Espectroscopia Gama LAvFis 2010-2S.

Apresentação em tema: "Espectroscopia Gama LAvFis 2010-2S."— Transcrição da apresentação:

1 Espectroscopia Gama LAvFis S

2 Altamente energéticos
Radiação Gama – Origem A gamma ray is a packet (or photon) of electromagnetic radiation emitted from the nucleus during radioactive decay and occasionally accompanying the emission of an alpha or beta particle.  Gamma rays are identical in nature to other electromagnetic radiations such as light or microwaves but are of much higher energy. Examples of gamma emitters are cobalt-60, zinc-65, cesium-137, and radium-226. Like all forms of electromagnetic radiation, gamma rays have no mass or charge and interact less intensively with matter than ionizing particles.  Because gamma radiation loses energy slowly, gamma rays are able to travel significant distances.  Depending upon their initial energy, gamma rays can travel tens or hundreds of meters in air. Gamma radiation is typically shielded using very dense materials (the denser the material, the more chance that a gamma ray will interact with atoms in the material) such as lead or other dense metals. Gamma radiation particularly can present a hazard from exposures external to the body. Z = número atômico = número de prótons N = número de nêutrons A = Massa atômica = Z+N Processo de decaimento nuclear => n=noe-lt Altamente energéticos Radiação estelar LAvFis S

3 Várias formas de detecção
Câmera de neblina Câmera de bolhas Cintilador Geiger-Muller LAvFis S

4 Cintilador MicroR Meter, with Sodium Iodide Detector — A solid crystal of sodium iodide creates a pulse of light when radiation interacts with it. This pulse of light is converted to an electrical signal by a photomultiplier tube (PMT), which gives a reading on the instrument meter. The pulse of light is proportional to the amount of light and the energy deposited in the crystal. These instruments most often have upper and lower energy discriminator circuits and, when used correctly as single-channel analyzers, can provide information on the gamma energy and identify the radioactive material. If the instrument has a speaker, the pulses also give an audible click, a useful feature when looking for a lost source. Common readout units are microroentgens per hour (μR/hr) and/or counts per minute (cpm). Sodium iodide detectors can be used with handheld instruments or large stationary radiation monitors. Special plastic or other inert crystal "scintillator" materials are also used in place of sodium iodide.  LAvFis S

5 Eqpto. do LAvFis Cintilador+Fonte+amostra Analisador multicanal PC
LAvFis S

6 Tampa suporte de amostra
Cjto do cintilador Tampa suporte de amostra Corpo do cintilador Fonte Alta Tensão LAvFis S

7 Colocar até 500V LAvFis S

8 Suporte da amostra Colocar amostra com a radiação dirigida para abaixo em direção ao cintilador LAvFis S

9 Software e manuais Software: WinDAS (windas11-v1.2.pdf e cont11-v.12.pdf ) GDM User eng.pdf stud11-v1.2.pdf teach11-v1.2.pdf LAvFis S

10 Eixo Canal indica energia, comparar com padrão de referência
Com o softaware WinDAS Eixo Canal indica energia, comparar com padrão de referência LAvFis S

11 Amostras para usar Cs 137 – amostra 1 Cs 137 – amostra 2 Co 60 Ra 226
Pó branco – sem referencia LAvFis S

12 Distribuição de radiação gama a 1m da superfície
Gamma Ray exposure in USA from Nat. geog. Survey. Elevation above sea level is a key factor. LAvFis S

13 Próxima? LAvFis S