Dear Experts,
I am using GPS to define Cs137 in my .mac like this:
/run/initialize
/gps/particle ion
/gps/ion 55 137 0 0.
/gps/pos/type Point
/gps/pos/centre -4625. 0. 200. mm
/gps/ang/type iso
/gps/energy 0 MeV
/run/bemOn 1
and i use
/tracking/verbose 2
to check soure information.
But i only see Ba137 ,not Ba137[661.2keV]
:----- List of secondaries ----------------
G4WT0 > Ba137: energy = 4.459 eV time = 24.61 y
G4WT1 > Number of events processed : 0
G4WT0 > anti_nu_e: energy = 616.4 keV time = 24.61 y
G4WT0 > e-: energy = 559.3 keV time = 24.61 y
G4WT0 > :------------------------------------------
So,i can’t get 662 keV gamma.
If there is any small example to just check this then it will be great help.
Thank you, I find the cause devote it is because i just beam On 1 event. I can see Ba137(661.6) when beam On is 2.
And I have some other questions need you help.
If i set up the beamOn to 100, dose it mean the source activity is 100Bq, or 10Bq source decay in 10sec? As i want to calculate dose equivalent for radiation protection.
What means of “stable stable “in the fifth column?
Hello maire,
Thanks for your reply. I saw the output file you uploaded, i want to make clear some questions which one of it is why every events can get Ba137(662keV) in yours and another is what relation of the sentence “Activity of Cs137 = 4.671e+12 Bq/g (126.2 Ci/g) “ with beamOn(10 events in your input).
Hope you reply , thanks again.
1- Not all; only 94.66 % ! This comes from data set RadioactiveDecay5.6, file z55.a137
2- activity of primary ion (eg. Cs137) is calculated in Run.cc, lines 342-355
Hi maire,
i check the code of Run.cc at lines 342-355, but i have some comfuse about it:
i simulate it under beamOn 1 and beamOn 10, but the result of Activity of Cs137 is no relation with event Number. i don’t clear relation between activity with event number.
2.the code at lines 342-355 introduce into track time, i don’t clear relation between activity with track time,so could you please tell me it?
What is computed is the mean activity of 1g of pur Cs137
To do that, you need only the mean time life of Cs137. You can read it from table or compute it from the simulated events. This is what is done at line 344. Of course, this computation has no meaning with only few events; the statistic must be big enough …
Thank you maire,
i clear the mean of this code that it purpose to caculate activity of all radioactive ion per gram. By the way, if i want to set source activity (suppose 10^6 Bq), what should i do ?
Zhenyu,
GEANT4 simulates a given number of gammas, N. In real life the activity is decay rate – a number of gammas in a given amount of time. So you decide what length of time, t, is represented in your simulation, then the rate is N/t.
One caution: You are using an isotropic emission. In a future simulation, if you decide to restrict the direction of the gammas that you generate to be less than the full 4pi solid angle, then the same number of simulated gammas corresponds to a higher activity of the source. The proportionality is the ratio of total solid angle (4pi) to simulated solid angle.
Hi Brian,
Thank you answer. Decay rate, for your reply, is equal to Number of events divided by time(seconds). So, if i want to simulates 1000 Bq Co60 and 1000 Bq Cs137 in one hour, i should set up events of number N to 3.610^6 (10003600)?