Ehave an incident flux of 106 neutrons/cm2-s impinging on the face of a 2.5-cm diameter right-cylindrical neutron detector, with a length of 15 cm. calculate and compare the efficiencies for the he-3 (2 atm pressure), bf3 (0.8 atm pressure), and a b-lined tube with a boron-thickness of 2 um (assuming 100% b-10). you will need to look up the thermal neutron capture cross section for b and he-3. (10 points)

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 -

Where are the options ?

The center is basically the heart of it

Since the pully is a simple machine so the mechanical advantage is a 1