Performance of a CCD tracker at room temperature

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Performance of a CCD tracker at room temperature

• T. Tsukamoto (Saga Univ.)

T. Kuniya, H. Watanabe (Saga Univ.) A. Miyamoto,
Y. Sugimoto (KEK) S. Takahashi, N.Tamura
(Niigata Univ.) K. Abe, T. Nagamine, Y.
Shirasaki (Tohoku Univ.) T. Aso (Toyama National
College of Maritime Technology)
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Outline

• Introduction
• HPK CCD
• Experimental setup
• Response to charged particles
• S/N, detection efficiency, energy resolution
• Position resolution
• Comparison with EEV CCD
• Summary

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Advantage of CCD for tracking device

• Pixel detector
• unambiguous reconstruction/high granularity
• Thin ?extremely low capacitance
• less multiple scattering
• Serial readout
• small number of channels
• Continuously sensitive
• no intrinsic limitation as regards trig. rate
• Other RD
• driven by commercial interest (video) as well as
  X-ray astronomer, etc.

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Vertex detector application in future LC

• Low repetition rate 150Hz ? serial r/o
• Highly collimated jets ? pixel detector
• Backgrounds ? pixel detector

Operation at room temp. (0ºC) ? compact cooling
system

• to reduce material
• to keep mechanically stable
• to avoid interference with the beam monitor

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Hamamatsu (HPK) CCD

• Feature
• Full frame transfer type
• 2phase CCD
• MPP operation to reduce dark current
• Developed for scientific researches
• Low light level measurements (e.g.
  spectroscopy)
• X-ray astronomy

? How about MIP detection?
Application for high energy physics
especially at higher temperature
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Structure of CCD

• HPK S5466 Full Frame Transfer Type (2phase)

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MPP(Multi Pinned Phase) Operation
Inverted Operation in other words

• Holes are accumulated under Si/SiO2 interface.
• Thermal excitation of electrons is significantly
  suppressed.

? Reduction of the dark current by one
order of magnitude
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Specification

• CCD Hamamatsu S5466

• Driver Hamamatsu C5934-1010

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Experimental setup

• 4 layers
• to reduce random hits
• minimize multiple scatterings
• a special package w/ a hole
• CCD2 CCD3 as close as possible
• KEK PS T1 line
• 4 sec/cycle
• 2.0GeV, 1.0GeV, 0.5GeV (?)

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Setup

• Standard CCD

1.2mm Al2O3 behind the chip

• Special CCD w/ a hole

2nd layer
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Response to Charged Particles

• 2x2 clustering
• S/N

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S/N as a function of temperature

• 4sec readout cycle

• 1.3sec readout cycle

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Detection Inefficiency for MIP

• Detection inefficiency

assume Gaussian shape in the low energy side of
Landau
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Energy Resolution for MIP

• Energy resolution

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Position Resolution

• After the careful alignment...

• Position resolution

Two components seen
? can fit to double Gaussian
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Charge sharing ? Position resolution

• Charge sharing

As ratio
gets close to 1,
Position resolution
gets worse.
component increases
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Momemtum dependence of position resolution

• Position resolution as a function of p

• Fits well to the formula (multiple scattering)

Resolution ? 0.20 ? 0.01 pixel
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Intrinsic Resolution

• Assuming all the sensors have the same
  resolution,

• ?intrinsic 3.0?0.2?m (weighted ? w/ double
  Gaussian)
• ?intrinsic 3.6?0.2?m (RMS)

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EEV CCD

• CCD 02-06
• pixels 385(H)?578(V)
• pixel size 22?m?22?m
• active depth 20?m

• Two operation modes
• normal mode
• inverted mode MPP mode in HPK

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EEV normal mode v.s. inverted mode

• Dark current

Normal mode

• Suppression factor 25

Inverted mode
Ratio
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Comparison of the dark current

• HPK(MPP) vs EEV(inverted)

• Similar in mV EEV HPK?1.3
• But measured gain EEV HPK?0.5

Dark current in electrons for CCDs under our
study EEV HPK ? 2.5
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Summary

• MIPs are successfully detected using HPK CCD
• Operation at room temperature 0ºC
• S/N gt10 up to 5ºC
• efficiency very close to 100
• position resolution 3.0µm
• Comparison with EEV CCD
• Both MPP and inverted mode suppress the dark
  current by one order of magnitude

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Future prospects

• Tracking performance of EEV CCD will be examined
  in June.
• Radiation damage

• affects CTE(Charge Transfer Efficiency)
• CTE measurements are on-going.
• Irradiation with a strong 90Sr will take place in
  the near future.