Differential Rigidity Spectrum Research Articles

Spectra and anisotropy of cosmic rays during gle64

Ground-based observations of cosmic rays by the spectrographic global survey method were used to study the ground-level enhancement in cosmic ray intensity on August 24, 2002. Spectra of variations of primary cosmic rays and their anisotropy were obtained. Based on measurements from the GOES spacecraft and global network of cosmic ray stations, the differential rigidity spectra of accelerated particles in the vicinity of the Sun were calculated. The maximum rigidity to which solar particles were accelerated was estimated.

Investigating the heliosphere, magnetosphere, atmosphere, and properties of cosmic rays during the 2018 Aug 25–26 strong geomagnetic storm

We investigated the conditions of the heliosphere, magnetosphere, and atmosphere from cosmic ray (CR) observations during the 2018 Aug 25–26 strong geomagnetic storm. The analysis involved the global survey (GS) and the spectrographic global survey (SGS) methods created and developed at the Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy of the Siberian Branch of the Russian Academy of Sciences (ShICRA SB RAS) and at the Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences (ISTP SB RAS). Also, in our analysis, we used the data on direct measurements of the interplanetary medium parameters from the known OMNI database, CR measurements at the GOES geostationary satellites, from the global network of neutron monitors and muon detectors, from the Sayan spectrograph, and from the A.I. Kuzmin Yakutsk spectrograph of CR. When analyzing this event, the SGS enabled to obtain the data on the orientation of the mean interplanetary magnetic field, on the geomagnetic cutoff rigidity and its variations during the geomagnetic storm. Also, this method allowed us to estimate the bulk temperature over the point of recording CR, the ring current and the magnetopause current, as well as their contributions to the Dst-index, and also to establish differential rigidity spectra of CR at different stages of the magnetic storm evolution. Through the GS method, we determined the value and the directions for the first two spherical harmonics of CR distribution, and the direction to their anisotropy source. The results obtained through two different global survey methods are shown to be agree and mutually supplement each other. Using the Yakutsk spectrograph records enabled to determine the index for the power energy spectrum of variations in CR intensity during the investigated event.

Pitch-angle anisotropy and differential rigidity spectra of cosmic rays during GLE on May 2 and 6, 1998

Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.

Питч-угловая анизотропия и дифференциальные жесткостные спектры космических лучей во время GLE 2 и 6 мая 1998 г.

Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.

Ground level enhancements of cosmic rays on October–November 2003

We study variations in the rigidity spectrum and anisotropy of cosmic rays (CRs) by using the data from satellite and ground-based observations within the worldwide network of cosmic-ray detectors through the global spectrographic survey. The studied period covers 28 and 29 October and 2 November 2003 (GLE65, GLE66, and GLE67). We determined CR differential rigidity spectra at individual hours of the investigated events. The maximal rigidity of accelerated protons in these GLEs is shown to equal ~ 4–14 GV.

Galactic cosmic ray transport in the heliosphere: Study with muon data

We use the galactic cosmic ray (GCR) solar diurnal anisotropy (SDA) data of Nagoya vertical muon telescope (NagV-MT) to compute the ratio α of GCR free paths normal and parallel to mean interplanetary magnetic field (IMF) B. The values are compared to those computed earlier for the neutron monitors (NMs) of the global network for three sunspot cycles (21–23) and parts of the other two (19, 24). Current GCR modulation theories do not provide any guidance for α, its rigidity and solar cycle dependence. We use a flat heliosphere current sheet and the Master equations derived by Ahluwalia and Dorman [1997] for computing α and study its rigidity dependence and correlation with solar activity for positive (p) and negative (n) polarity intervals of B at 1 AU; B points outward/ inward from the sun during p/n interval in north hemisphere; IMF polarity changes sign near SSN maximum. For NagV-MT (Rm = 60 GV), Rm being the median value of response to GCR differential rigidity spectrum, we find that α is high for p- and low for n-intervals, compared to being nearly flat for NMs; α for NM2 (Rm = 25 GV) is larger than that for NM1 (Rm = 15 GV), implying an increase in α with GCR rigidity. The α values for NagV-MT are low near SSN maximum as is the case for NMs and high near SSN minimum, when effective limiting GCR rigidity (Rc) for SDA is known to be lower than 100 GV. The results challenge the validity of current conceptual understanding of GCR modulation processes in the heliosphere, pointing to a great need to develop an acceptable theory to explain the empirical results reported in this paper.

Ground Level Enhancement of Cosmic Rays on October 28, 2003: Spectra and Anisotropy

Variations in the rigidity spectrum and anisotropy of cosmic rays (CRs) during the ground level enhancement (GLE) of CR intensity on October 28, 2003, are studied on the basis of ground and satellite observations by the worldwide network of CR stations using the spectrographic global survey approach developed at the Institute of Solar and Terrestrial Physics, Siberian Branch, Russian Academy of Sciences. Cosmic ray rigidity spectra are determined for different periods of the considered event. It is shown that acceleration of protons during this GLE was observed up to rigidities of ~10–14 GV, and neither a power law nor an exponential function of the rigidity of particles describes the CR differential rigidity spectra during the event. Analysis indicates that the Earth was in a loop-like structure of the interplanetary magnetic field at the time of the GLE event.

Spectra and Anisotropy of Cosmic Rays During the First GLE Event of Solar Cycle 24

By employing the method of spectrographic global survey, the spectra of protons and anisotropy of cosmic rays during the firstGround-Level Enhancement (GLE) of the intensity of cosmic rays in the solar cycle 24 onMay 17, 2012, a GLE71 event, are studied on the basis of data from ground-based observations of cosmic rays by means of the worldwide network of stations and data from spacecrafts. The rigidity spectra of cosmic rays and relative variations in the intensity of cosmic rays with rigidity 2 GV in the solarecliptic geocentric coordinate system are presented within individual periods of the event under study. It is shown that, in GLE71 periods, protons were accelerated to rigidities in the range of R ~ 2.3−2.5 GV and that the respective differential rigidity spectra of solar cosmic rays are not described by a power-law or an exponential function of the particle rigidity. During the event being considered, the Earth was in the loop-shaped structure of the interplanetary magnetic field.

Ground level enhancements of cosmic rays in solar cycle 24

Using data from ground-based observations of cosmic rays (CRs) on the worldwide network of stations and spacecraft, we have investigated the proton spectra and the CR anisotropy during the ground level enhancements of CRs on May 17, 2012 (GLE71) and January 6, 2014 (GLE72) occurred in solar cycle 24 by the spectrographic global survey method. We provide the CR rigidity spectra and the relative changes in the intensity of CRs with a rigidity of 2 GV in the solar–ecliptic geocentric coordinate system in specific periods of these events. We show that the proton acceleration during GLE71 and GLE72 occurred up to rigidities R ~ 2.3−2.5 GV, while the differential rigidity spectra of solar CRs are described neither by a power nor by an exponential function of particle rigidity. At the times of the events considered the Earth was in a loop-like structure of the interplanetary magnetic field.

Analysis of ground level enhancement on January 6, 2014

Variations in the rigidity spectrum and anisotropy of cosmic rays during ground level enhancement (GLE) on January 6, 2014, is investigated using ground-based observations of cosmic rays (CRs) from the worldwide network of stations and spacecraft measurements obtained via a spectrographic global survey. The CR rigidity spectrum and relative variations in the intensity of CRs with rigidity of 4 GV are presented in the solar–ecliptic geocentric coordinate system in certain periods of the investigated event. It is shown that protons were accelerated during this GLE up to a particle rigidity of R ~ 2.4 GV. In the ~0.3 to ~2.4 GV range of rigidity, the CR differential rigidity spectra during the considered event were described by neither a power function nor an exponential function of particle rigidity. At the time of GLE, the Earth was in a loop-like IMF structure.

Ground level enhancement of cosmic rays on November 6, 1997: Spectra and anisotropy

Variations of the rigidity spectrum and anisotropy of cosmic rays in the period of the ground-level enhancement (GLE) of cosmic rays on November 6, 1997, according to the data from the worldwide network of ground-based stations and satellites have been studied by the unique spectrographic global survey method developed at the Institute of Solar–Terrestrial Physics, Siberian Branch, Russian Academy of Sciences. Rigidity spectra of cosmic rays in various periods of the event under study have been determined. It has been shown that the acceleration of protons in the period of this GLE event was observed to a rigidity of ~10–12 GV, and neither a power-law nor an exponential function of the rigidity of particles describes the differential rigidity spectra of cosmic rays in the event under consideration. The analysis has indicated that the Earth at the time of the GLE event was in a looplike structure of the interplanetary magnetic field.

Estimation of index of power law rigidity spectrum of cosmic rays using effective rigidity of multidirectional muon detector

We develop a new approach for calculating index of power law for variations in the differential rigidity spectrum of cosmic rays registered by Nagoya multidirectional muon detector. Our approach is based on effective rigidity which we define for the entire instrument, not just for its individual channels. Our definition of effective rigidity can be straightforwardly extended to other multichannel instruments and networks of instruments. As examples, we calculate the power law index under quiet conditions and during 12 Forbush decrease events. We also discuss sensitivity of the Nagoya muon detector to different values of the power law index and different rigidities.

May 2005 Halo CMEs and Galactic Cosmic Ray Flux Changes at Earth’s Orbit

The pressure corrected hourly data from the global network of cosmic ray detectors, measurements of the interplanetary magnetic field (IMF) intensity (B) at Earth’s orbit and its components B x , B y , B z (in the geocentric solar ecliptic coordinates) are used to conduct a comprehensive study of the galactic cosmic ray (GCR) intensity fluctuations caused by the halo coronal mass ejection of 13 May 2005. Distinct differences exist in GCR timelines recorded by neutron monitors (NMs) and multidirectional muon telescopes (MTs), the latter respond to the high rigidity portion of the GCR differential rigidity spectrum. The Forbush decrease (FD) onset in MTs is delayed (∼5 h) with respect to the onset of a geomagnetic storm sudden commencement (SSC) and a large pre-increase is present in MT data before, during, and after the SSC onset, of unknown origin. The rigidity spectrum, for a range of GCR rigidities (≤200 GV), is a power law in rigidity (R) with a negative exponent (γ=−1.05) at GCR minimum intensity, leading us to infer that the quasi-linear theory of modulation is inconsistent with observations at high rigidities (>1 GV); the results support the force field theory of modulation. At present, we do not have a comprehensive model for the FD explaining quantitatively all the observational features but we present a preliminary model listing physical processes that may contribute to a FD timeline. We explored the connections between different phases of the FD and the power spectra of IMF components but did not find a sustained relationship.

The November 1970 Forbush decrease investigation at the cut-off rigidity where the latitude curve changes its curvature

The first recorded and analysed cosmic ray event since the Athens 3 NM-64 came into operation, that of 7 November 1970, is presented. The relative amplitude of the Forbush Decrease reached a value of (4.5 ± 0.3)% peak to peak which is comparatively large at a cut-off rigidity of 8.7 GV (Shea et al., 1968). According to the differential method (Amaldi et al., 1963 ; Bachelet et al, 1972) it has been computed that the slope of the primary differential rigidity spectrum varied at the Athens cut-off rigidity during the above mentioned F.D. by (6.3 ± 0.8)%. This information repairs the omission which was in the threshold rigidity region (8 ± 2) GV, which is quite important because the latitude curves change the algebraic sign of their curvatures (Geranios, 1971).

Rigidity spectrum of Z greater than or equal to 3 cosmic-ray nuclei in the range 4-285 GV and a search for cosmic antimatter

A measurement, using the magnetic emulsion spectrometer system, of the differential rigidity spectrum of Z greater than or equal to 3 nuclei of the galactic cosmic radiation is presented. The system was flown on Aug. 22, 1969, from Palestine, Texas. The instrument floated above 125,000 feet for eight hours. The data in the rigidity range 8-285 GV can be represented by a power-law spectrum in rigidity, J(rho) = A rho to the minus gamma power, with the exponent gamma = 2.6 plus or minus 0.10. The spectrum in the range 15-285 GV is also described by the same exponent, gamma = 2.6 plus or minus 0.25. The data below 8 GV cannot be described by the same power law without invoking solar modulation. A set of nonunique parameters for modulation are given. Upper limit for the fraction of antimatter in the rigidity range 4-125 GV is .005 with 95% confidence limit.

A Measurement of Cosmic-Ray Rigidity Spectra above 5 GV/c of Elements from Hydrogen to Iron

view Abstract Citations (126) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Measurement of Cosmic-Ray Rigidity Spectra above 5 GV/c of Elements from Hydrogen to Iron Smith, L. H. ; Buffington, A. ; Smoot, D. F. ; Alvarez, L. W. ; Wahlig, M. A. Abstract This paper presents measurements of the differential rigidity spectra of primary cosmic-ray nuclei between 5 OVIc and 100 GVIc. These measurements were performed with a balloon-borne superconducting magnetic spectrometer containing scintillation detectors, optical spark chambers, and associated electronics. We present a rigidity spectrum for each element from hydrogen through oxygen and for groups of elements through the iron group. In our data, at large rigidities, the elements lithium, beryllium, boron, and nitrogen become increasingly rare relative to the other elements. Since these four elements are thought to be fragmentation products from the interactions of carbon, oxygen, or heavier cosmic-ray elements with the interstellar gas, one possible explanation of this result is that less interstellar material was traversed by higher-rigidity nuclei in the cosmic rays. Subject headings: abundances, cosmic-ray - cosmic rays Publication: The Astrophysical Journal Pub Date: March 1973 DOI: 10.1086/152021 Bibcode: 1973ApJ...180..987S full text sources ADS |

Superconducting Magnetic Spectrometer for Cosmic Ray Nuclei

This paper describes the design, calibration, and operation of a magnetic spectrometer for particle astronomy. The spectrometer consists of a superconducting magnet, optical spark chambers, scintillation detectors, and associated electronics. The instrument has been flown in a balloon gondola to 4.8 g/cm2 residual atmosphere, where it was used to analyze the charge and differential rigidity spectra of primary nuclei from 5 to 100 GeV/c.

Rigidity spectrum of cosmic-ray helium nuclei

An experiment has been carried out using an oriented stack of nuclear emulsions to determine the rigidity spectrum of cosmic ray helium nuclei between 12 and 40 GV, by taking advantage of the variation of the geomagnetic cut-off rigidity in the east-west plane over Hyderabad, India. Altotal of 2433 identified helium nuclei recorded in the stack, has been divided into 8 angular intervals in the east-west plane corresponding to 8 different cut-off rigidities. From this the integral fluxes of helium nuclei at the top of the atmosphere have been obtained for all the 8 rigidity intervals. The vertical flux above an effective threshold rigidity of 16·73 GV has been determined with high statistical accuracy and has a value of 15·0±0·5 helium nuclei (m2.sr.sec.)−1. The rigidity spectrum of these nuclei between 12 and 40 GV can be well represented by a power law of the type N (>R) =1990 R−1.74±0.11 (m2.sr.sec.)−1 and is the first direct determination so far made in this rigidity region. The differential rigidity spectra of protons, helium nuclei and S-nuclei of the cosmic radiation in the vicinity of the earth at solar minimum (1965) have been constructed with the existing world data and it is found that for rigidities ≳ 10 GV, the three spectra have, within experimental errors, the same slope of 2·6. The ratio P/He and He/S of the differential fluxes have been studied as a function of rigidity. It is found that for R>2 GV, the ratio P/He has, within experimental errors, a constant value of 6·3; as for the ratio He/S, it seems that the experimental data above a GV is not inconsistent with a constant value of 14 over the entire rigidity interval considered here.

Cerenkov-scintillation counter measurements of nuclei heavier than helium in the primary cosmic radiation: 1. Charge composition and energy spectra between 200 Mev/nucleon and 5 bev/nucleon

Studies of the energy spectrum and charge composition of the primary cosmic radiation have been carried out on seven balloon flights at five geomagnetic latitudes using a Cerenkov-scintillation counter telescope that has geometrical factor ≃ 50 st cm². The calibration of the instrument for particles of various energy and charge is discussed. Particular attention is paid to the problem of ‘background’ as it affects the energy spectrum and charge resolution and to the effects of nonlinearities in light output in the scintillators for highly charged particles. The data are corrected to the top of the atmosphere using direct measurements of the atmospheric absorption of the various charge components. Differential spectra for particles with nuclear charges from 3 ≤ Z ≤ 26, covering the energy range 200 Mev/nucleon to 5 bev/nucleon are presented, based on the identification of some 6000 nuclei with charge greater than helium. These spectra are adjusted to the mean Mt. Washington bihourly neutron rate of 2440 that prevailed during this series of flights in 1964 and 1965. This rate is within 2% of the highest rate achieved by this monitor during the sunspot minimums in 1954 and 1965. Findings summarized in this paper are: (1) Between 2.5 and 12 bv rigidity, the differential rigidity spectra of helium and all heavier nuclei may be represented by power laws with negative exponent = −2.2 ± 0.05. There is some evidence that light nuclei and very heavy nuclei have slightly steeper spectra. At higher rigidities it appears that the spectral exponent for all charges must continue to increase reaching a value of −2.5 or −2.6 appropriate to rigidities > 100 bv. (2) The abundance of odd nuclei of charges 9–17 is so small at 4 g/cm² atmospheric depth that a major fraction of them would be expected to be secondaries created in the atmosphere. This observation suggests a very low fragmentation probability for even nuclei into odd nuclei in this charge range, both in the atmosphere and in interstellar space. The L/M ratio as a function energy/nucleon is also presented.

Solar modulation of primary cosmic rays as deduced from neutron monitor data

An empirical relation has been found that describes the rigidity and long-term time variations of the counting rates of neutron monitors at sea level. The formula is applicable for the period between the 1954–1955 and 1964–1965 solar minimums for stations with vertical threshold rigidities above 1.3 Gv. The data of the Mt. Washington, Climax, and Mt. Norikura neutron monitors have been used to establish the relation. Through the use of this empirical relation and the available neutron monitor response functions, the relative fractional time variations of the differential rigidity spectra of primary cosmic rays have been derived for rigidities above 2.5 Gv. The corresponding modulation of the integral spectra has been calculated on the assumption that the generally accepted quiet-time differential alpha spectrum is valid. The derived and the experimental fluxes have been shown to agree satisfactorily throughout the 1954–1965 solar cycle.