SCT Lorentz Angle Measurement and the 1 st Collision ID Plots - - PowerPoint PPT Presentation

SCT Lorentz Angle Measurement and the 1st Collision ID Plots

Reisaburo TANAKA ATLAS-LAL Meeting

• Dec. 17, 2009

2009.12.17 SCT Lorentz angle measurement

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ATL-COM-INDET-2009-039

Outline

• 1. SCT Digitization Model
• 2. Lorentz (Hall) Angle Measurement
• 3. Under-depleted Detector
• 4. ID Plots with the 1st Collision Data
• 5. After Irradiation
• 6. Summary

2009.12.17 SCT Lorentz angle measurement

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• 1. SCT Digitization Model

ATLAS Inner Detector

内部飛跡検出器

SCT Barrel 2T Solenoid Field

2009.12.17

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SCT

 4 barrel, 2x9 disk endcaps, |η|<2.5  2112 barrel SCT modules  80µm strip pitch, 768 strip daisy-chain  2x2 sensors with 40mrad stereo angle

SCT Digitization

2009.12.17 SCT Lorentz angle measurement Readout Amp Al strip SiO2 p implant n bulk MIP Landau-Vavilov distribution MPV(Median)=72(108) e-h pair/micron → Q=3.28(4.92) fC Reverse bias voltage Radiation damage

• n sensor

Crystal damage

SCT p-in-n (Pixel n-in-n)

Type inversion of bulk material n→p Depletion Drift Diffusion Capacitance Radiation damage

• n ABCD3T (DMILL)

Electric noise Trim DAC range/step Threshold non-uniformity Gain drop

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Strip gap 80µm Depth 285µm

150V

Threshold 1 fC

Ramo (weighting) potential and induced current

2009.12.17 SCT Lorentz angle measurement

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A B C D

e e h h

 V. Radeka, “Low Noise Techniques in Detectors,” Ann.Rev.Nucl.Part.Sci.38 (1988) 217-277.  H. Spieler ”Semiconductor Detector Systems,” Oxford Univ Press, 2005.

• H. Spieler

SCT (p-in-n) electron and hole drift in strip detector Strip detector signal for n-bulk device

VD=60V, Vbias=90V

(Pixel n-in-n) SCT p-in-n

Hole dominates Electron dominates

Total charge is the same.

Lorentz (Hall) angle model

2009.12.17

tanθL = µHB = rµdB µH : Hall mobility r : Hall factor ≈1 µd = vs /E c 1+ E /Ec

( )

β

[ ]

1/ β (drift mobility)

Parametrization:

• C. Jacoboni et al., Solid-State Electronics 20 (1977) 77-89.
• T. Lari, ATL-INDET-2001-004

Implemented into SCT Digitization S.Gadomski, ATL-SOFT-2001-005

Valid for T>250K, E along <111> crystallographic direction

ATL-INDET-2001-004

SCT Lorentz angle measurement

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Electrons (n-in-n) Holes (p-in-n)

Bias voltage dependence

2009.12.17

ATL-INDET-2001-004

∂θL V,T

( )

∂V

150V ,273K

≈ −0.005 /V

tanθL = µHB = rµdB µd = vs /E c 1+ E /Ec

( )

β

[ ]

1/ β (drift mobility)

drift velocity saturation at high electric field → drop of "mobility” =v/E → drop of Lorentz angle

T.Lari PhD thesis 150V 450V 150V 450V

SCT Lorentz angle measurement

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Doping and Temperature dependence

 LHC is not supposed to give effects

• n mobility due to doping concentration

increase by radiation. 1012 cm-3 at the beginning of LHC.  Mobility depends on temperature.

2009.12.17 SCT Lorentz angle measurement

∂θL V,T

( )

∂T

150V ,273K

≈ −0.027 /K

tanθL = µHB = rµdB µd = vs /E c 1+ E /Ec

( )

β

[ ]

1/ β (drift mobility) T.Lari PhD thesis

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• 2. Lorentz (Hall) Angle Measurement

θ: incidence angle d: cluster size θL: Lorentz (Hall) angle a: depletion depth b: minimum cluster size σ: charge career diffusion

Lorentz Angle

2009.12.17

d = atanθ −tanθL + b

( θL=0 when B=0)

Cosmic ray Cosmic ray SCT Barrel

SCT Lorentz angle measurement

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x y SCT module Incident particle Cluster Local incidence angle

Cosmic rays can traverse SCT module with large incidence angle.

θL θ

σ a d B

Incidence angle vs <cluster> width

2009.12.17 SCT Lorentz angle measurement

Charge sharing #strip(30°,60°,70°)=2.1,6.2,9.8 Q=1.0fC@90° incidence angle (80µm cross)

13 ?

Wide range plot

2009.12.17 SCT Lorentz angle measurement

atanθ − tanθL + b

( ) ⊗ Gauss(θ)

= atan ′ θ − tanθL + b

( )

1 2πσ exp − θ − ′ θ

( )

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2σ 2         d ′ θ

θ −5σ θ +5σ

∫

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B=2T B=0T <cluster>_min 1.134 ± 0.004 1.135 ± 0.006 Lorentz Angle -3.93 ± 0.03° 0.05 ± 0.05° Model prediction θL=-3.69 ± 0.26(syst.)°

2009.12.17 SCT Lorentz angle measurement

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Systematics Checks  Lorentz angle fitting range  Upper/Lower half of SCT barrel  Axial/Stereo modules  Positive/Negative tracks  Different run period  Module bow effect → No major effects seen

Bias voltage dependence

2009.12.17

Nominal bias voltage at 150V

SCT Lorentz angle measurement

∂θL V,T

( )

∂V

150V ,273K

≈ −0.005 /V

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SCT barrel module temperature

2009.12.17 SCT Lorentz angle measurement

Graham Beck SCT Software Meeting, Jan. 15, 2009 2008 running Hybrid <T>=+8.67℃ Sensor <T>=+5.0±1.0℃

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Temperature dependence

2009.12.17

Bias voltage at 150V

SCT Lorentz angle measurement

∂θL V,T

( )

∂T

150V ,273K

≈ −0.027 /K

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2009.12.17

Normalized at 150V, 273K. Straight line is the model prediction.

SCT Lorentz angle measurement

Magnetic field dependence

tanθL = µHB = rµdB

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Magnetic field dependence

2009.12.17 SCT Lorentz angle measurement

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Solenoidal field drops by -1.5% at the edge of barrel SCT

• 3. Under-depleted Detector

09.12.17

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Field Strength in the bulk

flat diode model uniform field model

• T. Kondo (KEK) 2009.11.27

SCT Operation with beam 1) "Super safe" : Barrel 5 V, Endcaps 20V 2) "Standby" : Barrel 20 V, Endcaps 20V … still efficiency~80%@1fC Thr. ! 3) "ON" : Barrel 150 V, Endcaps 150V VD = 64.8 ± 9.5V NIM A578 (2007)98-118.

TCAD simulation

Mathieu Benoit (LAL), Preliminary result.

2009.12.17 SCT Lorentz angle measurement

p-implant n-bulk

2250 6600 4425 2807 5263 7719

θL=4.15° θL=4.0° θL=4.6° θL=4.5° θL=3.8° θL=3.6°

−Ey = VB + VD d − 2VD d2 d − y

( )

Uniform flat diode model Current model agrees with exact calculation θL within 5% (syst. err.). <60µm from p-implant complicated. Note E-profile change after irradiation (type inversion).

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SCT bias voltage scan

2009.12.17 SCT Lorentz angle measurement

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Elias Coniavitis, Preliminary

SCT depletion depth measurement via Lorentz angle slope

2009.12.17 SCT Lorentz angle measurement

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θL θ

σ a d B

Depletion depth ! a ∝ √Vbias

PDG2009

• 28. Particle Detectors

partial depletion full depletion Why data are not pointing towards the origin ?

Without Gauss. Conv. With Gauss. Conv.

Elias Coniavitis, Preliminary

• 4. ID Plots with the 1st Collision Data

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2009.12.17 SCT Lorentz angle measurement

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Lorentz angle with collision data

2009.12.17 SCT Lorentz angle measurement

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Pixel SCT

θL ≅ +12 degrees θL ≅ -4 degrees

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> 700 dead strips in Disk 2

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2009.12.17 SCT Lorentz angle measurement

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2009.12.17 SCT Lorentz angle measurement

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• 5. After Irradiation

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SCT Cooling TF, Taka Kondo

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SCT Cooling TF, Taka Kondo

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SCT Cooling TF, Taka Kondo

• 6. Summary

Lorentz (Hall) angle

 Lorentz angle is powerful tool to study the semiconductor detectors.  θL can be measured < 0.10° statistical precision.  Studied incidence angle, bias voltage, temperature, B dependence.

 Max. 20µm Lorentz shift but clearly visible.

 Data agree with the model which is put in SCT digitization.

 Needs further investigation for under-depleted detector.

To do lists

 SCT Digitization Model Tuning (Lorentz angle, cluster width, timing)

• Parameter update as functions of bias voltage, sensor temperature

and dose of irradiation (important !).

• Effect of irradiation for SCT, Pixel (IBL, sLHC).

2009.12.17 SCT Lorentz angle measurement

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Back up

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2009.12.17

Min+-|fit range| fitting range

MC (-7°C,150V) Cosmic (5.0°C,150V)

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SCT bias voltage scan [30-300]V

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Elias Coniavitis, Preliminary