scholarly journals Neutron Monitors and Cosmogenic Isotopes as Cosmic Ray Energy‐Integration Detectors: Effective Yield Functions, Effective Energy, and Its Dependence on the Local Interstellar Spectrum

2017 ◽  
Vol 122 (10) ◽  
pp. 9790-9802 ◽  
Author(s):  
Eleanna Asvestari ◽  
Agnieszka Gil ◽  
Gennady A. Kovaltsov ◽  
Ilya G. Usoskin
1968 ◽  
Vol 46 (10) ◽  
pp. S1048-S1051 ◽  
Author(s):  
K. M. Wainio ◽  
T. H. Colvin ◽  
K. A. More ◽  
O. L. Tiffany

Results of calculations to determine specific yield functions for IGY neutron monitors are reported for vertically incident cosmic-ray protons in the range of 1 < Pc < 6 GV. The Monte Carlo method is used to calculate secondary nucleon-flux intensities at atmospheric depths of 312, 680, and 1 000 g/cm2. Experimental data on neutron monitor response are employed to relate the calculated flux data to count rates, and hence to specific yields, at the corresponding depths. Comparison with empirical data for the specific yield function at sea level shows fair agreement for rigidities less than 3 GV, but calculated yields are considerably smaller than the empirical data at higher rigidities. Various possible explanations for the discrepancy are discussed. At this time, the most probable cause appears to be the assumption that vertically incident cosmic rays produce most of the counts registered by neutron monitors.


2021 ◽  
Author(s):  
Kseniia Golubenko ◽  
Eugene Rozanov ◽  
Genady Kovaltsov ◽  
Ari-Pekka Leppänen ◽  
Ilya Usoskin

&lt;p&gt;We present the first results of modelling of the short-living cosmogenic isotope &lt;sup&gt;7&lt;/sup&gt;Be production, deposition, and transport using the chemistry-climate model SOCOLv&lt;sub&gt;3.0&lt;/sub&gt; aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme, &amp;#160;based on gas tracers with and without nudging to the known meteorological fields. Production of &lt;sup&gt;7&lt;/sup&gt;Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of &lt;sup&gt;7&lt;/sup&gt;Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope &lt;sup&gt;7&lt;/sup&gt;Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002&amp;#8211;2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past.&amp;#160;&lt;/p&gt;


2014 ◽  
Author(s):  
Fernando V. Laureano ◽  
Darryl E. Granger ◽  
Ivo Karmann ◽  
Valdir F. Novello

Isótopos cosmogênicos são formados na atmosfera, na superfície e nos primeiros metros da crosta terrestre através da colisão de partículas sub-atômicas com núcleos de elementos químicos ali existentes. Entre um largo espectro de isótopos gerados 10Be e 26Al produzidos no interior do mineral quartzo podem ser utilizados para calcular o soterramento de sedimentos e superfícies geológicas previamente expostos aos raios cósmicos. Três diferentes abordagens podem ser evocadas na obtenção de idades: (i) o soterramento simples para quando há um soterramento completo das amostras (> 10m); (ii) idades máximas e mínimas quando as amostras não se encontram a uma profundidade suficiente para interromper a produção pós-soterramento destes isótopos e (iii) o método da isócrona derivado de uma solução gráfica onde múltiplas amostras de uma mesma camada são utilizadas para obtenção de uma idade. Além das idades em si o emprego destes isótopos carrega outro importante resultado em estudos geomorfológicos, quer seja a taxa de erosão pré-soterramento. O método possui um alcance compreendido entre 100 mil e 4-5 milhões de anos antes do presente e uma resolução nunca inferior a 60 mil anos. A literatura registra a obtenção de idades em sedimentos de caverna, terraços fluviais, dunas, solos, entre outros, e soma resultados no campo da determinação de taxas de incisão fluvial, no balizamento geocronológico da evolução do modelado, na investigação da dinâmica de solos, bem como em investigações paleoclimáticas e arqueológicas.Palavras-chave: Isótopos cosmogênicos; Datação de soterramento; Sedimentos Abstract: BURIAL DATING WITH COSMOGENIC ISOTOPES 10BE AND 26AL: METHODOLOGICAL SYNTHESIS AND A BRIEF REVIEW OF APPLICATIONS IN GEOSCIENCES. Comogenic isotopes are formed in Earth’s atmosphere, surface and very shallow crust as a result of the collision of sub-atomic particles (cosmic ray) with nuclei in the atmosphere and rock. The cosmogenic isotopes 10Be and 26Al generated inside quartz grains may be used in burial dating of sediments or geological surfaces previously exposed to cosmic rays. Three different approaches can be used for age determinations: (i) simple burial dating when samples are totally buried from cosmic rays; (ii) minimum and maximum ages when samples did not get deep enough to avoid post burial production and (iii) an isochron method derived from a graphical solution where multiple samples from a single layer are used to obtain a single burial age. Burial dating also brings to light another important geomorphic result: the pre-burial erosion rate. The method can be applied in samples buried in a range of 100 thousand to 4-5 million years ago, with a resolution limited to about 60 thousand years. The literature records burial ages from cave sediments, fluvial terraces, dunes, soil related materials, and others, allowing researchers to constrain river incision rates, landscape evolution, soil dynamics and paleoclimate and archeological issues as well.Keywords: Cosmogenic isotopes; Burial dating, Sediments.


1962 ◽  
Vol 40 (7) ◽  
pp. 906-923 ◽  
Author(s):  
William Webber

By comparing the measured intensities and spectra of solar particles at the top of the atmosphere with measured neutron monitor intensity increases at sea level for several solar particle events, a set of yield functions has been derived for these neutron monitors in terms of low-rigidity (0.5–2 BV) particles incident on the top of the atmosphere. The monitors are found to be significantly more sensitive to these low-rigidity particles than has recently been believed. Various characteristics of the response of neutron monitors to solar flare particles are discussed. In particular a method is described by which the intensity increase vs. latitude curve for the neutron monitors during these events can be utilized to derive a measurement of the deviations in geomagnetic cutoff from those expected from the earth's internal field only. Applying this to the November 15, 1960, event suggests that a ring current of moment M = 0.6 ME and radius R = 7.7 RE was flowing at 1130 U.T. on this day.


1968 ◽  
Vol 46 (10) ◽  
pp. S819-S822
Author(s):  
Pekka J. Tanskanen

Data from super neutron monitors at Deep River, Churchill, Resolute, and Alert have been used to study the daily variation of cosmic-ray intensity during 1965 and 1966. Intensities have been examined on a daily, weekly, and monthly basis as a function of the asymptotic direction of vertically incident 7.5-BeV particles. The data have been analyzed in an earth-centered solar-ecliptic coordinate system in which daily (due to the earth's rotation) and seasonal (due to the inclination of the earth's axis to the ecliptic plane) variations of the asymptotic directions are considered.During undisturbed periods the daily variation has been examined by applying a digital filter to the pressure-corrected data and also to the data after subtraction of a variable-amplitude Parker–Axford theoretical diurnal variation. Particular attention has been paid to the dependence of the observed daily variation on the solar-ecliptic latitude of the asymptotic direction.Seventy-three percent of the weeks considered in 1965 and 1966 give the phase of the first harmonic in a direction 85° ± 35 °E. Sixty percent of the weekly periods show a daily variation as a function of solar-ecliptic latitude which is in agreement with the Parker–Axford "streaming-velocity" theory. During Forbush decreases the diurnal phase shifts towards earlier hours and the amplitude increases to two to three times the predecrease level.


1961 ◽  
Vol 39 (5) ◽  
pp. 668-676 ◽  
Author(s):  
S. M. Lapointe ◽  
D. C. Rose

The direction of maximum sensitivity of a neutron monitor is calculated numerically for a set of points on the same geomagnetic meridian but extending in latitude from the equator to the pole. This leads to two master curves, one for the longitude, the other for the latitude of this direction. From these curves this direction is obtained in geographic co-ordinates for some 20 cosmic-ray stations. The method of calculation is described taking into account atmospheric absorption and the energy spectrum of the incident particles. The aperture of the sensitive cone, or source width, is also calculated. Finally the accuracy of the results is discussed and the application of the concept of effective direction is described.


1968 ◽  
Vol 46 (10) ◽  
pp. S809-S811 ◽  
Author(s):  
L. I. Dorman ◽  
S. Fischer

Employing the data from cosmic-ray neutron monitors at high latitude, the spatial distribution of the axis of the diurnal anisotropy is determined. The effects of the earth's revolution around the sun on the diurnal intensity variation is investigated. A new method for further investigation of the spatial distribution of the anisotropy and for the determination of its spectra in various directions has been proposed.


Author(s):  
Fraser Baird ◽  
Alexander MacKinnon

For the first time, based on the experimental data of AMS-02, a three-parameter spectrum of variations of ga - lactic cosmic rays was obtained in the range of rigidity 1- 20 GV, to which neutron monitors are most sensitive. It was found that during the period of negative polarity of the solar magnetic field, a power-law spectrum of va - riations is observed with a strong exponential decay in the region of high rigidity. When the polarity changes to positive at the beginning of the new 24th solar cycle, the spectrum of cosmic ray variations becomes purely po- wer-law. The transition to the experimentally obtained spectrum of variations will make it possible to remove a number of uncertainties and increase the accuracy of the analysis of data from the ground network of detectors. This will make it possible to retrospectively obtain fluxes of galactic protons with an average monthly resolution for the period of the space era based on ground-based monitoring.


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