Speaker
Description
At the Mainz Microtron MAMI, the technique of high-resolution spectroscopy of decay-pions in strangeness electroproduction has been established to extract $\Lambda$ ground state binding energies of light hyperfragments. In a first series of measurements, a $^9$Be target was used to determine the $^4_\Lambda$H binding energy with unprecedented precision in a momentum setting near 133 MeV/c. The current measurement employs a novel lithium target of 50 mm length and only 0.75 mm thickness to precisely determine the hypertriton binding energy in a 114 MeV/c setting.
The complex setup in the spectrometer hall comprises a pre-target beam-line chicane, a high-luminosity lithium target, two high-resolution pion spectrometers, one zero-degree forward spectrometer for strangeness tagging, one photon beam-line and one electron exit beam-line. The focusing magnetic spectrometers provide a high momentum resolution at the 10$^{-4}$ level over the momentum range of hypernuclear decay-pions, a large acceptance in both angle and momentum, good position and angular resolution in the scattering plane, an extended target acceptance, and a large angular range to optimally accommodate for different beam-target angles. A thermal imaging system controls the target alignment with respect to the beam. A recalibration of the pion spectrometers will be possible due to the precise beam energy determination with the undulator light interference method.
The experiment aims for a statistical and systematic error of about 20 keV and will run during the summer of 2022.
| Collaboration | A1 |
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