20. NUCLEAR PHYSICS

21.       Nuclear structure
          (for nucleon structure, see 14.20.D Properties of protons and
          neutrons; 14.20.G for nucleon resonances; 13.40 for
          electromagnetic processes and properties; 13.60.H for deep-
          inelastic structure functions)

21.10.-k  Properties of nuclei; nuclear energy levels
          (for properties of specific nuclei listed by mass ranges, see 27)
21.10.Dr  Binding energies and masses
21.10.Ft  Charge distribution
21.10.Gv  Mass and neutron distributions
21.10.Hw  Spin, parity, and isobaric spin
21.10.Jx  Spectroscopic factors
21.10.Ky  Electromagnetic moments
21.10.Ma  Level density
21.10.Pc  Single-particle levels and strength functions
21.10.Re  Collective levels
21.10.Sf  Coulomb energies
21.10.Tg  Lifetimes

21.30.-x  Nuclear forces
          (see also 13.75.C Nucleon-nucleon interactions)
21.30.Cb  Nuclear forces in vacuum
21.30.Fe  Forces in hadronic systems and effective interactions

21.45.+v  Few-body systems

21.60.-n  Nuclear-structure models and methods
21.60.Cs  Shell model
21.60.Ev  Collective models
21.60.Fw  Models based on group theory
21.60.Gx  Cluster models
21.60.Jz  Hartree-Fock and random-phase approximations
21.60.Ka  Monte Carlo models

21.65.+f  Nuclear matter

......    Exotic atoms and molecules, see 36.10

21.80.+a  Hypernuclei

21.90.+f  Other topics in nuclear structure

23.       Radioactive decay and in-beam spectroscopy
          (see also 82.55 Radiochemistry)

23.20.-g  Electromagnetic transitions
23.20.En  Angular distribution and correlation measurements
23.20.Gq  Multipole mixing ratios
23.20.Js  Multipole matrix elements
23.20.Lv  Gamma transitions and level energies
23.20.Nx  Internal conversion and extranuclear effects
23.20.Ra  Internal pair production

23.40.-s  beta decay; double beta decay; electron and muon capture
23.40.Bw  Weak-interaction and lepton (including neutrino) aspects
          (see also 14.60.P Neutrino mass and mixing)
23.40.Hc  Relation with nuclear matrix elements and nuclear structure

23.50.+z  Decay by proton emission

23.60.+e  alpha decay

23.70.+j  Heavy-particle decay

23.90.+w  Other topics in radioactive decay and in-beam spectroscopy

24.       Nuclear reactions: general

24.10.-i  Nuclear-reaction models and methods
24.10.Cn  Many-body theory
24.10.Eq  Coupled-channel and distorted-wave models
24.10.Ht  Optical and diffraction models
24.10.Jv  Relativistic models
24.10.Lx  Monte Carlo simulations (including hadron and parton cascades and
          string breaking models)
24.10.Nz  Hydrodynamic models
24.10.Pa  Thermal and statistical models

24.30.-v  Resonance reactions
24.30.Cz  Giant resonances
24.30.Gd  Other resonances

24.50.+g  Direct reactions

24.60.-k  Statistical theory and fluctuations
24.60.Dr  Statistical compound-nucleus reactions
24.60.Gv  Statistical multistep direct reactions
24.60.Ky  Fluctuation phenomena
24.60.Lz  Chaos in nuclear systems

24.70.+s  Polarization phenomena in reactions

24.75.+i  General properties of fission

24.80.+y  Nuclear tests of fundamental interactions and symmetries

24.85.+p  Quarks, gluons, and QCD in nuclei and nuclear processes

24.90.+d  Other topics in nuclear reactions: general

25.       Nuclear reactions: specific reactions

25.10.+s  Nuclear reactions involving few-nucleon systems

25.20.-x  Photonuclear reactions
25.20.Dc  Photon absorption and scattering
25.20.Lj  Photoproduction reactions

25.30.-c  Lepton-induced reactions
25.30.Bf  Elastic electron scattering
25.30.Dh  Inelastic electron scattering to specific states
25.30.Fj  Inelastic electron scattering to continuum
25.30.Hm  Positron scattering
25.30.Mr  Muon scattering (including the EMC effect)
25.30.Pt  Neutrino scattering
25.30.Rw  Electroproduction reactions

25.40.-h  Nucleon-induced reactions
          (see also 28.20 Neutron physics)
25.40.Cm  Elastic proton scattering
25.40.Dn  Elastic neutron scattering
25.40.Ep  Inelastic proton scattering
25.40.Fq  Inelastic neutron scattering
25.40.Hs  Transfer reactions
25.40.Kv  Charge-exchange reactions
25.40.Lw  Radiative capture
25.40.Ny  Resonance reactions
25.40.Qa  (p,pi) reactions
25.40.Sc  Spallation reactions
25.40.Ve  Other reactions above meson production thresholds (energies > 400
          MeV)

25.43.+t  Antiproton-induced reactions

25.45.-z  [supon]2[supoff]H-induced reactions
25.45.De  Elastic and inelastic scattering
25.45.Hi  Transfer reactions
25.45.Kk  Charge-exchange reactions

25.55.-e  [supon]3[supoff]H-,[supon]3[supoff]He-, and [supon]4[supoff]He-
          induced reactions
25.55.Ci  Elastic and inelastic scattering
25.55.Hp  Transfer reactions
25.55.Kr  Charge-exchange reactions

25.60.-t  Reactions induced by unstable nuclei
25.60.Bx  Elastic scattering
25.60.Dz  Interaction and reaction cross sections
25.60.Gc  Breakup and momentum distributions
25.60.Je  Transfer reactions
25.60.Lg  Charge-exchange reactions
25.60.Pj  Fusion reactions

25.70.-z  Low and intermediate energy heavy-ion reactions
25.70.Bc  Elastic and quasielastic scattering
25.70.De  Coulomb excitation
25.70.Ef  Resonances
25.70.Gh  Compound nucleus
25.70.Hi  Transfer reactions
25.70.Jj  Fusion and fusion-fission reactions
25.70.Kk  Charge-exchange reactions
25.70.Lm  Strongly damped collisions
25.70.Mn  Projectile and target fragmentation
25.70.Pq  Multifragment emission and correlations

25.75.-q  Relativistic heavy-ion collisions
          (collisions induced by light ions studied to calibrate
          relativistic heavy ion collisions, should be classified under
          both 25.75 and the 13 or 25 category appropriate to the light
          ions)
25.75.Dw  Particle and resonance production
25.75.Gz  Particle correlations
25.75.Ld  Collective flow

25.80.-e  Meson- and hyperon-induced reactions
25.80.Dj  Pion elastic scattering
25.80.Ek  Pion inelastic scattering
25.80.Gn  Pion charge-exchange reactions
25.80.Hp  Pion-induced reactions
25.80.Ls  Pion inclusive scattering and absorption
25.80.Nv  Kaon-induced reactions
25.80.Pw  Hyperon-induced reactions

25.85.-w  Fission reactions
25.85.Ca  Spontaneous fission
25.85.Ec  Neutron-induced fission
25.85.Ge  Charged-particle-induced fission
25.85.Jg  Photofission

25.90.+k  Other topics in nuclear reactions: specific reactions

26.       Nuclear astrophysics
          (see also 95.30 Fundamental aspects of astrophysics)

26.10.+a  Energy generation

26.20.+f  Hydrostatic stellar nucleosynthesis
          (see also 97.10.C Stellar structure, interiors, evolution,
          nucleosynthesis, ages)

26.30.+k  Nucleosynthesis in novae, supernovae and other explosive
          environments

26.35.+c  Big Bang nucleosynthesis
          (see also 98.80.F Origin and formation of the elements)

26.40.+r  Cosmic ray nucleosynthesis

26.45.+h  Elemental and isotopic abundances and evolution

26.50.+x  Nuclear physics aspects of supernovae evolution

26.60.+c  Nuclear matter aspects of neutron stars

26.65.+t  Solar neutrinos

27.       Properties of specific nuclei listed by mass ranges
          (an additional heading must be chosen with these entries, where
          the given mass number limits are, to some degree, arbitrary)

27.10.+h  A <= 5

27.20.+n  6 <= A <= 19

27.30.+t  20 <= A <= 38

27.40.+z  39 <= A <= 58

27.50.+e  59 <= A <= 89

27.60.+j  90 <= A <= 149

27.70.+q  150 <= A <= 189

27.80.+w  190 <= A <= 219

27.90.+b  220 <= A

28.       Nuclear engineering and nuclear power studies

28.20.-v  Neutron physics
          (see also 25.40 Nucleon-induced reactions)
28.20.Cz  Neutron scattering
28.20.Fc  Neutron absorption
28.20.Gd  Neutron transport: diffusion and moderation

28.41.-i  Fission reactors
28.41.Ak  Theory, design, and computerized simulation
28.41.Bm  Fuel elements, preparation, reloading, and reprocessing
28.41.Fr  Reactor coolants, reactor cooling, and heat recovery
28.41.Kw  Radioactive wastes, waste disposal
28.41.My  Reactor control systems
28.41.Pa  Moderators
28.41.Qb  Structural and shielding materials
28.41.Rc  Instrumentation
28.41.Te  Protection systems, safety, radiation monitoring, accidents, and
          dismantling

28.50.-k  Fission reactor types
28.50.Dr  Research reactors
28.50.Ft  Fast and breeder reactors
28.50.Hw  Power and production reactors
28.50.Ky  Propulsion reactors
28.50.Ma  Auxiliary generators
28.50.Qd  Other reactors

28.52.-s  Fusion reactors
          (for fusion reactor types, see 52.55)
28.52.Av  Theory, design, and computerized simulation
28.52.Cx  Fueling, heating and ignition
28.52.Fa  Materials
28.52.Lf  Components and instrumentation
28.52.Nh  Safety

28.60.+s  Isotope separation and enrichment

28.70.+y  Nuclear explosions
          (see also 47.40 Compressional flows; shock and detonation
          phenomena; for radiation protection from fallout, see 87.50.N, P-
          -in medical physics)

28.90.+i  Other topics in nuclear engineering and nuclear power studies

29.       Experimental methods and instrumentation for elementary-particle
          and nuclear physics

29.17.+w  Electrostatic, collective, and linear accelerators

29.20.-c  Cyclic accelerators and storage rings
29.20.Dh  Storage rings
29.20.Fj  Betatrons
29.20.Hm  Cyclotrons
29.20.Lq  Synchrotrons
29.20.Mr  Other cyclic accelerators

29.25.-t  Particle sources and targets
29.25.Bx  Electron sources
29.25.Dz  Neutron sources
29.25.Lg  Ion sources: polarized
29.25.Ni  Ion sources: positive and negative
29.25.Pj  Polarized and other targets
29.25.Rm  Sources of radioactive nuclei

29.27.-a  Beams in particle accelerators
          (for low energy charged-particle beams, see 41.75)
29.27.Ac  Beam injection and extraction
29.27.Bd  Beam dynamics; collective effects and instabilities
29.27.Eg  Beam handling; beam transport
29.27.Fh  Beam characteristics
29.27.Hj  Polarized beams

29.30.-h  Spectrometers and spectroscopic techniques
29.30.Aj  Charged-particle spectrometers: electric and magnetic
29.30.Dn  Electron spectroscopy
29.30.Ep  Charged-particle spectroscopy
29.30.Hs  Neutron spectroscopy
29.30.Kv  X- and gamma-ray spectroscopy
29.30.Lw  Nuclear orientation devices

......    Energy loss and stopping power, see 34.50.B and 61.80.M

29.40.-n  Radiation detectors
          (for mass spectrometers, see 07.75)
29.40.Cs  Gas-filled counters: ionization chambers, proportional, and
          avalanche counters
29.40.Gx  Tracking and position-sensitive detectors
29.40.Ka  Cherenkov detectors
29.40.Mc  Scintillation detectors
29.40.Rg  Nuclear emulsions
29.40.Vj  Calorimeters
29.40.Wk  Solid-state detectors
29.40.Ym  Other detectors

29.50.+v  Computer interfaces
          (for special purpose electronic circuits, see 07.50.E)

29.85.+c  Computer data analysis

29.90.+r  Other topics in elementary-particle and nuclear physics
          experimental methods and instrumentation