1. December 5, 2007 P. Colas - LP cosmic trigger 1 The cosmic trigger for the Large Prototype Th. Chaminade, P. Colas, K. Dehmelt, G. De Lentdecker, X. Janssen, Y. Kato, H. Kuroiwa, Y. Kudenko, T. Matsuda, F. Pierre, J.M. Reymond, S. Turnbull

2. December 5, 2007P. Colas - LP cosmic trigger2 The Large Prototype Cosmics in March 08 Beam summer 08 7 panels mid 09

3. December 5, 2007P. Colas - LP cosmic trigger3 Slab size changed to 167 mm (better extrusion) Suggestion (by Takeshi Matsuda and Dean Karlen) Use MPPCs and scintillating slabs from T2K/SMRD Face-to-face meeting on October 11 in Orsay allowed revisiting the layout and plans K. Dehmelt

4. December 5, 2007P. Colas - LP cosmic trigger4 The trigger has to be in a field of order 0.4 T. MPPC : multi-pixel photo counters (so-called Silicon PM) produced by Hamamatsu 100 pixels on 1 mm 2. Each is a Photodiode in Geiger mode Operation voltage : V breakdown + fraction of a Volt Requires accurate supplies about 70 V. Need to sort the MPPCs in V breakdown to reduce the number of supplies. Signal: 3 mV/p.e. ( 10-20 p.e.) Dark counting rate and V bkd sensitive to temperature : needs good temperature control: Peltier devices + thermo. 1mm

5. December 5, 2007P. Colas - LP cosmic trigger5 The gain depends on V bias, and V breakdown depends on the temperature Requires both a stable and precise supply and a controlled temperature.

6. December 5, 2007P. Colas - LP cosmic trigger6

7. December 5, 2007P. Colas - LP cosmic trigger7 Box with photocouplers, MPPC, R,C circuit, Thermistance, Peltier device Wavelength shifting fiber Scintillator slab Controller Trigger logic TLU Supply Temperature control: Jean-Marc Reymond

8. December 5, 2007P. Colas - LP cosmic trigger8 Mechanics can be simple: wrapped slabs maintained by bars Tylic reflector to be ordered

9. December 5, 2007P. Colas - LP cosmic trigger9 5 slabs on top 3 slabs at bottom +4 perpendicular to limit the triggers to the detector length Present layout: 12 slabs (+ 3 spare) Many possible combinations, for instance: 1 top + 1 bottom : central region of central panel 3 top + 1 bottom : radial tracks on central panels 3 top + 3 bottom : vertical tracks on most of the central region Requires a ‘bridge’ to support the magnet and its movement system.

10. December 5, 2007P. Colas - LP cosmic trigger10

11. December 5, 2007P. Colas - LP cosmic trigger11 First step : hands on MPPC Build a box with 1MPPC and one diode and a readout circuit Build a box with 1MPPC and one diode and a readout circuit Advices from J-Ch Vannel (Polytechnique), H. Kuroiwa and Y. Kato, and I. K. Advices from J-Ch Vannel (Polytechnique), H. Kuroiwa and Y. Kato, and I. K.

12. December 5, 2007P. Colas - LP cosmic trigger12 Second step : choose supplies Must be accurate and stable, low-ripple, especially around 70 V. Candidates: Must be accurate and stable, low-ripple, especially around 70 V. Candidates: Keithley 2612, Keithley 237 Keithley 2612, Keithley 237 Modules from NIKHEF (Jos Steijger) in a Caen SY527 crate (K.Delmeht). But maybe not accurate enough Modules from NIKHEF (Jos Steijger) in a Caen SY527 crate (K.Delmeht). But maybe not accurate enough Need also 24 channels of PMT amplifiers and discriminators, coincidence units Need also 24 channels of PMT amplifiers and discriminators, coincidence units

13. December 5, 2007P. Colas - LP cosmic trigger13 Third step : design readout and thermalisation 3 parts top, bottom parallel, bottom perpendicular. 3 parts top, bottom parallel, bottom perpendicular. In each box: thermistance, peltier device In each box: thermistance, peltier device In a central place : controler In a central place : controler Design mechanics, system, cables Design mechanics, system, cables Light-tightness vs accessibility Light-tightness vs accessibility

14. December 5, 2007P. Colas - LP cosmic trigger14 Conclusion and plans Need a robust system: temperature control Need a robust system: temperature control Characterize MPPC, decide on supplies, Finalize design. Characterize MPPC, decide on supplies, Finalize design. Slabs delivered from mid-January Slabs delivered from mid-January Wrapping in Saclay 2 weeks after Wrapping in Saclay 2 weeks after Installation in February or March Installation in February or March Connexion to DAQ in March Connexion to DAQ in March