RMC Spectrometer

The RMC spectrometer is a large solid angle photon-pair spectrometer shown in Figure 3.3. The dimensions of the spectrometer elements are given in Table 3.2.

Figure 3.3: The RMC photon-pair spectrometer at TRIUMF. One notable modification to the old RMC set-up is the repositioning of the lead (Pb) converter from between the $B$ and $C$'s to between the $A$'s and $B$'s, where $A$ through $D$ are the scintillator rings.

The solid angle coverage for charged particles produced at the spectrometer center is $\sim 3\pi$ Sr. The spectrometer has full azimuthal acceptance for tracks with polar angles between $\sim \pm$45$^\circ$. Tracking of the $e^+e^-$ pairs is done with a large volume cylindrical drift chamber (DC) along with a multi-wire proportional chamber (IWC). The tracking chambers and scintillator elements are enclosed in a magnet, producing a highly uniform solenoidal field along the beam axis. A 1.2 kG magnetic field was chosen for the experiment after acceptance and trigger studies, described in Section 4.