a design study for a cobra upgrade to - Institut für Kern- und ...

86 6 Summary and future work
dimensions. Therefore, the event position reconstruction for the CsI
crystals should be investigated and implemented into the Venom simulation.
A background reduction for events with only one involved
CZT and CsI detector, being the majority of all coincident events, but
providing no angle information, should be investigated further.
The resolutions of the CZT and CsI:Tl detectors should be adjusted for
following more detailed studies. For this thesis, the CZT resolution
used in the analysis of Heine [54] was used and is expected to be larger
than the resolution of the new installed 64 CZT crystals with colourless
passivation. The position dependent resolution of the CsI:Tl crystals
should be determined for both crystals sizes with semiconductor readout.
The achievable half-life limits with a CsI:Tl COBRA upgrade has to be
studied in a more detailed analysis. Additionally, a future investigation
of an upgrade should study CWO, comparing achievable half-life limits
and prices with a CsI upgrade. CWO is with its relatively high light
yield and easier handling more suitable than NaI:Tl and BGO.
To study CWO, the written Geant4 applications can be used, but has
to be expanded. The application CsI must be adjusted for CWO. To
add new scintillator materials, their optical properties must be implemented.
This application can provide information about the possibility
of attaching diodes via wavelength shifter to the CWO crystal. Due
to the lower maximal emission wavelength of CWO in comparison to
CsI:Tl, this might be an option.
The VENOM package Scint64 has to be adjusted also. Here, no optical
properties must be implemented, but a change of the scintillator material
and the geometry for smaller crystals is necessary. The already
implemented Birks factor must also be adjusted for CWO. An analysis,
using pulse shape discrimination is as well possible for CWO.
Further studies with this package could use different resolutions for the
two different scintillator sizes or even for individual crystals. A corrected
energy, depending on the point of interaction in the scintillator
could also be added by later package developers.