Download Stuff for Thursday, May 3, 2012

Stuff for Thursday, May 3, 2012
No problem set due today!
Next two problem sets (Q12/13 and Q14/15) available.
No quiz this week!
Stuff about nuclei and radioactivity:
Nuclei: AZ X where A nucleons = Z protons + N neutrons
Radius: r ≈ r0 A1/3 with r0 = 1.2 fm
1 u = atomic mass unit ≡
1
12 (mass
closest α: rmin = k (2e)(Ze)/K0
of
12
6 C)
= 931.48 MeV/c 2
mp = 1.007277 u mn = 1.008665 u me = 0.0005486 u
Binding energy Eb ≡ Eparts − Esystem ,
∆m ≡ mparts − msys = Eb /c 2
nucleus: ∆m = Z mH + Nmn − matom where mH = 1.007825 u
Stability: Can the nucleus lower its energy by radioactive decay?
Decays: alpha, beta (neutron β − , proton β + , EC) =⇒ ν or ν, gamma
Unstable nuclei
Check Table of Nuclides (google, e.g., http://atom.kaeri.re.kr/)
Binding energy calculation:
(6*1.007825u + 9*1.008665u − 15.0105993u)*931.48 MeV/u = 106.501 MeV
Coulomb Energy
Symmetry Energy