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Diamond – Tungsten Calorimeter LCAL-group : K. Afanasiev, V. Drugakov, E. Kouznetsova, W. Lohmann, A. Stahl Workshop on Forward Calorimetry and Luminosity Measurement In the TESLA Detector 13-14 November 2002, DESY-Zeuthen

Diamond – Tungsten Calorimeter

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Diamond – Tungsten Calorimeter. LCAL-group : K. Afanasiev, V. Drugakov, E. Kouznetsova, W. Lohmann, A. Stahl. Workshop on Forward Calorimetry and Luminosity Measurement In the TESLA Detector 13-14 November 2002, DESY-Zeuthen. Location. Requirements. - PowerPoint PPT Presentation

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Page 1: Diamond – Tungsten Calorimeter

Diamond – TungstenCalorimeter

LCAL-group : K. Afanasiev, V. Drugakov,

E. Kouznetsova, W. Lohmann,

A. Stahl

Workshop on Forward Calorimetry and Luminosity Measurement

In the TESLA Detector13-14 November 2002, DESY-Zeuthen

Page 2: Diamond – Tungsten Calorimeter

Location

Requirements

• Detection and measurement of electrons and photons at small angles

• Fast beam diagnostic

• Improvement of the energy flow measurement in forward/backward direction

• Shielding of the inner part of the detector

Page 3: Diamond – Tungsten Calorimeter

Beam-beam Background

GUINEAPIG + BRAHMS( for √s = 500 GeV ) :

Per bunchcrossing :

• ~15000 e± hits• ~20 TeV of deposited energy

(R,)-distribution of the deposited energy:

High radiation resistivity is required

Two options for calorimeter technology :

Heavy scintillator

Diamond-tungsten sandwich

Page 4: Diamond – Tungsten Calorimeter

CVD DIAMONDproperties

 Silicon CVD-Diamond

Resistivity, ×cm 2.3×105 [b3] 1013-1016 [f]

Carrier density, cm-3 15×1010 [b3] <103 [b3]

Dielectric constant 11.9 [b3] 5.7 [f]

Capacity (1 cm2, 500 m), pF 35 17

Leakage current, pA/mm2 550 35

Breakdown field, V/cm 3×105 [b3] 107 [f]

     

Band gap, eV 1.12 [b3] 5.45 [f]

Cohesive energy, eV/atom 4.36 [b3] 7.37 [b2]

Energy/(e--h pair), eV 3.6 [b3] 13 [b3]

Mobility, cm2/(V×s)

e- 1350 [b3] 1800 [b3] - 2200 [f]

h 480 [b3] 1200 [b3] - 1600 [f]

Saturation velocity, ×107 cm/s

e- ~ 0.8 (?) 2.7 [b1]

h   1.0 [b1]

Saturation field Es, V/cm

e-

Es = f(L)1.24×104 [b1]

h 0.63×104 [b1]

     

Average e--h number per 100 m (for MIP)

9200 [b3] 3600 [b3]

Energy deposition per 100 m (for MIP), keV

40 50

Charge collection distance dc, m   60 - 250; dc = f(l)

Radiation length, cm 9.4 [Oh] 18.8[Oh]

Moliere radius, cm 5.28 12.31

Comparison to silicon :

Page 5: Diamond – Tungsten Calorimeter

CVD DIAMONDproperties

Radiation hardness :

www.desy.de/~ghodbane

Page 6: Diamond – Tungsten Calorimeter

Sandwich LCALgeometry

Tungsten absorber + Diamond sensor

RM ~ 1 cm

Z - Segmentation :

Tungsten 3.5 mm Layer = Diamond 0.5 mm

(R,) - Segmentation :

Page 7: Diamond – Tungsten Calorimeter

Sandwich LCALbackground

Average energy deposited in “bad” cells:

~ 7 GeV

Dose expected for “bad” cells :

~10 MGy/year

250 GeV e- + BG :

Page 8: Diamond – Tungsten Calorimeter

Sandwich LCALrecognition

Algorithm :

• “Suspected” cells : ECELL > 3 BG

reasonable z-location

• Requirement of longitudinal chain of such cells

Choice of a proper ADC :

sensor PA/discr ADC

reconstruction

Page 9: Diamond – Tungsten Calorimeter

Sandwich LCALrecognition

Efficiency vs radius :

Page 10: Diamond – Tungsten Calorimeter

Sandwich LCALrecognition

Energy resolution vs radius :

Page 11: Diamond – Tungsten Calorimeter

Sandwich LCALrecognition

Polar angle resolution vs radius :

Page 12: Diamond – Tungsten Calorimeter

Sandwich LCALRecognition

Calibration :

Averaged energy resolution :

Page 13: Diamond – Tungsten Calorimeter

Sandwich LCALRecognition

Averaged angular resolution :

Page 14: Diamond – Tungsten Calorimeter

Diamond/W LCALfollowing steps :

Real sensor test :to see mip-signal : ~1.5 fC

CONCLUSIONS

sandwich diamond-tungsten calorimeters seems to be a promising technology

high energetic e±, can be detected with reasonable efficiency even near the beam pipe

energy and angular resolution for diamond-tungsten are good

y = -2.3952x - 0.0672

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