Afluence of thermal neutrons is 6.5 x 10" d c m 2in a layer of muscle-equivalent tissue 0.1 gkm4 thick. what is the absorbed dose at the middle of the layer?
assume that the above neutron fluence is approximately uniform throughout
a tissue sphere 5 cm in radius, due to thermalization of a field of intermediate- energy neutrons penetrating the sphere. what is the absorbed dose at the center resulting from thermal-neutron-capture y rays? how does it compare with the total absorbed dose that results (directly or indirectly) from the thermal neu- trons?

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -