Reliability

The ATLAS on-detector electronics must operate for about ten years with little or no maintenance. This requires a careful evaluation of possible sources of failure and the consequences of those failures. We have started a study of failure modes based on techniques described in the literature[8], and plan to employ software tools such as BERT[9] to assess the MDT system reliability.

Possible radiation damage is a serious concern. A preliminary evaluation[2] indicated that the radiation levels would be sufficiently low that no special precautions would be required, however new information[10] suggests that in the first muon super-layer at there may be radiation levels high enough to damage standard CMOS ICs. If this proves to be true, there are several possible solutions:

• Rad-Hard process for IC's on front-end board. This is quite unattractive due to the additional cost and development effort.
• Remote mounting of electronics in high-radiation levels. Current data[10] shows that the dose falls off very rapidly with decreasing , so the channels in question could be mounted on cables a short distance from the end of the MDTs. Preliminary calculations show that this would not excessively degrade front-end performance.
• Periodic replacement of electronics in high-radiation areas.
• Rad-Tolerant processing for IC's on front-end board. It has been suggested[11] that the use of specially tailored design rules might significantly increase the radiation tolerance of standard CMOS.