Status of the Genova activity on a direction-sensitive optical module toward the KM3 detector M.Taiuti WP3 PYLOS 16/4/2007

Guidelines  We planned the construction of 2 directional optical module to be deployed together with the NEMO- Fase2 tower in Capo Passero  Integration to be completed by may 2008  Compatibility with the mechanical structure of the NEMO-Fase2 tower  Compatibility with the electronics of the NEMO- Fase2 tower

Basic Requirements  A direction-sensitive optical module requires: A.A position sensitive photo-detector B.A light collimation system C.A dedicated electronics

The Optical Module Conceptual Design Highly reflecting mirros (by 3M) Plexiglas (90 mm) PMT 10” Sphere 17” Mu-metal Optical Gel (7mm) PMT Frame To be optimized PMT Frame To be optimized

The Hamamatsu Prototypes  2 prototypes manufactured and received in Catania in May  Same shape as 10” standard PMT  Very large photocathode area  No data-sheet presently available. Hamamatsu is waiting for the publication of out tests

The Hamamatsu Prototype Properties  Preliminary test performed by Hamamatsu  Results confirmed in Catania  Good response Gain > (> ) PtoV > 2.5 (> 2) TTS < 5 ns(< 3)

Uniformity

Test in Catania

preliminary

Test in Catania  Preliminary tests performed with diffuse light source  This week new tests will begin with laser light source, including: Cathode uniformity Anode cross-talk Single photon peak Timing Linearity

The Light Collimator  Spherical geometry allows an easy solution to the problem of efficiently collect the Cherenkov light with three plane mirrors forming 90° intersections  Volume between mirrors must be filled with transparent media to match the refraction indexes (chosen low cost solution: Plexiglas) R x R x   

Test on Reflectance plexiglas photodiode laser

Power supply  ISEG PHQ-5912 board has been analyzed and evaluated.  A new prototype is in advanced design phase.  Design objectives: low power, good performances, reliability, compactness.  Main features: Positive voltage up to 2000 V Independent regulation of cathode to first dynode and first dynode to anodes voltages Single supply (+5 V) Remote On-Off switching Voltages setting using local DACs or analog values Voltages and current monitoring using local ADC On board thermometer  A working prototype is expected to be ready by June 2007

Read-out electronics  The information needed are: the total collected charge the index of the fired anodes signal time-evolution  A dedicated electronic board will be designed to provide the analog sum of the 4 anode signals and 4 discriminated digital signals.  The actual NEMO FEM can be used implementing dedicated firmware on it.  The NEMO FEM will provide the discriminator thresholds and the power to this module.  The data payload will contain the digitized data together with the index of the fired anodes.

Time scale  PMT test by May 2007  Light guide construction by May 2007  Mechanical assembly by July 2007  Tests with conventional electronics by December 2007  Read-out electronic board ready by December 2007  Final assembly and test by June 2008