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The research investigates coherent interactions between sub-GeV electrons and oriented scintillator crystals, leading to enhanced electromagnetic (EM) radiation. Experiments at Mainz Mikrotron (MAMI) involved PWO, BGO, and CsI crystals oriented along 〈 100 〉 , 〈 111 〉 , and 〈 100 〉 axes, respectively. Enhanced radiation emission was observed when the beam was aligned with crystal axes, especially in BGO and CsI for the first time. These findings are crucial for innovative detectors using oriented crystal scintillators, amplifying EM processes along specific crystallographic directions. Potential applications include ultra-compact, highly sensitive electromagnetic calorimeters for high-energy physics and astroparticles, as well as high-performance gamma detectors for nuclear physics and medical imaging. [ABSTRACT FROM AUTHOR]

Abstract The performance of solid-state photon detectors such as avalanche photodiodes or silicon photomultipliers (SiPMs) is strongly affected by temperature. Important device characteristics for the detection of low light levels or single photons are photon detection efficiency, dark noise, and gain. In the present work the C-series SiPMs from SensL was characterized in cryogenic environments. At 77 K the SiPMs proved to be an excellent choice for single photon detection and an operation point with minimum noise contributions was found. At 4 K the performance was degraded, exhibiting a smaller gain and a larger noise. Highlights • SiPMs from SensL were characterized in cryogenic environments. • At 77 K the SiPMs proved to be an excellent choice for single photon detection. • At 4 K the performance was degraded, the SiPMs were exhibiting a smaller gain and a larger noise. [ABSTRACT FROM AUTHOR]

A new method for the experimental study of ionization loss of relativistic negatively charged particles moving in a crystal in the channeling regime using a semiconductor surface-barrier detector with smoothly tunable thickness of the depleted layer is proposed. The thickness of the depleted layer in a flat semiconductor detector can be smoothly regulated by the value of the bias voltage applied to the detector. Therefore, the energy distribution of the ionization loss of relativistic particles which cross the detector and move in the channeling regime in the detector crystal can be measured along the path of the particles by varying the bias voltage of the detector and the dechanneling length can be found. Available literature data on experimental and theoretical researches of the dechanneling length are reviewed. The significant disagreement between the experimental and theoretical data is noted. Comparison of experimental data obtained by the detector-target with smoothly tunable thickness of the depleted layer with calculations can help to develop theoretical description of the dynamics of motion of negatively charged particles channeling in a crystal. A better understanding of the dechanneling length properties can be useful in the production of positrons and other particles such as neutrons by an electron beam in crystals, as well as in the development of crystalline undulators, and in the crystal-based extraction of electron beams from a synchrotron. [ABSTRACT FROM AUTHOR]

Abstract A novel interferometric method is presented for the measurement of the absolute energy of electron beams. In the year 2016, a pioneering experiment was performed using a 195 MeV beam of the Mainz Microtron (MAMI). The experimental setup consisted of two collinear magnetic undulators as sources of coherent optical synchrotron light and a high-resolving grating monochromator. Beam energy measurements required the variation of the relative undulator distance in the decimeter range and the analysis of the intensity oscillation length in the interference spectrum. A statistical precision of 1 keV was achieved in 1 h of data taking, while systematic uncertainties of 700 keV were present in the experiment. These developments aim for a relative precision of 1 0 − 5 in the absolute momentum calibrations of spectrometers and high-precision hypernuclear experiments. Other electron accelerators with beam energies in this regime such as the Mainz Energy Recovering Superconducting Accelerator (MESA) might benefit from this new method. [ABSTRACT FROM AUTHOR]

A prototype detector, called FLASH (Fast Light Acquiring Start Hodoscope), was built to provide precise Time-of-Flight (TOF) measurements and reference timestamps for detector setups at external beam lines. Radiator bars, made of synthetic fused silica, were coupled to a fast MCP-PMT with 64 channels and read out with custom electronics using Time-over-Threshold (TOT) for signal characterization. The TRB3 system, a high-precision TDC implemented in an FPGA, was used as data acquisition system. The performance of a system consisting of two FLASH units was investigated at a dedicated test experiment at the Mainz Microtron (MAMI) accelerator using its 855 MeV electron beam. The TOT measurement enabled time walk corrections and an overall TOF resolution of ∼70 ps could be achieved which translates into a resolution of ∼50 ps per FLASH unit. The intrinsic resolution of the frontend electronics including the TDC was measured to be less than 25 ps. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The light collection of several fiber configurations embedded in a box-shaped plastic scintillating counter was studied by scanning with minimum ionizing electrons. The light was read out by silicon photomultipliers at both ends. The light yield produced by the 855-MeV beam of the Mainz Microtron showed a strong dependence on the transverse distance from the beam position to the fibers. The observations were modeled by attributing the collection of indirect light inside of the counter and of direct light reaching a fiber to the total light yield. The light collection with fibers was compared to that of a scintillating counter without fibers. These studies were carried out within the development of plastic scintillating detectors as an active veto system for the DarkMESA electron beam-dump experiment that will search for light dark matter particles in the MeV mass range. [ABSTRACT FROM AUTHOR]