20.	NUCLEAR PHYSICS
	21.	Nuclear structure (for nucleon structure, see 14.20.Dh Properties of protons and neutrons; 13.40.−f for electromagnetic processes and properties; 13.60.Hb for deep-inelastic structure functions)
	21.10.-k	Properties of nuclei; nuclear energy levels (for properties of specific nuclei listed by mass ranges, see section 27)
	21.10.Dr	Binding energies and masses
	21.10.Ft	Charge distribution
S	21.10.Gv	Mass and neutron distributions
M	21.10.Gv	Nucleon distributions and halo features
	21.10.Hw	Spin, parity, and isobaric spin
	21.10.Jx	Spectroscopic factors and asymptotic normalization coefficients
	21.10.Ky	Electromagnetic moments
	21.10.Ma	Level density
	21.10.Pc	Single-particle levels and strength functions
	21.10.Re	Collective levels
S	21.10.Sf	Coulomb energies
M	21.10.Sf	Coulomb energies, analogue states
S	21.10.Tg	Lifetimes
M	21.10.Tg	Lifetimes, widths
	21.30.-x	Nuclear forces (see also 13.75.Cs Nucleon–nucleon interactions)
	21.30.Cb	Nuclear forces in vacuum
	21.30.Fe	Forces in hadronic systems and effective interactions
D	21.45.+v	Few-body systems (Use 21.45.-v)
N	21.45.-v	Few-body systems
N	21.45.Bc	Two-nucleon system
N	21.45.Ff	Three-nucleon forces
	21.60.-n	Nuclear structure models and methods
	21.60.Cs	Shell model
N	21.60.De	Ab initio methods
	21.60.Ev	Collective models
	21.60.Fw	Models based on group theory
	21.60.Gx	Cluster models
S	21.60.Jz	Hartree–Fock and random-phase approximations
M	21.60.Jz	Nuclear Density Functional Theory and extensions (includes Hartree–Fock and random-phase approximations)
	21.60.Ka	Monte Carlo models
D	21.65.+f	Nuclear matter (Use 21.65.-f)
N	21.65.-f	Nuclear matter
N	21.65.Cd	Asymmetric matter, neutron matter
N	21.65.Ef	Symmetry energy
N	21.65.Jk	Mesons in nuclear matter
N	21.65.Mn	Equations of state of nuclear matter (see also 26.60.Kp Equations of state of neutron−star matter)
N	21.65.Qr	Quark matter (see also 12.38.Mh Quark−gluon plasma in quantum chromodynamics; 25.75.Nq Quark deconfinement, quark−gluon plasma production and phase transitions in relativistic heavy-ion collisions)
	... ... ...	Exotic atoms and molecules, see 36.10.−k
	21.80.+a	Hypernuclei
N	21.85.+d	Mesic nuclei
	21.90.+f	Other topics in nuclear structure (restricted to new topics in section 21)
	23.	Radioactive decay and in-beam spectroscopy
	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	γ transitions and level energies
S	23.20.Nx	Internal conversion and extranuclear effects
M	23.20.Nx	Internal conversion and extranuclear effects (including Auger electrons and internal bremsstrahlung)
	23.20.Ra	Internal pair production
N	23.35.+g	Isomer decay
	23.40.-s	β decay; double β decay; electron and muon capture
	23.40.Bw	Weak-interaction and lepton (including neutrino) aspects (see also 14.60.Pq 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	α decay
	23.70.+j	Heavy-particle decay
	23.90.+w	Other topics in radioactive decay and in-beam spectroscopy (restricted to new topics in section 23)
	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
S	24.85.+p	Quarks, gluons, and QCD in nuclei and nuclear processes
M	24.85.+p	Quarks, gluons, and QCD in nuclear reactions
N	24.87.+y	Surrogate reactions
	24.90.+d	Other topics in nuclear reactions: general (restricted to new topics in section 24)
	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
S	25.30.Hm	Positron scattering
M	25.30.Hm	Positron-induced reactions
S	25.30.Mr	Muon scattering (including the EMC effect)
M	25.30.Mr	Muon-induced reactions (including the EMC effect)
S	25.30.Pt	Neutrino scattering
M	25.30.Pt	Neutrino-induced reactions
	25.30.Rw	Electroproduction reactions
	25.40.-h	Nucleon-induced reactions (see also 28.20.−v 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, π) 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	2H-induced reactions
	25.45.De	Elastic and inelastic scattering
	25.45.Hi	Transfer reactions
	25.45.Kk	Charge-exchange reactions
	25.55.-e	3H-, 3He-, and 4He-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
N	25.60.Tv	Radiative capture
	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.−q and sections 13 or 25 appropriate to the light ions)
N	25.75.Ag	Global features in relativistic heavy ion collisions
N	25.75.Bh	Hard scattering in relativistic heavy ion collisions
N	25.75.Cj	Photon, lepton, and heavy quark production in relativistic heavy ion collisions
	25.75.Dw	Particle and resonance production
S	25.75.Gz	Particle correlations
M	25.75.Gz	Particle correlations and fluctuations
	25.75.Ld	Collective flow
S	25.75.Nq	Quark deconfinement, quark-gluon plasma production, and phase transitions
M	25.75.Nq	Quark deconfinement, quark–gluon plasma production, and phase transitions (see also 12.38.Mh Quark–gluon plasma in quantum chromodynamics; 21.65.Qr Quark matter in nuclear matter)
	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 (restricted to new topics in section 25)
	26.	Nuclear astrophysics (see also 95.30.−k Fundamental aspects of astrophysics in astronomy)
D	26.20.+f	Hydrostatic stellar nucleosynthesis (see also 97.10.Cv Stellar structure, interiors, evolution, nucleosynthesis, ages in astronomy) (Use 26.20.-f)
N	26.20.-f	Hydrostatic stellar nucleosynthesis (see also 97.10.Cv Stellar structure, interiors, evolution, nucleosynthesis, ages in astronomy)
N	26.20.Cd	Stellar hydrogen burning
N	26.20.Fj	Stellar helium burning
N	26.20.Kn	s-process
N	26.20.Np	Nucleosynthesis in late stellar evolution
N	26.20.Qr	Quasistatistical processes
D	26.30.+k	Nucleosynthesis in novae, supernovae, and other explosive environments (Use 26.30.-k)
N	26.30.-k	Nucleosynthesis in novae, supernovae, and other explosive environments
N	26.30.Ca	Explosive burning in accreting binary systems (novae, x-ray bursts)
N	26.30.Ef	Explosive burning in supernovae shock fronts
N	26.30.Hj	r-process
N	26.30.Jk	Weak interaction and neutrino induced processes, galactic radioactivity
	26.35.+c	Big Bang nucleosynthesis (see also 98.80.Ft Origin, formation, and abundances of the elements in astronomy)
	26.40.+r	Cosmic ray nucleosynthesis
	26.50.+x	Nuclear physics aspects of novae, supernovae, and other explosive environments
D	26.60.+c	Nuclear matter aspects of neutron stars (Use 26.60.-c)
N	26.60.-c	Nuclear matter aspects of neutron stars
N	26.60.Dd	Neutron star core
N	26.60.Gj	Neutron star crust
N	26.60.Kp	Equations of state of neutron-star matter
S	26.65.+t	Solar neutrinos
M	26.65.+t	Solar neutrinos (see also 96.60.Vg Particle emission, solar wind in solar physics)
N	26.90.+n	Other topics in nuclear astrophysics (restricted to new topics in section 26)
	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
S	27.90.+b	220 ⩽ A
M	27.90.+b	A ≥ 220
	28.	Nuclear engineering and nuclear power studies
	28.20.-v	Neutron physics (see also 25.40.−h Nucleon-induced reactions and 25.85.Ec Neutron-induced fission)
	28.20.Cz	Neutron scattering
	28.20.Fc	Neutron absorption
	28.20.Gd	Neutron transport: diffusion and moderation
N	28.20.Ka	Thermal neutron cross sections
N	28.20.Np	Neutron capture γ-rays
S	28.41.-i	Fission reactors
M	28.41.-i	Fission reactors (see also 89.30.Gg nuclear fission power in energy resources)
	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
N	28.41.Vx	Fuel cycles
	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
S	28.52.-s	Fusion reactors
M	28.52.-s	Fusion reactors (see also 52.55.−s Magnetic confinement and equilibrium, 52.57.−z Laser inertial confinement, and 52.58.−c Other confinement methods in physics of plasmas; 89.30.Jj Nuclear fusion power in energy resources)
	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 (see also 87.55.N− Radiation monitoring, control, and safety in biological and medical physics)
	28.60.+s	Isotope separation and enrichment
N	28.65.+a	Accelerator-driven transmutation of nuclear waste
S	28.70.+y	Nuclear explosions
M	28.70.+y	Nuclear explosions (see also 47.40.−x Compressible flows; shock waves; for radiation protection from fallout, for dosimetry and exposure assessment, see 87.53.Bn; for nuclear explosion seismology, see 91.30.Rz)
	28.90.+i	Other topics in nuclear engineering and nuclear power studies (restricted to new topics in section 28)
	29.	Experimental methods and instrumentation for elementary-particle and nuclear physics
D	29.17.+w	Electrostatic, collective, and linear accelerators (Use 29.20.-c)
S	29.20.-c	Cyclic accelerators and storage rings
M	29.20.-c	Accelerators (for accelerators used in medical applications, see 87.56.bd)
N	29.20.Ba	Electrostatic accelerators
N	29.20.D-	Cyclic accelerators and storage rings
N	29.20.db	Storage rings and colliders
N	29.20.df	Betatrons
N	29.20.dg	Cyclotrons
D	29.20.Dh	Storage rings (Use 29.20.db)
N	29.20.dk	Synchrotrons
N	29.20.Ej	Linear accelerators
D	29.20.Fj	Betatrons (Use 29.20.df)
D	29.20.Hm	Cyclotrons (Use 29.20.dg)
D	29.20.Lq	Synchrotrons (Use 29.20.dk)
S	29.25.-t	Particle sources and targets
M	29.25.-t	Particle sources and targets (see also 52.59.−f Intense particle beams and radiation sources in physics of plasmas; 87.56.bg Radioactive sources in medical physics)
	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
S	29.27.-a	Beams in particle accelerators
M	29.27.-a	Beams in particle accelerators (for low energy charged-particle beams, see 41.75.−i and 41.85.−p)
	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 γ-ray spectroscopy
	29.30.Lw	Nuclear orientation devices
	... ... ...	Energy loss and stopping power, see 34.50.Bw and 61.85.+p
N	29.38.-c	Radioactive beams
N	29.38.Db	Fast radioactive beam techniques
N	29.38.Gj	Reaccelerated radioactive beams
S	29.40.-n	Radiation detectors
M	29.40.-n	Radiation detectors (for mass spectrometers, see 07.75.+h; see also 95.55.Vj Neutrino, muon, pion, and other particle detectors; cosmic ray detectors in astronomy)
	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
	29.50.+v	Computer interfaces
D	29.85.+c	Computer data analysis (Use 29.85.-c)
N	29.85.-c	Computer data analysis
N	29.85.Ca	Data acquisition and sorting
N	29.85.Fj	Data analysis
	29.87.+g	Nuclear data compilation
	29.90.+r	Other topics in elementary-particle and nuclear physics experimental methods and instrumentation (restricted to new topics in section 29)