void CosThetaBuilder::writeInfo(QFile& qOut) const {
    if(AP) qOut.insert("coilPositioner",AP->getInfo());
    if(ET) qOut.insert("coilTrans",ET->getInfo());
    Stringmap m;
    m.insert("length",length);
    m.insert("radius",radius);
    m.insert("ncoils",itos(ncoils));
    m.insert("current",j_total);
    qOut.insert("cosThetaCoil",m);
}