Scintillation detectors based on inorganic materials are still one of the most widely applied instrumentation techniques in physics. In particular in the field of hadron physics they will provide significantly higher light yield, an efficient interaction with electromagnetic probes due to the content of high-Z elements, a wider range of emission wavelength to adapt to the appropriate photo sensors and remain more resistant to radiation damage for long term operation.

Description of work and role of partners

Task 1. Development of the technology for fiber production

It will focus on the optimization of the growing technology as well as the characterization and first in-beam tests with produced fibers.
The work will concentrate on the best growth setup and optimum operating parameters to obtain high quality LYSO:Ce fibers. The goal is to obtain at least the same properties as known from bulk crystals. There will be several tests and detailed calculations to prepare the technical modifications (Task 1.1). The crystal length and the number of fibers grown at each run are limited by the inner volume of the crucible. Each production cycle requires several steps such as vacuum, heating and cooling, which is time consuming and determines the final price per piece. Increasing the crucible volume and the number of nozzles would lead to a higher productivity.
However, larger crucibles rely on a change in the classical micro-pulling-down configuration. This will require severe modifications of the facility such as the thermal gradients within the apparatus and a new design of the crucibles (Task 1.2). The investigations should provide sufficient information to design the final modifications necessary for preparation of mass production such as the presently used RF-heating system.

Task 2. Production of a fiber bundle made of LYSO:Ce

The spectrum of application of fibers can be significantly enlarged by the availability of fiber bundles. Presently, a first bundle comprising 6 fibers has proven the feasibility.
The development (Task 2.1) includes the selection of the optimum filling material (epoxy resins with different additives like Lu2O3) and a setup for the characterization of the performance and the cross-talk within the bundle (Task 2.2). The so far used laser system for inspection has to be replaced by a more sensitive device.