AMBER at SPS at CERN
AMBER is a fixed-target experiment at the SPS accelerator at CERN. Hadron and muon beams are used to conduct various experiments in hadron physics. The current focus is on measurements of antiproton production and the proton radius. In the future, the structure of pions and kaons will be investigated and kaon spectroscopy will be performed.
Kaon Spectroscopy
The kaon is a meson consisting of an up or down quark and a strange quark. Like other hadrons, a kaon can be excited into different states, resulting in a whole spectrum of kaons. Different models make different predictions about what this spectrum should look like based on the strong interaction. Accurate measurement of the kaon spectrum therefore allows these models and their underlying assumptions to be tested.
The COMPASS experiment, the predecessor of AMBER, recently published a study on the kaon spectrum. Many states were measured, including an unexpected and potentially exotic one. AMBER will extend this study and measure the kaon spectrum with unprecedented precision, searching for potentially exotic states.
SPS and AMBER
AMBER is located in the CERN North Area at the end of the M2 beam line. Protons are accelerated to up to 400 GeV in the Super Proton Synchrotron (SPS) and then strike a production target. This produces various hadrons as well as electrons and muons, which can then be selected by magnets according to charge and momentum before being directed to the AMBER experiment.
AMBER is a fixed target experiment. This means that the beam particles are directed at a stationary target (usually protons). The resulting reaction products are strongly focused forward by the Lorentz boost. For this reason, AMBER consists of a large number of detectors arranged one behind the other in the forward direction. A combination of particle identification detectors, tracking detectors, magnetic fields and calorimeters allows AMBER to measure final states of charged and uncharged particles with high precision. This makes AMBER an ideal place to conduct hadron spectroscopy.
Our involvement
The focus of our work is currently on preparing for the upcoming proton radius measurement in 2026. To this end, we are building a pixel tracking detector that will help to measure the tracks of muons scattered by protons with high precision.
Another focus is on planning and preparing a kaon spectroscopy experiment at AMBER.