Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007
The Galactic cosmic ray spectrum exhibits subtle variations over the 22 yr solar magnetic cyclein addition to the more dramatic variations over the 11 yr sunspot cycle. Neutron monitors arelarge ground-based detectors that provide accurate measurements of variations in the cosmic rayflux at the top...
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ftunivtasecite:oai:ecite.utas.edu.au:110302 2023-05-15T14:03:26+02:00 Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 Nuntiyakul, W Evenson, P Ruffalo, D Saiz, A Bieber, JW Clem, J Pyle, R Duldig, ML Humble, JE 2015 application/pdf http://ecite.utas.edu.au/110302 en eng Scuola Internazionale Superiore di Studi Avanzati (S I S S A),International School of Advanced Studies http://ecite.utas.edu.au/110302/1/ICRC2015_067.pdf Nuntiyakul, W and Evenson, P and Ruffalo, D and Saiz, A and Bieber, JW and Clem, J and Pyle, R and Duldig, ML and Humble, JE, Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007, Proceedings of Science, 30 July - 06 August, The Hague, Netherlands, pp. 1-8. ISSN 1824-8039 (2015) [Non Refereed Conference Paper] http://ecite.utas.edu.au/110302 Physical Sciences Astronomical and Space Sciences High Energy Astrophysics Cosmic Rays Non Refereed Conference Paper NonPeerReviewed 2015 ftunivtasecite 2019-12-13T22:10:52Z The Galactic cosmic ray spectrum exhibits subtle variations over the 22 yr solar magnetic cyclein addition to the more dramatic variations over the 11 yr sunspot cycle. Neutron monitors arelarge ground-based detectors that provide accurate measurements of variations in the cosmic rayflux at the top of the atmosphere above the detector. At any given location the magnetic field ofthe Earth excludes particles below a well-defined rigidity (momentum per unit charge) known asthe cutoff rigidity, which can be accurately calculated using detailed models of the geomagneticfield. By carrying a neutron monitor to different locations, e.g., on a ship, the Earth itself servesas a magnet spectrometer. By repeating such latitude surveys with identical equipment a sensitivemeasurement of changes in the spectrum can be made. In this work, we analyze data from the1994 through 2007 series of latitude surveys conducted by the Bartol Research Institute, the Universityof Tasmania, and the Australian Antarctic Division. We confirm the curious crossover"in spectra measured near solar minima during epochs of opposite solar magnetic polarity, andshow that it is related directly to a sudden change in the spectral behavior of solar modulation atthe time of the polarity reversal, as revealed from contemporaneous variations in the survey dataand a fixed station. We suggest that the spectral change and crossover result from the interactionof effects due to gradient/curvature drifts with a systematic change in the interplanetary diffusioncoefficient caused by turbulent magnetic helicity. Conference Object Antarc* Antarctic Australian Antarctic Division eCite UTAS (University of Tasmania) Antarctic |
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eCite UTAS (University of Tasmania) |
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ftunivtasecite |
language |
English |
topic |
Physical Sciences Astronomical and Space Sciences High Energy Astrophysics Cosmic Rays |
spellingShingle |
Physical Sciences Astronomical and Space Sciences High Energy Astrophysics Cosmic Rays Nuntiyakul, W Evenson, P Ruffalo, D Saiz, A Bieber, JW Clem, J Pyle, R Duldig, ML Humble, JE Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
topic_facet |
Physical Sciences Astronomical and Space Sciences High Energy Astrophysics Cosmic Rays |
description |
The Galactic cosmic ray spectrum exhibits subtle variations over the 22 yr solar magnetic cyclein addition to the more dramatic variations over the 11 yr sunspot cycle. Neutron monitors arelarge ground-based detectors that provide accurate measurements of variations in the cosmic rayflux at the top of the atmosphere above the detector. At any given location the magnetic field ofthe Earth excludes particles below a well-defined rigidity (momentum per unit charge) known asthe cutoff rigidity, which can be accurately calculated using detailed models of the geomagneticfield. By carrying a neutron monitor to different locations, e.g., on a ship, the Earth itself servesas a magnet spectrometer. By repeating such latitude surveys with identical equipment a sensitivemeasurement of changes in the spectrum can be made. In this work, we analyze data from the1994 through 2007 series of latitude surveys conducted by the Bartol Research Institute, the Universityof Tasmania, and the Australian Antarctic Division. We confirm the curious crossover"in spectra measured near solar minima during epochs of opposite solar magnetic polarity, andshow that it is related directly to a sudden change in the spectral behavior of solar modulation atthe time of the polarity reversal, as revealed from contemporaneous variations in the survey dataand a fixed station. We suggest that the spectral change and crossover result from the interactionof effects due to gradient/curvature drifts with a systematic change in the interplanetary diffusioncoefficient caused by turbulent magnetic helicity. |
format |
Conference Object |
author |
Nuntiyakul, W Evenson, P Ruffalo, D Saiz, A Bieber, JW Clem, J Pyle, R Duldig, ML Humble, JE |
author_facet |
Nuntiyakul, W Evenson, P Ruffalo, D Saiz, A Bieber, JW Clem, J Pyle, R Duldig, ML Humble, JE |
author_sort |
Nuntiyakul, W |
title |
Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
title_short |
Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
title_full |
Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
title_fullStr |
Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
title_full_unstemmed |
Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
title_sort |
latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007 |
publisher |
Scuola Internazionale Superiore di Studi Avanzati (S I S S A),International School of Advanced Studies |
publishDate |
2015 |
url |
http://ecite.utas.edu.au/110302 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Australian Antarctic Division |
genre_facet |
Antarc* Antarctic Australian Antarctic Division |
op_relation |
http://ecite.utas.edu.au/110302/1/ICRC2015_067.pdf Nuntiyakul, W and Evenson, P and Ruffalo, D and Saiz, A and Bieber, JW and Clem, J and Pyle, R and Duldig, ML and Humble, JE, Latitude survey investigation of galactic cosmic ray solar modulation during 1994-2007, Proceedings of Science, 30 July - 06 August, The Hague, Netherlands, pp. 1-8. ISSN 1824-8039 (2015) [Non Refereed Conference Paper] http://ecite.utas.edu.au/110302 |
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1766274094910668800 |