Ultra-high energy cosmic rays and prompt TeV gamma rays from gamma ray bursts

Gamma ray bursts (GRBs) have been proposed as one possible class of sources of the ultrahigh energy cosmic ray (UHECR) events observed up to energies ≳ 10²⁰ eV. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV γ-rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.     

Interpretations of the cosmic ray secondary-to-primary ratios measured by DAMPE

Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around 100 GeV/n, which provide important implications on the production, propagation, and interaction of Galactic cosmic rays. In this work we investigate a number of models proposed in literature in light of the DAMPE findings. These models can roughly be classified into two classes, driven by propagation effects or by source ones. Among these models discussed, we find that the re-acceleration of cosmic rays, during their propagation, by random magnetohydrodynamic waves may not reproduce sufficient hardenings of B/C and B/O, and an additional spectral break of the diffusion coefficient is required. The other models can properly explain the hardenings of the ratios. However, depending on simplifications assumed, the models differ in their quality in reproducing the data in a wide energy range. The models with significant re-acceleration effect will under-predict low-energy antiprotons but over-predict low-energy positrons, and the models with secondary production at sources over-predict high-energy antiprotons. For all models high-energy positron excess exists.     

Significance of the second dip in the ultra-high energy cosmic ray spectrum

A new feature in the spectrum of ultra high energy cosmic rays (UHECR) has been announced in the paper by Berezinsky, Gazizov and Kachelrieβ. The ratio of the solution of the exact transport equation to its solution in the continuous energy loss limit shows intriguing features which, according to the Authors, are related to the very nature of the energy loss processes of UHECR: the very sharp second dip predicted at 6.3 × 10¹⁹ eV can be used as an energy calibration point and also as the UHECR mass indicator for big future cosmic ray experiments. In the present paper we would like to advocate that this statement is an overinterpretation. The second dip is a result of an inappropriate approximation used, and thus it cannot help to understand the nature of UHECR in any way.      

宇宙线大气簇射μ子定点密度及原初能谱“膝”的研究

用梁王山宇宙线观测站的数据研究宇宙线大气簇射μ子定点密度谱,谱呈现明显的拐折.通过MonteCarlo模拟,得到拐点对应的能量约为1.7×10¹⁵eV,拐点前后原初能谱指数差约为0.43,证实了KASCADE实验μ子定点密度谱呈现拐折的首次观测结果,又一次推证了原初宇宙线能谱膝的存在.     

Influence of cosmic ray variations on cloudiness distribution over Northern Asia

Influence of cosmic ray (CR) flux variations on cloudiness over Northern Asia is investigated based on NOAA satellite images and data of neutron monitors of the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (ITMIRWP RAS, Moscow) and Institute of Cosmophysical Research and Aeronomy of the Siberian Branch of the Russian Academy of Sciences (ICPRA SB RAS, Yakutsk). The influence of the Forbush decrease of the CR intensity on the latitudinal distribution of the cloud cover is demonstrated. A positive correlation of the cloud cover change with the Forbush decrease is established in the case of the auroral activity index АЕ > 300 nT and an anticorrelation in the case of a smaller Forbush decrease (for АЕ < 300 nT). Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 16–20, February, 2009.     

Determining the primary cosmic ray energy from the total flux of Cherenkov light measured at the Yakutsk EAS array

We present a method for determining the energy of the primary particle that generates an extensive air shower (EAS) of comic rays based on measuring the total flux of Cherenkov light from the shower. Applying this method to Cherenkov light measurements at the Yakutsk EAS array has allowed us to construct the cosmic ray energy spectrum in the range 10¹⁵ ? 3 × 10¹⁹ eV.     

雷暴电场对宇宙射线次级粒子μ 子的影响研究

西藏羊八井宇宙射线观测站的中子监测器主要探测宇宙射线次级粒子中能量在500 MeV—20 GeV的核子成分和少量的负μ子成分. 本文分析了2008—2010年观测站附近发生的62次雷暴期间中子监测器和大气平均电场仪的同步观测资料, 发现27次雷暴期间中子监测器计数率发生明显变化, 显著性S>5σ, 其中13次变化显著, 显著性S>10σ . 显著性S>10σ的13次个例信号变化百分比与地面电场场强幅值之间存在大体一致的变化趋势, 而显著性在5σ <S<10σ之间的14次个例信号变化百分比与地面电场场强幅值之间不存在相似的变化趋势. 较强雷暴当顶时中子监测器计数率变化一般不明显, 而中子监测器计数率变化明显的个例则多发生于雷暴云不当顶, 但探测器仍处于雷暴云下部正电荷层的控制范围之内时, 或者当顶雷暴处于形成或消散阶段. Dorman等把雷暴期间中子监测器计数率的变化归因于雷暴云内电场对宇宙射线次级粒子μ子的作用, 并建立了雷暴期间中子监测器计数率变化与雷暴地面电场相关联的理论. 本文分析发现雷暴期间羊八井中子监测器计数率变化与地面电场场强之间相关性较小或者没有相关性, 不支持Dorman的理论.     

宇宙线研究进展评述与展望

近年来,宇宙线探测技术发展迅速,天基和地基宇宙线实验均取得了多项重要成果,打破了宇宙线研究领域多年来的沉寂．多手段复合观测是精确测量宇宙线能谱和成分的必要途径,甚高能伽玛射线天文学成为探索宇宙线起源这一世纪之谜的最有效手段．高海拔宇宙线观测站(LHAASO)计划将以最高的超高能伽玛射线探测灵敏度和甚高能伽玛射线巡天灵敏度以及最宽的宇宙线能量覆盖范围探索领域的基本问题．     

Analysis of proton-carbon inelastic cross sections measured in satellite experiment and upper limit on primary cosmic ray deuteron flux in the energy range 20 to 600 GeV

An analysis has been made of the experimental results of Akimovet al on the inelastic cross sections of proton on proton and carbon targets in the energy range 20 to 600 GeV obtained from artificial earth satellites. It is found that an upper limit of 4% at 95% confidence level can be set on the fraction of deuterons relative to the flux of protons in the primary cosmic radiation at energies in the range 20 to 60 GeV. There is an indication for a rise of (29±7) mb in the inelastic cross section of proton against carbon in the energy range of 200 to 600 GeV over and above what is expected from Glauber’s theory. If this rise has to be interpreted as due to contamination from cosmic ray deuterons, the fraction of deuterons relative to protons needed is (15±4)% in this energy region.     

Particle physics explanations for ultra-high energy cosmic ray events

The origin of cosmic ray events withE ≳ 10¹¹ GeV remains mysterious. In this talk I briefly summarize several proposed particle physics explanations: a breakdown of Lorentz invariance, the ‘Z-burst’ scenario, new hadrons with masses of several GeV as primaries, and magnetic monopoles with mass below 10¹⁰ GeV as primaries. I then describe in a little more detail the idea that these events are due to the decays of very massive, long-lived exotic particles.     

Relevance of multiple muons detected underground to the mass composition of primary cosmic rays

Summary Calculations have been made of the expected frequencies of multiple muons for the situation of the Soudan underground proton decay detector. Comparisons are made with the observations and it is concluded that with our model for high-energy collisions the flux of heavy nuclei (A>20, principally iron) in the range (10¹⁵÷10¹⁶ eV)/nucleus is at most 25% of the total particle flux in the same range.

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Riassunto Sono stati effettuati i calcoli delle frequenze attese di muoni multipli per situare il rivelatore di decadimento di protoni sotterraneo di Soudan. Si eseguono confronti con le osservazioni e si conclude che con il nostro modello per le collisioni ad alta energia il flusso di nuclei pesanti (A>20, specialmente ferro) nell'intervallo (10¹⁵÷10¹⁶) eV/nucleo è al massimo il 25% del flusso totale di particelle nello stesso intervallo.

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Резюме Вычисляются ожидаемые частоты появления множественных мюонов в суданском подземном детекторе распадов протонов. Проводится сравнение с результатами наблюдений. Делается вывод, что в рамках предложенной модели для соударений при высоких энергиях поток тяжелых ядер (A>20, в основном, ядра железа) в области энерий (10¹⁵÷10¹⁶) эВ составляет, в лучшем случае, 25% от полного потока частиц в этой области энергий.

     

Variations of the flux and the energy spectrum of neutrons born in the galactic cosmic ray proton interactions with the matter of Earth''s satellites and orbital stations

This paper presents the energy spectra of secondary neutrons obtained from Monte Carlo simulations of the interactions of protons of galactic cosmic rays with the material of a spacecraft, and also the variation of the fluxes of these particles as a function of latitude. The variations of the secondary neutron flux with changing geometry and orientation of the craft, and detector position were evaluated as well. The simulations were conducted over a wide range of masses of spacecraft, from 300 kg (Earth Probe Total Ozone Mapping Spectrometer) to 420,000 kg (International Space Station in its full configuration), with calculations for the ISS also being carried out for its first development stage (mass of approx. 20,400 kg) and its configuration with a mass of approx. 81,000 kg. The calculations were carried out for circular orbits at altitudes of 500 km and for the energy intervals 0.001–10 MeV and 10–10,000 MeV, for both maximum and minimum solar activity. The results obtained agree reasonably well with results from previous calculations and do not contradict experimental data.     

Characteristics of the sampling paddle modules of neutron wall from the cosmic ray test

In the construction of a large area neutron detector(neutron wall)that is used to detect neutrons at GeV energies,the performances of all the sampling paddle modules prepared for the neutron wall areinvestigated with a specially designed test bench.Tested by cosmic rays,an average intrinsic time resolution of 222.5 ps is achieved at the center of the modules.The light attenuation length and the effective speed of the light in the module are also investigated.     

Characteristics of the sampling paddle modules of neutron wall from the cosmic ray test

In the construction of a large area neutron detector （neutron wall） that is used to detect neutrons at GeV energies, the performances of all the sampling paddle modules prepared for the neutron wall are investigated with a specially designed test bench. Tested by cosmic rays, an average intrinsic time resolution of 222.5 ps is achieved at the center of the modules. The light attenuation length and the effective speed of the light in the module are also investigated.     

Implications on the origin of cosmic rays in light of 10 TV spectral softenings

Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons(and probably also for Helium nuclei).Very recently,the DArk Matter Particle Explorer(DAMPE)measurement about the proton spectrum clearly reveals such a softening with a high significance.Here we study the implications of these new measurements,as well as the groundbased indirect measurements,on the origin of CRs.We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously.In the framework of multiple components,we discuss two possible scenarios,the multiple source population scenario and the background plus nearby source scenario.Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies.Considering the anisotropy observations,the nearby source model is favored.     

Studies of anomalous cosmic ray N, O, and Ne using Cn track detectors

We report measurements of the energy spectra of anomalous cosmic ray N, O and Ne in the energy interval 5–25 MeV/nucleon made with stacks of cellulose nitrate sheets exposed on “Cosmos” satellites in Earth's vicinity in 1994. The successive etching was applied for the best charge identification.     

A possible explanation of the knee of cosmic light component spectrum from 100 TeV to 3 PeV

A mixed hydrogen and helium(H + He) spectrum with a clear steepening at ~700 TeV has been detected by the ARGO-YBJ experiments. In this paper, we demonstrate that the observed H + He spectrum can be reproduced well with a model of cosmic rays escaping from the supernova remnants(SNRs) in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism. Three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this model given a higher acceleration efficiency.     

Integral energy spectrum of primary cosmic rays at high energies

The integral energy spectrum of primary cosmic rays has been obtained. In the energy range (2.4×10³−1.1×10⁵ GeV), the spectrum of all nuclei is consistent with a power law of indexγ=1.55±0.06 and the flux of all nuclei is:N(⩾E ₀)⋍(5.1±1.8)×10⁻¹×E ₀ ^−1.55 particles/cm² sterad. sec., whereE ₀ is in GeV. The spectrum of primaryα-particles in the energy range (4.4×10³−4.8×10⁴) GeV is also consistent with a power law of indexγ=1.71±0.12 and the flux is:N(⩾E ₀)=(4.2±1.4)×10⁻¹×E ₀ ^−1.71 , particles per cm² sterad. sec, whereE ₀ is in GeV.     

Evidence for the production of new particles in cosmic ray experiments deep underground

In the cosmic ray experiments deep underground in the Kolar Gold Mines, a special class of events has been observed, at present 6 in number, characterised by several, (in general 3), charged particles arising from a vertex, either in air or in the thin material of the detectors, with large opening angles; the vertex is at a distance of around 70–100 cms from the rock wall. The most plausible interpretation of these events is that they are due to the decay of new, massive and long-lived particles produced in neutrino collisions inside rock, or through hitherto unknown processes.     

Flux variations of cosmic ray air showers detected by LHAASO-KM2A during a thunderstorm on June 10, 2021

The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA, and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during a thunderstorm on June 10, 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with a maximum fractional increase of 20%. The variations in trigger rates (increases or decreases) were found to be strongly dependent on the primary zenith angle. The flux of secondary particles increased significantly, following a trend similar to that of shower events. To better understand the observed behavior, Monte Carlo simulations were performed with CORSIKA and G4KM2A (a code based on GEANT4). We found that the experimental data (in saturated negative fields) were in good agreement with the simulations, assuming the presence of a uniform electric field of -700 V/cm with a thickness of 1500 m in the atmosphere above the observation level. Due to the acceleration/deceleration by the atmospheric electric field, the number of secondary particles with energy above the detector threshold was modified, resulting in the changes in shower detection rate.