|Message: Re: Scintillation rise time||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
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
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.
|Inline Depth:||Outline Depth:||Add message:|