Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Neutron Monitor Response Functions


The neutron monitor provides continuous ground-based recording of the hadronic component in atmospheric secondary radiation which is related to primary cosmic rays. Simpson (1948) discovered that the latitude variation of the secondary hadronic component was considerably larger than the muon component suggesting the response of a neutron monitor is more sensitive to lower energies in the primary spectrum. The different methods of determining the neutron monitor response function of primary cosmic rays are reviewed and discussed including early and recent results. The authors also provide results from a new calculation (Clem, 1999) including angle dependent yield functions for different neutron monitor types which are calculated using a simulation of cosmic ray air showers combined with a detection efficiency simulation for different secondary particle species. Results are shown for IGY and NM64 configurations using the standard 10BF3 detectors and the new 3He detectors to be used in the Spaceship Earth Project (Bieber et al., 1995). The method of calculation is described in detail and the results are compared with measurements and previous calculations. A summary of future goals is discussed.

This is a preview of subscription content, log in to check access.


  1. Allkofer, O. and Grieder, P.: 1984, 'Cosmic Rays on Earth', Fachinformationszentrum, Karlsruhe.

  2. Badwhar, G. D. and O'Neill, P. M.: 1996, 'Galactic Cosmic Radiation Model and its Applications', Adv. Space Res. 17, 7–17.

  3. Belov, A. V. and Struminsky, A. B.: 1997, 'Neutron Monitor Sensitivity to Primary Protons Below 3 GeV Derived From Data of Ground Level Events', Proc. 25th Int. Cosmic Ray Conf., Durban 1, 201.

  4. Belov, A., Struminsky, A., and Yanke, V.: 1999, 'Neutron Monitor Response Functions for Galactic and Solar Cosmic Rays', ISSI Workshop on Cosmic Rays and Earth, poster presentation and personal communication.

  5. Bercovitch, M. and Robertson, B.: 1966, 'Meteorological Factors Affecting the Counting Rate of Neutron Monitors', Proc. 9th Int. Cosmic Ray Conf., London 1, 489.

  6. Bieber, J. and Evenson, P.: 1995, 'Spaceship Earth – An Optimized Network of Neutron Monitors', Proc. 24th Int. Cosmic Ray Conf., Rome 4, 1316.

  7. Bieber, J. and Evenson, P., Humble, J., and Duldig, M.: 1997, 'Cosmic Ray Spectra Deduced from Neutron Monitor Surveys', Proc. 25th Int. Cosmic Ray Conf., Durban 2, 45–48.

  8. Brown, R.: 1957, 'Neutron Yield Functions of the Nucleonic Component of Cosmic Radiation', Nuovo Cimento 6, 2816.

  9. Bütikofer, R. and Flückiger, E.: 1999, 'Pressure Correction of GLE Measurements in Turbulent Winds', Proc. 26th Internat. Cosmic Ray Conf., Salt Lake City, 6, 395

  10. Carmichael, H., Shea, M., and Peterson, R.: 1969a, 'III. Cosmic-ray Survey in Western USA and Hawaii in Summer, 1966', Can. J. Phys. 47, 2057.

  11. Carmichael, H. and Bercovitch, M.: 1969b, 'V. Analysis of IQSY Cosmic-ray Survey measurements', Can. J. Phys. 47, 2073.

  12. Clem, J. M., Bieber, J.W., Evenson, P., Hall, D., Humble, J. E., and Duldig, M.: 1997, 'Contribution of Obliquely Incident particles to Neutron Monitor Counting Rate', J. Geophys. Res. 102, 26 919.

  13. Clem, J. M.: 1999, 'Atmospheric Yield Functions and the Response to Secondary Particles of Neutron Monitors', Proc. 26th Int. Cosmic Ray Conf., Salt Lake City 7, 317.

  14. Cook, D. J., Humble, J. E., Shea, M. A., Smart, D. F., Lund, N., Rasmussen, I. L., Byrnak, B., Goret, P., and Petrou, N.: 1991, 'On Cosmic Ray Cut-Off Terminology', Nuovo Cimento 14C, 213–234.

  15. Debrunner, H. and Brunberg, E.: 1968, 'Monte Carlo Calculation of Nucleonic Cascade in the Atmosphere', Can. J. Phys. 46, 1069.

  16. Debrunner, H., Lockwood, J., and Flückiger, E.: 1982, 8th Europe Cosmic Ray Symp., Rome, unpublished.

  17. Debrunner, H., Lockwood, J. A., Barat, C., Bütikoker, R., Dezalay, J. P., Flückiger, E., Kuznetsov, A., Ryan, J.M., Sunyaev, R., Terekhov, O. V., Trottet, G., and Vilmer, N.: 1997, 'Energetic Neutrons, Protons, and Gamma Rays During the 1990 May 24 Solar Cosmic-Ray Event', Astrophys. J. 479, 997.

  18. Dorman, L.: 1957, 'Cosmic Ray Variations', State Publishing House for Technical and Theoretical Literature 102.

  19. Dorman, L. I.: 1970, 'Coupling and Barometer Coefficients for Measurements of Cosmic Ray Variations at Altitudes of 260–400 mb', Acta Phys. Acad. Sci. Hung. 29, 233.

  20. Dorman, L. and Yanke, V.: 1981, 'The Coupling Functions of NM-64 Neutron Supermonitor', Proc. 17th Int. Cosmic Ray Conf., Paris 4, 326.

  21. Duldig, M.: 2000, 'Muon Observations', Space Sci. Rev., this volume.

  22. Engel, J., Gaisser, T., Lipari, P., and Stanev, T.: 1992, 'Nucleus-Nucleus Collisions and Interpretation of Cosmic Ray Cascades', Phys. Rev. D46, 5013.

  23. Fassò, A., Ferrari, A., Ranft, A., Sala, P. R., Stevenson, G. R., and Zazula, J. M.: 1993, 'A Comparison of FLUKA Simulations With Measurements of Fluence and Dose in Calorimeter Structures', Nucl. Instr. Meth. A332, 459.

  24. Fassò, A., Ferrari, A., Ranft, A., and Sala, P. R.: 1997, Proc. of the 2nd Workshop on Simulating Accelerator Radiation Environment, SARE-2, CERN-Geneva, October 9–11 1995, CERN Divisional Report CERN/TIS-RP/97-05, 158.

  25. Fisk, L. A. and W. I. Axford: 1969, 'Solar Modulation of Galactic Cosmic Rays I.', J. Geophys. Res. 74, 4973.

  26. Flückiger, E.: 1977, 'Theoretical Spectra of Cosmic Ray Neutrons in the Atmosphere for the Energy Range 50 MeV ≤ E ≤ 100 GeV', Proc. 15th Int. Cosmic Ray Conf., Plovdiv 4, 144.

  27. Fonger, W.: 1953, 'Cosmic Radiation Intensity-Time Variations and Their Origin. II. Energy Dependence of 27-Day Variation', Phys. Rev. 91, 351.

  28. Gaisser, T.: 1990, Cosmic Rays and Particle Physics, Cambridge University Press, Cambridge.

  29. Garcia-Munoz, M., Meyer, P., Pyle, K. R., Simpson, J. A., and Evenson, P.: 1986, 'The Dependence of Solar Modulation on the Sign of the Cosmic Ray Particle Charge', J. Geophys. Res. 91, 2858.

  30. Hatton, C. J.: 1971, 'The NeutronMonitor', Progress in Elementary Particle and Cosmic Ray Physics X, American Elsevier Publishing Company, New York.

  31. Iucci, N., Villoresi, G., Dorman, L., and Parisi, M.: 1999, 'Cosmic Ray Survey to Antarctica and Coupling Functions for Neutron Component Near Solar Minimum (1996–1997) 2. Meteorological Effects and Correction of Survey Data', Proc. 26th Int. Cosmic Ray Conf., Salt Lake City 7, 321.

  32. Koi, T., Muraki, Y., Masuda, K., Matsubara, Y., Sakakibara, S., Sako, T., Murata, T., Tsuchiya, H., Kato, Y., Yuki, A., Shibata, S., Munakata, Y., Sakai, H., Nonaka, T., Ohnishi, T., Hatanaka, K., and Wakasa, T.: 1999, 'Attenuation of Solar Neutrons in the Air Determined by an Accelerator Experiment', Proc. of the 26th Int. Cosmic Ray Conf., Salt Lake City 7, 325.

  33. Lockwood, J., Webber, W., and Hsieh, L.: 1974, 'Solar Flare Proton Rigidity Spectra Deduced from Cosmic Ray Neutron Monitor Observations', J. Geophys. Res. 79, 4149.

  34. Lin, Z., Bieber, J. W., and Evenson, P.: 1995, 'Electron Trajectories in a Model Magnetosphere: Simulation and Observation Under Active Conditions', J. Geophys. Res. 100, 23 543.

  35. Moraal, H., Potgieter, M. S., Stoker, P. H., and van der Walt, A. J.: 1989, 'Neutron Monitor Latitude Survey of Cosmic Ray Intensity During the 1986/1987 Solar Minimum', J. Geophys. Res. 94, 1459.

  36. Moraal, H., Belov, A., and Clem, J. M.: 2000, 'Design and Coordination of Multi-station International Neutron Monitor Networks', Space Sci. Rev., this volume.

  37. Nagashima, K., Sakakibara, S., and Murakami, K.: 1989, 'Response and Yield Functions of Neutron Monitor, Galactic Cosmic Ray Spectrum and its SolarModulation, Derived from all the Available World-Wide Surveys', Nuovo Cimento 12C, 173.

  38. Pyle, R, Evenson, P., Bieber, J. W., Clem, J. M., Humble, J. E., and Duldig, M. L.: 1999, 'The Use of 3He Tubes in a Neutron Monitor Latitude Survey', Proc. of the 26th Int. Cosmic Ray Conf., Salt Lake City 7, 386.

  39. Rao, U.R., McCraken, K. G., and D. Venkatesan: 1963, 'Asymptotic Cones of Acceptance and Their Use in the Study of the Daily Variation of Cosmic Radiation', J. Geophys. Res. 68, 345.

  40. Raubenheimer, B. and Stoker, P.: 1974, 'Various Aspects of the Attenuation Coeficient of a Neutron Monitor', J. Geophys. Res. 79, 5069.

  41. Raubenheimer, B. and Flückiger, E.: 1977, 'Response Functions of a Modified NM-64 Neutron Monitor', Proc. 15th Int. Cosmic Ray Conf., Plovdiv 4, 151.

  42. Raubenheimer, B., Flückiger, E., Mischke, C., and Potgieter, M.: 1980, 'Comparison Between the Experimental and Theoretical Responses of Neutron Monitors', S. Afr. J. Phys. 3, 29.

  43. Raubenheimer, B., Van Niekerk, F., and Potgieter, M.: 1981, 'The Calculation of Differential Response Functions From Latitude Surveys. I: Theory', Proc. 17th Int. Cosmic Ray Conf., Paris 4, 321.

  44. Rossi, B.: 1948, 'Interpretation of Cosmic Phenomena', Rev. Modern Phys. 20, No 3.

  45. Ryan, J. M., Lockwood, J. A., and Debrunner, H.: 2000, 'Solar Energetic Particles', Space Sci. Rev., this volume.

  46. Sandström, A. E.: 1958, 'Cosmic Ray Soft Component Measurements During a Flight from Scandinavia Across the North Pole and Around Asia and Europe', Suppl. Nuovo Cimento VIII, 363.

  47. Seo, E., Ormes, J. F., Streitmatter, R. E., Stochij, S. J., Jones, W. V. Stephens, S. A., and Bowen, T.: 1991, 'Measurement of Galactic Cosmic Ray Proton and Helium Spectra During the 1987 Solar Minimum', Astrophys. J. 378, 763.

  48. Shen, M.:, 1968, 'Neutron Production in Lead and Energy Response of Neutron Monitor', Suppl. Nuovo Cimento VI, 1177.

  49. Simpson, J.: 1948, 'The Latitude Dependence of Neutron Densities in the Atmosphere as a Function of Altitude', Phys. Rev. 73, 1389.

  50. Shibata, S.: 1994, 'Propagation of Solar Neutrons Through the Atmosphere of the Earth', J. Geophys. Res. 99, 6651.

  51. Shibata, S., Munakata, Y., Tatsuoka, R., Muraki, Y., Matsubara, Y., Sakakibara, Koi, T., Sako, T., Okada, A., Murata, T., Imaida, I., Tsuchiya, H., Ishida, Y., Sakai, H., Wakasa, T., Nonaka, T., Ohnishi, T., and Hatanaka, K.: 1997, 'Calibration of Neutron Monitor using an Accelerator', Proc. 25th Int. Cosmic Ray Conf., Durban 1, 45.

  52. Shibata, S., Munakata, Y., Tatsuoka, R., Muraki, Y., Matsubara, Y., Masuda, K., Koi, T., Sako, T., Okada, A., Murata, T., Tsuchiya, H., Imaida, I., Hoshida, T., Kato, Y., Yuki, A., Ohno, S., Hatanaka, K., Wakasa, T., Sakai, H., Nonaka, T., Ohnishi, T., and Ishida, Y.: 1999, 'Calibration of Neutron Monitor Using Accelerator Neutron Beam', Proc. of the 26th Int. Cosmic Ray Conf., Salt Lake City 7, 313.

  53. Smart, D.: 2000, 'Cutoff Rigidites in the Geomagnetic Field', Space Sci. Rev., this volume.

  54. Stoker, P. H.: 1981, 'Primary Spectral Variations of Cosmic Rays Above 1 GeV', Proc. 17th Int. Cosmic Ray Conf., Paris 4, 193.

  55. Stoker, P. H.: 1995, 'Neutron Monitor Latitude Surveys, Response Functions and 22-Year Modulation', Proc. of the 24th Int. Cosmic Ray Conf., Rome 4, 1082.

  56. Stoker, P., Clem, J., Bieber, J. W., and Evenson, P.: 1997, 'Apparent Geomagnetic Cutoffs and the Cosmic Ray Anomaly in the Cape Town Region', Proc. 25th Int. Cosmic Ray Conf., Durban 2, 385.

  57. Stoker, P., Dorman, L., and Clem, J.: 2000, 'Neutron Monitor Design Improvements', Space Sci. Rev., this volume.

  58. Sullivan, J. D.: 1971, 'Geometrical Factor and Directional Response of Single and Multi-element Particle Telescopes', Nucl. Instr. Meth. 95, 5.

  59. Swordy, S.: 1993, 'Cosmic Ray Observations Below 1014 eV (OG Rapporteur paper)', Proc. 24th Int. Cosmic Ray Conf., Calgary 5, 243.

  60. Villoresi, G., Iucci, N., Tyasto, M. I., Dorman, L. I., Re, F., Signoretti, F., Zangrilla, N., Cecchini, S., Parisi, M., Signorini, C., Danilova, O. A., and Ptitsyna, N. G.: 1997, 'Latitude Survey of Cosmic Ray Nucleonic Component (Italy-Antarctic, 1996–1997)', Proc. 25th Int. Cosmic Ray Conf., Durban 2, 421.

  61. Webber, W. R. and Quenby, J. J.: 1959, 'On the Deviation of Cosmic Ray Specific Yield Functions', Phil. Mag. 4, 654.

  62. Yanke, V. G.: 1980, 'On the Theory of Geophysical Effects of Secondary Cosmic Radiation', Cand. Thesis, IZMIRAN, Moscow, 1980 (in Russian).

  63. Zombeck, M.: 1982, Handbook of Space Astronomy and Astrophysics, Cambridge University Press.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Clem, J.M., Dorman, L.I. Neutron Monitor Response Functions. Space Science Reviews 93, 335–359 (2000).

Download citation


  • Yield Function
  • Neutron Monitor
  • Primary Spectrum
  • Solar Neutron
  • Geomagnetic Cutoff