Development of a large area silicon pad detector for the identification of cosmic ions

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Cory Randell Atkins
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1 Development of a large area silicon pad detector for the identification of cosmic ions M.Y. Kim 1,2 P.S. Marrocchesi 1, C. Avanzini 2, M.G. Bagliesi 1, G. Bigongiari 1,A. Caldarone 1,R. Cecchi 1,, P. Maestro 1, N. Malakhov 2, F.Morsani 2, R. Zei 1 1 Physics Dept., University of Siena / INFN, 56 v.roma, Siena, Italy 2 INFN sezione di Pisa, 2 v. F. Buonarroti, Pisa, Italy Abstract A silicon sensor with 64 large area pixels ( pads of 1 cm 2 area) was developed to identify relativistic ions in direct measurement of the elemental composition of cosmic rays. A single-element discrimination can be achieved via an accurate measurement of the electric charge Z, taking advantage of the of Z 2 dependence of specific ionization of the silicon. The next generation of space-based or balloon-borne cosmic ray experiments require the coverage of large sensitive areas with arrays of such detectors. Preliminary results on the performance of the sensor will be presented. IPRD06 Oct. 3, SIENA 2006 Oct. 1 st 5 th 2006

space), in operation or at design stage, where

rays is achieved by means of a Si detector

Exposed Facility of JEM on the ISS Si Matrix

2 Why a large area Si pad detector? Example of experiments (on balloons or in space), in operation or at design stage, where the charge identification of primary cosmic rays is achieved by means of a Si detector with "large" pixels of order 1 cm 2 CALET on Exposed Facility of JEM on the ISS Si Matrix ATIC Balloon Experiment CREAM Balloon Experiment CALET ISS Experiment

3 R&D of Si Matrix MATRIX : R&D project funded by INFN to develop a large area Charge Identifier (1-4 m 2 ) and low-noise front-end electronics with large dynamic range for the identification of relativistic ions up to Fe (Z = 26) and beyond. Conceptual scheme of a ladder readout (length up to 1 m) with pixel sensors of size ~ 8 cm x 8 cm and 64 pixels. readout side ladders readout side ladders ladders ladders readout side readout side

Detector Description Wafer information Thickness: 500 µm 6 Radius Phosphorous doped n-type : Resistivity: > 10000 Ω cm <1,0,0> Crystal lattice oriented Detector information PIN diode (B implantated

4 Detector Description Wafer information Thickness: 500 µm 6 Radius Phosphorous doped n-type : Resistivity: > Ω cm <1,0,0> Crystal lattice oriented Detector information PIN diode (B implantated pixels on N-sub) Pixel area: 1cm 2 Matrix:8 X 8 (64 pixels) Fabricated at ST Microelectronics in catania, Italy Test structure Test structure Photodiode: C-V measurement (Calculation of full depletion voltage and N d ) MOS capacitor: C-V measurement (Calculation of flat-band voltage, charge density and thickness of field oxide) Baby twin detectors: C-V measurement, I-V measurement, Interpixel resistance Mono pixel 1cm 2 : C-V measurement, I-V measurement

5 Electrical characteristics ( at RH < 55%, 22 C) IV_ Matrix (64pixels) CV of pixel(0,0) from 5 different matrix sensors 3.5E E E-09 Leakage current(a 2.5E E E E E E Rev erse bias v oltage(v) 1/C^2 (pf) 2.0E E E E E Reverse bias voltage(v) Wafer01 Pixel(0,0) Wafer02 Pixel(0,0) Wafer04 Pixel(0,0) Wafer10 Pixel(0,0) Wafer18 Pixel(0,0) Full depletion voltage < 100V Pixel capacitance at full depletion ~ 23pF Pixel leakage current at full depletion ~ 2nA/cm 2

6 Stability & Temperature Dependence Leakage current(a) 2.5E E E-09 Stability 100V of single pixel with biased guardring on wafer18(sp02) Time The leakage current stability is required for stable operation at overdepletion voltage over at least 24hours. (During this time the total leakage current must not increase more than 30% from the initial value.) The temperature dependence of leakage current has been measured at the temperature range between -10 ~ +30 to check the I ~ T 2 exp(-e 0 /2kT) dependence. Leakage current(a)@100v 2.50E E E E E-009 singlepixel 1stguard 2ndguard ln(i) st100V Singlepixel at 100V Linear Fit of lndata_1st100v 0.00E Temperature(Kelvin degree) 1/T

β-source Test - Source information : 106 Ru (Beta emission: ending point 3.

Sensitivity -> 0.42uV/electon, Bipolar output 1.2 MΩ 2) AMPTEK A-206 Voltage amp.

2 MΩ +HV 1 nf AMPTEK A-203 Charge sensitive preamp.

40000 e + X 0.42uV = 17mV AMPTEK A-206 Voltage amp.

7 β-source Test - Source information : 106 Ru (Beta emission: ending point 3.5MeV) - Amplifier information 1) AMPTEK A-203 Charge sensitive preamp/shaping amplifier : Sensitivity -> 0.42uV/electon, Bipolar output 1.2 MΩ 2) AMPTEK A-206 Voltage amp./low level discriminator : Gain -> X 10 nominal 1.2 MΩ um MΩ +HV 1 nf AMPTEK A-203 Charge sensitive preamp. /Shaping Amplifier ~40000 e + are generated by MIP at 500um of penetration depth e + X 0.42uV = 17mV AMPTEK A-206 Voltage amp. /Low level discriminator 17mV X 10 = 170mV Depletion voltage -> 20V 40V 60V 80V 100V 120V Output voltage -> 230mV 292mV 364mV 384mV 373mV 373mV (Err. : 20mV) Full depletion voltage of IPRD06 SIENA the tested detector (75V) Oct. 1 st 5 th 2006

Detector Mount with Front-end board front-end board 64 - pixels sensor A large area Si sensor has been mounted with FlexiblePCB for Signal Readout (by wire bonding) and Cu plate for

8 Detector Mount with Front-end board front-end board 64 - pixels sensor A large area Si sensor has been mounted with FlexiblePCB for Signal Readout (by wire bonding) and Cu plate for High-voltage bias. Operating voltage 130V through 1 MΩ resistor. New front-end chip HDR14.2 (32 channels) [M.G. Bagliesi IPRD06] 64 channels board with 16 bit ADC [M.G. Bagliesi IPRD06]

1 Trigger 2 Entries Row Column Trigger 3 11 pixels which

9 Atmospheric Muon Test Muon test with 3 scintillator triggers Event entries per pixel (Trigger shadow) Trigger 1 Trigger 2 Entries Row Column Trigger 3 11 pixels which have enough statistics have been chosen for the S/N Ratio calculation

Pedestal events (light blue) have been superimposed to the plot : their

10 Atmospheric Muon Test result S/N ~ 8 Landau distribution (dark blue) for pixels triggered by an external coincidence of 3 scintillators. Pedestal events (light blue) have been superimposed to the plot : their number was arbitrarily chosen and is not representative of the sensor's efficiency.

11 Summary A large area silicon pad detector for the identification of cosmic ions is being developed and tested. Detector thickness : 500 um Pixel size : 1 cm 2 Matrix array : 8 X 8 Full depletion voltage < 100 V Pixel capacitance at full depletion ~ 23 pf Pixel leakage current at full depletion ~ 2 na/cm 2 Signal to Noise Ratio with new HDR14.2 ~ 8

Status of ITC-irst activities in RD50

Status of ITC-irst activities in RD50 M. Boscardin ITC-irst, Microsystem Division Trento, Italy Outline Materials/Pad Detctors Pre-irradiated silicon INFN Padova and Institute for Nuclear Research of NASU,