Cluster convolution for GATE
In her MSc project, Silje Grimstad made a filtered library of the clusters from the summer beamtest in Heidelberg.
The result is ~15k Helium clusters stored as x/y arrays in a ROOT file included here.
x_mean | y_mean | size | hit_array | height | width | x_start | y_start | i_event | combined |
---|---|---|---|---|---|---|---|---|---|
float | float | int | list<int> | int | int | int | int | int | bool |
A random sample of 9 clusters is shown below:
We want to convolute a GATE simulation with clusters from this library. For each hit in the MC data, we pick a random cluster from the library and draw it around the hit position. To do this, use the code at the bottom, with the following result:
Below is example code to perform the diffusion on-fly using a Hits container class with Hit objects (x,y,layer,edep,eventID). For more information about the implementation see GitHub.
#include <TTree.h>
#include <TFile.h>
#include <TRandom3.h>
#include <list>
#include <vector>
using namespace std;
void makeSortedClusterDatabase();
Hits * diffuseHits(TRandom3 * gRandom, Hits * singlePixelHits);
TTree * CDB_treeCluster;
list<Int_t> * CDB_hit_array = 0;
TBranch * CDB_b_hit_array;
TTreeIndex * CDB_index;
Int_t CDB_clusterSize;
Double_t CDB_x_mean, CDB_y_mean;
Int_t CDB_sortIndex[50];
TFile * CDB_fCluster;
void makeSortedClusterDatabase() {
// From GlobalConstants/MaterialConstants.C / .h
Int_t lastClusterSize = -1;
CDB_fCluster = new TFile("Data/ClusterSizes/ALPIDE/database_final.root", "READ");
CDB_treeCluster = (TTree*) CDB_fCluster->Get("database");
CDB_treeCluster->SetBranchAddress("size", &CDB_clusterSize);
CDB_treeCluster->SetBranchAddress("x_mean", &CDB_x_mean);
CDB_treeCluster->SetBranchAddress("y_mean", &CDB_y_mean);
CDB_treeCluster->SetBranchAddress("hit_array", &CDB_hit_array, &CDB_b_hit_array);
// Sort clusters based on cluster size
for (int i=0; i<50; i++) CDB_sortIndex[i] = -1;
CDB_treeCluster->BuildIndex("size");
CDB_index = (TTreeIndex*) CDB_treeCluster->GetTreeIndex();
for (int i=0; i<CDB_index->GetN()-1; i++) {
Long64_t local = CDB_treeCluster->LoadTree(CDB_index->GetIndex()[i]);
CDB_treeCluster->GetEntry(local);
if (lastClusterSize < 0 || lastClusterSize != CDB_clusterSize) {
CDB_sortIndex[CDB_clusterSize] = i;
lastClusterSize = CDB_clusterSize;
}
}
}
Hits * diffuseHits(TRandom3 *gRandom, Hits * singlePixelHits) {
// From HelperTools/getTracks.C
Int_t nHits = singlePixelHits->GetEntriesFast();
Hits * diffusedHits = new Hits();
Int_t x, y, outX, outY, layer, cs, eventID, idx_x, binPos;
Float_t edep;
Int_t randomClusterIdx;
for (Int_t h=0; h<nHits; h++) {
x = singlePixelHits->getX(h);
y = singlePixelHits->getY(h);
layer = singlePixelHits->getLayer(h);
edep = singlePixelHits->getEdep(h);
eventID = singlePixelHits->getEventID(h);
// The correspondence between CS and Edep [keV/um] is calculated from Ganesh's NIM A Proceedings article.
cs = 4.2267 * pow(edep, 0.6500) + 0.5;
// To keep any outliers within the tabulated clusters in the database
if (cs<2) cs=2;
if (cs>=27) cs=26;
randomClusterIdx = gRandom->Integer(CDB_sortIndex[cs+1] - CDB_sortIndex[cs]) + CDB_sortIndex[cs];
CDB_treeCluster->GetEntry(CDB_treeCluster->LoadTree(CDB_index->GetIndex()[randomClusterIdx]));
idx_x = 0;
Int_t thisCS = 0;
for (Int_t n : *CDB_hit_array) {
for (Int_t binPosPow = 0; binPosPow < 10; binPosPow++) {
binPos = pow(2, binPosPow);
if (binPos & n) {
outX = x + (idx_x - CDB_x_mean) + 0.5;
outY = y + (binPosPow - CDB_y_mean) + 0.5;
diffusedHits->appendPoint(outX, outY, layer, eventID, edep/CDB_clusterSize);
}
}
idx_x++;
}
}
return diffusedHits;
}