Astroparticle Physics

302 16 GlossaryAn asymmetry created by some, so far unknown baryon-number-violating process in the early universe (see Sakharov conditions).baryon–antibaryon asymmetrybaryon numberbaryonsBATSEbeam-dump experimentbeta decayBethe–Bloch formulaBethe–Weizsäcker cycleBethe–Weizsäcker formulaBig BangBig Bang theoryBig CrunchThe baryon number B is unity for all strongly interacting particlesconsisting of three quarks. Quarks themselves carry baryon number1/3. For all other particles B = 0.Elementary particles consisting of three quarks like, e.g., protonsand neutrons.Burst And Transient Source Experiment on board of the CGROsatellite.If a high-energy particle beam is stopped in a sufficiently thicktarget, all strongly and electromagnetically interacting particles areabsorbed. Only neutral weakly interacting particles like neutrinoscan escape.In nuclear β decay a neutron of the nucleus is transformed into aproton under the emission of an electron and an electron antineutrino.The transition of the proton in the nucleus into a neutronunder emission of a positron and an electron neutrino is called β +decay, contrary to the aforementioned β − decay. The electron capturewhich is the reaction of proton and electron into neutron andan electron neutrino (p + e − → n + ν e ) is also considered as betadecay.Describes the energy loss of charged particles by ionization andexcitation when passing through matter.Carbon–nitrogen–oxygen cycle: nuclear fusion process in massivestars, in which hydrogen is burnt to helium with carbon as catalyzer(CNO cycle).Describes the nuclear binding energy in the framework of theliquid-drop model.Beginning of the universe when all matter and radiation emergedfrom a singularity.The theory of an expanding universe that begins from an infinitelydense and hot primordial soup. The initial instant is called the BigBang. The theory says nothing at all about time zero itself.If the matter density in the universe is larger than the critical density,the presently observed expansion phase will turn over into acontraction, which eventually will end in a singularity.