Objectif Efficient polarized electron sources are vital for experiments in nuclear and particle-physics at high energy electron accelerators.Strained short-period superlattice-based structures with a minimal conduction-band offset have a potential of becoming a base for the development of a new generation of effective highly polarized electron sources.A joint investigation is proposed, which includes comprehensive program of the strained superlattice MOCVD and MBE growth and characterisation. AlGaAs/InGaAs/GaAs, AlInGaAs/GaAs, InGaP/AlInGaP/GaAs and InGaP/InGaAsP/GaAs structures with optimal parameters for spin-polarized electron emission with high quantum efficiency will be obtained. It is planned to start with In_x Ga_1-x P / Al_y Ga_1-y As superlattices with x=0.5-0.6 and y=0-0.2 which were shown to be very promising for the polarized electron beam generation. The SLs with phosphorus promise to give larger (than in AlInGaAs/AlGaAs one) valence band splitting with high electron mobility. At the same time small conduction band offset is the property of the InGaP / AlGaAs SL. Then it is planned to tune it better by changing content of In and adding P in the second layer.The theoretical part of the program includes design of the superlattice structures on the base of band structure and optical orientation calculations, modelling the emission kinetics in the photoemitting heterostructures, investigations of the effects of the fluctuation potential in the band bending region at the activated surface in the case of high excitation power.Experimental part of the project includes investigations of the structures using a wide range of experimental methods to clarify mechanisms of spin vertical transport in the superlattice structures, spin relaxation mechanisms, and the role of band bending region fluctuations in the photoemission processes aiming to develop highly efficient spin-polarized photocathodes.The investigations are coupled with the tests of new superlattice-based polarized electron emitters in the electron gun facilities used for surface magnetisation studies and in MAMI, Kharkov LINAC and TJNAF accelerator electron guns for high-energy experiments. Special tests of the third generation photocathodes is planned in parity violation experiments at MAMI accelerator, which need the best possible symmetry of the photoemitted current under the operation of electron polarization reversal. Optimisation of the Moeller polarimetry with the aim to achieve high preciseness of the polarization measurements is planned as well.Experimental data will be obtained by using complementary techniques on the same superlattice samples and used for optimisation of the superlattice design and doping profile.Developments of MOVPE and MBE technologies, application of various experimental methods to the studies the same samples, practical using of the new polarized electron sources in high-energy experiments and polarized electron stimulated effects together with the theoretical interpretation of these experiments will prompt application of the strained short-period superlattices as highly efficient polarized electron sources.The project will result in the reproducible fabrication of the third generation photocathodes which will enable one to produce electron beams with polarization of 90% and quantum yield of 0.5 - 1 % at room temperature, both in DC and high power pulse modes of excitation with a minimal helicity correlated asymmetry.The collaboration of the technologists, experimentalists and theoreticians will be emphasised in order to achieve these goals. The participation of twelve NIS young scientists and several students in the project will be very useful for their educational and research progress. Rather often exchange of people in the frame of this project should strength the existing collaboration. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) 1B - Condensed Matter, Optics and Plasma Physics OPEN - OPEN Call Appel à propositions Data not available Régime de financement Data not available Coordinateur Ecole Polytechnique Contribution de l’UE Aucune donnée Adresse Ecole Polytechnique 91128 Palaiseau France Voir sur la carte Coût total Aucune donnée Participants (8) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire INFM -Istituto Nazionale per la Fisica della Materia Italie Contribution de l’UE Aucune donnée Adresse Piazza Leonardo da Vinci 32 20133 Milano Voir sur la carte Coût total Aucune donnée Institute of Physics of Semiconductors Russie Contribution de l’UE Aucune donnée Adresse Prospect Lavrent'eva,13 630090 Novosibirsk Voir sur la carte Coût total Aucune donnée National Academy of Sciences of Ukraine Ukraine Contribution de l’UE Aucune donnée Adresse Akademicheskaya Street, 1 310108 Kharkov Voir sur la carte Coût total Aucune donnée St.Petersburg State Technical University Russie Contribution de l’UE Aucune donnée Adresse Polytechnicheskaya 29 195251 St. Petersburg Voir sur la carte Coût total Aucune donnée St.Petersburg State Technical University Russie Contribution de l’UE Aucune donnée Adresse Polytechnicheskaya 29 195251 St. Petersburg Voir sur la carte Coût total Aucune donnée UNIVERSITY OF SHEFFIELD Royaume-Uni Contribution de l’UE Aucune donnée Adresse Mappin Street S1 3JD Sheffield Voir sur la carte Liens Site web Opens in new window Coût total Aucune donnée University of Edinburgh Royaume-Uni Contribution de l’UE Aucune donnée Adresse Mayfield Road EH9 3JZ Edinburgh Voir sur la carte Coût total Aucune donnée Universität Mainz Allemagne Contribution de l’UE Aucune donnée Adresse Becherweg-45 55099 Mainz Voir sur la carte Coût total Aucune donnée
