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S. Fred Singer and Terry Sloan correspond on CR deflection

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S. Fred Singer corresponds on the subject:

Some corrections to the letter from Terry Sloan:

1.  First, a minor point:  The solar particle stream (“wind”) does not ‘generate’ a mag field.  A somewhat turbulent solar surface field is ‘frozen in ‘ (a la Alfven) into the stream and decays only slowly

2.  The ‘deflection’ argument may be intuitive but doesn’t really work logically.  For every CR particle aimed at the Earth that’s deflected away, there will be one not aimed at the Earth that’s deflected to hit the Earth

3.  The 11-yr cycle seen in CR intensity (and other solar-modulated CR variations)  depend on deceleration (i e, a shift in the energy  spectrum) produced by scattering of CR from expanding regions of magnetic turbulence.  I have termed this mechanism an ‘inverse Fermi acceleration.’  The decrease in CR intensity then follows directly from an application of Liouville’s theorem.

S.F. Singer, “Cosmic Ray Time Variations Produced by Deceleration in Interplanetary Space.” Nuovo Cimento 8, Suppl. II, 334 – 341, 1958.  Laster, H., A.M. Lenchek and S.F. Singer. “Interplanetary Gas Cloud Modulation of Cosmic Rays.” Bull. Am. Phys. Soc., 5, 259, 1960:  J. Phys. Soc. Japan, 17, Suppl. AII, 583, 1962

I am not aware of any direct measurement of this shift in the primary CR energy spectrum but a comparison of CR neutron monitor data  with those of mu-mesons does suggest confirmation.

Best

Fred

and Terry Sloan responds:

Dear Fred,

Thank you for your e mail. I interleave some comments.

Regards, Terry.

Dear Benny

Some corrections to the letter from Terry Sloan:

1. First, a minor point: The solar particle stream (“wind”) does not ‘generate’ a mag field. A somewhat turbulent solar surface field is ‘frozen in ‘ (a la Alfven) into the stream and decays only slowly

—–> I agree that it is more complicated than my simple heuristic explanation.

2. The ‘deflection’ argument may be intuitive but doesn’t really work logically. For every CR particle aimed at the Earth that’s deflected away, there will be one not aimed at the Earth that’s deflected to hit the Earth

——> I agree with this point for very high energy CR but at low energy, where the deflections are larger, particles undergo sling shot effects and more are lost than are gained. Hence the influence of solar activity.

3. The 11-yr cycle seen in CR intensity (and other solar-modulated CR variations) depend on deceleration (i e, a shift in the energy spectrum) produced by scattering of CR from expanding regions of magnetic turbulence. I have termed this mechanism an ‘inverse Fermi acceleration.’ The decrease in CR intensity then follows directly from an application of Liouville’s theorem.

—-> Again I agree that it is more complicated than my simple argument. However, I do not like this argument since the particles themselves are not decelerated. However, I agree that there is a shift in the spectrum.

S.F. Singer, “Cosmic Ray Time Variations Produced by Deceleration in Interplanetary Space.” Nuovo Cimento 8, Suppl. II, 334 – 341, 1958. Laster, H., A.M. Lenchek and S.F. Singer. “Interplanetary Gas Cloud Modulation of Cosmic Rays.” Bull. Am. Phys. Soc., 5, 259, 1960: J. Phys. Soc. Japan, 17, Suppl. AII, 583, 1962

I am not aware of any direct measurement of this shift in the primary CR energy spectrum but a comparison of CR neutron monitor data with those of mu-mesons does suggest confirmation.

—-> There is another greater effect on muons which is the energy threshold when the CR interact in the atmosphere. Pion multiplicities grow with energy. So muons tend to be produced by much more energetic CRs than those which produce the majority of the neutron monitor counts. Hence they are less susceptible to variations in the solar activity.

I’m not quite convinced with Fred’s statement that the position is neutral for cosmic ray deflection in the case that the protons have the same energy as the solar wind or less, but I’ll have to do more calculations on that point.

Update: S. Fred Singer replies

Terry

You may be right about the last point (the muons).

It would help if someone could measure the shift in energy spectrum over the solar cycle — or during Forbush decreases.

Just the latitude variation of total counts, measured from a satellite.

Can you get such data?

Best

Fred

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Written by John A

August 17, 2009 at 2:04 pm

Posted in Svensmark

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