Entwicklung einer aktiven 238 Uran(VI)-fluorid-Detektor-Kammer für Präzisionsexperimente in der photoneninduzierten Spaltung am S-DALINAC

Entwicklung einer aktiven 238 Uran(VI)-fluorid-Detektor-Kammer für Präzisionsexperimente in der photoneninduzierten Spaltung am S-DALINAC

PhD thesis

Anode and Cathode Signal
Anode and Cathode Signal

The polarized injector SPIN at the S-DALINAC provides spin polarized electrons for circularly polarized bremsstrahlung with a high degree of polarization near the endpoint energy of the spectrum, enabling the search for forward-backward asymmetries of the light and heavy ?fission fragment originating from parity nonconservation in the photon-induced ?fission process of 238U. An active 238uranium(VI)-fluoride gas target has been developed along the lines of a simple Frisch grid ionization chamber to raise the luminosity and to study the properties of an 238uranium(VI)-fluoride/argon gas mixture. The active 238uranium(VI)-fluoride gas target has been ?filled with argon and 238uranium(VI)-fluoride using mass ?ow controllers. At different settings data has been acquired and interpreted. Instantly after ?filling the chamber with some 238uranium(VI)-fluoride the anode and cathode signal are severely lowered and gain only slowly. Apparently the 238uranium(VI)-fluoride acts as a very efficient electron collector because of its complexity and the high amount of ?fluorine and its electronegativity. Over time, the amount of gaseous 238uranium(VI)-fluoride is reduced and different processes are possible to explain this effect. In the present configuration of the active 238uranium(VI)-fluoride gas target no sound quantitative information on the properties of an 238uranium(VI)-fluoride/argon gas mixture can be given. Raising the luminosity for precision experiments in photon-induced ?fission at the S-DALINAC with an active 238uranium(VI)-fluoride gas target appears to be impossible.