GEANT4 - Science topic

Hi everyone

I am trying to detect ion products during ionisation by the electric field in geant4 .

i have implemented electric field inside the box which have been fiiled by some materials that is being exposed by electrons with energy equal to the ionisation energy (incident electrons energy range 5 ev - 30 ev ) of inside material.

i want to detect ion after ionisation,but electrons are being produced and there are no ions.

I have used G4VModularPhysicsList class and have used G4EmStandardPhysics , G4DecayPhysics and G4RadioactiveDecayPhysics at construct method of physicslist class.

Why i can not detect ions? Are there any Physicslists to produce ion products during ionisation in geant4?

Regards,

Tabaei

Very many published papers exist on radiation shielding glasses, all with identical simulation techniques, performed with the MCNPX, FLUKA and GEANT4. I don't really realize if such extensive simulation practices are necessary to be published.

I want to calculate deposited energy of the electron pencil beam in the z direction inside a sphere filled with water which its edge located at z=5 cm. If you have any resource, input file or guidance, help me please.

Dosimetry

dosimetry simulation

Hello everyone,

I am working on cell dosimetry by simulating cell irradiation in biological wells. In the wells, a volume of water in which the cells are constructed independently. Concerning the irradiation source, I want it to just fill the water volume but not the cells, and inversely. By researching, I found the (confine) method using GPS. However I could not apply it appropriately. Can have any help on how to apply it, or any already constructed example that implement this method ? Or even if there are any different methods ?

Thanks in advance for any help.

I am using Ubuntu 20..04.4 LTS and the version of geant4 is 10.07.

I am attaching the error file here.

Hello dear all;

I am a beginner in GEANT4 use and I have issue to determine the neutron flux spectrum entering in a small cylindrical detector (n/cm2/event). But I can't add the appropriate code concerning this aim in my application.

Please someone tell me how can I do that?

I'll be very grateful for any help.

Thank you in advance!

-Abdesslam LAMRABET-

I would like to add TOF into my GEANT4 simulation, but I want to get TOF for each radiation detector.

I know that TOF can be done through GetGlobalTime function, but I do not understand well the physics behind.

I employed GetGlobalTime in the Stepping Action Class, and a counter (k). I understand that Stepping is called several times around a whole event, so to avoid count again the same particle I used counter (k). I saved the TOF and plot it for a run in different ntuples.

I did something like this:

if (volume == fScoringVolume1 && k1==0) {

G4StepPoint *preStepPoint = step->GetPreStepPoint();

G4double tof1 = preStepPoint->GetGlobalTime();

k1+=1;

fEventAction->AddTOF1(tof1); }

I got a TOF of 10 ns for a gamma source at 10 cm from the detector's cover; however, I am not quite sure if my simulation works properly.

Perhaps, someone who can help me with a GEANT4 example which does something similar or a GitHub repository.

I am trying to run a simulation in geant4. I have written a macro file and I need to run the code for about 50 times for some research related task. I have tried to use /control/foreach but does not seem to work.

I have an interview to face and I don't know any thing about GEANT. But I am sure the question will be from that topic. Can any body help about giving some idea regarding GEANT, and what kind of questions can be expected.

Are there any specific classes in geant4 for nano-materials? Or anyone could share an example of detectorconstruction.cc for simulating nanoparticles induced detectors?

Good day!

I have indefinite situation for me arose with gamma particle detection simulations.

My detector is a 10 * 10 pixel of cadmium_telluride.

pixel size 55 * 55 um, thickness 0.5 cm.

Beam gamma 80 keV.

When using G4EmStandardPhysics_option4, I get secondary gamma photons with energy ~ 23 keV.

The question arises with the LengthTracks for this secondary particle, in some cases it is over 300 micrometers.

This happens when there "CoupledTransportation" process takes place without any interactions along the path of the particle.

Tell me what caused this movement of the particle, or am I missing something when creating PhysicsList?

I am working on the simulation of a HPGe detector, and when I do simulations for a cylindrical source of radium 226, I can't reproduce the Compon Edge, I use the standard phystic list option2

Hello, I want to produce radioisotopes from different targets, specially for simulating a cyclotron operation. I tried STCyclotron example but it is valid only for few solid targets like Ni, Co. Is there any similar example which can be modified to get my desired outcome? If not, how can I achieve it? please suggest. Thanks in advance. Arnab

Hello everyone,

As you've probably guessed I'm fairly new to Geant4 and I am working on a project where I have to determine energy deposits in various organs after Irradiating the thyroid with I(131).

For starter I want to use the available human phantom just to get the gist of it but my problem is how should I simulate the radiation, provided that Iodine is concentrated in the thyroid and that it has a half life of 8 days, said Iodine disintegrate by emitting an electron and a gamma ray.

My questions are many:

1/Should I take the thyroid as the point from where the radiation is being emitted?

2/How will the half life be taken into account?

3/Do the organs provided in the example have sensitive detectors or should I create them?

4/How does the scoring goes?

All in all I would appreciate any and all help and if anyone has a clear idea of how I should proceed please your help is most welcome.

Thank you.

Hi,

I tried to simulate the SPECT system with GATE and I could visualize interactions in the detector. However, I would like to visualize source energy distribution too.

I tried to simulate a SPECT system and set up source as below:

/gate/source/addSource SourceConfinement

/gate/source/SourceConfinement/gps/type Volume

/gate/source/SourceConfinement/gps/shape Sphere

/gate/source/SourceConfinement/gps/radius 1.5 mm

/gate/source/SourceConfinement/gps/centre 0. 0. 0. mm

/gate/source/SourceConfinement/gps/particle gamma

/gate/source/SourceConfinement/gps/energy 140. keV

/gate/source/SourceConfinement/setActivity 740000. Bq

/gate/source/SourceConfinement/gps/angtype iso

I didn't mention any energy distribution here. So, what will be the actual energy distribution with this simulation and is there any way to plot the source energy distribution?

Hello Experts,

I want to know that how to find theta maximum when i am using GPS and sphere and surface type distribution. and using cosine distribution.

then i want to know that is there any mathematical calculation to find theta maximum for biasing.

like in the Geant4/examples/advanced/radio-protection theta maximum is 0.003 deg. how they got this using the surface area of source or object. like how can i get for my object ?

any type of help will be appreciated.

Thanks in advance !

Best Regards

Priyanshu

I am a novice in using Geant4, and I want to use Geant4 to do some study or research in radiobiology. What comes to my mind is to use Geant4 to simulate heavy ion irradiation. Could anyone please give me some suggestions?

Hi,

Can anyone please help me that how i can see the connections between all the Src file as i am very new to Geant4 and also know very less knowledge of C++.

so how can i proceed ?

Thanks in advance !

I have created a geometry of a concrete hollow box, placed a point source inside it. I got the Edep plot, now I need to calculate the depth dose profile in it.

I see extended example TestEm2,4, and 11 but I got bogged down seeing the enormous jungle of code. My understanding so far is, I need to access longitudinal and radial depth of the detector. Then need to get dose= edep/mass in each profile. Then show it in a histogram.

I need instructions whether my way is right and how can I do it simply.

Please do help, I got stuck here for a long.

Regards,

Hello every one,

I am trying to simulate beta spectrum using Geant4/example/extended/radioactivedecay/rdecay01. In fact the problem is that when asking for the beta spectrum, it gives me a beta spectrum but with gamma pics. I am trying to understand why the program includes gamma pics in the beta spectrum, if there is any one can help me ?

In the two donwloaded images, it is possible to note that ceratain pics, corresponding to the deexcitation pics are removed thus by removing the deexcitation process in the physicslist, but gamma pics are stil there.

Thanks any way fo any help.

I am thinking of simulating Gamma rays in FEM software like Ansys, COMSOL, etc. I tried to see some reference papers to start with but haven't got any relevant ones. Also, I have been looking for any sort of previous work done in this part, but unfortunately found none.

I saw somewhere that Gamma rays can be simulated in software like GEANT4 but I am not thinking of learning a new software only to simulate gamma rays and later it becomes of no use to me. So I am sticking with the common software used in academic institutes.

Can anyone tell me what do you think that whether gamma rays can be simulated in FEM or not? If yes, can you share some relevant papers or modules to start with.

I am making a simulation of energy deposited of some radioactive sources in scintillation detector. I have some results, but I don't have the same distribution energy between experimental spectra and simulated spectra. I do not know why.

For instance, the spectra of Cs-137 is shown. However, it does not have the same resolution.

Someone who can help me how to improve the simulation.

The scintillation detector is of NaI:Tl.

Hi everyone,

I need to achieve some radiation protection calculation with MCNP6.2 but my partner is using Geant4. Does somebody know a simple way to swap from Geant4 to MCNP6.2?

Kind regards

Lucas

Hello,

I am a newbie in geant4. I'm learning it playing with example. Sometimes, when I go to simulate an example code, it doesn't create an executable file (the green one in my ubuntu terminal). Why does it happen? There is no error while building the file.

Please help.

File lists from terminal, there is no executable file.

I have tweaked around and modified the examples to learn how the coding works. But I want to build a detector from scratch. After reading the documents from the official website I got a rough idea but still not something concrete enough to start working. It'll be really helpful if someone can give me rough idea.

hi everyone. i'm a PhD student and i'm stuck when i came to developing my own simulation code using GEANT4 ; i know how to define the detector , the physics list , the generator and the action initialization ; but it's hard for me to deal with scoring , the run and the event action; i need a practical example which covers those points and help me finish the simulation.

thanks.

Very long simulations may be subject to computer failure for many reasons. Is there a command in Gate to save (or dump) the state of a simulation and be able to resume it later?

I would like to estimate proton damage during an irradiation with either Geant IV or MCNP X softwares and I would like to know what are the pros and contras of these two different softwares.

I would like also to estimate neutron damage during a different irradiation on the same material and then make a transferability study of proton irradiation to neutron irradiation.

What software would you recommend and why?

thank you

I want to make radio-active source in G4PrimaryGeneratorAction.cc class. How to do?

I have built a detector for the detection of the cosmic-ray muon. Till now, I was using point particle gun for shooting high energy muons into the detector. Now I want to create a rectangular plane above the detector to throw thousands on particles in a single event by covering the whole detector plane. It is easy to do in a macro file. But I want to implement it in src file so that I can visualize the entire process. Kindly answer.

Hi,

I am a beginning user of Geant4. I am trying to work with voxel phantoms. Therefore, I have some difficulties:

- following the title of my question - my Geant4 environment is creating .wrl file instead of .gdd. First type of file is not supported by gMocren viewer.

- additionaly - I cannot visualize voxels in OGLSWin32 Mode (OpenGL). Without QT. Is it normal situation?

I am working on Windows 10 with cMake and Visual Studio 2019.

I would appreciate any tip any help or files.

Thanks in advance.

Mateusz

Hello, I am trying to simulate the collision of two proton beams in the VeLo in LHCb by using Geant4. However, it does not seem possible to interact two beams with each other and so, I was wondering if it is possible to use ions (protons in this case) as target material instead.

Furthermore, I found that PYTHIA 6 (or 8) might offer a solution and I was wondering if anyone has experience in importing PYTHIA package in Geant4, since I cannot find anything helpful in doing this online.

Hopefully someone can help, thanks in advance.

Does anyone have a fully modeled proton therapy treatment unit available?

It can be in either Geant4 (G4/Topas/Gate) or MCNP.

I am trying to get cross sections for photonuclear reactions (gamma, n). So I have gamma beam with energy from 0.1 MeV up to 50 MeV and gold target. And I want to get cross sections for the next reactions for different gamma beam energy: Au197 + gamma = A196 + n, Au197 + gamma = A194 + 3n (attached image, I want to get the to compare). Now I use ShieldingLEND physics list.

Hi,

I am trying to simulate a pinhole SPECT system in GATE. I want to block gamma penetration through collimator in this simulation(no penetration of pinholes through collimator other than holes as in ideal collimator). How can I stop penetration?

am I need to modify the following command:

or any other command. I am new to GATE simulation and I will be grateful for your reply.

Thanks in Advance !

Manu

Hi all,

I’m running a modified version of Example B1 for my graduate thesis. Pretty simple setup, the geometry is all modded and brand new (Basically just a bunch of boxes) and I cleared all overlaps so that part is good to go. For my source, I’m trying to use a GPS that takes up 99.9999% of the world volume in the shape of the world volume (world volume is a square, so I have a ParaP with all angles set to 90’), which shoots off gamma’s. So the problem I’m having is that the GPS code is seg Faulting when a gamma leaves the world volume instead of killing the interaction. I’m wondering how to fix the issue? I’ve tried to modify it in the stepping action, but do I need to find the StackingAction.hh file and modify it there/include it in exampleB1.cc?

Here is the error:

Some /vis commands (optionally) take a string to specify colour. “/vis/list” to see available colours. Checking overlaps for volume FrontWall1 … OK! Checking overlaps for volume FrontWall2 … OK! Checking overlaps for volume RightWall … OK! Checking overlaps for volume LeftWall … OK! Checking overlaps for volume BackWall … OK! Checking overlaps for volume TopWall … OK! Checking overlaps for volume BottomWall … OK! Checking overlaps for volume PbFW … OK! Checking overlaps for volume PbBW … OK! Checking overlaps for volume PbRW … OK! Checking overlaps for volume PbLW … OK! Checking overlaps for volume PbTW … OK! Checking overlaps for volume PbBottom … OK! Checking overlaps for volume WATER … OK! Issue /vis/viewer/refresh or flush to see effect. /tracking/storeTrajectory 1 Attributes available for modeling and filtering with “/vis/modeling/trajectories/create/drawByAttribute” and “/vis/filtering/trajectories/create/attributeFilter” commands: G4TrajectoriesModel: Event ID (EventID): G4int Run ID (RunID): G4int G4Trajectory: Charge (Ch): unit: e+ (G4double) Track ID (ID): G4int Initial kinetic energy (IKE): G4BestUnit (G4double) Initial momentum magnitude (IMag): G4BestUnit (G4double) Initial momentum (IMom): G4BestUnit (G4ThreeVector) No. of points (NTP): G4int PDG Encoding (PDG): G4int Parent ID (PID): G4int Particle Name (PN): G4String G4TrajectoryPoint: Position (Pos): G4BestUnit (G4ThreeVector) WARNING: Trajectory storing has been requested. This action may be reversed with “/tracking/storeTrajectory 0”. G4VisManager: Using G4TrajectoryDrawByCharge as fallback trajectory model. See commands in /vis/modeling/trajectories/ for other options. HepRepFile writing to G4Data0.heprep /run/verbose 1 /event/verbose 1 /tracking/verbose 1 /gps/verbose 1 /gps/particle gamma /gps/pos/type Plane /gps/pos/shape Rectangle /gps/pos/centre 0 0 0 cm /gps/pos/halfx 816 cm /gps/pos/halfy 228 cm /gps/pos/halfz 230 cm /gps/ang/type iso /gps/energy 10 MeV /gps/ene/min 0.1 MeV /gps/ene/max 30 MeV /run/beamOn 100

========= Table of registered couples ==============================

Index : 0 used in the geometry : Yes Material : G4_AIR Range cuts : gamma 1 mm e- 1 mm e+ 1 mm proton 1 mm Energy thresholds : gamma 990 eV e- 990 eV e+ 990 eV proton 100 keV Region(s) which use this couple : DefaultRegionForTheWorld

Index : 1 used in the geometry : Yes Material : G4_STAINLESS-STEEL Range cuts : gamma 1 mm e- 1 mm e+ 1 mm proton 1 mm Energy thresholds : gamma 20.9232 keV e- 1.31345 MeV e+ 1.22809 MeV proton 100 keV Region(s) which use this couple : DefaultRegionForTheWorld

Index : 2 used in the geometry : Yes Material : G4_PLEXIGLASS Range cuts : gamma 1 mm e- 1 mm e+ 1 mm proton 1 mm Energy thresholds : gamma 2.78665 keV e- 389.196 keV e+ 376.336 keV proton 100 keV Region(s) which use this couple : DefaultRegionForTheWorld

Index : 3 used in the geometry : Yes Material : G4_Pb Range cuts : gamma 1 mm e- 1 mm e+ 1 mm proton 1 mm Energy thresholds : gamma 101.843 keV e- 1.36749 MeV e+ 1.27862 MeV proton 100 keV Region(s) which use this couple : DefaultRegionForTheWorld

Index : 4 used in the geometry : Yes Material : G4_WATER Range cuts : gamma 1 mm e- 1 mm e+ 1 mm proton 1 mm Energy thresholds : gamma 2.94056 keV e- 351.877 keV e+ 342.545 keV proton 100 keV Region(s) which use this couple : DefaultRegionForTheWorld

====================================================================

/vis/scene/notifyHandlers scene-0

Run 0 starts.

Rotated and Translated position (-2113.3,-799.247,0) Generating isotropic vector: (0.759379,0.522945,-0.387133)

G4EventManager::ProcessOneEvent()

G4PrimaryTransformer::PrimaryVertex (-2113.3(mm),-799.247(mm),0(mm),0(nsec)) 1 primaries are passed from G4EventTransformer. !!! Now start processing an event !!!

Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName 0 -2.11e+03 -799 0 10 0 0 0 World initStep 1 -1.47e+03 -357 -328 10 0 846 846 RightWall Transportation 2 -1.46e+03 -349 -333 10 0 14.6 861 World Transportation 3 -573 262 -785 10 0 1.17e+03 2.03e+03 BackWall Transportation 4 -551 277 -797 10 0 28.5 2.06e+03 World Transportation 5 5.69e+03 4.57e+03 -3.98e+03 10 0 8.21e+03 1.03e+04 OutOfWorld Transportation Segmentation fault (core dumped)

I made a detector consisting of one adsorber and gap by replicating then throughout the volume in GEANT4. Now I want to place a single converter box in a particular gap. I have modified' Basic example B4'. But the problem is when I assigned another box, it has been replicating in all the gaps as its physical volume is replicated. Are there other ways to do it?

Hi everyone,

I tried to simulate Th232 source in Geant4 using two different formats to get the data: in root and .csv, the root format is giving funny Gaussian shape and .csv output is giving me 3 columns. Is there a way to make the peaks look like the experimental one instead of dotted lines? Also what could be the problem of getting 3 columns? and how do I identify my counts from the columns? I have attached the two formats below.

Note: If I try with Co60 or Na22, the spectra normally comes out with nice Gaussian shape but with a lot of gamma energies the shape is something else.

Regards,

Mistura.

Hi

I am trying to calculate PDD using Geant4

I divided a water phantom to voxels (2 mm x 2mm x 2 mm) by G4NestedParameterisation and i have created a class derived from Sensitive Detector class using Hit (I am not sure that this sensitive detector must be used)

How can I calculate the dose at each voxel?

I am trying to simulate the electroluminescence process in noble gases (argon and xenon) through Geant4 but I haven't found any documentation on how to add this process to the physics list.

Is there a standard physics list that already has this process? Or a simple way by which I can define the secondary scintillation phenomena within the simulation?

Dear Experts, I am beginner in Geant4. I have modified geant4/examples/basic/B4d input to score energy spectrum in the sensitive volume. I have used the following code for energy binning char name[16]; for (G4int i=0; i<48;i++){ std::sprintf(name,“current%03d”,i); G4String name; primitive= new G4PSSphereSurfaceCurrent(“current”, fcurrent_in); G4double kmin=i*0.025MeV; G4double kmax=(i+1)*0.025MeV; G4SDParticleWithEnergyFilter*filter=new G4SDParticleWithEnergyFilter(flrname = “filter”); filter->add(“gamma”); filter->SetKineticEnergy(kmin,kmax); primitive->SetFilter(filter);

logvol->RegisterPrimitive(primitive); Now as per B4d examples, B4dEventAction.cc for hist collection I did the foloowing

 fphotonCurrentHCID=G4SDManager::GetSDpointer()->GetCollectionID("Det/current"); Then auto current=GetSum(GetHitsCollection(  fphotonCurrentHCID, event)); Now as per B4d examples,  B4dRunAction.cc for hist collection I did the foloowing analysismanager->CreateH1("current","photon current", 48, 0., 1.2*MeV); Now, how I feel that some modification is required in B4dEventAction.cc and B4dRunAction.cc to get histogram in the format of (energy-bin vs counts)?But I do not know how to do it.

Kindly give me some suggestion. Thanking you in advance.

How we can define a small molecule in geant4-DNA,for example water (H2O)?,May we define it in idle?

I am seeking for the possible procedures to install Geant4 on Windows 7.

I simulated a SPECT camera using GATE (GEANT4 Application for the the Tomographic Emission) code . I am going to reconstruct the GATE output using iterative methods from STIR. How can I deform projection data ( .sin) to sinogram data (.s)?

Please someone tell me what is the difference in the Target material of world volume and sensitive detector material of chamber volume of B2 Basic example in Geant4 simulation?

I am using QGSP_BERT_HP physics list in B2 Basic example.

I am changing target material to Boron-10, sensitive detector material to Si and particle to neutron in B2 Basic example of Geant4.10.01. I am getting the secondary particles Lithium,alpha and gamma.

If I am changing sensitive detector material to Boron-10, target material to Xe and particle to neutron in the same example. I am getting the same secondary particle. Just at the output file in the bottom there are just displaying the energy deposition. Nothing else everything is the same as above.

I really want to know the difference in Target material and sensitive detector material in B2 Basic example?

I was thinking of simulating a cyclotron using GATE as a platform and I was wondering if it's the correct platform to use or is it better to use another platform (Geant4 for example).

Hi all,

I'm running a simulation involving many particles. How can I decrease the time for checking the overlap of geometries in my code when there are more than million particles in the geant4 code?

Thanks a million in advance

Hi,

It is posible to create geant4 simulations under qtcreator ide ? 

I want to send a pencil beam of electrons onto a target. I am modifying the example B1 to get this. I do send electrons with defined energy and direction on to the given geometry via command line by using /gun and /run commands but I do not know how to define them as a pencil beam.

I guess we need the optical part of GATE. But how do I modify / set the physics to simulate this effect (because geant4 seems to have it already)?

This is my first time using Geant4 . I use it in calculating mass attenuation coefficient. i know that TestEm13 is used for that but i can not run it or edit the source or target. and from where can i get easy and clear instruction to deal with Geant4

Hi, I use rdecay02 to implemented my application. In README, I read on point 5 (visualization) the following instructions: "Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An example of display the geometry and tracks using VRML is given in the macro file macros/vis.mac." But in my macros files in this example, I don't have a file name's vis.mac. I use geant4 V10.2. if anyone had already perform this example with visualization set, help me please.

I want to randomize particle gun within the volume of body phantom. what should be the code for PrimaryGeneratorAction.cc....

I'm planning to use Geant4 to calculate the effective dose for mammography examination but I faced two problems:

1. I was trying to use the human phantom in advance example but some of the organs eg liver, lung and thyroid etc are missing. People suggests I could use XCAT phantom but it is quite expensive and I'm not so sure whether this phantom is suitable for mammography dosimetry or not?

2. Unlike PET or SPECT in GATE there are no benchmark for mammography unit do I need to build it from scratch? Even I modeled the mammography unit I cannot verify my simulation results...

Hi all,

I'm trying to simulate the photon decay spectrum of Eu155 in Geant4. I'm not using the decay file provided by Geant4 because the energies and intensities listed are incorrect. I've changed/added values to match trusted literature, ensuring that the syntax is the same and the intensity column sums to 100.

The resulting spectra however is not right. There are too few photons per decay for most energies. I'm confident I'm collecting all the photons. I've attached my decay file and the resulting plot. The picture also has a 2nd plot of what the spectra should approximately look like for comparison.

I want to know what the intensity column is actually doing and how to adjust it such that the photons per decay match the values I've placed in the intensity column (noting that it's as a percentage there).

Any help is greatly appreciated

Thanks,

- Giuseppe

Hello Everyone

I'm trying to simulate a LaBr3(Ce) detectors with GEANT4. The dopant (Ce) concentration is 5% (given by the manufacturer). Do I have or have not, when declaring the material components in GEANT4, to include the 5% Cerium??

Thank you

Walid

Using G4PrimaryVertex and G4PrimaryParticle, i can get the energy at the beginning of an event, but i want to know how much energy each particle loses during an event. I'm simulating particles travelling through a medium.

Dear All,

I want to simulate Protontherapy machine by using Geant4 Monte Carlo code. I'm asking if there is any document in which I can find all data required to perform a Monte Carlo model of ProtonTherapy.

Thanks,

Best Regards,

i have installed geant 4 on my win7 64 bit. after running an example when i want to rotate the geometry, force close happens.what is the problem?

I have simulated Varian 2100, 6MV with Beamnrc Code and now I want to apply driven phase space file to Geant4.

i use MCNPX  code for calculate the neutron and photon dose in BNCT but for GdNCT we have auger and conversion electron and i don't know how can i calculate electron dose.

My system include: Resource, (PMT or MPPC) and analysis system. I would like to know: if i add 1 photodiode in dark box (in dark box include: resource, photodiode), Can i limit the lost of electron when from dynode to anode or increase the PDE measurement?. And i would like to make a dark box, what is the best materials to make it? (I use the optical resource: Co-60, X- ray or Po-210).

My English is not good. I try to show my thinking. I Hope I can receive your suggestion.

Thank you so much.

I am working with MCNP. The set-up is simply trying to carry out a radiotherapy simulation where I can use a point source of gamma photons to destroy cancerous cells.

My Problem: I am losing particles so the run is terminated.

Geometry: A cylinder is the skull in it there is a sphere>>>Tumor. I put them into a big rectangular box. My point source is another sphere inside the box.

I need help. Am I going the right way?

Dear Colleagues;

I am MCNP user since several years. I working with MCNPX version with WinNc32 complier but nowadays i have MCNP5 and i want to use it with WinNc32 complier as my previous studies. Somebody have this experience? I have total folder of MCNP5 but somehow i can't use it with WinNc32. Thank you in Advance...

Rather than using predefined Geant4 physics reference lists such as FTFP_BERT, I am trying to create a physics list with particles and processes more relevant with the experiment I am simulating. Has anyone tried similar things? Would you mind sharing your experience?

Dear all,

I tried to simulate Co60 source in Geant4.

I did it in 2 different ways:

A) I simulated two gaussian peaks in the gamma peak position and I get the gamma picture attached

B) after that I have simulated the source with example rdecay02 but I have a different spectrum.

Any of you can help me to solve this problem? I do not understand how is possible that I have something so different.

Thanks in advance

Alessia

I have run a program for detector efficiency simulation. The output file is in root format. Can anyone help me to extract the result of simulation in another file format? txt format is the best one I think

Thank you.

Can anyone kindly help me with the geometry construction of Ortec GMX30-70-SV-CW HPGe detector? The bias voltage is +3200V at the N contact.

Hello. I am a complete novice in using Geant4 and I need to build a 2D array of detectors (like 1024x1024, their size in the order of millimeters, with gaps between them). I wish to know exactly the method (exact syntax), and if it can be done using a double for loop, in the source or in a macro. Also I need to know subsequently their indexes (i,j) and/or center position. Your help is greatly appreciated.

Hello everyone,

I have some troubles with my GEANT4 results.

In my simulation i have some poistrons e+ , so i'm looking for the Gamma ennergies from the annihilation. Normally i have 2 gamma with an energy around 0.511 Mev.

There is generally 2 gammas of annihilation, and when the problem appened, the sum of both gamma's energy is more than 1.4 Mev .

exemples : Egamma (Mev) = {1.265 + 0.2071 ; 1.205 + 0.613 ; 0.836 + 0.564 ; 0.910 + 0.451 ; 1.557 + 0.385 }

So do you have any explanation about that ?

Your faithfully ;)

( i have some screenshots if you want to see . ID(e+) = 4  and parentsID(gamma)=4, so we are sure that the 2 gamma come from the annihilation)

I have already played with FTFB_BERT_HP and QGSP_BIC_HP. For DD reactions, neutron emission appears for incident energy above 3 MeV only. But below this limit, nothing! It seems that existing libraries does not allow to simulate DD and DT fusion at low energy. Is there any way to simulate low energy fusion reactions at keV incident energies with existing libraries in GEANT4? Or should I create my own physical process with dedicated cross-sections and fusion products angular distributions? In advance, thank you for your help. Cheers.

Dear all

We did Monte Carlo-simulations of a fluoroscopy experiment with Geant4 by irradiating XCAT voxel phantoms. The simulation returns a dose per voxel. Together with the organ information we get organ doses etc.

In a first analysis we calculated the effective dose using  ICRP 103 tissue weighting factors. This seems incorrect, since ICRP 103 says: ".. nor should it be used for detailed specific retrospective investigations of individual

exposure and risk".

We now produce dose-volume-histograms to see the dose distribution in each organ and the maximum dose in a voxel.

What do you consider a good value to estimate radiation risk from MC results and to compare it to legal requirements?

Thanks for your input,

  Patrik 

Need excellence documentations on Geant4, version 10.1. Where could I get the sources?

Recently we have come across some, rather mind-boggling, difficulties concerning the noted Monte-Carlo code. First and foremost, it is of significant importance to us to know what changes are needed to be implemented in the installation, or execution procedures of the code to enable multi-threaded use of all the CPU processing cores. The defined commands are rather complex and demand optimum usage of all available hardware. Secondly, It is extremely vital for us to make sure that the GEANT4 code understands the cross-sections of heavy charged particle interactions with the nanoscale materials apparent in our geometry. Thus, we wanted to know if such directory exists, by default, and if not, wanted guidance on the data, and/or changes which are needed to input the required information. This is an absolute necessity for the accuracy of our results. please inform me of your thoughts and ideas.

Many thanks in advance for all your efforts.

Results in experiment every time and computation done in Geant4 of the same experiment  are random, then how we can find E/C ratio.