The installation of two new neutron monitors, HLEA and THIMON, at the summit of Haleakalฤ, Hawaiโi, marks a significant advancement in cosmic ray and solar neutron studies. Situated at 3,055 meters above sea level, these monitors benefit from minimal atmospheric interference, enabling high-precision measurements of galactic cosmic rays (GCRs) and solar neutron flux. Operational since December...
The leader fraction, L, is defined as the fraction of neutron monitor counts that are not temporally associated with a later count in the same neutron monitor counter due to the same cosmic ray shower. L was extracted from time-delay histograms and serves as a precise indicator of spectral variations in cosmic rays above the cutoff rigidity. In this work, we analyze long-term variations in L...
Solar storms can disturb Galactic cosmic-ray (GCR) fluxes within the heliosphere at short time scales in events known as Forbush decreases (FDs). We extract hourly GCR spectral variations during FDs from a global network of ground-based neutron monitors and muon detectors using two independent methods: A) fitting a GCR rigidity spectral model with anisotropy up to second order, and B)...
Neutron monitors (NMs) are basic instruments to measure Galactic cosmic ray variations in the range of ~ 1 to 50 GeV. The upgraded electronics at a few NM stations enable the analysis of the relative time delays and relative positions of multiple secondary particles produced by the same primary particle in Earthโs atmosphere. In this work, we performed atmospheric Monte Carlo Simulations using...
The Sun can occasionally accelerate particles to become solar energetic particles, some of which may collide with the Earthโs atmosphere and produce secondary air showers that ground-based neutron monitors can detect. This work investigates the Princess Sirindhorn Neutron Monitor (PSNM) response to solar neutrons originating from solar activity such as solar flares and coronal mass ejections....
A latitude survey using the Changvan neutron monitor, a ship-borne detector, was conducted aboard the South Korean Icebreaker "Araon" in 2023โ24, spanning from Antarctic and Arctic regions to study cosmic ray modulation. The monitor features a 3NM64-like configuration with three proportional counters: a leaded BFโ tube from LND Inc. at one edge, an unleaded BP28 tube in the middle, and a...
The ALPACA experiment, which consists of the large air shower array (83,000 m^2) and the water-Cherenkov-type muon detector (3,600 m^2), is a new project to observe cosmic rays and gamma rays in the energy range between TeV and PeV in the southern hemisphere. The prototype air shower array, named ALPAQUITA (18,000 m^2), has been fully operated at the Chacaltaya plateau (4,740 m a.s.l.) in...
The Moon-Aiming Thai-Chinese Hodoscope (MATCH) is designed as a space weather payload for the ChangโE-7 lunar orbiter, aimed at enhancing space weather monitoring in the Earth-Moon region and measuring lunar albedo ions up to approximately 100 MeV/n. Additionally, it will provide continuous measurements of cosmic ray electrons up to around 120 MeV/n, thereby clarifying the contributions from...
LunPAN (Lunar Particle Analyzer Network) is a three-year mission proposal designed to comprehensively map the particle spectra in the lunar radiation field. It aims to provide precise measurements of Galactic Cosmic Rays (GCR), Solar Energetic Particles (SEP), and albedo particles, including charged particles, neutrons, and gamma-rays, originating from the Moon's surface. Therefore it will...
TSC-1 is the first Thai scientific research mission on a microsatellite, which has been designed and developed by the Thai Space Consortium. The satellite is planned to operate in Sun-synchronous Earth orbit at 500 - 600 km altitude and should be launch ready at the end of 2026. All design, construction, system integration, and testing are to be carried out in Thailand. The payloads include...
The China Seismo-Electromagnetic Satellite (CSES) program, a collaboration between the China National Space Administration (CNSA) and the Italian Space Agency (ASI), offers a new window into solar-terrestrial interactions through continuous monitoring of the near-Earth space environment. Since its launch in 2018, CSES-01 has provided valuable data on space weather phenomena, ionospheric...
The CALorimetric Electron Telescope (CALET) installed on the International Space Station (ISS) has been measuring high-energy cosmic rays (CRs) and gamma rays to understand the cosmic-ray acceleration and propagation. The CALET adopts a low-energy electron (LEE) trigger working at high geomagnetic latitudes that can measure the low-energy CR electrons in the energy region from 1 GeV to 10 GeV,...
The precision measurement of the daily proton and helium fluxes with AMS during 13.5 years of operation will be presented. The period of observation covers solar cycle 24 from the ascending phase through its maximum going toward its minimum and solar cycle 25 through solar maximum. Detailed time variations of fluxes and ratio, including periodicities, will be presented. Remarkably, a...
The Forbush Decrease (FD) is characterized by a sharp decline followed by a gradual
recovery in the intensity of low-energy cosmic rays. This phenomenon is thought to
be caused by disruptions in the heliosphere caused by solar events, such as coronal
mass ejections (CMEs). The Dark Matter Particle Explorer (DAMPE), a
satellite-based experiment designed for detecting the cosmic radiation,...
Galactic cosmic rays, as well as particles, accelerated to high energies either at the solar surface, corona, or in the interplanetary medium, are subject to various phenomena that can modify their energy distribution, intensity, and composition over different time scales. These effects are greater in the low-energy portion of the spectrum, and it is crucial to have instruments that can...
The steady-state gamma-ray emission from the Sun arises from interactions with Galactic cosmic rays and consists of two components: (1) a hadronic disk component and (2) a leptonic component peaking at the solar edge and extending into the heliosphere. Their flux is expected to vary with the 11-year solar cycle, peaking at solar minimum due to the higher cosmic-ray flux. However, no previous...
The development of advanced space-based cosmic ray observation experiments (such as AMS, PAMELA, and DAMPE) have provided precise data, offering new opportunities for the study of cosmic ray solar modulation. During 2007-2008, as the period of longest-live coronal holes and corresponding variation in all heliospheric characteristics, the pronounced 27-day wave in the GCR intensity had been...
Galactic cosmic ray (GCR) intensities exhibit recurrent variations caused by their passage through heliospheric structures co-rotating with the Sun, with the โผ27-day periodicity being the most prominent one. To study this periodicity, data collected by the High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite (CSES-01) in Low-Earth Orbit have been used to...
The flux of galactic cosmic rays (GCR) traversing into and inside the heliosphere are modulated by the magnetic activity of the Sun through the heliospheric magnetic field, as the particles are deflected and slowed down by magnetic discontinuities. This modulation of GCR in the heliosphere can be parametrized by the modulation (potential) parameter ฯ, which is estimated using the force field...
The DArk Matter Particle Explorer (DAMPE) is a satellite-borne cosmic particle detector which was launched on Dec. 17th, 2015 into a sun-synchronous orbit with the tilt angle of 97.4 degree. The high energy resolution and large geometric acceptance make the detector suitable for the cosmic ray electron (plus positron) measurement. In this work, the time-dependent electron flux was measured...
We present COSMICA, an opensource high-performance GPU-accelerated numerical code for modeling cosmic ray solar modulation, and its application to study CR diffusion parameters. Developed within the framework of the ICSC-Italian Research Center on High-Performance Computing, Big Data and Quantum Computing (Spoke-3), COSMICA is undergoing continuous software optimization to maximize efficiency...
The interest in the study of the global features of the modulation of galactic cosmic rays has been increasing since the 23rd solar minimum. This is supported by various detectors such as PAMELA, AMS-02 and HEPD01, providing cosmic ray particles measurements at Earth over two complete solar cycles i.e., the 23rd and 24th. These exceptional observations provide an opportunity for enhanced...
A new full model of the atmospheric transport of cosmogenic 10Be is presented which allows linking its production by cosmic rays with the measured concentrations in ice cores. The model is based on the focused SOCOLโAERv2โBE chemistryโclimate model coupled with the CRAC:10Be isotope production model. It includes all the relevant atmospheric processes and allows computing the isotope...
The main aim of the SAMADHA project is to monitor the cosmic ray neutron
spectrum and dose at very high altitudes in the South Atlantic Anomaly
region during the maximum activity of the 25$^{th}$ solar cycle.
The experimental setup for this measurement consists of an Extended Bonner
Sphere System and a commercial Rem counter. A linear energy transfer
spectrometer to measure the...
Exoplanets orbiting red dwarf stars in the habitable zone are easier to detect than those orbiting Sun-like stars. In recent years, there has been increased interest in modelling the Galactic cosmic ray fluxes reaching exoplanets orbiting stars other than the Sun. This is because Galactic cosmic rays can affect exoplanet habitability by for instance, driving the formation of prebiotic...
This study confronts the Standard Solar Model (SSM) with observed neutrino fluxes (pp, pep, Be7, B8, CNO) by constructing parameterized solar core models (SCMs) with variable helium/metallicity profiles and equilibrium nuclear burning assumptions for pp chains. We find key tension emerges that no SCM simultaneously satisfies all observed neutrino fluxes, notably due to core temperature-driven...
Solar energetic particles (SEPs) and cosmic rays are high energy particles that impact Earth's atmosphere. One key way that these particles interact with the material in the atmosphere is by ionising atoms and molecules, resulting in changes in the atmosphereโs chemistry. They may even have contributed to the formation of prebiotic molecules, the โbuilding blocksโ for life, on Earth's surface...
Unlike cosmic ray protons, the antiproton local interstellar spectrum (LIS) was not observed by the Voyager missions when crossing the heliopause into the interstellar medium. As a result, the shape and values of the antiproton LIS at lower energies (rigidities) are still unknown. The recent AMS-02 observations, averaged over a Bartel rotation (27 days), confirmed earlier model predictions...
Anisotropy of galactic cosmic-rays (GCRs) represents their momentum-space distribution in the interplanetary plasma, playing a key role in revealing the solar modulation of GCRs. The Global Muon Detector Network (GMDN; http://hdl.handle.net/10091/0002001448) has been a unique means to observe the anisotropy, thanks to its excellent angular resolution, angular acceptance, and statistics....
Solar activity variations strongly impact the modulation of the flux of low-energy Galactic Cosmic Rays (GCRs) reaching the Earth. The secondary particles, which originate from the interaction of GCRs with the atmosphere, can be revealed by an array of ground detectors. We show that the low-threshold rate (scaler) time series recorded over 16 years of operation by the surface detectors of the...
Understanding the heliospheric modulation of galactic cosmic rays is essential for studying the acceleration and propagation processes of these particles, as well as for establishing models of radiation exposure and associated risks in space missions. Here we present our efforts in the development of an effective data-driven model describing the time- and energy-dependent solar modulation...
The solar steady emission in gamma rays is due to the interactions of Galactic Cosmic Rays with the solar atmosphere and with the low-energy solar photon field via inverse Compton scattering. The emission is sensitive to the magnetic field nearby the Sun and to the cosmic-ray transport in the magnetic field in the inner solar system. Modeling the inverse Compton emission in the presence of a...
Galactic cosmic rays (GCRs) are high-energy charged particles originating from the Milky Way and widely distributed throughout the heliosphere. The space radiation environment induced by GCRs significantly impacts spacecraft operations. Numerical modeling provides a cost-effective approach to simulate space radiation environments, thus serves as a critical tool for predicting and evaluating...
The interest in the origin and modulation of cosmic ray deuterons is expected to increase significantly now that observations from AMS-02 and PAMELA detectors have become available. Observations made by AMS-02 reveal the spectral shape and features of galactic deuteron over the rigidity range 1.92 GV โ 19.5 GV, whereas that from PAMELA are at a lower rigidity, from 0.75 GV โ 2.5 GV. These...
Any stars permanently loose small amounts of mass during their lifetimes. This mass is propelled outward at velocities in the range 100 to 3000 km/s at ionization temperatures forming a continuous flow called stellar wind. As cosmic rays permanently and ubiquitously pervade the Galaxy, while impacting on stellar winds, loose energy.
This is empirically known since 70 years. Due...
It was proposed previously that Galactic Cosmic-Rays(GCRs) are trapped in a region where the weak local interstellar magnetic field lines are spreaded apart by the heliopause in the northern hemisphere. Such a trapped region acts like a magnetic mirror for GCR particles. Once entering the trapped region from the outside interstellar space, GCR particles will encounter more complicated...
As measured by neutron monitors the flux of galactic cosmic rays exhibits non-statistical fluctuations at all observed timescales. Many of these fluctuations can be identified with specific structures in the solar wind. There is also a rather steady diurnal variation due to cosmic ray streaming in the overall pattern of solar modulation. There is also a spectrum of fluctuations usually termed...
After thirteen years of operations on board the International Space Station, AMS has performed precise measurements of solar energetic particle (SEP) mostly observed during solar maximum of solar cycle 24 and 25. AMS has collected more than 40 extreme SEP events accelerated during M- and X-class flares and associated with fast coronal mass ejections. AMS detects these SEPs in the GV rigidity...
The observed composition of solar energetic particle (SEP) events can be influenced by a number of factors, including the acceleration mechanism, transport effects, and properties of the particle seed population. Generally the abundances of heavy ions relative to oxygen are higher in events where the dominant acceleration mechanism is flare-associated reconnection as compared to events where...
An average solar active region (AR) does not usually generate any enhancement in Solar Energetic Particles (SEPs) near Earth. A small subset of regions are able to produce one or a few SEP events and these are typically taking place at times of fairly good magnetic connection with near-Earth locations via the interplanetary magnetic field (IMF). However a small minority of ARs are...
The properties of solar energetic particle (SEP) event profiles have been researched extensively to investigate the acceleration and transport of SEPs. The effects on SEP intensity profiles of particle-filled magnetic flux tubes corotating with the Sun are generally considered to be negligible. However, corotation has recently been suggested to have an effect on SEP decay phases, based on...
Solar activity events release vast amounts of energy,
including radio waves, X-rays, ultraviolet radiation, and energetic
particles, which interact with the Earth's ionosphere and can disrupt radio
wave propagation, affecting radio communications. They can either
enhance reflections, enhancing long-distance terrestrial communications,
or cause signal degradation and absorption,...
The ISOIS/EPI-Hi/HET instrument on Parker Solar Probe can detect neutrals if they interact in the instrument and produce a charged particle (e.g., a gamma ray Compton scattering to produce an electron) when that particle stops in a shielded central region of silicon detectors without triggering the surrounding guards or outer detectors. A background of gamma rays is continuously created when...
The propagation of the Solar Energetic Particles (SEPs) in the heliosphere is guided by the large-scale Parker spiral magnetic field. The gradient and the curvature of the magnetic field give rise to drift of the particlesโ guiding centres in the direction perpendicular to the magnetic field, leading the SEPs to gradually move away from their initial Parker spiral field lines. SEP propagation...
On May 11 2024 a train of at least three magnetic cloud connected to fast coronal mass ejections impacted Earth during a very short period of less than 24 hours. In this so complicated solar wind conditions around Earth, a ground level enhancement was observed by neutron monitors the same 11 May at 2 AM just in between of the first magnetic cloud and the second one. In this time, to twins...
The characterization of the effects of solar disturbances on the Earth's ionosphere is crucial for the monitoring and understanding of space weather. While satellites orbiting outside of the Van Allen belts allow for direct measurements of the ejected particles and of magnetic field perturbations, low Earth orbit spacecraft, such as the China Seismo-Electromagnetic Satellite (CSES-01), provide...
Solar eruptive activity has many forms, the most important and well-studied are solar flares, coronal mass ejections, and solar energetic particle (SEP) events. It is mostly unknown what is the upper limit for the intensity of different eruptive activity events. For now, only traces of extreme solar particle events (ESPEs) were discovered in cosmogenic isotope data in datable natural archives,...
We report on the sources of gamma-ray emission above 100 MeV in the very impulsive GOES M3.3 class flare SOL2012-06-03. The >100 MeV emission during the prompt phase displayed a double-peaked temporal structure, with the highest peak occurring 17$\pm$2 seconds after the first peak with a difference in flux of almost a factor of 3. The HXR and gamma-ray time profiles during the impulsive phase...
The energy spectrum of solar energetic electron (SEE) events carries crucial information on the origin/acceleration at the Sun. We present ten solar energetic electron (SEE) events measured by Wind/3DP at ~1 to 200 keV with a bump break in the electron peak flux vs. energy spectrum. We assume that these bump SEE events consist of two electron populations: primary population (described by the...
Galactic Cosmic Rays (GCRs) are a source of major radiation hazards in space, therefore the forecast and nowcast of their spectrum time evolution during the passage of Coronal Mass Ejections (CMEs) is a desired part of radiation hazard prediction models. GCRs are generated in galactic sources and propagate until they approach the heliopause, where their Local Interstellar Spectrum (LIS) can be...
This study employs the Monte Carlo simulation method to investigate the shock stacking effect driven by coronal mass ejections (CMEs) and corotating interaction regions (CIRs). First, a probability distribution model incorporating characteristic parameters of CMEs and CIRsโsuch as velocity, density, and magnetic fieldโwas constructed to reflect their stochasticity and diversity in solar...
The Sun is a target of cosmic rays , CR. Their secondary photons by such CR skimming on solar edges, while scattering solar atmosphere and making neutral pions , is one of the expected and partially observed signal. However there are discrepancies in the gamma spectra within the the Sun disk that are not well understood. We first are reconsidering the role of such skimming and scattering CR...
Study of solar energetic particles is important to provide the necessary basis to understand the mechanisms of their acceleration and propagation in interplanetary space. It is known that following solar eruptive processes, such as solar flares and/or coronal mass ejections, solar ions can be accelerated to high energies, even in the GeV/n range. In this latter case, the SEP energy is great...
The inner heliosphere, spanning from the solar corona to Earth's orbit, is a dynamic region where energetic particles are accelerated and transported. Understanding these processes is crucial for comprehending space weather phenomena and their impact on Earth. This abstract discusses the key mechanisms involved in particle acceleration near the Sun, primarily driven by solar flares and coronal...
