Fix failing GUISuite functional tests

Core/Algorithms/src/Instrument.cpp

@@ -38,6 +38,7 @@ Instrument::Instrument(const Instrument& other)
 Instrument &Instrument::operator=(const Instrument &other)
 {
     if (this!=&other) {
+        m_beam = other.m_beam;
         mP_detector.reset(other.mP_detector->clone());
         setName(other.getName());
         init_parameters();