9 jan 2017/ learning physics Are we science literates ?/Hypernucleus/ 9 april 2015.

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Are we science literates ?/Hypernucleus/ 9 april 2015.

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Are we science literates ?/Hypernucleus/ 9 april 2015.

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4/9/15

to mandalay-unive. Hypernucleus From Wikipedia, the free encyclopedia A hypernucleus is a nucleus which contains at least one hyperon in addition to nucleons. The first was discovered by Marian Danysz and Jerzy Pniewski in 1952. Since the strangeness quantum number is conserved by the strong and electromagnetic interactions, at least hypernuclei containing the lightest hyperon, the Lambda, live long enough to have sharp nuclear energy levels. Therefore they offer opportunities for nuclear spectroscopy, as well as reaction mechanism study and other types of nuclear physics (hypernuclear physics). Their physics is different from that of normal nuclei because a hyperon, having a different value of the strangeness quantum number, can share space and momentum coordinates with the usual four nucleons that can differ from each other in spin and isospin. The ground state of helium-5-Lambda, for example, must resemble helium-4 more than it does helium-5 or lithium-5 and must be stable, except for the weak decay of the Lambda. Sigma hypernuclei have been sought with apparent success.[1] Hypernuclei can be made by a nucleus capturing a Lambda or K meson and boiling off neutrons in a compound nuclear reaction, or, perhaps most easily, by the direct strangeness exchange reaction. K + nucleus → π + hypernucleus A generalized mass formula developed for both the non-strange normal nuclei and strange hypernuclei can estimate masses of hypernuclei containing Lambda, Lambda-Lambda, Sigma, Cascade and Theta+ hyperon(s).[2][3] The neutron and proton driplines for hypernuclei are predicted and existence of some exotic hypernuclei beyond the normal neutron and proton driplines are suggested.[4] This generalized mass formula was named as "Samanta Formula" by Botvina and Pochodzalla and used to predict relative yields of hypernuclei in multifragmentation of nuclear spectator matter.[5] Hypernuclei were first observed by their energetic but delayed decay, but have also been studied by measuring the momenta of the K and pi mesons in the direct strangeness exchange reactions. In particle physics, a hyperon is any baryon containing one or more strange quarks, but no charm, bottom, or top quark.[citation needed] Contents 1 Properties and behavior of hyperons 2 List of hyperons 3 Hyperon research 4 See also 5 References Properties and behavior of hyperons A combination of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. The lower six are hyperons. Being baryons, all hyperons are fermions. That is, they have half-integer spin and obey Fermi–Dirac statistics. They all interact via the strong nuclear force, making them types of hadron. They are composed of three light quarks, at least one of which is a strange quark, which makes them strange baryons. Hyperons decay weakly with non-conserved parity. Standard Model of particle physics Large Hadron Collider tunnel at CERN Background[show] Constituents[show] Limitations[show] Scientists[show] Hyperons Particle Symbol Makeup Rest mass MeV/c2 Isospin I Spin(Parity) JP Q S C B' Mean lifetime s Commonly decays to Lambda [1] Λ0 uds 1 115.683(6) 0 1⁄2+ 0 −1 0 0 2.60×10−10 [2] p+ + π− or n0 + π0 Sigma [3] Σ+ uus 1 189.37(0.7) 1 1⁄2+ +1 −1 0 0 (8.018±0.026)×10−11 p+ + π0 or n0 + π+ Sigma [4] Σ0 uds 1 192.642(24) 1 1⁄2+ 0 −1 0 0 (7.4±0.7)×10−20 Λ0 + γ Sigma [5] Σ− dds 1 197.449(30) 1 1⁄2+ −1 −1 0 0 (1.479±0.011)×10−10 n0 + π− Sigma resonance [6] Σ∗+(1385) uus 1 382.8(4) 1 3⁄2+ +1 −1 0 0 Λ + π or Σ + π Sigma resonance [6] Σ∗0(1385) uds 1 383.7±1.0 1 3⁄2+ 0 −1 0 0 Λ + π or Σ + π Sigma resonance [6] Σ∗−(1385) dds 1 387.2(5) 1 3⁄2+ −1 −1 0 0 Λ + π or Σ + π Xi [7] Ξ0 uss 1 314.83(20) 1⁄2 1⁄2+ 0 −2 0 0 (2.90±0.09)×10−10 Λ0 + π0 Xi [8] Ξ− dss 1 321.31(13) 1⁄2 1⁄2+ −1 −2 0 0 (1.639±0.015)×10−10 Λ0 + π− Xi resonance [9] Ξ∗0(1530) uss 1 531.80(32) 1⁄2 3⁄2+ 0 −2 0 0 Ξ + π Xi resonance [9] Ξ∗−(1530) dss 1 535.0(6) 1⁄2 3⁄2+ −1 −2 0 0 Ξ + π Omega[10] Ω− sss 1 672.45(29) 0 3⁄2+ −1 −3 0 0 (8.21±0.11)×10−11 Λ0 + K− or Ξ0 + π− or Ξ− + π0 Notes: Since strangeness is conserved by the strong interactions, the ground-state hyperons cannot decay strongly. However, they do participate in strong interactions. Λ0 may also decay on rare occurrences via these processes: Λ0 → p+ + e− + ν e Λ0 → p+ + μ− + ν μ Ξ0 and Ξ− are also known as "cascade" hyperons, since they go through a two-step cascading decay into a nucleon. The Ω− has a baryon number of +1 and hypercharge of −2, giving it strangeness of −3. It takes multiple flavor-changing weak decays for it to decay into a proton or neutron. Murray Gell-Mann's and Yuval Ne'eman's SU(3) model (sometimes called the Eightfold Way) predicted this hyperon's existence, mass and that it will only undergo weak decay processes. Experimental evidence for its existence was discovered in 1964 at Brookhaven National Laboratory. Further examples of its formation and observation using particle accelerators confirmed the SU(3) model. Hyperon research The first research into hyperons happened in the 1950s, and spurred physicists on to the creation of an organized classification of particles. Today, research in this area is carried out on data taken at many facilities around the world, including CERN, Fermilab, SLAC, JLAB, Brookhaven National Laboratory, KEK, and others. Physics topics include searches for CP violation, measurements of spin, studies of excited states (commonly referred to as spectroscopy), and hunts for exotic states such as pentaquarks and dibaryons. Isospin In particle physics, isospin (isotopic spin, isobaric spin) is a quantum number related to the strong interaction. Particles that are affected equally 21 KB (2,543 words) - 00:56, 31 March 2015 Click here to Reply or Forward 6.02 GB (40%) of 15 GB used Manage Terms - Privacy Last account activity: 2 minutes ago Details		Mandalay-University-Family-2006 -2006 group

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