INTELUM: Advanced scintillating fibres and Cerenkov fibres for new hadron and jet calorimeters for future colliders(European project, Intelum Rise2020. International and intersectoral mobility)Axes: Materials & Structure DesignLeaders: Yoshikawa AKIRA (IMR, TU) & KheirreddineLEBBOU (iLM, CNRS/UCBL)Participants: Christophe DUJARDIN(iLM, UCBL), Andrei BELSKEY (iLM, CNRS/UCBL), Gilles LEDOUX (iLM, CNRS/UCBL), Philippe VEBER (iLM, CNRS/UCBL), Georges BOULON (iLM, CNRS/UCBL), Yuui YOKOTA (IMR, TU), Shunsuke KUROSAWA (IMR, TU), Kei KAMADA (IMR, TU), Masao YOSHINO (IMR, TU), Akihiro YAMAJI (IMR, TU)PhD student: Rekia BOUITA (iLM, UCBL)Post-Doc: Omar BENAMARA (iLM, UCBL), Guillaume ALLOMBERT-GOGET (iLM, UCBL)Currently, new concepts are being considered for hadron and jet calorimetry in high energy physics experiments, in order to improve the energy resolution of these detectors by a factor of at least two. This is a prerequisite for future studies at the high luminosity, large hadron collider as well as at future electron and proton colliders. Amongst the few concepts being proposed, scintillating and Čerenkov fibers are considered very promising candidates. The collaboration between Lyon and Sendai is focused on the academic exchanges to develop micro-pulling-down crystal growth and other new types of fiber technology. This new fiber production technology has the potential to enable fast, low-cost, manufacture of heavy crystal scintillating fibers. In order to prove the new fibre technology concept, two key technical issues have been addressed during the project:
- demonstrate feasibility of producing between 20-200km of fibers with consistent quality and well-defined production costs
- demonstrate sufficient radiation hardness of the fibers that the degradation of their optical properties is below 10% at 1 MGy level.
In the frame of this collaboration we collaborate to develop raw material quality control and micro-pulling down process engineering for doped crystals, respectively. Generally, the former technology seems to provide higher quality scintillation material. Raw powders from several producers were tested by several experimental techniques and many tens of fibers of both LuAG:Ce and YAG:Ce have been grown and delivered to CERN for further tests. A novel optimization concept, related to the development of based on Mg2+or Li+codoping of Ce-doped garnets (LuAG,YAG and novel GAGG hosts) has been introduced and provided a new technological way to obtain faster scintillation response and higher light yield. The novel material, namely GGAG:Ce single crystal of big dimensions, is also suitable for fiber cutting and has been successfully grown in ILM Laboratory and partners from ISMA. A detailed discussion was held with Japanese researchers from Sendai regarding the ability of their micro-pulling down technology to produce YAG:Ce and LuAG:Ce fibers and the possibilities for multiple pulling. Multiple pulling of fibers is also under consideration at ILM Laboratory. Following the optimization work done on LuAG, similar work on YAG:Ce-based fibers were performed at ILM. Several YAG fibers have been produced of 2 mm dia. or 2x2 mm2cross-section were produced by the µ-PD method at ILM (Lyon, France) and Yoshikawa Laboratory (Sendai, Japan). Ir crucibles with round (2 mm dia.) and square (2x2 mm2) capillary dyes, correspondingly, were used for fiber pulling. Optimization of thermal conditions provided us with the increase of Lattby 10-13 times in 21-52 cm long fibers.