Performance of THGEM as a Neutron Detector
Chapter One
Gas Quenching
Gas quenching is one of the most important factors that control gaseous detectors. The gas mixture that contains the ionization event consists of gas atoms as a main source of electrons and gas molecules that has a large cross sections for excitation and vibration states to cool the electrons' energy to the non-ionizing mode modes, such a process is called gas quenching. Consequently, a higher electric fields required to get a higher gain.<ref name="Sharma"> A.Sharma,F. Sauli, first tawsend coefficients measurements for argon gas european organization for nuclear research (1993) </ref >
Gas quenching experimentally can be measured by evaluating Townsend fist coefficient A,B for different gas mixtures. the following table represents the Townsend first coefficient values for different ratio of Ar/CO2 gas mixtures:<ref name="Sharma"/>
| Percentage of CO2 | 3.7 | 22.8 | 87.2 | 100 |
| A | 5.04 | 221.1 | 158.3 | 145.1 |
| B | 90.82 | 207.6 | 291.8 | 318.2 |
| 16.2 | 21.6 | 32.9 | 36.4 |
The electric field pressure ratio in the last row is the upper limit of the reduced electric field which Townsend's equation fits and the electric field is uniform for these measurements.
References
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