- Elastic charge form factor of the Deuteron
Data has been taken in March 2014. In addition to the proposed elastic kinematics the deuteron breakup was studied at very low momentum transfer. The elastic cross section data will be used to extract the charge radius of the deuteron whereas the breakup data contains information of the polarizibility. Both data sets experiments may shed some light on the proton radius puzzle. The analysis is ongoing.
- High precision pion spectroscopy of Λ-hypernuclei
In 2012 the ﬁrst high-resolution spectroscopy of pionic decays of strange systems was performed in electron scattering of a 9Be target in order to study ground-states masses of Λ-hypernuclei. Kaons were detected in a short-orbit spectrometer with a broad momentum acceptance at zero degree with respect to the beam. Positrons were suppressed by a lead wall. With this dedicated setup reactions of strangeness production were efﬁciently tagged. In coincidence, pions were detected with two high-resolution spectrometers. About 103 pionic weak decays were collected, the majority from a wide momentum distribution. A monochromatic peak at pπ ≈ 133MeV/c was observed that is a unique signature for the two-body decay 4 ΛH→4He +π- of hyperhydrogen stopped inside the target. Its binding energy is BΛ = 2.14 ± 0.02 (stat.) ± 0.09 (syst.) MeV with respect to the 3H + Λ mass. A publication is in preparation.
In June 2014 a second run was performed yielding a signiﬁcant improvement of statistics. At the same time we expect better a mass resolution and less background from free hyperon decays in ﬂight. The analysis has started. First results are expected end 2014.
- Inclusive electron scattering on 3,4He at low momentum transfer
The 2009 data set is being analysed, currently. First results, including a comparison with ab-initio calculations, can be expected by the end of 2014.
- Technical development of a 6,7Li target for use in electron scattering experiments
To achieve high luminosities without melting the target the lithum was mounted on a water cooled frame. A 2mm target (106mg/cm2) has been tested successfully with beam currents up to 30µA. The Li-target is ready for production.
- Neutron detector development and construction
This is a common Project with S1. The commissioning of the ﬁrst two layers of the neutron detector is planned for october 2014.