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

Outline

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

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

Kπ

Tracker (GTK)

CHANTI: prototype• Built in Naples end of July 2010• All bars tested for response before

assembly using a b source• Tested using prototype FEE for MIP

response and time resolution Results show O(100) pe/plane and O(1 ns) resolution.

Npe

CHANTI: prototype

ns

Time resolution

• Built in Naples end of July 2010• All bars tested for response before

assembly using a b source• Tested using prototype FEE for MIP

response and time resolution Results show O(100) pe/plane and O(1 ns) resolution.

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)

New bar-connector coupling

New mini prototype

Built with new technique. Satisfactory mechanical stability. Now at LNF for FEE tests

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.

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.

Sensors• We decided to use Hamamatsu MPPC 13-50

type (1.3 X 1.3 mm^2, 50 mm pixel size)• Already bought and delivered all necessary

sensors + spares (310 pcs)

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 !

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

The SiPM test station

The SiPM test station(Aka «the microwave oven»…)

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

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

Temperature dependence

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

16 CH

TOT boards (9X)

32 CH

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

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.