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Forum: Hadronic Processes
Re: Question Tc-99m decay is wrong? (Glen Warren)
Date: 14 Aug, 2018
From: Glen Warren <Glen Warren>

I think I have identified the issue. In G4LevelReader, there is the following code

        if(fAlpha < fAlphaMax) {
	  G4float x = 1.0f + fAlpha;
	  fNorm1 += x*fProb;
	  vGammaCumProbability[j] = fNorm1;
	  vGammaProbability[j] = 1.0f/x;
	} else {
	  // only internal conversion case - no gamma conversion at all
	  fNorm1 += fProb;
	  vGammaCumProbability[j] = fNorm1;
	  vGammaProbability[j] = 0.0f;
	} 

The problem is the calculation of fNorm1 in the else statement, which occurs for very large alpha. For large alpha, it should be fNorm1 = fAlpha*fProb. Also, at least in this context, vGammaCumProbability is poorly named, as it is really the transition cumulative probability (g + CE).

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