte, T. Arai, T. Arihara, S. Arimoto, Y. Ashida, E. T. Atkin, N. Babu, V. Baranov, G. J. Barker, G. Barr, D. Barrow, P. Bates, L. Bathe-Peters, M. Batkiewicz-Kwasniak, N. Baudis, V. Berardi, L. Berns , et al. (357 additional authors not shown)

Abstract: This article presents a study of single $π^+$ production in neutrino neutral-current interactions (NC1$π^+$) using the FGD1 hydrocarbon target of the ND280 detector of the T2K experiment. We report the largest sample of such events selected by any experiment, providing the first new data for this channel in over four decades and the first using a sub-GeV neutrino flux. The signal selection strateg… ▽ More This article presents a study of single $π^+$ production in neutrino neutral-current interactions (NC1$π^+$) using the FGD1 hydrocarbon target of the ND280 detector of the T2K experiment. We report the largest sample of such events selected by any experiment, providing the first new data for this channel in over four decades and the first using a sub-GeV neutrino flux. The signal selection strategy and its performance are detailed together with validations of a robust cross section extraction methodology. The measured flux-averaged integrated cross-section is $ σ= (6.07 \pm 1.22 )\times 10^{-41} \,\, \text{cm}^2/\text{nucleon}$, 1.3~$σ~$ above the NEUT v5.4.0 expectation. △ Less

Submitted 1 July, 2025; v1 submitted 9 March, 2025; originally announced March 2025.

Reverse Carleson measures for spaces of analytic functions

Authors: Evgueni Doubtsov, Anton Tselishchev, Ioann Vasilyev

Abstract: Let $X$ be a quasi-Banach space of analytic functions in the unit disc and let $q>0$. A finite positive Borel measure $μ$ in the closed unit disc $\overline{\mathbb{D}}$ is called a $q$-reverse Carleson measure for $X$ if and only if there exists a constant $C>0$ such that $$\|f\|_{X}\leq C \|f\|_{L^q(\overline{\mathbb D},dμ)} $$ for all $f\in X\cap C(\overline{\mathbb D})$. We fully characterize… ▽ More Let $X$ be a quasi-Banach space of analytic functions in the unit disc and let $q>0$. A finite positive Borel measure $μ$ in the closed unit disc $\overline{\mathbb{D}}$ is called a $q$-reverse Carleson measure for $X$ if and only if there exists a constant $C>0$ such that $$\|f\|_{X}\leq C \|f\|_{L^q(\overline{\mathbb D},dμ)} $$ for all $f\in X\cap C(\overline{\mathbb D})$. We fully characterize the $q$-reverse Carleson measures with all $q>0$ for Hardy spaces $H^p(\mathbb D)$ with all $0<p\leq \infty$, for the space $\mathrm{BMOA}(\mathbb D)$ and for the Bloch space. In addition, we describe $q$-reverse Carleson measures for the holomorphic Triebel--Lizorkin spaces $HF_0^{q,r}$ and the holomorphic Besov spaces $HB_0^{q,r}$. Related results are obtained for the Hardy spaces and certain holomorphic Triebel--Lizorkin spaces in the unit ball of $\mathbb{C}^d$. △ Less

Submitted 3 December, 2024; originally announced December 2024.

Comments: 25 pages, no figures. Comments are welcome !

MSC Class: 30H10; 30H25; 30H30; 30H99; 32A35; 32A37; 46E35

Characterization of the optical model of the T2K 3D segmented plastic scintillator detector

Authors: S. Abe, I. Alekseev, T. Arai, T. Arihara, S. Arimoto, N. Babu, V. Baranov, L. Bartoszek, L. Berns, S. Bhattacharjee, A. Blondel, A. V. Boikov, M. Buizza-Avanzini, J. Capó, J. Cayo, J. Chakrani, P. S. Chong, A. Chvirova, M. Danilov, C. Davis, Yu. I. Davydov, A. Dergacheva, N. Dokania, D. Douqa, T. A. Doyle , et al. (106 additional authors not shown)

Abstract: The magnetised near detector (ND280) of the T2K long-baseline neutrino oscillation experiment has been recently upgraded aiming to satisfy the requirement of reducing the systematic uncertainty from measuring the neutrinonucleus interaction cross section, which is the largest systematic uncertainty in the search for leptonic charge-parity symmetry violation. A key component of the upgrade is Super… ▽ More The magnetised near detector (ND280) of the T2K long-baseline neutrino oscillation experiment has been recently upgraded aiming to satisfy the requirement of reducing the systematic uncertainty from measuring the neutrinonucleus interaction cross section, which is the largest systematic uncertainty in the search for leptonic charge-parity symmetry violation. A key component of the upgrade is SuperFGD, a 3D segmented plastic scintillator detector made of approximately 2,000,000 optically-isolated 1 cm3 cubes. It will provide a 3D image of GeV neutrino interactions by combining tracking and stopping power measurements of final state particles with sub-nanosecond time resolution. The performance of SuperFGD is characterized by the precision of its response to charged particles as well as the systematic effects that might affect the physics measurements. Hence, a detailed Geant4 based optical simulation of the SuperFGD building block, i.e. a plastic scintillating cube read out by three wavelength shifting fibers, has been developed and validated with the different datasets collected in various beam tests. In this manuscript the description of the optical model as well as the comparison with data are reported. △ Less

Submitted 31 October, 2024; originally announced October 2024.

Comments: 31 pages, 15 figures

Sharp Rise in Cosmic Ray Irradiation of Organisms on Earth Caused by a Nearby SN Shockwave Passage

Authors: A. A. Shchepkin, G. I. Vasilyev, V. M. Ostryakov, A. K. Pavlov

Abstract: The work considers the modelling of nearby supernova (SN) effects on Earth's biosphere via cosmic rays (CRs) accelerated by shockwaves. The rise of the radiation background on Earth resulted from the external irradiation by CR high-energy particles and internal radiation in organisms by the decay of cosmogenic ${}^{14}$C is evaluated. We have taken into account that the CR flux near Earth goes up… ▽ More The work considers the modelling of nearby supernova (SN) effects on Earth's biosphere via cosmic rays (CRs) accelerated by shockwaves. The rise of the radiation background on Earth resulted from the external irradiation by CR high-energy particles and internal radiation in organisms by the decay of cosmogenic ${}^{14}$C is evaluated. We have taken into account that the CR flux near Earth goes up steeply when the shockwave crosses the Solar System, while in previous works the CR transport was considered as purely diffusive. Our simulations demonstrate a high rise of the external ionization of the environments at Earth's surface by atmospheric cascade particles that penetrate the first 70-100 m of water depth. Also, the cosmogenic ${}^{14}$C decay is able to irradiate the entire biosphere and deep ocean organisms. We analyzed the probable increase in mutation rate and estimated the distance between Earth and an SN, where the lethal effects of irradiation are possible. Our simulations demonstrate that for SN energy of around $10^{51}$ erg the lethal distance could be $\sim$ 18 pc. △ Less

Submitted 30 August, 2024; originally announced September 2024.

Journal ref: Astrobiology, 24:6, p. 604-612 (2024)

The property $\log(f) \in BMO(\mathbb R^n)$ in terms of Riesz transforms

Authors: Ioann Vasilyev

Abstract: The condition mentioned in the title is equivalent to the representability of $f$ as the quotient $f=v_1/v_2$, where $v_1$ and $v_2$ obey the inequalities $|R_j v_i| \leq C |v_i|$ for $i=1,2$ and $j=1,\ldots, n$. Here, $R_1,\ldots, R_n$ are the Riesz transformations. The condition mentioned in the title is equivalent to the representability of $f$ as the quotient $f=v_1/v_2$, where $v_1$ and $v_2$ obey the inequalities $|R_j v_i| \leq C |v_i|$ for $i=1,2$ and $j=1,\ldots, n$. Here, $R_1,\ldots, R_n$ are the Riesz transformations. △ Less

Submitted 20 May, 2024; v1 submitted 19 February, 2024; originally announced February 2024.

Comments: 8 pages, no figures; typos in the Abstract corrected

Journal ref: Journal of Mathematical Sciences, Vol. 202, No. 4, October, 2014

Some remarks on K-closedness of the couples of real Hardy spaces

Authors: Ioann Vasilyev

Abstract: In this paper K closedness is proved in the case of the couple of real Hardy spaces in the corresponding couple of Lebesgue spaces. This means roughly that any measurable decomposition of an analytic function gives rise to an "analytic" decomposition with summands of roughly the same size. The proof uses Bourgain's method, the atomic decomposition for Hardy spaces and the subharmonic property of t… ▽ More In this paper K closedness is proved in the case of the couple of real Hardy spaces in the corresponding couple of Lebesgue spaces. This means roughly that any measurable decomposition of an analytic function gives rise to an "analytic" decomposition with summands of roughly the same size. The proof uses Bourgain's method, the atomic decomposition for Hardy spaces and the subharmonic property of the gradient of a system of conjugate harmonic functions. △ Less

Submitted 19 February, 2024; originally announced February 2024.

Comments: 9 pages, no figures

Journal ref: Journal of Functional Analysis 270 (2016) 705--717

High efficiency muon registration system based on scintillator strips

Authors: A. Artikov, V. Baranov, A. Boikov, D. Chokheli, Yu. I. Davydov, V. Glagolev, A. Simonenko, Z. Tsamalaidze, I. Vasilyev, I. Zimin

Abstract: Experiments such as mu2e (FNAL, USA) and COMET (KEK, Japan), seeking the direct muon-to-electron conversion as part of the study of Charged Leptons Flavor Violation processes, should have a extremely high, up-to 99.99\%, efficiency muon detection system with a view to their subsequent suppression as background. In this article, the possibility to achieve such efficiency for a short and long term i… ▽ More Experiments such as mu2e (FNAL, USA) and COMET (KEK, Japan), seeking the direct muon-to-electron conversion as part of the study of Charged Leptons Flavor Violation processes, should have a extremely high, up-to 99.99\%, efficiency muon detection system with a view to their subsequent suppression as background. In this article, the possibility to achieve such efficiency for a short and long term is discussed for modules based on 7- or 10-mm-thick but same 40-mm-wide plastic scintillation strips with single 1.2 mm WLS fiber glued into the groove along the strip and using MPPC/SiPM for light detection. A Simplified Light Yield Distribution method to estimate the efficiency of the module was proposed and the simulation results obtained with GEANT 4 for a system based on a 4-by-4 array of 7x40x3000 mm strips compared with the experimental data. Found that for the systems required the high level registration efficiency at the 99.99\% and more, it is important to improve the light yield as much as possible and achieve the gap between neighbor scintillation volumes as small as possible. △ Less

Submitted 3 October, 2023; v1 submitted 25 September, 2023; originally announced September 2023.

The Beurling and Malliavin Theorem in Several Dimensions

Authors: Ioann Vasilyev

Abstract: The present paper is devoted to a new multidimensional generalization of the Beurling and Malliavin Theorem, which is a classical result in the Uncertainty Principle in Fourier Analysis. In more detail, we establish by an elegant but simple new method a sufficient condition for a radial function to be a Beurling and Malliavin majorant in several dimensions (this means that the function in question… ▽ More The present paper is devoted to a new multidimensional generalization of the Beurling and Malliavin Theorem, which is a classical result in the Uncertainty Principle in Fourier Analysis. In more detail, we establish by an elegant but simple new method a sufficient condition for a radial function to be a Beurling and Malliavin majorant in several dimensions (this means that the function in question can be minorized by the modulus of a square integrable function which is not zero identically and which has the support of the Fourier transform included in an arbitrary small ball). As a corollary of the radial case, we also get a new sharp sufficient condition in the nonradial case. The latter result provides an answer to a question posed by L. Hörmander. Our proof is different in the cases of odd and even dimensions. In the even dimensional case we make use of one classical formula from the theory of Bessel functions due to N. Ya. Sonin. △ Less

Submitted 1 January, 2026; v1 submitted 21 June, 2023; originally announced June 2023.

Comments: The introduction section slightly modified. 16 pages, no figures, submitted. I am grateful to Alex Cohen and Semyon Dyatlov for valuable comments on my paper. Several points in the introduction section explained better

Journal ref: Mathematische Annalen Volume 391, pages 6057--6072, (2025)

Density-dependent incompressible Navier--Stokes equations in critical tent spaces

Authors: Raphaël Danchin, Ioann Vasilyev

Abstract: In this article, we prove the existence of global solutions to the inhomogeneous incompressible Navier--Stokes equations, whenever the initial velocity belongs to a certain subspace of $\mathrm{BMO}^{-1}$, and the initial density is sufficiently close to $1$ in the uniform metric. This is a natural extension to the variable density case of the celebrated result by H. Koch and D. Tataru concerning… ▽ More In this article, we prove the existence of global solutions to the inhomogeneous incompressible Navier--Stokes equations, whenever the initial velocity belongs to a certain subspace of $\mathrm{BMO}^{-1}$, and the initial density is sufficiently close to $1$ in the uniform metric. This is a natural extension to the variable density case of the celebrated result by H. Koch and D. Tataru concerning the classical Navier-Stokes equations. △ Less

Submitted 22 July, 2026; v1 submitted 15 May, 2023; originally announced May 2023.

Comments: Many typos corrected; a few references added. In the current version, we added estimates of several terms in technical lemmas that were missing

MSC Class: 35Q30; 76D05; 42B35

Neutrinoless Double Beta Decay

Authors: C. Adams, K. Alfonso, C. Andreoiu, E. Angelico, I. J. Arnquist, J. A. A. Asaadi, F. T. Avignone, S. N. Axani, A. S. Barabash, P. S. Barbeau, L. Baudis, F. Bellini, M. Beretta, T. Bhatta, V. Biancacci, M. Biassoni, E. Bossio, P. A. Breur, J. P. Brodsky, C. Brofferio, E. Brown, R. Brugnera, T. Brunner, N. Burlac, E. Caden , et al. (207 additional authors not shown)

Abstract: This White Paper, prepared for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting related to the 2023 Nuclear Physics Long Range Plan, makes the case for double beta decay as a critical component of the future nuclear physics program. The major experimental collaborations and many theorists have endorsed this white paper. This White Paper, prepared for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting related to the 2023 Nuclear Physics Long Range Plan, makes the case for double beta decay as a critical component of the future nuclear physics program. The major experimental collaborations and many theorists have endorsed this white paper. △ Less

Submitted 21 December, 2022; originally announced December 2022.

Comments: white paper submitted for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting in support of the US Nuclear Physics Long Range Planning Process

Boosting Heterogeneous Catalyst Discovery by Structurally Constrained Deep Learning Models

Authors: Alexey N. Korovin, Innokentiy S. Humonen, Artem I. Samtsevich, Roman A. Eremin, Artem I. Vasilyev, Vladimir D. Lazarev, Semen A. Budennyy

Abstract: The discovery of new catalysts is one of the significant topics of computational chemistry as it has the potential to accelerate the adoption of renewable energy sources. Recently developed deep learning approaches such as graph neural networks (GNNs) open new opportunity to significantly extend scope for modelling novel high-performance catalysts. Nevertheless, the graph representation of particu… ▽ More The discovery of new catalysts is one of the significant topics of computational chemistry as it has the potential to accelerate the adoption of renewable energy sources. Recently developed deep learning approaches such as graph neural networks (GNNs) open new opportunity to significantly extend scope for modelling novel high-performance catalysts. Nevertheless, the graph representation of particular crystal structure is not a straightforward task due to the ambiguous connectivity schemes and numerous embeddings of nodes and edges. Here we present embedding improvement for GNN that has been modified by Voronoi tesselation and is able to predict the energy of catalytic systems within Open Catalyst Project dataset. Enrichment of the graph was calculated via Voronoi tessellation and the corresponding contact solid angles and types (direct or indirect) were considered as features of edges and Voronoi volumes were used as node characteristics. The auxiliary approach was enriching node representation by intrinsic atomic properties (electronegativity, period and group position). Proposed modifications allowed us to improve the mean absolute error of the original model and the final error equals to 651 meV per atom on the Open Catalyst Project dataset and 6 meV per atom on the intermetallics dataset. Also, by consideration of additional dataset, we show that a sensible choice of data can decrease the error to values above physically-based 20 meV per atom threshold. △ Less

Submitted 2 October, 2022; v1 submitted 11 July, 2022; originally announced July 2022.

Journal ref: Materials Today Chemistry 2023, 30, 101541

SuperFGD prototype time resolution studies

Authors: I. Alekseev, T. Arihara, V. Baranov, L. Bartoszek, L. Bernardi, A. Blondel, A. V. Boikov, M. Buizza-Avanzini, F. Cadoux, J. Capó, J. Cayo, J. Chakrani, P. S. Chong, A. Chvirova, M. Danilov, Yu. I. Davydov, A. Dergacheva, N. Dokania, D. Douqa, O. Drapier, A. Eguchi, Y. Favre, D. Fedorova, S. Fedotov, Y. Fujii , et al. (65 additional authors not shown)

Abstract: The SuperFGD will be a part of the ND280 near detector of the T2K and Hyper Kamiokande projects, that will help to reduce systematic uncertainties related with neutrino flux and cross-section modeling. The upgraded ND280 will be able to perform a full exclusive reconstruction of the final state from neutrino-nucleus interactions, including measurements of low momentum protons, pions and, for the f… ▽ More The SuperFGD will be a part of the ND280 near detector of the T2K and Hyper Kamiokande projects, that will help to reduce systematic uncertainties related with neutrino flux and cross-section modeling. The upgraded ND280 will be able to perform a full exclusive reconstruction of the final state from neutrino-nucleus interactions, including measurements of low momentum protons, pions and, for the first time, event-by event measurements of neutron kinematics. The time resolution defines the neutron energy resolution. We present the results of time resolution measurements made with the SuperFGD prototype that consists of 9216 plastic scintillator cubes (cube size is 1 cm$^3$) readout with 1728 wavelength-shifting fibers going along three orthogonal directions. We use data from the muon beam exposure at CERN. The time resolution of 0.97 ns was obtained for one readout channel after implementing the time calibration with a correction for the time-walk effect. The time resolution improves with energy deposited in a scintillator cube. Averaging two readout channels for one scintillator cube improves the time resolution to 0.68 ns which means that signals in different channels are not synchronous. Therefore the contribution from the time recording step of 2.5 ns is averaged as well. Averaging time values from N channels improves the time resolution by $\sim 1/\sqrt{N}$. Therefore a very good time resolution should be achievable for neutrons since neutron recoils hit typically several scintillator cubes and in addition produce larger amplitudes than muons. Measurements performed with a laser and a wide-bandwidth oscilloscope demonstrated that the time resolution obtained with the muon beam is not far from its expected limit. The intrinsic time resolution of one channel is 0.67 ns for signals of 56 photo-electron typical for minimum ionizing particles. △ Less

Submitted 18 January, 2023; v1 submitted 21 June, 2022; originally announced June 2022.

Comments: 12 pages, 9 figures. Revised text, results unchanged

Journal ref: JINST 18 P01012 (2023)

On Busemann--Hausdorff densities of dimension two and of codimension two, with an application to Plateau Problem

Authors: Ioann Vasilyev

Abstract: The purpose of this paper is twofold. First, we describe one (presumably) new case, in which Busemann--Hausdorff densities are convex. We apply the corresponding result to prove the existence of minimizing rectifiable chains of codimension two in complex finite dimensional normed vector spaces. Second, we prove that for each $n\geq 4$, there exists an $n$ dimensional normed space in which the corr… ▽ More The purpose of this paper is twofold. First, we describe one (presumably) new case, in which Busemann--Hausdorff densities are convex. We apply the corresponding result to prove the existence of minimizing rectifiable chains of codimension two in complex finite dimensional normed vector spaces. Second, we prove that for each $n\geq 4$, there exists an $n$ dimensional normed space in which the corresponding two dimensional Busemann--Hausdroff density is not totally convex. This gives a negative answer to a question posed by H. Busemann and E. Strauss. △ Less

Submitted 19 February, 2024; v1 submitted 31 March, 2022; originally announced March 2022.

Comments: Yet another result for the existence in Plateau Problem added (which caused a change of the title) plus some minor revisions. The introduction section slightly modified. 18 pages, no figures

MSC Class: 28A75; 49Q15; 49Q20; 28A78; 52A51

A generalization of the Beurling--Malliavin Majorant theorem

Authors: Ioann Vasilyev

Abstract: In this article we prove a generalization of the Beurling--Malliavin Majorant Theorem. In more detail, we establish a new sufficient condition for a function to be a Beurling--Malliavin Majorant. Our result is strictly more general than that of the Beurling--Malliavin Majorant Theorem. We also show that our result is sharp in a number senses. In this article we prove a generalization of the Beurling--Malliavin Majorant Theorem. In more detail, we establish a new sufficient condition for a function to be a Beurling--Malliavin Majorant. Our result is strictly more general than that of the Beurling--Malliavin Majorant Theorem. We also show that our result is sharp in a number senses. △ Less

Submitted 19 February, 2024; v1 submitted 30 March, 2022; originally announced March 2022.

Comments: A slight inaccuracy corrected. This caused a modification of the main result. 16 pages, 2 figures. To appear in the journal Analysis & PDE. ( https://msp.org/soon/coming.php?jpath=apde )

Journal ref: ANALYSIS AND PDE Vol. 17 (2024), No. 9, pp. 3355-3369

Mu2e-II: Muon to electron conversion with PIP-II

Authors: K. Byrum, S. Corrodi, Y. Oksuzian, P. Winter, L. Xia, A. W. J. Edmonds, J. P. Miller, J. Mott, W. J. Marciano, R. Szafron, R. Bonventre, D. N. Brown, Yu. G. Kolomensky, O. Ning, V. Singh, E. Prebys, L. Borrel, B. Echenard, D. G. Hitlin, C. Hu, D. X. Lin, S. Middleton, F. C. Porter, L. Zhang, R. -Y. Zhu , et al. (83 additional authors not shown)

Abstract: An observation of Charged Lepton Flavor Violation (CLFV) would be unambiguous evidence for physics beyond the Standard Model. The Mu2e and COMET experiments, under construction, are designed to push the sensitivity to CLFV in the mu to e conversion process to unprecedented levels. Whether conversion is observed or not, there is a strong case to be made for further improving sensitivity, or for exa… ▽ More An observation of Charged Lepton Flavor Violation (CLFV) would be unambiguous evidence for physics beyond the Standard Model. The Mu2e and COMET experiments, under construction, are designed to push the sensitivity to CLFV in the mu to e conversion process to unprecedented levels. Whether conversion is observed or not, there is a strong case to be made for further improving sensitivity, or for examining the process on additional target materials. Mu2e-II is a proposed upgrade to Mu2e, with at least an additional order of magnitude in sensitivity to the conversion rate over Mu2e. The approach and challenges for this proposal are summarized. Mu2e-II may be regarded as the next logical step in a continued high-intensity muon program at FNAL. △ Less

Submitted 16 March, 2022; v1 submitted 14 March, 2022; originally announced March 2022.

Comments: Contribution to Snowmass 2021 46 pages 43 figures 7 tables

Report number: 20220310: [CONF-22-123]

Helium fluxes measured by the PAMELA experiment from the minimum to the maximum solar activity for solar cycle 24

Authors: N. Marcelli, M. Boezio, A. Lenni, W. Menn, R. Munini, O. P. M. Aslam, D. Bisschoff, M. D. Ngobeni, M. S. Potgieter, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, E. A. Bogomolov, M. Bongi, V. Bonvicini, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, A. M. Galper, S. V. Koldashov , et al. (31 additional authors not shown)

Abstract: Time-dependent energy spectra of galactic cosmic rays (GCRs) carry fundamental information regarding their origin and propagation. When observed at the Earth, these spectra are significantly affected by the solar wind and the embedded solar magnetic field that permeates the heliosphere, changing significantly over an 11-year solar cycle. Energy spectra of GCRs measured during different epochs of s… ▽ More Time-dependent energy spectra of galactic cosmic rays (GCRs) carry fundamental information regarding their origin and propagation. When observed at the Earth, these spectra are significantly affected by the solar wind and the embedded solar magnetic field that permeates the heliosphere, changing significantly over an 11-year solar cycle. Energy spectra of GCRs measured during different epochs of solar activity provide crucial information for a thorough understanding of solar and heliospheric phenomena. The PAMELA experiment had collected data for almost ten years (15th June 2006 - 23rd January 2016), including the minimum phase of solar cycle 23 and the maximum phase of solar cycle 24. In this paper, we present new spectra for helium nuclei measured by the PAMELA instrument from January 2010 to September 2014 over a three Carrington rotation time basis. These data are compared to the PAMELA spectra measured during the previous solar minimum providing a picture of the time dependence of the helium nuclei fluxes over a nearly full solar cycle. Time and rigidity dependencies are observed in the proton-to-helium flux ratios. The force-field approximation of the solar modulation was used to relate these dependencies to the shapes of the local interstellar proton and helium-nuclei spectra. △ Less

Submitted 4 January, 2022; originally announced January 2022.

Comments: 9 pages, 5 figures

Light outputs of yttrium doped BaF$_2$ crystals irradiated with neutrons

Authors: V. Baranov, Yu. I. Davydov, I. I. Vasilyev

Abstract: The fast luminescence component of barium fluoride (BaF$_2$) crystals with a subnanosecond decay time can find wide application in particle physics and nuclear physics. However, the slow luminescence component with the 630~ns decay time could cause pile-up signals at a high rate environment. Doping of BaF$_2$ crystals with rare earth elements suppresses the slow emission component, but at the same… ▽ More The fast luminescence component of barium fluoride (BaF$_2$) crystals with a subnanosecond decay time can find wide application in particle physics and nuclear physics. However, the slow luminescence component with the 630~ns decay time could cause pile-up signals at a high rate environment. Doping of BaF$_2$ crystals with rare earth elements suppresses the slow emission component, but at the same time the radiation hardness of the crystals deteriorates. This work presents the results of studying crystal samples, both pure BaF$_2$ and those doped with yttrium in a proportion of 1at.\%Y, 3at.\%Y and 5at.\%Y, irradiated with a fast neutron fluence of about 2.3$\times$10$^{14}$~n/cm$^2$. Their light output and decay kinetics were measured before and after irradiation. It is found that the light output loss of a pure BaF$_2$ crystal after irradiation is about 7\%, and the light output loss of yttrium doped samples after irradiation is about two times higher. The measurement results demonstrate that after irradiation the fast component of each sample has a relative light output loss 2-3\% larger than the slow one. △ Less

Submitted 18 November, 2021; originally announced November 2021.

On the use of tent spaces for solving PDEs: A proof of the Koch-Tataru theorem

Authors: Pascal Auscher, Ioann Vasilyev

Abstract: In these notes we will present (a part of) the parabolic tent spaces theory and then apply it in solving some PDE's originated from the fluid mechanics. In more details, to our most interest are the incompressible homogeneous Navier-Stokes equations. These equations have been investigated mathematically for almost one century. Yet, the question of proving well-posedness (i.e. existence, uniqueness… ▽ More In these notes we will present (a part of) the parabolic tent spaces theory and then apply it in solving some PDE's originated from the fluid mechanics. In more details, to our most interest are the incompressible homogeneous Navier-Stokes equations. These equations have been investigated mathematically for almost one century. Yet, the question of proving well-posedness (i.e. existence, uniqueness and regularity of solutions) lacks satisfactory answer. A large part of the known positive results in connection with Navier-Stokes equations are those in which the initial data $u_0$ is supposed to have a small norm in some critical or scaling invariant functional space. All those spaces are embedded in the homogeneous Besov space $\dot B^{-1}_{\infty,\infty}.$. A breakthrough was made in the paper [16] by Koch and Tataru, where the authors showed the existence and the uniqueness of solutions to the Navier-Stokes system in case when the norm $\|u_0\|_{\mathrm{BMO}^{-1}}$ is small enough. The principal goal of these notes is to present a new proof of the theorem by Koch and Tataru on the Navier-Stokes system, namely the one using the tent spaces theory. We also hope that after having read these notes, the reader will be convinced that the theory of tent spaces is highly likely to be useful in the study of other equations in fluid mechanics. These notes are mainly based on the content of the article [1] by P. Auscher and D. Frey. However, in [1] the authors deal with a slightly more general system of parabolic equations of Navier-Stokes type. Here we have chosen to write down a self-contained text treating only the relatively easier case of the classical incompressible homogeneous Navier-Stokes equations. △ Less

Submitted 6 April, 2022; v1 submitted 9 September, 2021; originally announced September 2021.

Comments: Lecture notes with complete details

Solar-Cycle Variations of South-Atlantic Anomaly Proton Intensities Measured With The PAMELA Mission

Authors: A. Bruno, M. Martucci, F. S. Cafagna, R. Sparvoli, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V. Bonvicini, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, A. M. Galper, S. V. Koldashov, S. Koldobskiy, A. N. Kvashnin, A. Lenni, A. A. Leonov, V. V. Malakhov, L. Marcelli , et al. (28 additional authors not shown)

Abstract: We present a study of the solar-cycle variations of >80 MeV proton flux intensities in the lower edge of the inner radiation belt, based on the measurements of the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission. The analyzed data sample covers an ~8 year interval from 2006 July to 2014 September, thus spanning from the decaying phase of the 23rd solar cycl… ▽ More We present a study of the solar-cycle variations of >80 MeV proton flux intensities in the lower edge of the inner radiation belt, based on the measurements of the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission. The analyzed data sample covers an ~8 year interval from 2006 July to 2014 September, thus spanning from the decaying phase of the 23rd solar cycle to the maximum of the 24th cycle. We explored the intensity temporal variations as a function of drift shell and proton energy, also providing an explicit investigation of the solar-modulation effects at different equatorial pitch angles. PAMELA observations offer new important constraints for the modeling of low-altitude particle radiation environment at the highest trapping energies. △ Less

Submitted 13 August, 2021; originally announced August 2021.

Comments: accepted for publication in the Astrophysical Journal Letters

Comparison of $pp$ and $p \bar{p}$ differential elastic cross sections and observation of the exchange of a colorless $C$-odd gluonic compound

Authors: V. M. Abazov, B. Abbott, B. S. Acharya, M. Adams, T. Adams, J. P. Agnew, G. D. Alexeev, G. Alkhazov, A. Alton, G. A. Alves, G. Antchev, A. Askew, P. Aspell, A. C. S. Assis Jesus, I. Atanassov, S. Atkins, K. Augsten, V. Aushev, Y. Aushev, V. Avati, C. Avila, F. Badaud, J. Baechler, L. Bagby, C. Baldenegro Barrera , et al. (451 additional authors not shown)

Abstract: We describe an analysis comparing the $p\bar{p}$ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in $pp$ collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections extrapolated to a center-of-mass energy of $\sqrt{s} =$ 1.96 TeV are compared with the D0 measurement… ▽ More We describe an analysis comparing the $p\bar{p}$ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in $pp$ collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections extrapolated to a center-of-mass energy of $\sqrt{s} =$ 1.96 TeV are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the $pp$ cross section. The two data sets disagree at the 3.4$σ$ level and thus provide evidence for the $t$-channel exchange of a colorless, $C$-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same $C$-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic scattering amplitude in $pp$ scattering. The combined significance of these results is larger than 5$σ$ and is interpreted as the first observation of the exchange of a colorless, $C$-odd gluonic compound. △ Less

Submitted 25 June, 2021; v1 submitted 7 December, 2020; originally announced December 2020.

Comments: D0 and TOTEM Collaborations

Journal ref: Phys. Rev. Lett. 127, 062003 (2021)

Optical properties of YAG:Ce and GGG:Ce scintillation crystals irradiated with a high fluence proton beam

Authors: V. Baranov, Yu. I. Davydov, M. Mkrtchian, I. I. Vasilyev

Abstract: In this paper, we report on the study of the optical properties of YAG:Ce and GGG:Ce garnet crystals after irradiation in a 660~MeV proton beam with a fluence up to 8.9$\times$10$^{14}$ protons/cm$^2$. We found that the transparency of both crystals fell by no more than 7\% in the region of their own luminescence. The light yield of a YAG:Ce sample, measured one year after irradiation, dropped by… ▽ More In this paper, we report on the study of the optical properties of YAG:Ce and GGG:Ce garnet crystals after irradiation in a 660~MeV proton beam with a fluence up to 8.9$\times$10$^{14}$ protons/cm$^2$. We found that the transparency of both crystals fell by no more than 7\% in the region of their own luminescence. The light yield of a YAG:Ce sample, measured one year after irradiation, dropped by about 35\%. △ Less

Submitted 18 May, 2020; originally announced May 2020.

Journal ref: Physics of Particles and Nuclei Letters, 17(6), 878-881 (2020)

Time dependence of the flux of helium nuclei in cosmic rays measured by the PAMELA experiment between July 2006 and December 2009

Authors: N. Marcelli, M. Boezio, A. Lenni, W. Menn, R. Munini, O. P. M. Aslam, D. Bisschoff, M. D. Ngobeni, M. S. Potgieter, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, E. A. Bogomolov, M. Bongi, V. Bonvicini, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, A. M. Galper, S. V. Koldashov , et al. (31 additional authors not shown)

Abstract: Precise time-dependent measurements of the Z = 2 component in the cosmic radiation provide crucial information about the propagation of charged particles through the heliosphere. The PAMELA experiment, with its long flight duration (15th June 2006 - 23rd January 2016) and the low energy threshold (80 MeV/n) is an ideal detector for cosmic ray solar modulation studies. In this paper, the helium nuc… ▽ More Precise time-dependent measurements of the Z = 2 component in the cosmic radiation provide crucial information about the propagation of charged particles through the heliosphere. The PAMELA experiment, with its long flight duration (15th June 2006 - 23rd January 2016) and the low energy threshold (80 MeV/n) is an ideal detector for cosmic ray solar modulation studies. In this paper, the helium nuclei spectra measured by the PAMELA instrument from July 2006 to December 2009 over a Carrington rotation time basis are presented. A state-of-the-art three-dimensional model for cosmic-ray propagation inside the heliosphere was used to interpret the time-dependent measured fluxes. Proton-to-helium flux ratio time profiles at various rigidities are also presented in order to study any features which could result from the different masses and local interstellar spectra shapes. △ Less

Submitted 18 May, 2020; originally announced May 2020.

Journal ref: The Astrophysical Journal, Volume 893, Number 2, 2020

Variation on a theme by Kiselev and Nazarov: H{ö}lder estimates for non-local transport-diffusion, along a non-divergence-free BMO field

Authors: Ioann Vasilyev, François Vigneron

Abstract: We prove uniform Hölder regularity estimates for a transport-diffusion equation with a fractional diffusion operator,and a general advection field in BMO, as long as the order of the diffusion dominates the transport term at small scales;our only requirement is the smallness of the negative part of the divergence in some critical Lebesgue space. In comparison to a celebrated result by L.Silvestre… ▽ More We prove uniform Hölder regularity estimates for a transport-diffusion equation with a fractional diffusion operator,and a general advection field in BMO, as long as the order of the diffusion dominates the transport term at small scales;our only requirement is the smallness of the negative part of the divergence in some critical Lebesgue space. In comparison to a celebrated result by L.Silvestre (2012), our advection field does not need to be bounded. A similar result can be obtained in the super-critical case if the advection field is Hölder continuous. Our proof is inspired by A.Kiselev and F.Nazarov (2010) and is based on the dual evolution technique. The idea is to propagate an atom property (i.e. localization and integrability in Lebesgue spaces) under the dual conservation law, when it is coupled with the fractional diffusion operator. △ Less

Submitted 26 February, 2020; originally announced February 2020.

Journal ref: Journal of the Institute of Mathematics of Jussieu , Volume 21 , Issue 5 , September 2022 , pp. 1651 - 1675

On the multidimensional Nazarov lemma

Authors: Ioann Vasilyev

Abstract: In this article we prove a multidimensional version of the Nazarov lemma. The proof is based on an appropriate generalisation of the regularised system of intervals introduced by Havin, Nazarov and Mashreghi to several dimensions. In this article we prove a multidimensional version of the Nazarov lemma. The proof is based on an appropriate generalisation of the regularised system of intervals introduced by Havin, Nazarov and Mashreghi to several dimensions. △ Less

Submitted 17 November, 2019; originally announced November 2019.

Journal ref: Proc. Amer. Math. Soc. 150(4) (2022), 1601-1611

Mu2e calorimeter readout system

Authors: N. Atanov, V. Baranov, L. Baldini, J. Budagov, D. Caiulo, F. Cei, F. Cervelli, F. Colao, M. Cordelli, G. Corradi, Yu. I. Davydov, F. D'Errico, S. Di Falco, E. Diociaiuti, S. Donati, R. Donghia, B. Echenard, S. Faetti, S. Giovannella, S. Giudici, V. Glagolev, F. Grancagnolo, F. Happacher, D. G. Hitlin, L. Lazzeri , et al. (21 additional authors not shown)

Abstract: The Mu2e electromagnetic calorimeter is made of two disks of un-doped parallelepiped CsI crystals readout by SiPM. There are 674 crystals in one disk and each crystal is readout by an array of two SiPM. The readout electronics is composed of two types of modules: 1) the front-end module hosts the shaping amplifier and the high voltage linear regulator; since one front-end module is interfaced to o… ▽ More The Mu2e electromagnetic calorimeter is made of two disks of un-doped parallelepiped CsI crystals readout by SiPM. There are 674 crystals in one disk and each crystal is readout by an array of two SiPM. The readout electronics is composed of two types of modules: 1) the front-end module hosts the shaping amplifier and the high voltage linear regulator; since one front-end module is interfaced to one SiPM, a total of 2696 modules are needed for the entire calorimeter; 2) a waveform digitizer provides a further level of amplification and digitizes the SiPM signal at the sampling frequency of $200\ \text{M}\text{Hz}$ with 12-bits ADC resolution; since one board digitizes the data received from 20 SiPMs, a total of 136 boards are needed. The readout system operational conditions are hostile: ionization dose of $20\ \text{krads}$, neutron flux of $10^{12}\ \mathrm{n}(1\ \text{MeVeq})/\text{cm}^2$, magnetic field of $1\ \text{T}$ and in vacuum level of $10^{-4}\ \text{Torr}$. A description of the readout system and qualification tests is reported. △ Less

Submitted 9 July, 2019; originally announced July 2019.

Journal ref: Nuclear Inst. and Methods in Physics Research, A, 2019

The Mu2e calorimeter: quality assurance of production crystals and SiPMs

Authors: N. Atanov, V. Baranov, J. Budagov, D. Caiulo, F. Cervelli, F. Colao, M. Cordelli, G. Corradi, Yu. I. Davydov, S. Di Falco, E. Diociaiuti, S. Donati, R. Donghia, B. Echenard, S. Giovannella, V. Glagolev, F. Grancagnolo, F. Happacher, D. G. Hitlin, M. Martini, S. Miscetti, T. Miyashita, L. Morescalchi, P. Murat, E. Pedreschi , et al. (12 additional authors not shown)

Abstract: The Mu2e calorimeter is composed of two disks each containing 1348 pure CsI crystals, each crystal read out by two arrays of 6x6 mm2 monolithic SiPMs. The experimental requirements have been translated in a series of technical specifications for both crystals and SiPMs. Quality assurance tests, on first crystal and then SiPM production batches, confirm the performances of preproduction samples pre… ▽ More The Mu2e calorimeter is composed of two disks each containing 1348 pure CsI crystals, each crystal read out by two arrays of 6x6 mm2 monolithic SiPMs. The experimental requirements have been translated in a series of technical specifications for both crystals and SiPMs. Quality assurance tests, on first crystal and then SiPM production batches, confirm the performances of preproduction samples previously assembled in a calorimeter prototype and tested with an electron beam. The production yield is sufficient to allow the construction of a calorimeter of the required quality in the expected times. △ Less

Submitted 19 December, 2018; originally announced December 2018.

Comments: 2 pages, 2 figures, 14th meeting on Advanced Detectors

On the existence of mass minimizing rectifiable G chains in finite dimensional normed spaces

Authors: Thierry De Pauw, Ioann Vasilyev

Abstract: We introduce the notion of density contractor of dimension m in a finite dimensional normed space X. If m+1=dim X this includes the area contracting projectors on hyperplanes whose existence was established by H. Busemann. If m=2, density contractors are an ersatz for such projectors and their existence, established here, follows from work by D. Burago and S. Ivanov. Once density contractors are a… ▽ More We introduce the notion of density contractor of dimension m in a finite dimensional normed space X. If m+1=dim X this includes the area contracting projectors on hyperplanes whose existence was established by H. Busemann. If m=2, density contractors are an ersatz for such projectors and their existence, established here, follows from work by D. Burago and S. Ivanov. Once density contractors are available, the corresponding Plateau problem admits a solution among rectifiable G chains, regardless of the group of coefficients G. This is obtained as a consequence of the lower semicontinuity of the $m$ dimensional Hausdorff mass, of which we offer two proofs. One of these is based on a new type of integral geometric measure. △ Less

Submitted 11 December, 2018; originally announced December 2018.

Journal ref: Annales de l'Institut Fourier, Volume 73 (2023) no. 2, pp. 635-694

On the local Hölder boundary smoothness of an analytic function in the unit ball compared with the smoothness of its modulus

Authors: Ioann Vasilyev

Abstract: Local boundary smoothness of an analytic function f on the unit ball of C^n is compared to the smoothness of its modulus. We prove that different conditions imposed on the zeros of f imply different drops of the smoothness. We also show that some of the drops are the best possible. Local boundary smoothness of an analytic function f on the unit ball of C^n is compared to the smoothness of its modulus. We prove that different conditions imposed on the zeros of f imply different drops of the smoothness. We also show that some of the drops are the best possible. △ Less

Submitted 16 May, 2019; v1 submitted 29 November, 2018; originally announced November 2018.

Journal ref: J Fourier Anal Appl 26, 28 (2020)

Littlewood--Paley characterizations of $\mathrm{BMO}$ and Triebel--Lizorkin spaces

Authors: Anton Tselishchev, Ioann Vasilyev

Abstract: We prove one generalization of the Littlewood--Paley characterization of the $\mathrm{BMO}$ space where the dilations of a Schwartz function are replaced by a family of functions with suitable conditions imposed on them. We also prove that a certain family of Triebel--Lizorkin spaces can be characterized in a similar way. We prove one generalization of the Littlewood--Paley characterization of the $\mathrm{BMO}$ space where the dilations of a Schwartz function are replaced by a family of functions with suitable conditions imposed on them. We also prove that a certain family of Triebel--Lizorkin spaces can be characterized in a similar way. △ Less

Submitted 21 November, 2018; originally announced November 2018.

MSC Class: 42B25

Journal ref: Mathematische Nachrichten. 2020; 293: 2029--2043

Effects of neutron radiation on the optical and structural properties of blue and green emitting plastic scintillators

Authors: Vladimir Baranov, Yuri Davydov, Rudolph Erasmus, Chamunorwa O Kureba, Nthabiseng Lekalakala, Thabo C Masuku, Joyful E Mdhluli, Bruce Mellado, Gaogalalwe Mokgatitswane, Elias Sideras-Haddad, Ilya Vasilyev, Petr N Zhmurin

Abstract: We report on the optical and structural properties of plastic scintillators irradiated with neutron beams produced by the IBR-2 reactor of the Frank Laboratory of Neutron Physics in JINR, Dubna. Blue UPS-923A and green plastic scintillators were irradiated with neutron fluence ranging from 10$^{13}$ to 10$^{17}$ n/cm$^2$. Discolouring in the plastic scintillators was observed after irradiation. Th… ▽ More We report on the optical and structural properties of plastic scintillators irradiated with neutron beams produced by the IBR-2 reactor of the Frank Laboratory of Neutron Physics in JINR, Dubna. Blue UPS-923A and green plastic scintillators were irradiated with neutron fluence ranging from 10$^{13}$ to 10$^{17}$ n/cm$^2$. Discolouring in the plastic scintillators was observed after irradiation. The effects of radiation damage on the optical and structural properties of the samples were characterized by conducting light yield, light transmission, light fluorescence and Raman spectroscopy studies. The results showed that neutron radiation induced damage in the material. The disappearance of the Raman peak features in green scintillators at frequencies of 1165.8, 1574.7 and 1651.2 cm$^{-1}$ revealed significant structural alterations due to neutron bombardment. Losses in fluorescence intensity, light yield and light transmission in the plastic scintillators were observed. △ Less

Submitted 11 October, 2018; originally announced October 2018.

Comments: 19 pages, 9 figures

Report number: ICPP-05

Journal ref: Nuclear Inst. and Methods in Physics Research, B 436C (2018) pp. 236-243

Suppression of the slow component of BaF$_{2}$ crystal luminescence with a thin multilayer filter

Authors: A. M. Artikov, V. Baranov, J. A. Budagov, A. N. Chivanov, Yuri Davydov, E. N. Eliseev, E. A. Garibin, V. V. Glagolev, A. V. Mihailov, P. A. Rodnyi, V. V. Terechschenko, I. I. Vasilyev

Abstract: The fast component of the barium fluoride (BaF$_{2}$) crystal luminescence with the emission peak at 220 nm allows those crystals to be employed in fast calorimeters operating in harsh radiation environment. However, the slow component with the emission peak at 330 nm and about 85\% of the total emission light could create big problems when working at a high radiation rate. In this work we repor… ▽ More The fast component of the barium fluoride (BaF$_{2}$) crystal luminescence with the emission peak at 220 nm allows those crystals to be employed in fast calorimeters operating in harsh radiation environment. However, the slow component with the emission peak at 330 nm and about 85\% of the total emission light could create big problems when working at a high radiation rate. In this work we report results of tests of multilayer filters that can suppress luminescence in the range from 250 nm to 400 nm, which covers most of the BaF$_{2}$ slow component luminescence. The filters are made by spraying layers of rare earth oxides on a quartz glass substrate. Filters typically comprise 200-220 layers. A few filters were prepared by spraying thin layers on quartz glass. The filters have a peak transmittance of about 70-80\% in the range of 200-250 nm. Measurements of the light output of the BaF$_{2}$ crystal with and without a filter between the crystal readout end and the PMT demonstrate substancial suppression of the slow component. To our knowledge, this kind of filters are produced and tested for the first time. △ Less

Submitted 5 September, 2018; originally announced September 2018.

Journal ref: J.Phys.Conf.Ser. 1162 (2019) no.1, 012028

Solar energetic particle events observed by the PAMELA mission

Authors: A. Bruno, G. A. Bazilevskaya, M. Boezio, E. R. Christian, G. A. de Nolfo, M. Martucci, M. Merge', V. V. Mikhailov, R. Munini, I. G. Richardson, J. M. Ryan, S. Stochaj, O. Adriani, G. C. Barbarino, R. Bellotti, E. A. Bogomolov, M. Bongi, V. Bonvicini, S. Bottai, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis , et al. (33 additional authors not shown)

Abstract: Despite the significant progress achieved in recent years, the physical mechanisms underlying the origin of solar energetic particles (SEPs) are still a matter of debate. The complex nature of both particle acceleration and transport poses challenges to developing a universal picture of SEP events that encompasses both the low-energy (from tens of keV to a few hundreds of MeV) observations made by… ▽ More Despite the significant progress achieved in recent years, the physical mechanisms underlying the origin of solar energetic particles (SEPs) are still a matter of debate. The complex nature of both particle acceleration and transport poses challenges to developing a universal picture of SEP events that encompasses both the low-energy (from tens of keV to a few hundreds of MeV) observations made by space-based instruments and the GeV particles detected by the worldwide network of neutron monitors in ground-level enhancements (GLEs). The high-precision data collected by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment offer a unique opportunity to study the SEP fluxes between $\sim$80 MeV and a few GeV, significantly improving the characterization of the most energetic events. In particular, PAMELA can measure for the first time with good accuracy the spectral features at moderate and high energies, providing important constraints for current SEP models. In addition, the PAMELA observations allow the relationship between low and high-energy particles to be investigated, enabling a clearer view of the SEP origin. No qualitative distinction between the spectral shapes of GLE, sub-GLE and non-GLE events is observed, suggesting that GLEs are not a separate class, but are the subset of a continuous distribution of SEP events that are more intense at high energies. While the spectral forms found are to be consistent with diffusive shock acceleration theory, which predicts spectral rollovers at high energies that are attributed to particles escaping the shock region during acceleration, further work is required to explore the relative influences of acceleration and transport processes on SEP spectra. △ Less

Submitted 26 July, 2018; originally announced July 2018.

Comments: 26 pages, 13 figures, 2 tables

Journal ref: The Astrophysical Journal, 862:97, 2018 (17pp)

Geomagnetically trapped, albedo and solar energetic particles: trajectory analysis and flux reconstruction with PAMELA

Authors: A. Bruno, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V. Bonvicini, S. Bottai, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, E. C. Christian, C. De Donato, G. A. de Nolfo, C. De Santis, N. De Simone, V. Di Felice, A. M. Galper, A. V. Karelin, S. V. Koldashov, S. Koldobskiy , et al. (37 additional authors not shown)

Abstract: The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetic… ▽ More The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival. △ Less

Submitted 11 July, 2016; originally announced July 2016.

Comments: Accepted for publication in Advances in Space Research, 2016. 21 pages, 7 figures

Time dependence of the electron and positron components of the cosmic radiation measured by the PAMELA experiment between July 2006 and December 2015

Authors: O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V. Bonvicini, S. Bottai, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, V. Di Felice, A. M. Galper, A. V. Karelin, S. V. Koldashov, S. A. Koldobskiy, S. Y. Krutkov, A. N. Kvashnin, A. Leonov, V. Malakhov , et al. (30 additional authors not shown)

Abstract: Cosmic-ray electrons and positrons are a unique probe of the propagation of cosmic rays as well as of the nature and distribution of particle sources in our Galaxy. Recent measurements of these particles are challenging our basic understanding of the mechanisms of production, acceleration and propagation of cosmic rays. Particularly striking are the differences between the low energy results colle… ▽ More Cosmic-ray electrons and positrons are a unique probe of the propagation of cosmic rays as well as of the nature and distribution of particle sources in our Galaxy. Recent measurements of these particles are challenging our basic understanding of the mechanisms of production, acceleration and propagation of cosmic rays. Particularly striking are the differences between the low energy results collected by the space-borne PAMELA and AMS-02 experiments and older measurements pointing to sign-charge dependence of the solar modulation of cosmic-ray spectra. The PAMELA experiment has been measuring the time variation of the positron and electron intensity at Earth from July 2006 to December 2015 covering the period for the minimum of solar cycle 23 (2006-2009) till the middle of the maximum of solar cycle 24, through the polarity reversal of the heliospheric magnetic field which took place between 2013 and 2014. The positron to electron ratio measured in this time period clearly shows a sign-charge dependence of the solar modulation introduced by particle drifts. These results provide the first clear and continuous observation of how drift effects on solar modulation have unfolded with time from solar minimum to solar maximum and their dependence on the particle rigidity and the cyclic polarity of the solar magnetic field. △ Less

Submitted 28 June, 2016; originally announced June 2016.

Comments: 11 pages, 2 figures

PAMELA's measurements of geomagnetic cutoff variations during the 14 December 2006 storm

Authors: O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V. Bonvicini, S. Bottai, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Donato, G. A. de Nolfo, C. De Santis, N. De Simone, V. Di Felice, A. M. Galper, A. V. Karelin, S. V. Koldashov, S. Koldobskiy, S. Y. Krutkov , et al. (33 additional authors not shown)

Abstract: Data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment were used to measure the geomagnetic cutoff for high-energy (>80 MeV) protons during the 14 December 2006 geomagnetic storm. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to spacecraft orbital periods (94 mi… ▽ More Data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment were used to measure the geomagnetic cutoff for high-energy (>80 MeV) protons during the 14 December 2006 geomagnetic storm. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to spacecraft orbital periods (94 min). Estimated cutoff values were compared with those obtained by means of a trajectory tracing approach based on a dynamical empirical modeling of the Earth's magnetosphere. We found significant variations in the cutoff latitude, with a maximum suppression of about 7 deg at lowest rigidities during the main phase of the storm. The observed reduction in the geomagnetic shielding and its temporal evolution were related to the changes in the magnetospheric configuration, investigating the role of interplanetary magnetic field, solar wind and geomagnetic parameters. PAMELA's results represent the first direct measurement of geomagnetic cutoffs for protons with kinetic energies in the sub-GeV and GeV region. △ Less

Submitted 3 March, 2016; v1 submitted 17 February, 2016; originally announced February 2016.

Comments: 26 pages, 6 figures and 1 table. Accepted for publication in Space Weather