Low-Energy Scattering

In this chapter we summarize the current status of the low-energy scattering of noble-gas metastable atoms in molecular beams. A brief summary of potential scattering theory that is relevant to the understanding of collision dynamics, as well as a description of the experimental method, precedes the presentation of experimental findings. The experimental results presented are mainly from the authors laboratories. 

Pertinent information concerning the interaction of free electrons with rare gas atoms is obtained from low energy scattering data in the gas phase. Table I presents the scattering lengths, a, for the rare gas atoms, defined as... 

O Malley, T.F., Spruch, L. and Rosenberg, L. (1962). Low-energy scattering of a charged particle by a neutral polarizable system. Phys. Rev. 125 1300-1310. 

Koester L, Yelon WB (1983) Summary of low energy scattering lengths and cross sections. Neutron diffraction Newsletter, IUCr. 

For pH, the new world average of the 2p—level width, derived from the intensity balance, is = 32.5 2.1 meV. The small error achieved for this quantity combined with the width of the 2 Pq hyperhne state as measured with the crystal spectrometer allows to correct for the different annihilation widths from the 2p sublevels. The corrected value P2p (see Tabled) deviates significantly from due to the large width of the 2 Pq state [21] and is now in good agreement with low-energy scattering experiments [8]. 

Fig. 6. The second virial coefficient of neon. The triangles are data from Ref. 15a and the open circles, from Ref. 15b. The dot-dashed curve was the Lennard-Jones fit of the virial coefficient data. The solid curve was calculated from the Joining of the low energy scattering with Amdur s high energy scattering potential. The dashed curve was from the scattering potential of Fig. 3.

G. Rasche, W.S. Woolcock, Connection between low-energy scattering parameters and energy shifts for pionic hydrogen, Nucl. Phys. A 381 (1982) 405 18. 

As we have seen above the observed low energy scattering lengths may nevertheless be determined by the proximity of sharp neutron resonances. Adair S... 

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