Fermi National Laboratory

Operation Terminology


This experiment will test Chemical Vapor Deposition (CVD) diamond pixel detectors. Our research in this area began nearly a decade ago when we realized that CVD diamond is a promising, radiation-hard alternative to silicon. The tests will use slow resonantly extracted, Main Injector proton beam focused onto the MTest target. The tests require a beam of untagged, charged particles of energy approximately 80 GeV.

The most distinctive feature of diamond is its large band gap, 5.5 eV. This large band gap along with the associated large cohesive energy is responsible for much of the radiation hardness of diamond. The large band gap also makes diamond an excellent electrical insulator. As a result, a large electric field can be applied without producing significant leakage current. Thus, there is no need for a reverse biased pn-junction and the diamond detector functions much like a "solid-state" ionization chamber. Diamond has two additional properties that are favorable compared to silicon. Its smaller dielectric constant yields a smaller detector capacitance and, thereby, better noise performance of the associated front-end electronics. In addition, even though diamond is an electrical insulator, it is an excellent thermal conductor with a thermal conductivity exceeding that of copper by a factor of five. A common problem with large strip detector systems is the management of the thermal load generated by the large number of electronic channels used in the detector readout. The handling of this thermal load would be simplified if the detectors were constructed from diamond.

last modified 7/26/2002   email Fermilab
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