A. Malinin 1 , A. Petrov 1 , V. Shevchenko 1 For the LHCb collaboration A SciFi production center in NRC KI for LHCb upgrade Abstract: The Scintillating Fibre Tracker, SciFi for short, will be the main new tracking detector in LHCb. It will provide better than 100 μm spatial resolution, and high rate capability and radiation hardness enabling a fast, 40 MHz, trigger rate with a capability to withstand 50 fb -1 integrated luminosity, delivered by LHC, without a major performance degradation. The main active element of the tracker is a scintillating fibre ribbon with the SiPM readout. The ribbons consist of 6 layers of the 250 μm scintillating fibres Kuraray SCSF-78MJ, assembled by winding and bound together by the epoxy glue. NRC Kurchatov Institute, Moscow, together with the colleagues from ITEP, CERN, TU of Dortmund and RWTH of Aachen are developing dedicated production centers with the aim to reach by 2016 production rate one ribbon per day per center, necessary to supply more than 1300 fibre ribbons (mats) needed for a new LHCb tracker. SciFi detector concept and performance SciFi Tracker design and construction [1] CERN-LHCC-2014-001 ; LHCB-TDR-015 , https://cds.cern.ch/record/1647400 [2] P. von Doetinchem, H. Gast, Th. Kirn, G. Roper Yearwood, S. Schael, Nucl.Instrum.Meth.A581:151-155, 2007, arXiv:astro-ph/0702567v1 [3] Th. Kirn et al., Production of Scintillating Fiber Modules for high resolution tracking devices TIPP2014, Conference proceedings, Amsterdam, 5th June 2014 [4] CERN-LHCb-PUB-2015-008, LHCB-EDR-M-M http://cds.cern.ch/record/2004811 The 3 rd Annual Large Hadron Collider Physics Conference St. Petersburg, Russia August 31 st – September 5 th , 2015. SciFi modules series production and the quality assurance (QA) winding, as well as many other technological and QA units which are being developed together by the groups of the SciFi project. The production of the SciFi fibre mats and modules is organized at This work is supported by Contract with Ministry of Education and Science of Russia № 14.610.21.0002 and RFBR grant 14-02-03030. We wish to thank CERN for their excellent beam facility and services. Acknowledgements and References Figure 1. The Outer Tracker position in the LHCb experiment to be replaced by the SciFi Tracker. Figure 10. The fibre QA scanner principal scheme. Figure 11. KI fibre quality scanner 3D-model. Figure 12. The fiber ribbon winding machine. Figure 13. SciFi modules production flow-chart developed for LHCb VELO upgrade (with 10 μm track resolution) and the SciFi modules. themselves. The result is shown in Fig.6. The double Gaussian fit to the residuals distribution for the charge weighted cluster hits gives σ 1 = 59 μm σ 2 = 203 μm with 79 μm weighted average effective sigma. . Module Centre Fibre Quality Centre (CERN) 10,000 km scintillating fibre Fibre Winding Centre Fibre Winding Centre Fibre Winding Centre Fibre Winding Centre Aachen Dortmund Lausanne Moscow Tested fibre Module Centre Heidelberg Amsterdam 1300 tested fibre mats 144 tested modules CERN Half-panel: Honeycomb (Nomex) + CFRP skin Mirror side Readout side Figure 6. SciFi module spatial resolution with one side mirror (beam track residuals) Figure 9. 128-ch SiPM to readout SciFi signals Figure 7. Modular design: 1 of 3 SciFi stations Figure 8. SciFi module consists of 8 fibre mats 1 NRC Kurchatov Institute, akademika Kurchatova sq.,1 Moscow, 123182, Russia [email protected] Figure 3. The SciFi detector fabrication concept Figure 2. The radiation environment of the LHCb tracker area, which corresponds to the integrated dose of 50 fb -1 : a) The total dose, and b) the 1 MeV equivalent neutron fluence per cm 2 . Figure 5. The Kuraray SCSF-78MJ scintillating fibre irradiation tests summary: The ratio of the irradiated fibre attenuation length Λ irr to initial attenuation length Λ 0 , as a function of the integrated dose in kGy. Increased luminosity of the LHC requires a substantial upgrade of the LHCb experiment [1]. One of the first detectors to be completely replaced is the LHCb Outer Tracker (Fig.1). A much higher radiation dose and neutron fluence, which correspond to 50fb -1 (Fig.2a,b) require a new tracker concept. The concept of the scintillating fibre tracking detector is not new, but the SciFi highest resolution and largest area detector with the direct multichannel SiPM readout, providing better than 100 μm spatial resolution over several square meters area, comes from the PEBS experiment tracker proposal [2] by RWTH group. They, together with other LHCb members of the SciFi project, developed the winding technique, using a precise, threaded with 275 μm pitch, rotating drum a winding wheel, (Fig.3,4) to produce a 6 layer, 2500 mm long and 132 mm wide Figure 6 shows a new modular layout of the SciFi tracker’s one out of three (Fig.1) tracking stations. Each station consist of four layers of SciFi modules mounted on C-frames with two vertical (X) and two stereo (U,V), at ± 5º to the vertical, fiber orientations. The modules (Fig.7) have the same design except for two innermost in each layer, and consist of 8 mats readout from one side by four 128-channel SiPMs (Fig.8), directly connected to the end of the mat. Other ends of the fiber mats are equipped with mirrors. The structure is closed by two half-panels which are made from a honeycomb core and single carbon skin by gluing. A readout box with front-end electronics is attached to the top and bottom of each module. It has an insulated cold compartment to keep the SiPMs at -40°C working temperature during the run. Figure 14. Production clean zone of 240 m 2 ISO7-ISO8 class is being constructed at NRC KI Figure 15. NRC KI production clean room layout The series production of the SciFi mats requires a clean room and a set of equipment (Fig.10-12) for fibre quality assurance, and mat’s seven centers (Fig.13) four of which are set up to produce over 1300 mats. The center at NRC Kurchatov Institute is shown in Fig.14,15. The clean zone (Fig.15) is divided in four compartments, for entrance, the QA fibre scanner (Fig.11), winding machine (Fig.12), and assembly. The fibre QA scanner measures the fibre diameter, with high frequency and 1 μm accuracy, it monitors the attenuation length and light yield, and detects eventual structural defects such as the bumps, necks and cracks. Its principal scheme is shown in Fig.10. The main part of the production is winding. The mixture of Epotec 301-2 epoxy glue and the TiO 2 powder (20% by weight) is prepared in the winding compartment and applied 6 times after each fibre layer is completed. The curing process takes 48 hours and 3 precision wheels (Fig.4) are needed to make 1 mat per day to ensure the required production rate per shift. At NRC KI center, work in 2 shifts is foreseen. mats out of 250 μm diameter scintillating optical fibre [3], packaged in a dense, hexagonal structure and bounded together by epoxy glue. The fibre was carefully chosen after many tests. It is SCSF-78MJ, produced by Kuraray company in Japan. Its radiation hardness (Fig.5) was measured with different linear energy transfer beams and dose rates. The data demonstrates less than 20% of expected transparency loss for the highest dose near the LHCb beam pipe, covering only a few tens of cm in Y direction (fibre direction in the mats). a) b) The SciFi spatial resolution was measured in the test beam at SPS [4]. The beam tracks were reconstructed using the Si-pixel tracker Figure 4. The NRC KI precision winding wheel Shape accuracy: 70 μm Outer Ø = 817 mm