Dickmann, Marcel; Egger, Werner; Kögel, Gottfried; Vohburger, Sebastian; Hugenschmidt, Christoph
Dokumenttyp:
Zeitschriftenartikel / Journal Article
Titel:
Upgrade of the NEPOMUC Remoderator
Zeitschrift:
Acta Physica Polonica A
Jahrgang:
137
Heftnummer:
2, Proceedings of 15th International Workshop on Slow Positron Beam Techniques & Applications (SLOPOS-15) Prague, Czech Republic, September 2–6, 2019
Jahr:
2020
Seiten von - bis:
149-151
Sprache:
Englisch
Abstract:
The neutron-induced positron source Munich (NEPOMUC) provides a monochromatic low-energy positron beam with an intensity of >1×109e+ s-1 and a full width at half maximum (FWHM) diameter of about 10 mm. To create a small beam focus or sharp positron pulses of 100 ps FWHM the beam brightness needs to be enhanced by remoderation. This is achieved by focusing the primary beam magnetically onto a tungsten single crystal W(100) in reflection geometry. Afterwards the beam exhibits an intensity of >5×107e+ s-1 and a diameter of <2 mm FWHM. To further optimize the beam quality of NEPOMUC we redesigned the remoderation unit. The new setup allows a precise positioning of the remoderator crystal within the focus of the magnetic lens. Additionally, a replacement of the crystal within several minutes and without breaking the beamline vacuum is possible that offers the opportunity for systematic tests of different remoderator materials.