14. Nu­clei [Un­fin­ished Draft]

This chap­ter has not been fin­ished. Since I think some parts of it are al­ready of in­ter­est, like the fig­ures, I am post­ing it as is. The reader be­ware, much of it has been poorly proof­read, if at all. The fig­ures should be fine.

So far, the fo­cus in this book has been mostly on elec­trons. That is nor­mal be­cause elec­trons are im­por­tant like noth­ing else for the phys­i­cal prop­er­ties of mat­ter. Atomic nu­clei ap­pear in the story only as mas­sive an­chors for the elec­trons, hold­ing onto the elec­trons with their pos­i­tive elec­tric charge. But then there is nu­clear en­ergy. Here the nu­clei call the shots. Nu­clei are dis­cussed in this chap­ter.

The the­ory of nu­clear struc­ture is much less ad­vanced than that of the elec­tronic struc­ture of atoms. Un­like the elec­tro­mag­netic forces, the nu­clear forces are very poorly un­der­stood. Ex­am­in­ing them with well-un­der­stood elec­tro­mag­netic probes is lim­ited since nu­clear forces are ex­tremely strong, re­sist­ing ma­nip­u­la­tion. Ac­cu­rate di­rect mea­sure­ment of quan­ti­ties of in­ter­est is usu­ally not pos­si­ble.

Nu­clear physi­cists re­sponded to that with a tidal wave of in­ge­nious ex­per­i­ments, usu­ally lever­ag­ing one ac­cepted fact to de­duce the next one (and at the same time check the old one). Much of this data is pre­sented in this chap­ter in the form of overview fig­ures. This is in­tended to al­low you to un­der­stand the big pic­ture.

Some im­por­tant ap­prox­i­mate quan­tum mod­els have been de­vel­oped by nu­clear physi­cists to ex­plain all that data. This chap­ter also tries to ex­plain these mod­els in rel­a­tively sim­ple terms.

The first few sec­tions of the chap­ter give an overview of key con­cepts im­por­tant for un­der­stand­ing nu­clei. It is highly rec­om­mended that you read these be­fore read­ing any later sec­tions in this chap­ter.

But first one word of cau­tion about the fig­ures. Most of their data has been care­fully ma­chine-read from stan­dard nu­clear data bases. How­ever, the used data bases date from around the year 2003. So check any data you get from the fig­ures for any more re­cent up­dates that may be avail­able. Also note that var­i­ous fig­ures that de­pend on rel­a­tively del­i­cate math­e­mat­i­cal analy­sis were ma­chine pro­duced too. Typ­i­cally this was done us­ing rea­son­able sim­pli­fi­ca­tions and/or a pri­ori as­sump­tions. Use such fig­ures to un­der­stand the big pic­ture, but do not pick in­di­vid­ual data from them with­out check­ing it. A sim­ple au­to­mated pro­ce­dure pro­cess­ing about 3 000 dif­fer­ent nu­clei from some key data us­ing an ap­prox­i­mate model can­not com­pete with a nu­clear spe­cial­ist an­a­lyz­ing a sin­gle nu­cleus based on all the ex­ten­sive knowl­edge that is avail­able for that one nu­cleus.