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Lecture I.2 Nuclear Structure Observables

Lecture I.2 Nuclear Structure Observables. Alexandru Negret. Lecture I.2 – Nuclear Structure Observables A. Negret. Outline. The nuclear level scheme ; The gamma transitions ; The energy and the intensity of the gamma transitions; The branching ratio ; The coincidences ;

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Lecture I.2 Nuclear Structure Observables

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  1. Lecture I.2Nuclear Structure Observables Alexandru Negret

  2. Lecture I.2 – Nuclear Structure Observables A. Negret Outline • The nuclear level scheme; • The gamma transitions; • The energy and the intensity of the gamma transitions; • The branching ratio; • The coincidences; • The lifetime of a level; The isomers.

  3. Lecture I.2 – Nuclear Structure Observables A. Negret The nuclear levels. The level scheme A quantum system N neutrons Z protons The nuclear force The energy is quantified: ENERGY LEVELS Ground state

  4. Lecture I.2 – Nuclear Structure Observables A. Negret The gamma transitions Deexcitation from one level to another => gamma transitions Branching ratio

  5. Lecture I.2 – Nuclear Structure Observables A. Negret Question Why ? How much is - ? The RECOIL OF THE NUCLEUS:

  6. Lecture I.2 – Nuclear Structure Observables A. Negret Lifetime of a level. Isomers. • – lifetime of a level • T1/2 – half-life Range of the lifetime of most nuclear levels: <1ps – 1 ns If t is of the order of 1ms or larger (ms, s, or larger) the nuclear level is an ISOMER.

  7. Lecture I.2 – Nuclear Structure Observables A. Negret The coincidences • Time resolution of a • detector: • HPGe ~ 10 ns • Scintillator ~ 0.5 ns

  8. Lecture I.2 – Nuclear Structure Observables A. Negret The discreteregion and the continuum

  9. Lecture I.2 – Nuclear Structure Observables A. Negret Exercise: calculate brancing ratios AnElectron Capture experiment: the decay of 152Eu to 152Sm. • Calculate the branching ratios for the transitions starting from • 685 keV level • 810 keV level • 963 keV level

  10. Lecture I.2 – Nuclear Structure Observables A. Negret Summary • The nuclear level scheme; • The gamma transitions; • The energy and the intensity of the gamma transitions; • The branching ratio; • The coincidences; • The lifetime of a level; The isomers.

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