IS IT POSSIBLE TO OBTAIN POLARIZED POSITRONS DURING MULTIPLE COMPTON BACKSCATTERING PROCESS

1. In existing projectsofelectron-positron colliders,the option ofpolarized electron and positron beam sisconsidered [1,2].W hileonecan considertheproblem ofproducing the polarized electron beam swith required characteristicsashaving been solved [3],the existingapproachestopolarized positronsgeneration [4-7]donotproviderequired param eters.In quoted paperstheschem eswereo ered,in which by m eansofvariousm ethods abeam ofcircularly-polarized (CP)photonswith energy of 10 M eV isgenerated tobe subsequently used forproducing thelongitudinally polarized positronsduringtheprocess ofpaircreation in theam orphousconverter. In thispaper an alternate approach is discussed -atthe rst stage the unpolarized positronsaregenerated by theconventionalschem e(interaction ofan electron beam with energy of 10 GeV with an am orphousorcrystalline converter),which are accelerated up to energy 5 10 GeV and then interactwith intense CP laserradiation. In theschem e of"lasercooling" ofan electron beam suggested in thepaper[8],electrons with energy of5 GeV in head-on collisions with laser photons lose their energy practically withoutscattering.Thus,asaresultofam ultipleCom pton scattering(M CS), theelectron beam "isdecelerated" resulting in som e energy distribution,which variance isdeterm ined by theelectron energy and laser ash param eters.Itisclearthatthelaser cooling processwillaccom pany also theinteraction ofpositronswith laserphotons. Ifwe consider unpolarized positron beam as a sum oftwo fractions ofthe identical intensity with opposite signesof100% longitudinalpolarization,itsinteraction with CP laserradiationresultsindi erentCom ptone ectcross-sectionsforpositronswithopposite helicity. In otherwords,positronspolarized in opposite directionslose a variouspartof theinitialenergy,therefore,by m eansofm om entum selection oftheresulting beam ,itis possibleto geta polarized positron beam with som eintensity loss.