The ratio of the transverse and longitudinal components of polarization transfer to protons in the quasielastic ((e) over right arrow, e'(p) over right arrow) reaction, P'(x)/P'(z), is sensitive to the proton's electromagnetic form factor ratio, G(E)/G(M). To explore density-dependent in-medium modifications, a comparison of polarization transfer ratios involving protons from distinct nuclear shells, each with different local nuclear densities, has been proposed. In this study, we present such comparisons between four shells, 1s(1/2), 1p(3/2) in C-12 and 1d(3/2), 2s(1/2) in Ca-40. In an effort to account for other many-body effects that may differ between shells, we use a state-of-the-art relativistic distorted-wave impulse-approximation (RDWIA) calculation and present the double ratios (P'(x)/P'(z))(Data)/(P'(x)/P'(z))(RDWIA) as well as the superratios [(P'(x)/P'(z))(A)/(P'(x)/P'(z))(B)](Data)/[(P'(x)/P'(z))(A)/(P'(x)/P'(z))(B)](RDWIA), for chosen shells A and B, as a function of effective local nuclear densities. We find that double ratios for individual shells show a dependence on the probed effective nuclear densities. Studying the super-ratios, we observed a systematic variation between pairs of higher- and lower-density shells.

The ratio of the transverse and longitudinal component of polarization transfer to protons in quasi-elastic $(\vec{e}, e^{\prime} \vec{p}\,)$ reaction, $P^{\prime}_x/P^{\prime}_z$, is sensitive to the proton's electromagnetic form factor ratio, $G_E/G_M$. To explore density-dependent in-medium modifications, a comparison of polarization transfer ratios involving protons from distinct nuclear shells, each with different local nuclear densities, has been proposed. In this study, we present such comparisons between four shells, $1s_{1/2}$, $1p_{3/2}$ in $^{12}\mathrm{C}$ and $1d_{3/2}$, $2s_{1/2}$ in $^{40}\mathrm{Ca}$. In an effort to account for other many-body effects that may differ between shells, we use state-of-the-art relativistic distorted-wave impulse-approximation (RDWIA) calculation and present the double ratios, $(P^{\prime}_x/P^{\prime}_z)_{\rm Data}/(P^{\prime}_x/P^{\prime}_z)_{\rm RDWIA}$ as well as the super ratios, $\left[(P^{\prime}_x/P^{\prime}_z)_{\rm A}/(P^{\prime}_x/P^{\prime}_z)_{\rm B}\right]_{\rm Data}/\left[(P^{\prime}_x/P^{\prime}_z)_{\rm A}/(P^{\prime}_x/P^{\prime}_z)_{\rm B}\right]_{\rm RDWIA}$, for chosen shells A and B, as a function of effective local nuclear densities. We find that double ratios for individual shells show a dependence on the probed effective nuclear densities. Studying the ratios, we observed a systematic variation between pairs of higher- and lower-density shells.

A new neutron polarimeter for measuring the neutron's electric form factor was designed and constructed to complement the A1 spectrometer setup at the Mainz Microtron (MAMI). The design is based on a previous polarimeter with significant improvements to halve the error of the extracted form factor. A higher granularity of the polarimeter sections and a deeper first section on the one hand, and a faster readout employing Time-over-Threshold methods to measure the signal amplitudes combined with a high-precision FPGA-based TDC on the other hand will allow to achieve this goal. The performance of the new polarimeter during a first measurement campaign in 2019 using liquid hydrogen and deuterium targets will be discussed.

. - Hypernuclear decay pion spectroscopy was established in 2012 at MAMI as a mass spectroscopy method for light hypernuclei. A monochromatic pion peak from 4 Lambda H was successfully observed, and the Lambda binding energy was determined to be B Lambda = 2.157 +/- 0.005(stat.)+/- 0.077(syst.) MeV in the 2014 run. In 2022, an upgrade experiment for 3 Lambda H spectroscopy was conducted using a newly developed Li target. interferometry, which will be applied with the spectrometer calibration to improve the systematic error. The decay pion spectroscopy is planned to be performed at of hypernuclear physics.

The CALICE collaboration is developing highly granular electromagnetic and hadronic calorimeters for detectors at future energy frontier electron-positron colliders. After successful tests of a physics prototype, a technological prototype of the Analog Hadron Calorimeter has been built, based on a design and construction techniques scalable to a collider detector. The prototype consists of a steel absorber structure and active layers of small scintillator tiles that are individually read out by directly coupled SiPMs. Each layer has an active area of 72 × 72 cm^2 and a tile size of 3 × 3 cm^2. With 38 active layers, the prototype has nearly 22,000 readout channels, and its total thickness amounts to 4.4 nuclear interaction lengths. The dedicated readout electronics provide time stamping of each hit with an expected resolution of about 1 ns. The prototype was constructed in 2017 and commissioned in beam tests at DESY. It recorded muons, hadron showers and electron showers at different energies in test beams at CERN in 2018. In this paper, the design of the prototype, its construction and commissioning are described. The methods used to calibrate the detector are detailed, and the performance achieved in terms of uniformity and stability is presented.

Polarization transfer to a bound proton in polarized electron knock-out reactions, $\mathrm{A}(\vec{e},e^{\prime}\vec{p})$, is a powerful tool to look for in-medium modification of the bound proton. It requires comparison to calculations which consider the many-body effects accompanying the quasi-free process. We report here measured components $P_x^{\prime}$, $P_z^{\prime}$, and their ratio $P_x^{\prime}/P_z^{\prime}$, of polarization transfer to protons bound in $^{40}\mathrm{Ca}$, which is described well by the shell model and for which reliable calculations are available. While the calculations capture the essence of the data, our statistical precision allows us to observe deviations which cannot be explained by simple scaling, including by varying the proton electromagnetic form factor ratio $G_E/G_M$. We further explore the deviations of the ratio of the polarization transfer components from that of a free proton, $(P_x^{\prime}/P_z^{\prime})_{\rm A}/(P_x^{\prime}/P_z^{\prime})_{\rm H}$, and its dependence on the bound-proton virtuality.

A high-precision hypernuclear experiment has been performed at the Mainz Microtron (MAMI) to determine the hypertriton Λ binding energy via decay-pion spectroscopy. A key element of this measurement is an accurate calibration of the magnetic spectrometers with the MAMI beam. For such an absolute calibration with small statistical and systematic uncertainties the undulator light interference method will be applied. In this contribution the basic principle of this method is discussed and the analysis status of the measured synchrotron radiation spectra is presented

A database is under construction to provide a complete collection of published basic properties of hypernuclei such as Λ binding energies, lifetimes, or excitation energies. From these values, averages with related errors are computed in a systematic way. For each property, the overall experimental situation is depicted in form of an ideogram showing the combined probability density function of the measurements. The database is accessible via a dynamic website at https://hypernuclei.kph.uni-mainz.de with an user interface offering customizable visualizations, selections, or unit conversions. The capabilities of the database are demonstrated for the puzzling and disputed data situation of the hypertriton.

A beam position detector was developed that is based on a thin octagonal-shaped scintillator which is read out by silicon photomultipliers on its eight lateral sides. Its main application is beam diagnostics and triggering for sensitive detector setups using extremely low beam intensities. In-beam tests at the Mainz Microtron have demonstrated that the position of single electrons can be obtained with a precision of below 1 mm when adding systematic and statistical uncertainties. Measurements have been complemented by a simulation with Geant4 to optimize the detector geometry.

In this paper, we describe an experiment measuring low -Q2 elastic electron-proton scattering using a newly developed cryogenic supersonic gas jet target in the A1 three-spectrometer facility at the Mainz Microtron. We measured the proton electric form factor within the four-momentum transfer range of 0.01 Q2 0.045 (GeV/c)2. The experiment showed results consistent with the existing measurements. The data we collected demonstrated the feasibility of the gas jet target and the potential of future scattering experiments using high-resolution spectrometers with this gas jet target.

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, using a momentum setting covering 133MeV/c. and a Be-9 target, the H-4(Lambda) binding energy was determined with unprecedented precision. 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 setting covering its two-body decay momentum of 114MeV/c. The experiment aims for statistical and systematic errors of approximately 20 keV and is running during the summer of 2022.

A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a new generation of high-precision electron scattering experiments at high-intensity electron accelerators.

The Mu3e experiment aims to find or exclude the lepton flavour violating decay mu -> eee at branching fractions above 10(-16). A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of 2.10(-15). We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to 10(8) muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.

A high-precision hypernuclear experiment has been commissioned at the Mainz Microtron (MAMI) to determine the hypertriton Λ binding energy via decay-pion spectroscopy. The method has been successfully pioneered with 4 Λ H studies in the last decade. The experiment makes use of a novel high luminosity lithium target with a length of 45mm while being only 0.75mm thick to keep momentum smearing of the decay pions low. The target-to-beam alignment as well as the observation of the deposited heat is achieved with a newly developed thermal imaging system. Together with a precise beam energy determination via the undulator light interference method a recalibration of the magnetic spectrometers will be done to obtain a statistical and systematic error of about 20 keV. The experiment started in the summer of 2022 and initial optimization studies for luminosity and data quality are presented.

We report on a new measurement of the beam-normal single spin asymmetry A_n in the elastic scattering of 570 MeV transversely polarized electrons off ^28Si and ^90Zr at Q^2=0.04 GeV^2/c^2. The studied kinematics allow for a comprehensive comparison with former results on ^12C. No significant mass dependence of the beam-normal single spin asymmetry is observed in the mass regime from ^12C to ^90Zr.

MuTRiG is a mixed signal Silicon Photomultiplier readout ASIC designed in UMC 180 nm CMOS technology for precise timing and high event rate applications in high energy physics experiments and medical imaging. It is dedicated to the readout of the scintillating fiber detector and the scintillating tile detector of the Mu3e experiment. The MuTRiG chip extends the excellent timing performance of the STiCv3 chip with a fast digital readout for high rate applications. The high timing performance of the fully differential SiPM readout channels and 50 ps time binning TDCs are complemented by an upgraded digital readout logic and a 1.28 Gbps LVDS serial data link. The design of the chip and the characterization results of the analog front-end, TDC and the LVDS data link are presented.

Showers produced by positive hadrons in the highly granular CALICE scintillator-steel analogue hadron calorimeter were studied. The experimental data were collected at CERN and FNAL for single particles with initial momenta from 10 to 80 GeV/c. The calorimeter response and resolution and spatial characteristics of shower development for proton- and pion-induced showers for test beam data and simulations using Geant4 version 9.6 are compared.

We present a study of showers initiated by electrons, pions, kaons, and protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE scintillator-tungsten analogue hadronic calorimeter. The data were recorded at the CERN Super Proton Synchrotron in 2011. The analysis includes measurements of the calorimeter response to each particle type as well as measurements of the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to Geant4 simulations (version 9.6.p02). In the study of the energy resolution we include previously published data with beam momenta from 1 GeV to 10 GeV recorded at the CERN Proton Synchrotron in 2010.

We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 mu m) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data.

Lepton colliders are considered as options to complement and to extend the physics programme at the Large Hadron Collider. The Compact Linear Collider (CLIC) is an e(+)e(-) collider under development aiming at centre-of-mass energies of up to 3 TeV. For experiments at CLIC, a hadron sampling calorimeter with tungsten absorber is proposed. Such a calorimeter provides sufficient depth to contain high-energy showers, while allowing a compact size for the surrounding solenoid.A fine-grained calorimeter prototype with tungsten absorber plates and scintillator tiles read out by silicon photomultipliers was built and exposed to particle beams at CERN. Results obtained with electrons, pions and protons of momenta up to 10 GeV are presented in terms of energy resolution and shower shape studies. The results are compared with several GEANT4 simulation models in order to assess the reliability of the Monte Carlo predictions relevant for a future experiment at CLIC.