RE: Reality check

["H.B. Knowles" <hbknowls@ix.netcom.com>]

At 15:33 11/17/1999 Wednesday-0600, you wrote:
>Well if the airplane was at 30,000 feet it is above what about half of the
>atmosphere?  So about 76/2*13 g/cm^2 ~ 500 g/cm^2 of predominantly N2.
>Energy loss due to ionization would be about a GeV, but energy loss due to
>nuclear reactions would dominate.  The p-p cross section is about 40 mb in
>the GeV regime.  Cross section scale as about A^.333 so p-N cross section
>should be around 100 mb.
>
>500 g/cm^2 /14 g/mol *6E23 * 1E-25 = 2.14
>
>exp(-2.14) = .12 
>
>So it would be feasible for about 10% of a proton beam emitted directly
>below the plane to reach it _IF_ it were a very high energy beam such that
>the coulomb scattering didn't blow up the beam.  Without digging out a text
>book to get a coulomb scattering equation a 1 GeV energy loss should cause a
>1 TeV beam to diverge at least 1 part in a thousand so the beam would be at
>least 30 feet in diameter.  So a 1 microamp beam (huge at this energy) would
>contain a megawatt of energy.  But accounting for beam loss 90% and
>divergence one would end up with about a 0.1 watt/cm^2 flux at the plane
>(and probably only a small fraction of that would interact with the plane).
>
>
>Hmmm.....
>
>The plane was not flying over Fermilab or CERN
>
>It would be hard to fit either FNAL or CERN on a ship
>
>So one would probably have to have an airborne accelerator of somewhat lower
>energy.  The weight, power, and distance tradeoffs there are many, but the
>question then becomes why would anyone develop a particle beam weapon that
>wasn't even useful at 6 miles?
>
>> -----Original Message-----
>> From:        Neil, David M [SMTP:neildm@id.doe.gov]
>> Sent:        Wednesday, November 17, 1999 10:11 AM
>> To:  Multiple recipients of list
>> Subject:     Reality check
>> 
>> I was listening to one of the 'fringe' talk radio shows last night, where
>> an
>> opinion was advanced that the Egypt Air plane was downed by a release from
>> a
>> particle beam weapon.  My opinion as stated to my wife (after a prolonged
>> razzberry :-P ) was that a particle beam in 1 atm air had, shall we say, a
>> limited range due to attenuation.
>> 
>> But I thought I should double-check my opinion with the group, since I
>> didn't have numbers to back it up.
>> 
>> Before drawing any conclusions from my media choices, bear in mind that I
>> did refer to it as 'fringe' - sometimes thought-provoking, often amusing,
>> and usually interesting.
>> 
>> Dave Neil
>> neildm@id.doe.gov

Radsafers:

A little more reality, with some physics. The protons themselves cause a little
of the 30 km dose, but make lots of secondary particles-pions (which eventually
become muons) and above all, neutrons. here is a big bump at fission neutron
energy, a minoer bump at about 100 MeV, and they cause 40% of the dose, using
PRESENT neutron quality factors.  First published data in Physical Review by
Hess, Wallace, Patterson and Chupp, about 1958, and not substantially improved
since then. The neutrons are zero-threshold particles, incidentally, although
not quite linear in energy.


H.B. Knowles, PhD, Physics Consulting
4030 Hillcrest Rd, El Sobrante, CA 94803
Phone\Fax (510)758-5449
hbknowls@ix.netcom.com
<www.hbknowles.com>
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