X-ray absorption in a GEM:

Production of X-ray X-ray absorbsion in GEM detectorsCalculation of Charge – up effectCalibration of single GEM

Yalçın KALKANUludağ University Physics Department

Bursa -TURKEY

23-11-2011, RD51 miniweek

Production of X-ray

Wavelength of X-ray photon ≈ 1.541 A

Energy of X-ray photon ≈ 8 keV

Energy of X-ray photon

DriftArea

• Gas Atoms

GEM Sheet

• Crom Layers• Copper Layers• Polyimide

İnduction,Area • Gas Atoms

Absorption

Expanential Absorption

Absorption of Gas Atoms

44.009 g/mol

39.948 g/mol

1 Atm

R = T = 295

Attenuation Coefficient of Argon

Attenuation Coefficient of Carbondioxide

Absorption of Unit Distance

0.176 1/cm

Drift AreaZ = 0.3 cm

İn HoleZ = 0.006 cm

İnduction AreaZ = 0.2 cm

Absorption of Copper Layer

Absorption of Crom Layer

Absorption of Polyimide (Pmda oda)

(www.beyochem.com)

Charge-Up Effect

(Garfield ++)(low Voltage)

(High Voltage)

Charge-up Effect (Bulk)

Bulk Resistivity

Polyimide

Bulk Resistance

Capacitance

Relaxation Time

Charge-up Effect (Surface)

Surface Resistivity

Polyimide

Surface Resistance

Capacitance

Relaxation Time

For cm2 area (5900 holes)

Calibration of Single GEM

Acknowledgements

Rob Veenhof, Leszek Ropelewski - RD51,İlhan TAPAN, Özkan Şahin, Mythra Varun Nemallapudi,Laura Franconi,Turkish Atomic Energy Authority.