Logo ROOT   6.10/09
Reference Guide
parallel_world.C File Reference

Detailed Description

Misaligning geometry generate in many cases overlaps, due to the idealization of the design and the fact that in real life movements of the geometry volumes have constraints and are correlated.

This typically generates inconsistent response of the navigation methods, leading to inefficiencies during tracking, errors in the material budget calculations, and so on. Among those, there are dangerous cases when the hidden volumes are sensitive. This macro demonstrates how to use the "parallel world" feature to assign highest navigation priority to some physical paths in geometry.

pict1_parallel_world.C.png
void align();
//______________________________________________________________________________
void parallel_world(Bool_t usepw=kTRUE, Bool_t useovlp=kTRUE)
{
TGeoManager *geom = new TGeoManager("parallel_world", "Showcase for prioritized physical paths");
TGeoMaterial *matV = new TGeoMaterial("Vac", 0,0,0);
TGeoMedium *medV = new TGeoMedium("MEDVAC",1,matV);
TGeoMaterial *matAl = new TGeoMaterial("Al", 26.98,13,2.7);
TGeoMedium *medAl = new TGeoMedium("MEDAL",2,matAl);
TGeoMaterial *matSi = new TGeoMaterial("Si", 28.085,14,2.329);
TGeoMedium *medSi = new TGeoMedium("MEDSI",3,matSi);
TGeoVolume *top = gGeoManager->MakeBox("TOP",medV,100,400,1000);
// Shape for the support block
TGeoBBox *sblock = new TGeoBBox("sblock", 20,10,2);
// The volume for the support
TGeoVolume *support = new TGeoVolume("block",sblock, medAl);
support->SetLineColor(kGreen);
// Shape for the sensor to be prioritized in case of overlap
TGeoBBox *ssensor = new TGeoBBox("sensor", 19,9,0.2);
// The volume for the sensor
TGeoVolume *sensor = new TGeoVolume("sensor",ssensor, medSi);
sensor->SetLineColor(kRed);
// Chip assembly of support+sensor
chip->AddNode(support, 1);
chip->AddNode(sensor,1, new TGeoTranslation(0,0,-2.1));
// A ladder that normally sags
TGeoBBox *sladder = new TGeoBBox("sladder", 20,300,5);
// The volume for the ladder
TGeoVolume *ladder = new TGeoVolume("ladder",sladder, medAl);
ladder->SetLineColor(kBlue);
// Add nodes
top->AddNode(ladder,1);
for (Int_t i=0; i<10; i++)
top->AddNode(chip, i+1, new TGeoTranslation(0, -225.+50.*i, 10));
if (usepw) pw = gGeoManager->CreateParallelWorld("priority_sensors");
// Align chips
align();
if (usepw) {
if (useovlp) pw->AddOverlap(ladder);
}
TString cname;
cname = usepw ? "cpw" : "cnopw";
TCanvas *c = (TCanvas*)gROOT->GetListOfCanvases()->FindObject(cname);
if (c) c->cd();
else c = new TCanvas(cname, "",800,600);
top->Draw();
// top->RandomRays(0,0,0,0,sensor->GetName());
// Track random "particles" coming from the block side and draw only the tracklets
// actually crossing one of the sensors. Note that some of the tracks coming
// from the outer side may see the full sensor, while the others only part of it.
timer.Start();
top->RandomRays(100000,0,0,-30,sensor->GetName());
timer.Stop();
timer.Print();
TView3D *view = (TView3D*)gPad->GetView();
view->SetParallel();
view->Side();
if (usepw) pw->PrintDetectedOverlaps();
}
//______________________________________________________________________________
void align()
{
// Aligning 2 sensors so they will overlap with the support. One sensor is positioned
// normally while the other using the shared matrix
Double_t sag;
for (Int_t i=0; i<10; i++) {
node = gGeoManager->MakePhysicalNode(TString::Format("/TOP_1/chip_%d",i+1));
sag = 8.-0.494*(i-4.5)*(i-4.5);
TGeoTranslation *tr = new TGeoTranslation(0., -225.+50.*i, 10-sag);
node->Align(tr);
if (pw) pw->AddNode(TString::Format("/TOP_1/chip_%d",i+1));
}
}
Author
Andrei Gheata

Definition in file parallel_world.C.