1. Update on CHANTI F.Ambrosino, M.B. Brunetti*, F. Canfora*, T. Capussela**, D. Di Filippo, P. Massarotti, M. Napolitano, L. Roscilli, G. Saracino Università degli Studi di Napoli «Federico II» e Sezione INFN, Napoli *Undergraduate students **Former KLOE member, new Assegno di Ricerca started Sept 2011

2. Outline Reminder Lesson learned from prototype Mechanics of the frame and of the supports SiPM testing FEE and TDAQ Perspectives

3. CHANTI: purpose and methods Six “guard rings” to veto K inelastic interactions on GTK-3 (affecting  10 -3 of kaons) Staggered triangular scintillator bars coupled with fast WLS fibers with SiPM readout to form 6 xy planes G4 simulation: full detector rate O(2 MHz), vetoing efficiency  99% dominated by acceptance K π Tracker (GTK)

4. CHANTI: prototype Built in Naples end of July 2010 All bars tested for response before assembly using a  source Tested using prototype FEE for MIP response and time resolution Results show O(100) pe/plane and O(1 ns) resolution. Npe

5. CHANTI: prototype ns Time resolution Built in Naples end of July 2010 All bars tested for response before assembly using a  source Tested using prototype FEE for MIP response and time resolution Results show O(100) pe/plane and O(1 ns) resolution.

6. CHANTI prototype: lessons Construction and test of the prototype smooth and within expectations, but… In the original solution optical glue used also to fix connectors to the scintillator bars. Apparently «clean» solution, with possibility to inject glue from below with the connector not yet glued to the scintillator Poor mechanical stability, after some handling connectors start to unglue New solution using a sligthly modified bar design, with minimal need for glue + + 3M «black» glue used instead of optical one (better)

7. New bar-connector coupling

8. New mini prototype Built with new technique. Satisfactory mechanical stability. Now at LNF for FEE tests

9. Frame and supports Frame and suports (also for cables) desing completed All components for one station built in Napoli’s mechanical workshop We will test the frame as soon as we build our first station.

10. The vessel Preliminary sketch of the vessel done Contacts with Louvain, technical meeting in Napoli next week to understand constraints and start the finalization of the design.

11. Sensors We decided to use Hamamatsu MPPC 13-50 type (1.3 X 1.3 mm^2, 50  m pixel size) Already bought and delivered all necessary sensors + spares (310 pcs)

12. Known features Hamamatsu provides some info for each device. All info is related to operation at 25 °C Vop (a suggested operational bias voltage) Gain @ Vop 1 pe dark rate @ Vop (typically order 500kHz) 2 pe dark rate @ Vop (typically order 10 kHz) …but we need to be able to extrapolate this info at different temperatures and bias voltages !

13. The SiPM test station Up to 32 sensors can be tested simultaneously Temperature stable and controlled within 0.1°C Voltage stability O(10mV), currents measured better than 1nA

14. The SiPM test station

15. (Aka «the microwave oven»…)

16. Measurements At fixed temperature I-V curve approximatively described by relation Used to extract Vbd for each sensor with an automatic fit procedure in LabView Since gain depends linearly on Vbias-Vbd the info at Vop can be extrapolated at any Vbias after Vbd is known

17. Temperature dependence Vbd itself depends on temperature, and thus if the sensor is not operated at 25°C this effect must be corrected We performed measurements on 15 sensor of 3 different types at various temperatures Quite good «universal» slope of Vbd vs T of about 50 mV/K

18. Temperature dependence

19. Chanti FEE scheme Re-use LAV ToT boards in a two level scheme CHANTI boards: Set Vbias (mV), FAST amplification, Single ch current (nA), read temp probes Design of prototype board started at LNF Vacuum vessel Flange CHANTI boards (9X) 16 CH TOT boards (9X) 32 CH

20. TDAQ Currently procured and switched on a TELL1 board Bought one TDCB + cables D. Di Filippo at CERN to start using TEL62, contribute to the development of the common firmware and be able to design the specific part for CHANTI. Expected manpower from Electronic Service in Napoli in 2012

21. Perspectives The mechanical design of the CHANTI station is almost completed. Construction of the first station is starting today. 3-4 weeks per station needed, including quality test on each bar Extensive test after first station construction, then build all detector Vessel design still to be finalized: first technical meeting next week SiPM semi automatic test system setup. All sensors delivered by Hamamatsu FEE scheme agreed with G. Corradi. Prototype board in advanced design status. TDAQ: just starting, but we have the hardware, (and the people..) We will try to participate with a CHANTI station to the technical run.