Projekta Nr.ISO/TS 23878:2024
Nosaukums<p class="MsoBodyText"><span lang="EN-GB">This document describes a method for performing positron annihilation lifetime measurements using a <sup>22</sup>Na positron source that decays with β<sup>+</sup> emission. The β<sup>+</sup> (positron) lifetime is determined from a measurement of the lifetime of the <em style="mso-bidi-font-style: normal;">ortho</em>-positronium which ranges from 1 ns to 10 ns (ascribed to a pore size from approximately 0,3 nm to 1,3 nm in diameter), as observed for polymeric materials in which the positronium atoms mostly annihilate via a two-gamma annihilation process. </span></p> <p class="MsoBodyText"><span lang="EN-GB">This document is not applicable to thin surface layers (that are less than several micrometers).</span></p> <p class="MsoBodyText"><span lang="EN-GB">This document does not apply to measuring:</span></p> <p class="MsoBodyText"><span lang="EN-GB">— non-positronium forming materials; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that induce a spin conversion reaction; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that contain chemicals influencing the annihilation process of <em style="mso-bidi-font-style: normal;">ortho</em>-positronium by chemical reactions; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that contain<span style="mso-spacerun: yes;">  </span>mesoporous silica gels with a large contribution from the three-gamma annihilation process.</span></p>
Reģistrācijas numurs (WIID)77259
Darbības sfēra<p class="MsoBodyText"><span lang="EN-GB">This document describes a method for performing positron annihilation lifetime measurements using a <sup>22</sup>Na positron source that decays with β<sup>+</sup> emission. The β<sup>+</sup> (positron) lifetime is determined from a measurement of the lifetime of the <em style="mso-bidi-font-style: normal;">ortho</em>-positronium which ranges from 1 ns to 10 ns (ascribed to a pore size from approximately 0,3 nm to 1,3 nm in diameter), as observed for polymeric materials in which the positronium atoms mostly annihilate via a two-gamma annihilation process. </span></p> <p class="MsoBodyText"><span lang="EN-GB">This document is not applicable to thin surface layers (that are less than several micrometers).</span></p> <p class="MsoBodyText"><span lang="EN-GB">This document does not apply to measuring:</span></p> <p class="MsoBodyText"><span lang="EN-GB">— non-positronium forming materials; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that induce a spin conversion reaction; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that contain chemicals influencing the annihilation process of <em style="mso-bidi-font-style: normal;">ortho</em>-positronium by chemical reactions; </span></p> <p class="MsoBodyText"><span lang="EN-GB">— positronium-forming materials that contain<span style="mso-spacerun: yes;">  </span>mesoporous silica gels with a large contribution from the three-gamma annihilation process.</span></p>
StatussStandarts spēkā
ICS grupa07.120