2001 PACS Summary of Scheme 20.-29.

20. NUCLEAR PHYSICS

21. Nuclear structure (for nucleon structure, see 14.20.Dh
Properties of protons and neutrons;
13.40 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 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.Cs 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 (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 Gamma transitions and level energies
23.20.Nx Internal conversion and extranucleareffects
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.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 Alpha 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

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

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
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 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

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
(restricted to new topics in section 25)

26. Nuclear astrophysics (see also 95.30.-k Fundamental
aspects of astrophysics in astronomy)

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

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

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

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 is less than or equal to 5

27.20.+n  A is greater than or equal to 5 and is less than or equal to 19

27.30.+t  A is greater than or equal to 20 and is less than or equal to 38

27.40.+z  A is greater than or equal to 39 and is less than or equal to 58

27.50.+e  A is greater than or equal to 59 and is less than or equal to 89

27.60.+j  A is greater than or equal to 90 and is less than or equal to 149

27.70.+q  A is greater than or equal to 150 and is less than or equal to 189

27.80.+w  A is greater than or equal to 190 and is less than or equal to 219

27.90.+b  A is greater than or equal to 220

28. Nuclear engineering and nuclear power studies

28.20.-v Neutron physics (see also 25.40 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

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

28.52.-s Fusion reactors (see also 52.55.-s, 52.57.-z, and 52.58.-c in physics of plasmas)
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 87.52 in biological and medical physics)

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

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

29.25.-t Particle sources and targets (see also 52.59.-f in physics of plasmas)
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.Bw and 61.85.+p
in atomic and molecular physics and condensed matter, respectively

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

29.50.+v Computer interfaces (see also 07.05.Wr in computers in experimental physics)

29.85.+c Computer data analysis

29.90.+r Other topics in elementary-particleand nuclear physics
experimental methods and instrumentation
(restricted to new topics in section 29)