Charge Collection in CVD Diamond

R. KassDPF Santa Cruz 24

R. Kass 26

Radiation Damage - Basics

Charge trapping the only relevant radiation damage effect NIEL scaling questionable a priori

Egap in diamond 5 times larger than in Si

Many processes freeze out

Typical emission times order of months

Like Si at 300/5 = 60 K – Boltzmann factor

A rich source of effects and (experimental) surprises !

Radiation induced effect

DiamondOperational consequence

SiliconOperational consequence

Leakage current

small &

decreasesnone

I/V = αΦ

α ~ 4x10-17 A/cm

Heating

Thermal runaway

Space charge ~ none noneΔNeff ≈ -βΦ

β ~ 0.015 cm-1

Increase of full depletion

voltage

Charge trapping

YesCharge loss

Polarization

1/τeff = βΦ

β ~ 5-7x10-16 cm2/ns

Charge loss

Polarization

t

thttteff

vPN

)1(1

DPF Santa Cruz

Summary of RD42 Test Beam Resultsfor CVD Diamond

R. KassDPF Santa Cruz 27

Particle Energy Relative k

p 24GeV 1.0

800MeV 1.6-1.8

70MeV 2.5-2.8

25MeV 4.0-5.0

π 200MeV 2.5-3.0

k is relative damage constant