Surface-barrier detector with smoothly tunable thickness of depleted layer for study of ionization loss and dechanneling length of negatively charged particles channeling in a crystal

Abstract

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.