CLAS apparatus
Apparatus
Target
The target materials used in the EG1b experiments were and . The first one was used for the polarized protons and the second for the polarized deuterons. These materials satisfy several conditions which are suitable for scattering experiments. Ammonia targets produce high polarization and are resistant to radiation damage(it will be changed) which can be easily repaired by an annealing process. Also,it has high ratio of free nucleons(3/18).
The target material was prepared in the following way. The ammonia gas was frozen at 77 K and then crushed into little
pieces, about 1-3 mm in diameter, because it heps to have them efficiently cooled by the liquid helium during the experiment and prevent from potential damage by the beam heating.
Tracking System
Scintillators
Cherenkov detector
The six superconducting coils placed by angles of 60 degrees in the azimuthal angle around the electron beam produces the 5T magnetic field.It is important to minimize the amount of material in all of the detectors to minimize hadron and electron absorption and secondary particle production upstream of the time-of-flight scintillators and calorimeters.