HYP2018: 13th International Conference on Hypernuclear and Strange Particle Physics

Continuation of High-Precision Hypernuclear Mass Measurements at the Mainz Microtron

Not scheduled

15m

2nd Floor

Abstract Submission

Speaker

Prof. Patrick Achenbach (Johannes Gutenberg-Universität Mainz)

Description

In recent years the method of decay-pion spectroscopy was pioneered at the Mainz Microtron (MAMI). This method has the potential to achieve ground state mass measurements of light hypernuclei with unprecedented precision. Ongoing activities and future projects for the determination of masses of several light hypernuclei, in particular of the hypertriton, will be presented. We are aiming at statistical and systematic uncertainties of about 20 keV each. The hypertriton provides several important bench-marks for the strong interaction theory dealing with strange baryons, comparable to the role of deuterium for conventional baryon interactions. The present systematic uncertainty of these mass measurements is approximately 80 keV. The largest systematic error originates from the uncertainty in the MAMI beam energy affecting the absolute momentum calibration of the spectrometers by $\delta p \pm$ 100 keV/c, the sum of all other systematic errors contributes one order of magnitude less. In order to reduce this uncertainty, a novel high precision beam energy measurement based on undulator radiation was developed. The method takes advantage of the interference pattern produced by the two spatially separated undulators driven by the relativistic electrons. A high resolving monochromator was used to analyze the spectrum of the light. A preliminary pilot experiment proved the principle. However, systematic effects coming from calibration limitations and beam instabilities have to be considered and minimized. A successful experiment in 2018 has demonstrated the potential of such a new high precision beam energy measurement. A hypernuclear physics campaign with a lithium target is foreseen in the future. It will be complemented by extensive calibration measurements.