[gate-users] Photons ID's from decay sources

Mon Jun 20 15:29:56 CEST 2005

Hi Dirk,

Thanks for the help.  This addition looks like it will be very useful
for the whole collaboration.

Cheers,

ross

-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Dirk Kruecker
Sent: Monday, June 20, 2005 8:48 AM
To: GATE feedback and helpline for Users
Subject: Re: [gate-users] Photons ID's from decay sources

Hi Ross,

Unfortunately the origin of the photon is not registered.
The primaryID is always 1 because it is always the decaying nucleus. Not
very useful to record this. 
The parentID is not useful, either. It may be everything, It is just
what the 
name says: the ID of the parent track of the track that caused the hit.
The photonID contains some info: (0 -> cascade ) but not (cascade -> 0).

I use my own extension to the root files. I have include the code I use
to 
identify the gammas, look for //dk in the code to find my modifications.
I did not include the changes to modify the root output  since I changed
a lot 
in my code. But it is straightforward work to add an additional entry to
the 
root file.

Please, verify the code if you want to use it!

Dirk

> Hi Dirk and Dimitris,
>
> I figure you both are the most likely to know the answer to this 
> question but if anyone else knows please speak up ;).
>
> I have been looking at the root output for Hits, Singles, and 
> Coincidences and am trying to determine the source particle's identity

> be it positron or cascade photon?  Inside the Hit's Branch I am 
> looking into ParentID, PhotonID, and PrimaryID.  So far ParentID looks

> the most likely but I don't know how to interpret this.
>
> Thanks,
>
> ross
>
> -----Original Message-----
> From: gate-users-bounces at lphe1pet1.epfl.ch
> [mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Dirk 
> Kruecker
> Sent: Tuesday, June 14, 2005 5:52 AM
> To: GATE feedback and helpline for Users
> Subject: Re: [gate-users] source of germanium68
>
>
> Hello everybody,
>
> Let me summarise the present status on the beta decay module in 
> GEANT4:
>
> There is a beta decay module in GEANT4 that works quiet nice. It 
> allows you to simulate the decay of all kinds of nuclei using the 
> ENSDF (http://www.nndc.bnl.gov/ensdf/).
> It simulates any possible decay, taking into account the latest
> knowledge on
> branching ratios and creates all possible gammas from the
de-excitation
> of
> the daughter-nucleus.
> So you get the right ratio between beta+ and EC, and for each possible
> decay
> channel the appropriate gamma spectrum in coincidence with the
positron.
>
> In GATE the commands to implement e.g. Y86 looks like: 
> /gate/source/addSource ytt86 /gate/source/ytt86/setActivity 500000000.

> becquerel /gate/source/ytt86/gps/particle ion 
> /gate/source/ytt86/gps/ion 39 86 0 0 /gate/source/ytt86/gps/energytype

> Mono /gate/source/ytt86/gps/monoenergy 0. MeV 
> /gate/source/ytt86/gps/angtype iso /gate/source/ytt86/gps/number 1 
> /gate/source/ytt86/gps/centre 0. 0. 0. cm /gate/source/ytt86/gps/type 
> Volume /gate/source/ytt86/gps/shape Sphere 
> /gate/source/ytt86/gps/radius 0.1 mm
> /gate/source/ytt86/gps/mintheta    0. deg
> /gate/source/ytt86/gps/maxtheta  180. deg
> /gate/source/ytt86/gps/minphi      0. deg
> /gate/source/ytt86/gps/maxphi    360. deg
>
> The important part here is the /gate/source/ytt86/gps/ion 39 86 0 0 
> command where Z and A are defined. You can define all kinds of isotops

> here.
>
> Unfortunately there had been several bugs in the GEANT4 code for the 
> beta decay and even the latest version  does not run absolutely 
> stable. In addition the original implementation is astonishing 
> inefficient (i.e.
> slow)
> but there is a fast mode sufficient for our purposes.
>
> For GEANT4 version 4.52-4.62 you need patches in 
> GateRadioactiveDecay5.cc and G4NuclearDecayChannel.cc which I can 
> provide but I would rather use gate 1.2 with GEANT 4.7. For this 
> version of GEANT I have provided an improved
> algorithm for simulating the beta energy spectra.
>
> To my knowledge the version GEANT 4.7 will give you correct physical 
> results but it still contains some bugs which affect the stability of 
> the program.
> There are at least 2 memory leaks. One I already fixed
> http://geant4.cern.ch/asdcgi/geant4/problemreport/show_bug.cgi?id=711
> but this is not yet part of any GEANT4 patch. Presently you have to
> include it
> by hand.
>
> I am still hunting for the second memory leak. Usually it only show up

> after simulating several millions of decays. On average my jobs run 
> for 24h/12
>
> million events and about 1 of 8 jobs crashes. If you can live with 
> this I would give it a try.
>
> I hope the helps. Let me know if you really want to work with the 
> older GEANT4 version.
>
> Best Regards,
> Dirk
>
>
>
>
>
>
>
>
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