Experimental Hall B

Jefferson Lab has four experimental halls. Hall B is the smallest of the experimental staging areas. It is 98 feet in diameter and 65 feet from floor to ceiling.

Experiments that take data in Hall B employ beams of either electrons or photons. From 1995 to 2012, the heart of the Hall B physics program involved the use of the CEBAF Large Acceptance Spectrometer, or CLAS. This detector system spanned nearly the full angular range about the target and was specifically developed for the study of exclusive reactions with multiple particles in the final state. At the heart of CLAS was a six-coil superconducting toroid magnet. The detector was instrumented with layers of drift chambers for charged particle tracking, Cherenkov detectors for electron/pion separation, scintillators for time-of-flight measurements, and electromagnetic calorimeters for electron and neutral particle identification.

Major research programs in Hall B include experiments to measure the spectrum of excited states of the nucleon to understand nucleon structure and quark confinement, to perform three-dimensional imaging of the quark structure of the nucleon, to characterize nucleon-nucleon correlations in nuclei, and to search for the existence of heavy photons.

At the present time, the CLAS detector in Hall B has been decommissioned and installation of the new CLAS12 detector is underway. This new large acceptance detector system is part of Jefferson Lab's 12 GeV upgrade and will be used to study hadron structure with unprecedented accuracy.

An international collaboration of scientists participate in experiments carried out in Hall B. Scientists collaborating on research in Hall B represent more than 60 institutions and 26 countries.

For more detailed information about Hall B and its experimental program, click here.