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Idea Re: Scintillation rise time 

Forum: Processes Involving Optical Photons
Re: Question Scintillation rise time (Martin Goettlich)
Re: Feedback Re: Scintillation rise time (Gumplinger Peter)
Re: None Re: Scintillation rise time (Martin Goettlich)
Re: Feedback Re: Scintillation rise time (Michael)
Date: 13 Oct, 2010
From: Michael <Michael>

I also have an issue with the rise time definition according to Martin's equation. If I input a 7.5 ps rise (BC422 ref. D. Lerche LLNL) I most definitely do not get a 7.5 ps rise. In fact plugging the numbers into Martin's equation gives somthing like 23-24 ps.

Martin's equation is

I = exp(-Ldt)*(1-exp(-Lrt)).

Where Ld and Lr are (lambda) decay constants for decay and rise respectively, I is the function intensity and t is time.

The definition for rise time is the time difference between 10% and 90% max of the rising signal. A simple manipulation of Martin's equation gives

Lr= (1/tr)*(ln(0.9)-ln(0.1))

where tr is the actual temporal difference between 10 and 90 percent of the rising edge. So to actually get the geant4 beta to obtain this rise you have to input your rise time as 1/Lr...This comes from the previous comment I made on this thread yesterday which explained how there is a missing factor of ln(2) in the exponent.

Ok so in conclusion...!

Peter, could you modify the G4scintillation.cc file to accont for this issue? It would be great if a user could simply enter a rise time defined as delta between 10 and 90 percent and let the code rearrange it into the correct decay constant as per the above equations.

Please email me if you want to discuss this further.

Kind regards,

Mike.

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1 None: Re: Scintillation rise time   (Michael - 15 Oct, 2010)
1 Warning: Re: Scintillation rise time   (Martin Goettlich - 29 Oct, 2010)
1 Feedback: Re: Scintillation rise time   (Michael - 29 Oct, 2010)
... 1 Message(s)
2 Question: Re: Scintillation rise time   (Qiang - 10 Mar, 2016)
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