No Arabic abstract
This article includes the description of the geometric parameter gage device prototype for synchrotron radiation of HERA collider (DESY). The system construction which capable to measure photo current, caused by such a radiation in a refractory metal, described here. The system component parts are: measuring heads and photo current measuring electronics designed by IHEP, stepper motor by Vacuum Generators with HEDS-550X encoder by Hewlett Packard, PCI-STEP-4CX 4-Axis Closed Loop Step controller by National Instruments. The device is controlled by means of Microsoft Visual Basic program using Value Motion Windows Libraries. The device prototype was tested in the beam of the DORIS storage ring.
A single channel, high precision ionization chamber has been built for monitoring the relative intensity of X-rays in the energy range above 5 keV. It can be used in experiments, such as EXAFS, where simultaneous high precision monitoring of the relative intensity during the actual experiment is required. In this paper the construction of the chamber and its performance during test measurements with an X-ray tube are presented.
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 hour of data taking, while systematic uncertainties of 700 keV were present in the experiment. These developments aim for a relative precision of $10^{-5}$ 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.
Polarisation analysis of synchrotron THz radiation was carried out with a standard stretched polyethylene polariser and revealed that the linearly polarised (horizontal) component contributes up to 22 +/- 5% to the circular polarised synchrotron emission extracted by a gold-coated mirror with a horizontal slit inserted near a bending magnet edge. Comparison with theoretical predictions shows a qualitative match with dominance of the edge radiation. Grid polarisers 3D-printed out of commercial acrilic resin were tested for the polariser function and showed spectral regions where the dichroic ratio DR > 1 and < 1 implying importance of molecular and/or stress induced anisotropy. Metal-coated 3D-printed THz optical elements can find a range of applications in intensity and polarisation control of THz beams.
A novel interferometric method for absolute beam energy measurement is under development at MAMI. At the moment, the method is tested and optimized at an energy of 195 MeV. Despite the very small statistical uncertainty of the method, systematic effects have limited the overall accuracy. Recently, a measurement has been performed dedicated to the evaluation of these effects. This report comprises a description of the method and results of the recent data taking period.
To solve the discharge of the standard Bulk Micromegas and GEM detector, the GEM-Micromegas detector was developed in Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the GEM preamplification decreased the working voltage of Micromegas to reduce the effect of the discharge significantly. In the paper, the performance of detector in X-ray beam was studied at 1W2B laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. It indicated that the GEM-Micromegas detector had the energy response capability in all the energy range and it could work better than the standard Bulk-Micromegas.