From: chuck@coplex.com (Chuck Sites)
Subject: Re: Hydrogen bands and excited deuterons
Organization: Copper Electronics, Inc.
Date: Fri, 9 Oct 1992 06:17:35 GMT

colin@physci.uct.ac.za (COLIN HENDERSON) writes:

>Chuck Sites speculates about excited states in deuterons which have escaped 
>detection.

>When looking at Photodisintegration the inverse ("time reversed") reaction 

> n + p -> d + gamma

>is often looked at.  Thus far, a monoenergetic beam of neutron has only been 
>seen to produce a monoenergetic (for a given angle) set of gammas.  If there 
>were an excited state in deuterons, we'd almost certainly have seen two 
>different gammas, as the deuterons will be formed in the excited state at 
>times.  Also, we'd see a resonance structure in the neutron capture cross 
>section around the deuteron excited state. This hasn't been seen either.  
>The same goes for the gammas.  The first photodis. experiments looked at the 
>gamma attenuation as well, I think.


   The time reversal of the reaction D + gamma -> n + p is a good  
arguement against such a sub-photodesintegration D+gamma interaction.
It does shine some light on the interworkings of the strong force;-)
The gamma realeased from the n+p->d+gamma can be considers as the 
*snap* of the strong force as the charged particles are accelerated
towards the D ground state.  Since accelerated charge particles
radiate, the result is the release of gamma.  This is also a system
guilded by quantum mechanical rules, so you would think *if* there are
QM states for the d-nucleus below the energy of photodisintrigration
these would show up in the photon spectrum.  But I can see an argument
why this would not be seen.  The strong force can impart so much 
force to binding n+p that the momentum of these massive particles 
causes a collapse direct to ground state, basically skipping past 
any quantum states in between.  One telling factoid that suggests 
there may be more to D+gamma->n+p is that the maximum cross section
for photodisintegration occurs not at 2.224Mev binding energy of n+p,
but at twice that value near 4.448Mev.  If the photon emmision was
purely a perfectly reversable state transition like that of atomic
physics then this difference wouldn't exist.  This suggest that the
physics behind the mix of the strong interaction and the E-M forces
the nucleons in interaction with a photon are complicated indeed,
and poorly understood. 

    What I'm trying to suggest with the D+gamma->D* is that some low
energy gamma interactions could tie up the photon far longer in the
nucleus than one would expect in comparison to the atomic models. 
Because the tied up photon is interacting with the currents of the np
guage, other photons do not interact, the result to gamma spectroscopy
is that at low energies D+gamma, gamma energy in = gamma energy out
but with a time delay.  The only way I can think of to test this idea
is to blast D with a monochromatic beam of gamma, shut it off, and look
for the after glow.  Perhaps a simpiler way would be to backscatter an
large spectra switchable gamma source on a D target and look for gamma
energies with an after glow.  Be warned, I expect the after glow to 
be fairly short lived.

   Anyway, while I agree p(n,gamma)D ought to reveal any D sub-photo-
disintegration states, like a "slap in the face with cold fish", but I'm
not sure that it will.  I think the effect I'm describing is a "I didn't
get slaped in the face with a cold fish until I looked" type thing.
Anybody care to site the anti-thesis? Anyone for sushi?

Have fun,
Chuck Sites
chuck@coplex.com  (502) 9688495  

>--

>Colog "nku-e-shweleng" the Henderdog
>Physics Dept, UCT, South Africa.