Maxwell equations in nonuniformly moving media

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17: 474-477

Abstracts

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(1962)

Papers

to Appear

in Future

issues

.l/esons and th.e &‘/ruclure oj :Vurleotcs. Part IV--The Nlc~leon.-~~:u~~luorl i’ofenlial. (i. COSTA and B. T. FELD. Physics I>epartrttent and Laboratory for ?Juclear Science, hl.I.T., Cambridge, Mass. The atomic model, in which physical nucleons are described as compound systems of a nucleon core plus a single pion, has been used as the basis for a computation of the low energy interaction between two physical nucleons. ildvantage is taken of previous work fot the specification of t,he interactJiott bet,wecn the pion and the nucleot1 core in the different possible states of total angular momentum and isot,opir spin. An initial simplificattion, where we replace one of the “atoms” by an “eft‘ective scat,tering center” is ottly modetxtely successful in reproducing t.he gross features of the observed nucleon-mtcleon intrractiott. The full computat.ion (approached in the spirit, of the Heitler-London approsimatiott to the H-H interaction) improves on the qualitative fit, but it turns our to be impossible to reproduce simultaneously the as?-mptotic behavior of hoth the central and tensor terms in the nucleon-nucleon potent,ial using a reasonable set of piowcore interactions. 9 significant result is the derivation, using the simplified tttodel, of a nucleon-ttucleott spin-orbit interaction whose range is shorter than t,hat, of other terms in the potential. Out computation thus provides a strong indication that. the spiworhit, interaction mat?- arise from the same features of the pionwtucleon interaction as give rise to the resonant pion-nucleon srntt.ering in t.hr st.at.e of 2’ = .I = 3/‘2. h’e/ntions in He& MYU lhe ~l/elfiny C’uwe rind the X-Line. E;. R. (FRILLY and University of California, Los .4l:tmos Scientific I,at~oratorp, Los Alwmos, Measurenient,s on He4 from 1 to L’ ’ Ii were made of: the melting pressure; change on melting; and t.he compressibility and thermal expansion coefficiettts ttear melting. The a-y transformation in the solid was studied, and values of the tion pressure and associated voluttte change are reported. The P1’7’ properties in the high pressure region of the h-line were investigated. The compressitri1it.y has a tnasimum at t.he X-pressure, and thr thermal expansion vs temperature mum at the X-temperature. The thermal expansion is negative below (7’~ + titnates indicate negative values for the thermal expansion in the solid. PT77

R. L. RLILw. Sew Mexico the voluttte of t.he liquid transformaof the liquid I’S pressure has a mitti0.08)“K. Es-

l\fa.rwell Eyitations i/~ ~~onwl~jo~rn~~j ~\fozliny Atlediu. ALLAN N. KAI.FM.~~. I,awrence Rudi:Ltion Laboratory, University of California, Livermore, California The covariant Maxwell equat,ions for material media in arbitrary motion are derived by means of a statistical average of t,he microscopic equations. Special-relativistic considerat.ions are used throughout,, even though accelerated motion is treated. The Minkonski to be generally valid for nonform, originally derived for uniform motion only, is found uniform motion, in the macroscopic quantities are suitably defined. In particular, the covariant polarization is defined in terms of the molecular electromagnetic dipole moments. .llulfiple

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