Front End Electronics for GEM detector

1. F. Murtas CERN-INFN Front End Electronics for GEM detector • Neutron detectors and GEM technology • Readout and electronics • Carioca and Gemini Chip • FPGA data acquisition board • HVGEM power supply • GEMpix • Summary A.Balla, A.Baschirotto, G.Claps, G.Corradi, G.Croci, A.Pietropaolo, A.Pezzotta, S.Puddu, L.Quintieri, D.Tagnani

2. 10B Cathode for thermal neutron Thermal Neutrons interact with 10B, and alfas are emitted entering in the gas volume generating a detectable signal. Low Efficiency Big active area Beam Monitor and transmission Gas gap (Ar CO2) Alfas 10B Al Support Thermal neutrons Side-On detector High Efficiency Small active area Alfas Thermal neutrons cathode Actually 4% efficiency ... working to obtain 70%.Good candidate as 3He replacement detector

3. Polyethilene for fast neutron Fast Neutrons interact with H, and protons are emitted entering in the gas volume generating a detectable signal. Low Efficiency Big active area Beam Monitor and transmission Gas gap (Ar CO2) Protons Al Idrogenate Support Thermal neutrons Side-On detector High Efficiency Small active area Protons Thermal neutrons cathode Actually 0.1% efficiency ... working to obtain few %.

4. Gas Electron Multiplier A Gas Electron Multiplier (F.Sauli, NIM A386 531 1997) is made by 50 m thick kapton foil, copper clad on each side and perforated by an high surface-density of bi-conical channels; different shapes 70 µm 140 µm 50 µm 1.1m x 0.45m

5. Working point for GEM detectors The alfas produce an higher ionization respect to protons that allow a wider plateau before the gamma background Really low level of gamma background

6. Particle conversion Cartesian Gain Small angle Readout Pads GEM Readout • Gain and readout functions on separate electrodes • Fast electron charge collected on patterned anode 40% of electron signal (from HV) 60% of electron signal

7. The frame for the G3 foil has been modified for the gas inlet A Sealed Triple GEM construction The glued detectors described in this seminar are built starting form the standard 10x10cm2 : only one GEM foil has been modified to have central electrodes. 128 pads 6x12 mm2 G3 G2 G1 The GEM are stretched and a G10 frame is glued on top

8. Pad readouts Different pad geometry but always with 128 channels 0.5x0.5 mm2 0.5x3 mm2 2x2 mm2 Radiotherapy CNAO and Lead Ion CNAO and cyclotron 3x6 mm2 3x24 mm2 6x12 mm2 Thermal neutron Radioactive waste Neutron and TPC

9. All the anode PCB have been designed with the same connector layout for a total of 128 channels The FEE board Carioca GEM The card is based on *Carioca Chip and has been designed and realized in Frascati by Gianni Corradi ; Total dimension : 3x6 cm2 16 channels for each card: channel density of 1 ch/cm2 Sensitivity of 2-3 fC; LVDS output (25 ns); Radhard; Extremely modular and usable for GEM applications * Development of the CARIOCA front-end chip for the LHCb muon detector. W. Bonivento, et al NIM A491:233-243,2002

10. Carioca Card Sensitivity Q = 5 fC width=10 ns Q = 5 fC width=20 ns LVDS 5 ns LVDS 15 ns The sensitivity has been measured injecting a charge between 5 and 20 fC with different width Q = 5 fC width=30 ns LVDS 17 ns

11. Carioca Card Sensitivity The sensitivity is measured vs two different thresholds DAC Threshold on power supply Threshold on Carioca 6mV/fC

12. Gemini chip • We are working with Milano Bicocca for the • construction of a new chip : • Radiation hardness • Charge measurement • Higher channel density A.Baschirotto,G.Corradi,F.Murtas,A.Pezzzotta Time development On September 2013 we received the first chips with 8 channels Test in progress

13. GEMINI vs Carioca Performance Photo of the GEMINI chip (8 channels)

14. FPGA Board : Realtime DAQ We have an Intelligent Mother Board with an FPGA(Field Programmable Gate Array) on board able to count the 128 channel hits and/or measure the time respect to a trigger (1 ns) ; the data are readable through an Ethernet connection (LNF A.Balla, P.Ciambrone, M.Gatta). Threshlds settings Slices acquisition Integration time (untill 20-30 µs) Delay to trigger Total Counts vs time

15. NIM standard HVGEM Modlue Power Supply Labview Control Pannel for the High Voltage GEM Voltage (gain) Fields High Voltage Module for triple-GEM detector G.Corradi Real-time electrodes current measurements: each channel has a nano-Ammeter which measures the current with a sensitivity of 10 nA.

16. A triple GEM detector system Charged particles X Ray Gammas Neutrons 12 V PS HVGEM HV Filters 3 GEM detector FPGA Board 128 ch Netbook

17. Measurements with time slices at NTOF online measurement Single event 100 events online measurement Time spectrum (1ms/bin)150ms total gate

18. GEMPIX detector

19. Pixelated detector The Medipix is a silicon detector with 50x50 micron pixels Matrix of 256x256 pixels Active area of 1.4x1.4 mm Power supplied by USB The idea is to use the readout ASIC Chip without the Si sensor to measure the electron clusters produced by the GEM

20. GEMpix Assembling The detector has two main parts : - The quad medipix with a naked devices - The triple gem detector with HV filters and connector New HV GEM board Quad medipix board M.Campbell, J.Alzoy Top view

21. Head on detector Particles to be analysed 3 mm ionization gap Mylar window Triple GEM Gas flux AR CO2 The detector is a quadnaked medipix : The active area is 9 cm2 This type of device can be used for neutron detection if a film of polyethylene or Boron is deposited on the cathode

22. Gem foils and frame A new GEM layout has been designed Active area of 28x28 mm2 The electordes path have been designed to avoid the medipix wire bonding. Produced by Rui De Oliveira. New frames were designed 10x10 cm2 to fit the Quadmedipix board 5 different thickness (from 1 to 5 mm) Wire bonding position

23. Assembling the GEM foils A new board for HV power supply as been designed and made in Frascati (D.Tagnani) The three GEM foils are assembled on top of HV GEM board

24. Two prototype of GEMPIX HV Connector Medipix DAQ box Head-on detector Side-on detector

25. Signals from radioactive source Cosmic Xray These pictures were taken with radiactive sources of 55Fe Cesium and Americium Using a gas mixture of Ar/CO2/CF4 45/15/40 With a gain of 6000 and an induction field of 2 kV/cm Cobalt Compton electron Alpha Alphas

26. Cluster Analysis Xray(55Fe) vs Gammas (60Co) Cluster type Cluster volume Inner size Size y vs size x Size Border size

27. Medipix for neutron detector Medipix is a silicon detector with 50x50 micron pixels Matrix of 256x256 pixels Active area of 1.4x1.4 mm Power supplied by USB Different converters have been placed in front of medipix and background measurement made around the ATLAS experiment at CERN First tryals of boron deposition on Medipix made by G.Celentano (ENEA) Test in progress at CERN.

28. Summary • In Frascati a compact and complete system of Front End Electronics for GEM detectors has been developed. • Recently very good results have been obtained withfast and thermal neutron detectors withhigh spatial and time resolution • High dinamic range in rate measurements with very low gamma backgroundhave been obtained. • The new GEMINI chip is under construction and test and it will replace the old Carioca chip with higher performance. • Interesting progress on neutron detection with high pixelated detector both with GEMpix and Medipix but they are slow devices that require a pattern recognition program