The GlueX Experiment at Jefferson Lab
CEBAF at Jefferson Lab
The Thomas Jefferson National Accelerator Facility, known as Jefferson Lab or JLab for short, is home to the Continuous Electron Beam Accelerator Facility (CEBAF). CEBAF is an electron accelerator capable of providing energies of up to 12 GeV for experiments in JLab's four experimental halls (A, B, C and D).
Experiments on many aspects of nuclear and particle physics are conducted at Jefferson Lab. Halls A and C house extremely high-precision spectrometer arms, which, however, only have small angular acceptances. Halls B and D house the wide-angle spectrometers CLAS12 and GlueX.
Hybrid Meson
Conventional mesons consist of a quark and an anti-quark, which together are colour-neutral. However, since the gluon, which mediates the strong force between quarks, also has a colour charge, meson states are also possible in which a quark-antiquark system only becomes colour-neutral through a gluon. In these cases, we speak of a hybrid meson. Such mesons can assume quantum numbers that conventional mesons are not allowed to have, which is why they are also referred to as exotic. The quantum numbers of mesons are determined with the aid of so-called partial wave analyses. In this way, mesons with exotic quantum numbers can be searched for, which allows the search for this exotic type of matter.
The main task of the GlueX experiment is to find exotic mesons and analyse their spectrum. This represents an important step in understanding the strong interaction.
More than 100 Mio
photons per second hit the target
Up to 80.000
events per second are recorded by the data acquisition system
More than 7PB
of data was recorded so far
The GlueX Experiment
The GlueX experiment is located in Hall D at the CEBAF accelerator. In the upstream tagger hall, a linearly polarised photon beam is generated from the 12 GeV electron beam by means of coherent bremsstrahlung on a diamond. After travelling approximately 70 m, this beam strikes a liquid hydrogen target. The target is surrounded by various detectors that provide good energy and momentum resolution for neutral and charged particles in the final state over almost the entire solid angle. This makes GlueX an excellent detector for the search for new particles that can decay into many different final states.
Our contributions
AG Hurck is mainly involved in data analysis at GlueX. We focus on reactions with strangeness.
One focus of our studies is the measurement of the weak decay constant of the lambda baryon, which can be measured at GlueX using a unique method. To do this, we use an elliptically polarised photon beam to obtain both linear and circular polarisation components. The precise measurement of the angular distribution of the decay products of the lambda baryon then allows us to draw conclusions about the weak decay constant.