scholarly journals Updated Neutron‐Monitor Yield Function: Bridging Between In Situ and Ground‐Based Cosmic Ray Measurements

2020 ◽  
Vol 125 (2) ◽  
Author(s):  
Alexander L. Mishev ◽  
Sergey A. Koldobskiy ◽  
Gennady A. Kovaltsov ◽  
Agnieszka Gil ◽  
Ilya G. Usoskin
Keyword(s):  
Neutron Monitor ◽  
Cosmic Ray ◽  
Yield Function

scholarly journals Cosmic-Ray Driven Outflows to Mpc Scales from L* Galaxies

2020 ◽  
Author(s):  
Philip F Hopkins ◽  
T K Chan ◽  
Suoqing Ji ◽  
Cameron B Hummels ◽  
Dušan Kereš ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Plane Layer ◽  
Equilibrium Density ◽  
Pressure Gradients ◽  
Low Velocity ◽  
Star Forming ◽  
Stellar Feedback ◽  
Massive Halos ◽  
Halo Masses

Abstract We study the effects of cosmic rays (CRs) on outflows from star-forming galaxies in the circum and inter-galactic medium (CGM/IGM), in high-resolution, fully-cosmological FIRE-2 simulations (accounting for mechanical and radiative stellar feedback, magnetic fields, anisotropic conduction/viscosity/CR diffusion and streaming, and CR losses). We showed previously that massive (Mhalo ≳ 1011 M⊙), low-redshift (z ≲ 1 − 2) halos can have CR pressure dominate over thermal CGM pressure and balance gravity, giving rise to a cooler CGM with an equilibrium density profile. This dramatically alters outflows. Absent CRs, high gas thermal pressure in massive halos “traps” galactic outflows near the disk, so they recycle. With CRs injected in supernovae as modeled here, the low-pressure halo allows “escape” and CR pressure gradients continuously accelerate this material well into the IGM in “fast” outflows, while lower-density gas at large radii is accelerated in-situ into “slow” outflows that extend to >Mpc scales. CGM/IGM outflow morphologies are radically altered: they become mostly volume-filling (with inflow in a thin mid-plane layer) and coherently biconical from the disk to >Mpc. The CR-driven outflows are primarily cool (T ∼ 105 K) and low-velocity. All of these effects weaken and eventually vanish at lower halo masses (≲ 1011 M⊙) or higher redshifts (z ≳ 1 − 2), reflecting the ratio of CR to thermal+gravitational pressure in the outer halo. We present a simple analytic model which explains all of the above phenomena. We caution that these predictions may depend on uncertain CR transport physics.

scholarly journals Observing the neutron component during thunderstorm activity at a mountain CR station

2019 ◽  
Vol 5 (3) ◽  
pp. 54-58
Author(s):  
Анна Луковникова ◽  
Anna Lukovnikova ◽  
Виктор Алешков ◽  
Viktor Aleshkov ◽  
Алексей Лысак ◽  
...  
Keyword(s):  
Field Strength ◽  
Sea Level ◽  
Neutron Monitor ◽  
Electromagnetic Interference ◽  
Count Rate ◽  
Cosmic Ray ◽  
Thunderstorm Activity ◽  
Signal Discrimination ◽  
Lightning Discharges ◽  
Neutron Component

During three summer months in 2015, the Cosmic Ray (CR) station Irkutsk-3000, located at 3000 m above sea level, measured the CR neutron component intensity with the 6NM64 neutron monitor, as well as the atmospheric electric field strength and the level of electromagnetic interference during lightning discharges. It is shown that the level of electromagnetic interference, when registered during lightning discharges, depends considerably on the fixed level of signal discrimination. During observations, we observed no effects of thunderstorm discharges at the neutron monitor count rate at the CR station Irkutsk-3000.

scholarly journals Application of the verified neutron monitor yield function for GLE analysis

2021 ◽  
Author(s):  
Aleksandar Mishev ◽  
Ilya Usoskin ◽  
Sergey Koldobskiy ◽  
Gennady Kovaltsov ◽  
Leon Kocharov
Keyword(s):  
Neutron Monitor ◽  
Yield Function

scholarly journals A Novel Lithium Foil Cosmic-Ray Neutron Detector for Measuring Field-Scale Soil Moisture

2021 ◽  
Vol 3 ◽  
Author(s):  
Andres Patrignani ◽  
Tyson E. Ochsner ◽  
Benjamin Montag ◽  
Steven Bellinger
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Atmospheric Pressure ◽  
Lower Cost ◽  
Cosmic Ray ◽  
Absolute Difference ◽  
Atmospheric Conditions ◽  
Volumetric Soil Water Content ◽  
The Mean

During the past decade, cosmic-ray neutron sensing technology has enabled researchers to reveal soil moisture spatial patterns and to estimate landscape-average soil moisture for hydrological and agricultural applications. However, reliance on rare materials such as helium-3 increases the cost of cosmic-ray neutron probes (CRNPs) and limits the adoption of this unique technology beyond the realm of academic research. In this study, we evaluated a novel lower cost CRNP based on moderated ultra-thin lithium-6 foil (Li foil system) technology against a commercially-available CRNP based on BF3 (boron trifluoride, BF-3 system). The study was conducted in a cropped field located in the Konza Prairie Biological Station near Manhattan, Kansas, USA (325 m a.s.l.) from 10 April 2020 to 18 June 2020. During this period the mean atmospheric pressure was 977 kPa, the mean air relative humidity was 70%, and the average volumetric soil water content was 0.277 m3 m−3. Raw fast neutron counts were corrected for atmospheric pressure, atmospheric water vapor, and incoming neutron flux. Calibration of the CRNPs was conducted using four intensive field surveys (n > 120), in combination with continuous observations from an existing array of in situ soil moisture sensors. The time series of uncorrected neutron counts of the Li foil system was highly correlated (r2 = 0.91) to that of the BF-3 system. The Li foil system had an average of 2,250 corrected neutron counts per hour with an uncertainty of 2.25%, values that are specific to the instrument size, detector configuration, and atmospheric conditions. The estimated volumetric water content from the Li foil system had a mean absolute difference of 0.022 m3 m−3 compared to the value from the array of in situ sensors. The new Li foil detector offers a promising lower cost alternative to existing cosmic-ray neutron detection devices used for hectometer-scale soil moisture monitoring.

scholarly journals Neutron monitor yield function at several altitudes above sea level: new improved computation

2019 ◽  
Author(s):  
Aleksandar Mishev ◽  
Gennady Kovaltsov ◽  
Ilya Usoskin
Keyword(s):  
Sea Level ◽  
Neutron Monitor ◽  
Yield Function

scholarly journals Validation of the Neutron Monitor Yield Function Using Data From AMS‐02 Experiment, 2011–2017

2019 ◽  
Author(s):  
Sergey A. Koldobskiy ◽  
Veronica Bindi ◽  
Claudio Corti ◽  
Gennady A. Kovaltsov ◽  
Ilya G. Usoskin
Keyword(s):  
Neutron Monitor ◽  
Yield Function ◽  
Using Data

scholarly journals Investigating temporal field sampling strategies for site-specific calibration of three soil moisture–neutron intensity parameterisation methods

2015 ◽  
Vol 19 (7) ◽  
pp. 3203-3216 ◽  
Author(s):  
J. Iwema ◽  
R. Rosolem ◽  
R. Baatz ◽  
T. Wagener ◽  
H. R. Bogena
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Satellite Remote Sensing ◽  
Cosmic Ray ◽  
Sampling Strategies ◽  
Site Specific ◽  
Neutron Intensity ◽  
Soil Wetness ◽  
Semi Arid

Abstract. The Cosmic-Ray Neutron Sensor (CRNS) can provide soil moisture information at scales relevant to hydrometeorological modelling applications. Site-specific calibration is needed to translate CRNS neutron intensities into sensor footprint average soil moisture contents. We investigated temporal sampling strategies for calibration of three CRNS parameterisations (modified N0, HMF, and COSMIC) by assessing the effects of the number of sampling days and soil wetness conditions on the performance of the calibration results while investigating actual neutron intensity measurements, for three sites with distinct climate and land use: a semi-arid site, a temperate grassland, and a temperate forest. When calibrated with 1 year of data, both COSMIC and the modified N0 method performed better than HMF. The performance of COSMIC was remarkably good at the semi-arid site in the USA, while the N0mod performed best at the two temperate sites in Germany. The successful performance of COSMIC at all three sites can be attributed to the benefits of explicitly resolving individual soil layers (which is not accounted for in the other two parameterisations). To better calibrate these parameterisations, we recommend in situ soil sampled to be collected on more than a single day. However, little improvement is observed for sampling on more than 6 days. At the semi-arid site, the N0mod method was calibrated better under site-specific average wetness conditions, whereas HMF and COSMIC were calibrated better under drier conditions. Average soil wetness condition gave better calibration results at the two humid sites. The calibration results for the HMF method were better when calibrated with combinations of days with similar soil wetness conditions, opposed to N0mod and COSMIC, which profited from using days with distinct wetness conditions. Errors in actual neutron intensities were translated to average errors specifically to each site. At the semi-arid site, these errors were below the typical measurement uncertainties from in situ point-scale sensors and satellite remote sensing products. Nevertheless, at the two humid sites, reduction in uncertainty with increasing sampling days only reached typical errors associated with satellite remote sensing products. The outcomes of this study can be used by researchers as a CRNS calibration strategy guideline.

scholarly journals Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: ULYSSES COSPIN/KET and neutron monitor network observations

2003 ◽  
Vol 21 (6) ◽  
pp. 1295-1302 ◽  
Author(s):  
A. V. Belov ◽  
E. A. Eroshenko ◽  
B. Heber ◽  
V. G. Yanke ◽  
A. Raviart ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Neutron Monitor ◽  
Solar Minimum ◽  
Latitudinal Gradient ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Alpha Particles ◽  
Polar Regions

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The Kiel Electron Telescope (KET) measures also protons and alpha-particles in the energy range from 5 MeV/n to >2 GeV/n. To derive radial and latitudinal gradients for >2 GeV/n protons and alpha-particles, data from the Chicago instrument on board IMP-8 and the neutron monitor network have been used to determine the corresponding time profiles at Earth. We obtain a spatial distribution at solar maximum which differs greatly from the solar minimum distribution. A steady-state approximation, which was characterized by a small radial and significant latitudinal gradient at solar minimum, was interchanged with a highly variable one with a large radial and a small – consistent with zero – latitudinal gradient. A significant deviation from a spherically symmetric cosmic ray distribution following the reversal of the solar magnetic field in 2000/2001 has not been observed yet. A small deviation has only been observed at northern polar regions, showing an excess of particles instead of the expected depression. This indicates that the reconfiguration of the heliospheric magnetic field, caused by the reappearance of the northern polar coronal hole, starts dominating the modulation of galactic cosmic rays already at solar maximum.Key words. Interplanetary physics (cosmic rays; energetic particles) – Space plasma physics (charged particle motion and acceleration)

scholarly journals Hydrogen isotopic anomalies in extraterrestrial organic matter: role of cosmic ray irradiation and implications for UCAMMs

2019 ◽  
Vol 627 ◽  
pp. A122 ◽  
Author(s):  
B. Augé ◽  
E. Dartois ◽  
J. Duprat ◽  
C. Engrand ◽  
G. Slodzian ◽  
...  
Keyword(s):  
Organic Matter ◽  
Infrared Spectroscopy ◽  
Spatial Scale ◽  
Secondary Ion Mass Spectrometry ◽  
Isotopic Fractionation ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Ex Situ

Context. Micrometeorites represent, at timescales shorter than a few million years, the dominant source of extraterrestrial matter at the surface of the Earth. Analyses of ultracarbonaceous micrometeorites recovered from Antarctica, known as UCAMMs reveal an exceptionally N-rich organic matter associated with spatially extended high D enrichments. Experiments show that this specific organic matter might have been formed in the outer solar system by energetic irradiation of N-rich icy surfaces. Aims. We experimentally investigate the hydrogen isotopic fractionation resulting from irradiation of normal and D-rich N2-CH4 ices by high energy ions, simulating the exposition to Galactic cosmic rays of icy bodies surfaces orbiting at large heliocentric distances. Methods. Films of N2-CH4 ices and a N2-CH4/CD4/N2-CH4 “sandwich” ice were exposed to 129Xe13+ ion beams at 92 and 88 MeV. The chemical evolution of the samples was monitored using in situ Fourier transform infrared spectroscopy. After irradiation, targets were annealed to room temperature. The solid residues of the whole process left after ice sublimation were characterized in situ by infrared spectroscopy, and the hydrogen isotopic composition measured ex situ by imaging secondary ion mass spectrometry at the sub-micron scale (NanoSIMS). Results. Irradiation leads to the formation of new molecules and radicals. After annealing, the resulting poly-HCN-like macro-molecular residue exhibits an infrared spectrum close to that of UCAMMs. The residue resulting from irradiation of N2-CH4 ices does not exhibit a significant deuterium enrichment comparable to that found in extraterrestrial organic matter. The residue formed by irradiation of D-rich ices shows the formation of isotopic heterogeneities with localised hotspots and an extended contribution likely due to the diffusion of the radiolytic products from the D-rich layer. Conclusions. These results show that high-energy cosmic ray irradiation does not induce the large hydrogen isotopic fractionation observed at small spatial scale in interplanetary organics. By contrast, large D/H ratio heterogeneities at the sub-micron spatial scale in extraterrestrial organic matter can result from isotopically heterogeneous ices mixtures (i.e. condensed with different D/H ratios), which were transformed into refractory organic matter upon irradiation.

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