Performances of the Photo-Diode Detectors for the T/BCD in the ISS-CREAM Experiment

ISS-CREAM Experiment

ISS-­‐CREAM  InstrumentE.S.  Seo,  ICRC2013

• Cosmic rays follow a broken power law : one at ‘knee’ and one at ‘ankle’

• knee : galactic accelerators reach their energetic limits

• ankle : the galactic cosmic ray intensity falls below the intensity of cosmic rays from ultra high-energy (UHE) cosmic rays (Swordy, 2001)

• The ISS-CREAM instrument consists of a Silicon Charge Detector (SCD) to identify incident cosmic rays, a sampling tungsten/scintillator calorimeter for energy measurement of all nuclei, a segmented Top/Bottom Counting Detector (TCD and BCD) for e/p separation, and a Boronated Scintillator Detector (BSD) for additional e/p separation and detecting neutron signals

CREAM  Interface  Loca<on  on  JEM-­‐EF  (EFU2)

hCp://www.physics.utah.edu/~whanlon/spectrum.html

• ISS-CREAM (Cosmic Ray Energetics And Mass on the International Space Station experiment)

• planned for a launch to the ISS in Feb. 2015

• measure the energy spectral features from 1012 eV to > 1015 eV and composition that might be related to the supernova acceleration limit

• provide keys to understanding the origin, acceleration and propagation of cosmic rays

H.  J.  HYUN  (hjhyun@gmail.com)1,  T.  ANDERSON2,  D.  ANGELASZEK3,  J.  B.  BAE1,  

S.  J.  BAEK4,M.  COPLEY3,  S.  COUTU2,  J.  H.  HAN3,  H.  G.  HUH3,  Y.  S.  HWANG1,  D.  H.  KAH1,  K.  H.  KANG1,  H.  J.  KIM1,  K.  C.  KIM3,  

K.  KWASHNAK3,  J.  LEE4,  M.  H.  LEE3,  J.  T.  LINK5,6,  L.  LUTZ3,  J.  W.  MITCHELL5,  S.  NUTTER7,  O.  OFOHA3,  

H.  PARK1,  I.  H.  PARK4,  J.  M.  PARK1,  P.  PATTERSON3,  E.  S.  SEO3,  J.  WU3,  Y.  S.  YOON3

1  Kyungpook  NaSonal  University,  Daegu  702-­‐701,  South  Korea  2  Pennsylvania  State  University,  University  Park,  PA  16802,  USA3  University  of  Maryland,  College  Park,  MD  20740,  USA4  Sungkyunkwan  University,  Suwon  440-­‐746,  South  Korea  5  NASA  GSFC,  Greenbelt,  MD  20771,  USA  6  CRESST(USRA),  Columbia,  MD  21044,  USA7  Northern  Kentucky  University,  Highland  Heights,  KY41099,  USA

• Electron/proton separation for electron and gamma-ray physics ⇐ by using the difference between electromagnetic and hadronic showers

• Provide redundant trigger for ISS-CREAM calorimeter and MIP (Minimum Ionizing Particle) trigger for calibration

Schema<c  diagram  of  the  TCD  and  BCD

Photo-Diode Detectors, TCD and BCD

Opera<onal  principle  of  the  TCD  and  BCD

• The silicon photo-diode converts scintillation light to electric current, and electron-hole pairs are also produced by penetrating cosmic rays

• The charge signals are amplified by VLSI charge amp/hold circuits (VA-TA)

Exploded  view  of  the  (a)  TCD,  and  (b)  BCD

TCD

BCD

TCD BCD

Thickness of plastic scintillator (mm)

5 10

Number of PDs 400 400

Area covered by PDs (mm2)

500 × 500 600 × 600

Dimension (mm3) 901 × 551 × 30 951 × 651 × 33

Assembly  of  photo-­‐diodes  and  plas<c  scin<llator

Photograph  of  the  photo-­‐diodes  on  6-­‐inch  and  650  μm  thickness  silicon  wafer

Quantum  efficiency  

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60 ~ 75 % for the wavelength range

from 400 to 450 nm

• Silicon photo-diodes (PD) is fabricated on 6-inch, high resistivity, <100>, 650 μm thick, and n-type silicon wafers

• The real size of the PD is 2.3 × 2.3 cm2 with an active area of 2.0 × 2.0 cm2

• The PDs are fabricated at ETRI (Electronics and Telecommunications Research Institute) in Daejeon, Korea

Bulk  capacitance  (le\)  and  leakage  currents  (right)  of  the  photo-­‐diodes  as  a  func<on  of  the  reverse  bias  voltages

Silicon Photo-Diode

mean 8.47sigma 1.89 MPV 143

pedestal signal

Signal-­‐to-­‐noise  ra<o  measurement  result  by  using  cosmic  muons  and  coincidence  trigger

• Radiation hardness test using a 45 MeV proton beam • Exposed to 1.18 × 1011 protons/cm2 (> 5000 rad)• The leakage current is increased up to about 50 nA/

cm2 but the quality of the PD does not change in our criteria for the best sensor (<100 nA/cm2)

Thermal-Vacuum Test @ KARI+55 ℃+40 ℃

-20 ℃

-40 ℃

4 hrs

3 hrs

3 hrs

3 hrs

3 hrs

3 hrs

3 hrs 3 hrs

3 hrs 3 hrs

2 hrs

• Because there is a glitch in one of control signals, the detectors show the abnormal behavior such as not turned on at low temperature and this is debugged after the test

Vibration Test @ Keimyung Univ.

• During the test, the detectors are normally operated except for at low temperature

• Rigidity check by comparing distribution of resonant frequencies and by functionally operating before/after each test

• The detectors are normally operated during the test and there is no crack and no broken parts by visual inspection

SummaryandPlan

• The photo-diode detectors, TCD and BCD are developed for the ISS-CREAM experiment and are functionally well operated

• They are ready for integration and whole integrated ISS-CREAM instrument will be launched in Feb. 2015

TCD  in  Z-­‐axis  vibraSon  test BCD  in  X-­‐axis  vibraSon  test

TCD  and  BCD  in  thermal-­‐vacuum  chamber

Swept  Sine

Sine  Burst

Random  VibraSon

SignatureSineSweep

TCD  in  Z-­‐axis  random  vibra<on  test BCD  in  X-­‐axis  random  vibra<on  test