1. ECAL LED monitoring system upgrade Pavel Shatalov ITEP, Moscow, Russia Yuri Guz IHEP Protvino, Russia

2. Fiber The 105/125µm rad hard fiber of DRAKA (pure-silica core/F-doped cladding) with acrylate coating + black painting was chosen, 300 m of such fiber purchased from DRAKA for tests. Total diameter of this fiber is ~ 258 µm

3. Procedure for Module end ( for every fiber in a bundle): Remove the coating by a stripper on the length of about 12mm; Cut the fiber end by a cleaver; Glue the fiber into the connector; control with a digital microscope, polish if necessary Procedure for LED end (all the 16 (9) fibers): Remove the coating by a stripper for every fiber; Glue all fibers together into the brass tube 1.25 mm inner diameter; polish with a polishing machine, controlling by digital microscope; gluing into the Plexiglas holder, together with a piece of 1.2 mm clear fiber (for PIN diode control). Module end connector Production of a test bundle with 16 fibres - I LED end connector

4. Production of a test bundle with 16 fibres - II Gluing the fibers into end pieces control by digital 500x microscope, polishing if necessary cutting the fiber ends with a cleaver the 16 8m fibers are stretched at the table

5. Production of a test bundle with 16 fibres - III the test bundle is ready, waiting for lab tests preparing the LED end: polishing the LED end, view by microscope quartz fiber bundle (16x8m) clear PSM fiber for PIN diode the LED end and module end connectors

6. Injection test The measurements were performed with a standard ECAL LED driver at max intensity with PMT LA4956 and U ctrl =1.53 V (HV=650 V). The setup included 50 cm clear fiber Ø1.2 mm, similar to that installed in each ECAL cell. Installation of the test bundle to ECAL and measurement at HV values corresponding to different ECAL zones is necessary to understand the calibration signal magnitude in FEBs and its variations.

7. Preparations for irradiation tests in Protvino ( March 2013) During the irradiation test in Protvino (22-31 March 2013) we are going to irradiate 10 m of fiber to 1-2 Mrad. 10 m of fiber The attenuation of the fiber will be continuously monitored with Ocean Optics SD2000 spectrometer. The light from a blue LED will be sent via 70 m standard optical cable to the test fiber installed in the irradiation zone. The output spectrum will be recorded by SD2000 every 5 minutes. The intensity of the input LED light will be monitored with a PIN diode.

8. The Multicomp “MegaBright Blue” LED was chosen. With this type of LED, fiber with core diameter of 100µm is already enough for ECAL calibration system: > 500 ADC channels for the Inner zone is expected. LED type selection