Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 1 Design and Characterization of a double-layered silicon charge detector for cosmic ray measurements in CALET INFN sezione di Pisa Meyoung Kim O. Adriani 3, C. Avanzini 2, M. G. Bagliesi 1, A. Basti 2, K. Batkov 1, L. Bonechi 3, S. Bonechi 1, G. Bigongiari 1, R. Cecchi 1, M. Y. Kim 2, P. Maestro 1, P. S. Marrocchesi 1, V.Millucci 1, F. Morsani 2, P.Papini 3, S. Ricciarini 3, L.E. Vannuccini 3, A.Viciani, R. Zei 1 1 University of Siena and INFN, Italy 2 INFN sezione di Pisa, Italy 3 University of Florence and INFN, Italy

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 2 Contents CALET (CALorimetric Electron Telescope) 3 Identification of Cosmic Ray 4 ~ 6 Silicon Charge Detector in CALET 7 ~ 8 Detector Characterization 9 ~ 17 Schedule 18

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 3 CALorimetric Electron Telescope : CALET CALET SIA IMC TASC SACS(ACD) Cosmic Ray Sources SNR Pulsar AGN γ e P γ Dark Matter γ Pair Annihilation χχ e+e+ e-e- Observations - Electrons (1 GeV - 10 TeV) - Gamma-rays(20 MeV - Sevral TeV) Gamma-ray Bursts(7 keV - 20 MeV) - Protons, Heavy Nuclei (10 GeV TeV) - Solar Particles Instruments - Silicon Pixel Array - Imaging Calorimeter - Total Absorption Calorimeter - Segmented Plastic Scintillators for Anti-Coincidence

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 4  The measurement of CR nuclei spectra: Improve our understanding of space environment (amount of interstellar medium, radiation level … etc)  The cosmic ray propagation models shall be validated and constrained by fitting to CR Flux ratio with Primary to Secondary. Identification of Cosmic Ray

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 5 The ratio of Secondary/Primary fluxes (e.g. B/C, Sub-Fe/Fe) reveals information about propagation theory. It is just depends on the energy dependence of diffusion coefficient. N Primary are produced in the cosmic ray source regions. N Secondary are produced predominantly through spallation interactions of primary nuclei. This ratio is important to be considered in the high-energy part (energy greater than some tens of GeV). ▪ Solar modulation plays a minor role ▪ Diffusive reacceleration (which introduces a new free parameter, the Alfven velocity) plays a minor role ▪ Energy losses due to spallation are less important ▪ Production cross section are known with less uncertainty In the high energy part the slope only depends on δ. Identification of Cosmic Ray

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 6 Exemples of experiment where the charge identification of primary cosmic rays is achieved by means of a Si detector with "large" pixels of order 1 cm 2. CREAM Balloon Experiment ATIC Balloon Experiment Examples of Silicon charge identifier Astroparticle Physics 30 (2008) 133–141 [CREAM] Horizontal errors : systematic error in the overall energy scale Vertical errors: statistical error of the ratio Grey bars: the systematic uncertainty in the ratio. ★ HEAO ○ CREAM δ = 0.33 δ = 0.60 δ = 0.70

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 7 4,608 pads (~ 1.26cm 2 ) 54 X 54 cm 2 active area Two layers of Silicon Charge detector Array - Back-extrapolation of track reconstructed in the finely segmented Imaging Calorimeter (IMC) - Impact point reconstruction and identification of the pixel hit by the incident cosmic nucleus Background from calorimeter albedo Example of simulation with Fluka : 1 TeV/n Carbon interacting in the IMC IMC SIA TASC two independent Z-measurements from SIA Silicon Charge Detector in CALET

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 8 Silicon Charge Detector in CALET Charged Particle SIPIN FLUKA Simulation for 500um Thick Silicon Heavy nuclei Z=1 to 28, Energy 10 GeV/n Pixel Size ~ 1 cm 2 Energy loss has Z 2 dependenceExpected spectrum B C N O Fe Mn F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Co Ni Charge Resolution 0.12 for B/C 0.20 for Sub-Fe/Fe

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 9 Silicon Charge Detector - Sensor 90.7mm 94.7mm Pixel area: × cm 2 Thickness: 500 µm Matrix: 8 × 8 pixels Active area: 9.07 × 9.07 cm 2 Full area: 9.47 × 9.47 cm 2 Full depletion voltage: < 20V Breakdown voltage: > 200V Dark current per pixel: < ~ 1nA Junction capacitance per pixel : ~ 25pF Guard rings 80µm 2000µm Edge structure From SINTEF - Norway CV Characteristics IV 25 °C

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 10 Silicon Charge Detector - Sensor Leakage current distribution in a sensor Example 25 °C Channel #6: High leakage current Example 01 Leakage current Stability test (a half day)

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 11 Silicon Charge Detector - Electronics Front-end ASIC · Large dynamic range (~1000 MIP) · Low-noise : 0.13 MIP (Board level) · Low-power consumption : 1W · Number of channels : 128 · 16bit ADC · Peaking Time: 2  s · Gain Distribution: 3.4 ± 0.2 ADU/1fC Linearity within±1% Fe Gain Curve(VAB16 CHAN0) TH 2.0usGain Residual (VAB16 CHAN0)

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 12 Silicon Charge Detector – Basic Detector Module X-Z view Sensor 1 Sensor 2 Front-end Board Y-Z view Distance: 4mm Ladder : with 12 sensors (Active length cm) Overlap : 8.0 mm Including 2.0 mm width guard-ring and edge structure from each sensor Full overlap for incident tracks at angles up to 45 degrees Basic module: one pair of aligned sensors + front-end (VAB) board

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 13 Silicon Charge Detector – Array Array Active area : 516 mm x 516mm Total Channel : 4608 Total Weight: 60kg Total Power : 120W System Temperature: °C Material Radiation Length: < 20% X 0

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 14 Silicon Charge Detector – Test Module LAC MATRIX 00,01 MATRIX 02,03 Strip x Strip y LAC MATRIX 00,01 MATRIX 02,03

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 15 Most probable S/N ~ 6.7 Ped Sigma 3.09 Langaus MP Cosmic Muon Test – S/N Entries: Trigger Shadow Pulse-height Correlation Chan to Chan Hit Correlation

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 16 Cosmic Muon Test – Efficiency Efficiency Check (Sensor + Electronics) Event selection 1) Vertical Entry only 2) the other 3 sensors pulse height> 5 sigma_ped SENSOR ±0.06 % SENSOR ±0.13 % SENSOR ±0.17 % SENSOR ±0.14 %

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors 17 1 Sensor2 Sensors3 Sensors4 Sensors Gsigma Ratio Expected Ratio Cosmic Muon Test – dE/dx multiple measurements Charge Resolution can be improved by using the average pulseh from different layers.

Meyoung Kim 30 September - 2 October 2009, Florence, Italy RD th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors Design Sensor Production Expected Schedule System Space qualification Assembly CALET IT & T bCALET-3 (1/4 scale of CALET) From Brazil To Australia CALET-POLAR Long Duration Flight Svalbard